JP6456474B2 - Method for producing mixed negative electrode material for nonaqueous electrolyte secondary battery and mixed negative electrode material for nonaqueous electrolyte secondary battery obtained by the production method - Google Patents
Method for producing mixed negative electrode material for nonaqueous electrolyte secondary battery and mixed negative electrode material for nonaqueous electrolyte secondary battery obtained by the production method Download PDFInfo
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Description
本発明は、非水電解質二次電池用混合負極材料の製造方法及びその製造方法によって得られる非水電解質二次電池用混合負極材料に関する。本発明の混合負極材料によれば、エネルギー密度が高く、入出力特性に優れた非水電解質二次電池を提供することができる。 The present invention relates to a method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery and a mixed negative electrode material for a nonaqueous electrolyte secondary battery obtained by the method. According to the mixed negative electrode material of the present invention, a nonaqueous electrolyte secondary battery having high energy density and excellent input / output characteristics can be provided.
携帯電話やノートパソコンなどの小型携帯機器は高機能化が進み、その電源である二次電池の高エネルギー密度化が期待されている。高エネルギー密度の二次電池として、炭素質材料を負極として用いる非水溶媒系リチウム二次電池が提案されている(特許文献1)。 Small mobile devices such as mobile phones and laptop computers are becoming more sophisticated, and the secondary battery that is the power source is expected to have higher energy density. As a high energy density secondary battery, a non-aqueous solvent type lithium secondary battery using a carbonaceous material as a negative electrode has been proposed (Patent Document 1).
近年、環境問題への関心の高まりから、エネルギー密度が高く、出力特性の優れた大型の二次電池が、電気自動車へ搭載されつつある。例えば、モーターのみで駆動する電気自動車(EV)、内燃エンジンとモーターとを組み合わせたプラグインハイブリッド型電気自動車(PHEV)、又はハイブリッド型電気自動車(HEV)等の自動車用途での普及が期待されている。特に、非水溶媒系リチウム二次電池であるリチウムイオン二次電池は、高いエネルギー密度を有する二次電池として広く使用されており、EV用途において一回の充電での航続距離を延ばすため、一層の高エネルギー密度化及び入出力特性の改善が期待されている。 In recent years, due to increasing interest in environmental problems, large secondary batteries with high energy density and excellent output characteristics are being installed in electric vehicles. For example, it is expected to spread in automobile applications such as an electric vehicle (EV) driven only by a motor, a plug-in hybrid electric vehicle (PHEV) combining an internal combustion engine and a motor, or a hybrid electric vehicle (HEV). Yes. In particular, a lithium ion secondary battery that is a non-aqueous solvent type lithium secondary battery is widely used as a secondary battery having a high energy density, and in order to extend the cruising distance in one charge in EV applications, High energy density and improved input / output characteristics are expected.
本発明者らは、高いエネルギー密度及び優れた入出力特性を有する非水電解質二次電池について、鋭意研究し、難黒鉛化性炭素質材料、及び易黒鉛化性炭素質材料及び/又は黒鉛質材料を混合した炭素質材料を用いることにより、優れた入出力特性を示す非水電解質二次電池が得られることを見出した。すなわち、難黒鉛化性炭素質材料、及び易黒鉛化性炭素質材料及び/又は黒鉛質材料を混合した炭素質材料は、高い平均真密度を有している。従って、この混合した炭素質材料を負極活物質として用いた二次電池においては、高い体積当たりの入出力特性を得ることができる。しかしながら、本発明者らは、前記混合炭素質材料を用いた非水電解質二次電池について、研究する過程において、不可逆容量の増大、それによる直流抵抗(DC−R)の増大が起こることに気付いた。そして、この直流抵抗の増大は、入出力特性を低下させた。
従って、本発明の目的は、混合炭素質材料を用いる非水電解質二次電池において高エネルギー密度及び優れた入出力特性を有する非水電解質二次電池を提供することである。The present inventors have earnestly researched a non-aqueous electrolyte secondary battery having a high energy density and excellent input / output characteristics, and obtained a non-graphitizable carbonaceous material and a graphitizable carbonaceous material and / or a graphite. It has been found that a nonaqueous electrolyte secondary battery exhibiting excellent input / output characteristics can be obtained by using a carbonaceous material mixed with materials. That is, the non-graphitizable carbonaceous material and the carbonaceous material obtained by mixing the easily graphitizable carbonaceous material and / or the graphite material have a high average true density. Therefore, in the secondary battery using the mixed carbonaceous material as the negative electrode active material, high input / output characteristics per volume can be obtained. However, the present inventors have noticed that an increase in irreversible capacity and thereby an increase in DC resistance (DC-R) occur in the process of studying a non-aqueous electrolyte secondary battery using the mixed carbonaceous material. It was. And this increase in DC resistance deteriorated the input / output characteristics.
Accordingly, an object of the present invention is to provide a non-aqueous electrolyte secondary battery having high energy density and excellent input / output characteristics in a non-aqueous electrolyte secondary battery using a mixed carbonaceous material.
本発明者らは、炭素質材料について鋭意研究した結果、前記の不可逆容量の増大、及び直流抵抗(DC−R)の増大が、混合炭素質材料に含まれる難黒鉛質材料が保存中に吸湿することが原因であることを見出した。本発明者らは、更に研究を進め、驚くべきことに、特定の製造方法によって得られた難黒鉛化性炭素質材料が、水分の吸湿性が低いことを見出した(特願2014−039741号及び特願2014−039742号)。水分を吸湿した難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合した混合負極材料は、直流抵抗値が上昇した。すなわち、水分を吸湿した難黒鉛化性炭素質材料は、Li金属の析出が生じやすい易黒鉛化性炭素質材料及び/又は黒鉛質材料への負担を強いるものであった。しかしながら、本発明者らが見出した吸湿性の低い難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合した混合負極材料は、直流抵抗値が低下し、優れたエネルギー密度及び入出力特性を有することを見出した。すなわち、水分を吸湿した難黒鉛化性炭素質材料の直流抵抗値が抑制され、易黒鉛化性炭素質材料及び/又は黒鉛質材料の負担を軽減できるものであった。
本発明は、こうした知見に基づくものである。
従って、本発明は、
[1](1)難黒鉛化性炭素前駆体と揮発性有機物とを800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む非水電解質二次電池用混合負極材料の製造方法であって、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である、非水電解質二次電池用混合負極材料の製造方法、
[2]ラマンスペクトルにおいて観察される前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値が、175〜190cm−1の範囲にある、[1]に記載の非水電解質二次電池用混合負極材料の製造方法、
[3]ラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値が、230〜260cm−1の範囲にある、
[1]又は[2]に記載の非水電解質二次電池用混合負極材料の製造方法、
[4](1)比表面積100〜500m2/gの難黒鉛化性炭素前駆体と揮発性有機物との混合物を800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む非水電解質二次電池用混合負極材料の製造方法、
[5]広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、そして
窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にある、[4]に記載の非水電解質二次電池用混合負極材料の製造方法、
[6]前記難黒鉛化性炭素前駆体が植物由来である、[1]〜[5]のいずれかに記載の非水電解質二次電池用混合負極材料の製造方法、
[7]前記揮発性有機物が、常温で固体状態であり、そして残炭率が5重量%未満であって、前記残炭率は、前記揮発性有機物1gを、不活性ガス中で常温から10℃/分の昇温速度で800℃まで昇温した後、800℃で1時間灰化して得た残存物の重量と前記残存物の炭素含有率との積により定まる数値である、[1]〜[6]のいずれかに記載の非水電解質二次電池用混合負極材料の製造方法、
[8]前記[1]〜[7]のいずれかに記載の製造方法によって得ることのできる、非水電解質二次電池用混合負極材料、
[9]前記[8]に記載の混合負極材料を含む非水電解質二次電池用負極、及び
[10]前記[9]に記載の負極を含む、非水電解質二次電池、
に関する。
本明細書は、
[11]難黒鉛化性炭素質材料と易黒鉛化性炭素質材料及び/又は黒鉛質材料とを含む非水電解質二次電池用混合負極材料であって、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される難黒鉛化性炭素質材料の炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である、非水電解質二次電池用混合負極材料、
[12]ラマンスペクトルにおいて観察される前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値が、175〜190cm−1の範囲にある、[11]に記載の非水電解質二次電池用混合負極材料、
[13]ラマンスペクトルにおいて観察される前記難黒鉛化性炭素質材料の炭素前駆体の1360cm−1付近のピークの半値幅の値が、230〜260cm−1の範囲にある、[11]又は[12]に記載の非水電解質二次電池用混合負極材料、又は
[14]前記難黒鉛化性炭素質材料の炭素源が植物由来である、[11]〜[13]のいずれかに記載の非水電解質二次電池用混合負極材料、
を開示する。As a result of intensive studies on carbonaceous materials, the present inventors have found that the increase in the irreversible capacity and the increase in direct current resistance (DC-R) indicate that the hardly graphitic material contained in the mixed carbonaceous material absorbs moisture during storage. I found out that it was the cause. The present inventors have further researched and surprisingly found that the non-graphitizable carbonaceous material obtained by a specific production method has low moisture absorption (Japanese Patent Application No. 2014-039741). And Japanese Patent Application No. 2014-039742). The mixed negative electrode material obtained by mixing the non-graphitizable carbonaceous material that absorbs moisture with the graphitizable carbonaceous material and / or the graphite material has an increased DC resistance value. That is, the hardly graphitizable carbonaceous material that has absorbed moisture imposes a burden on the easily graphitizable carbonaceous material and / or the graphite material in which Li metal is likely to precipitate. However, the mixed negative electrode material obtained by mixing the non-graphitizable carbonaceous material having low hygroscopicity found by the present inventors with the graphitizable carbonaceous material and / or the graphitic material has a low DC resistance value. And found to have excellent energy density and input / output characteristics. That is, the direct current resistance value of the non-graphitizable carbonaceous material that has absorbed moisture is suppressed, and the burden on the graphitizable carbonaceous material and / or the graphite material can be reduced.
The present invention is based on these findings.
Therefore, the present invention
[1] (1) A step of firing a non-graphitizable carbon precursor and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a non-graphitizable carbonaceous material, and (2) the above-mentioned difficulty A method for producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery, comprising a step of mixing a graphitizable carbonaceous material with an easily graphitizable carbonaceous material and / or a graphite material, and comprising a wide-angle X-ray diffraction The average interplanar spacing d 002 of the (002) plane of the non-graphitizable carbonaceous material calculated using the Bragg equation in the method is in the range of 0.38 to 0.40 nm, and is determined by the nitrogen adsorption BET three-point method. The specific surface area of the non-graphitizable carbonaceous material is in the range of 1 to 10 m 2 / g, and the half-width of the peak near 1360 cm −1 of the non-graphitizable carbon precursor observed in the Raman spectrum. Value and the non-graphitizable carbonaceous material A method for producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery, wherein a difference from a half-width value of a peak near 1360 cm −1 of the material is 50 to 84 cm −1 ;
[2] The nonaqueous electrolyte according to [1], wherein the half-value width of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material observed in the Raman spectrum is in the range of 175 to 190 cm −1. Manufacturing method of mixed negative electrode material for secondary battery,
[3] The half-value width of the peak near 1360 cm −1 of the non-graphitizable carbon precursor observed in the Raman spectrum is in the range of 230 to 260 cm −1 .
[1] or [2], a method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery,
[4] (1) A mixture of a non-graphitizable carbon precursor having a specific surface area of 100 to 500 m 2 / g and a volatile organic substance is fired in an inert gas atmosphere at 800 to 1400 ° C. A mixed negative electrode material for a nonaqueous electrolyte secondary battery, comprising: a step of obtaining a material; and (2) a step of mixing the non-graphitizable carbonaceous material with the graphitizable carbonaceous material and / or the graphite material. Manufacturing method,
[5] is calculated using the Bragg equation at the wide-angle X-ray diffraction method, the average spacing d 002 of (002) plane of the flame graphitizable carbonaceous material is in the range of 0.38~0.40Nm, And manufacture of the mixed negative electrode material for nonaqueous electrolyte secondary batteries as described in [4] whose specific surface area of the said non-graphitizable carbonaceous material calculated | required by the nitrogen adsorption BET 3 point method exists in the range of 1-10 m < 2 > / g. Method,
[6] The method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery according to any one of [1] to [5], wherein the non-graphitizable carbon precursor is derived from a plant.
[7] The volatile organic substance is in a solid state at room temperature, and the residual carbon ratio is less than 5% by weight, and the residual carbon ratio is 10 to 10 grams of the volatile organic substance in an inert gas. It is a numerical value determined by the product of the weight of the residue obtained by heating to 800 ° C. at a rate of temperature increase of 800 ° C./min and then ashing at 800 ° C. for 1 hour, and the carbon content of the residue [1] A method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery according to any one of to [6],
[8] A mixed negative electrode material for a nonaqueous electrolyte secondary battery obtainable by the production method according to any one of [1] to [7],
[9] A negative electrode for a nonaqueous electrolyte secondary battery including the mixed negative electrode material according to [8], and [10] a nonaqueous electrolyte secondary battery including the negative electrode according to [9],
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[11] A mixed negative electrode material for a non-aqueous electrolyte secondary battery including a non-graphitizable carbonaceous material and an easily graphitizable carbonaceous material and / or a graphite material, wherein the Bragg formula is expressed by a wide-angle X-ray diffraction method. The non-graphitizable carbonaceous material calculated by using the non-graphitizable carbonaceous material having an average interplanar spacing d 002 of (002) plane in the range of 0.38 to 0.40 nm and determined by a nitrogen adsorption BET three-point method. The half-width value of the peak near 1360 cm −1 of the carbon precursor of the non-graphitizable carbonaceous material observed in the Raman spectrum, wherein the specific surface area of the carbonaceous material is in the range of 1 to 10 m 2 / g A mixed negative electrode material for a non-aqueous electrolyte secondary battery, wherein a difference from a half-width value of a peak near 1360 cm −1 of the non-graphitizable carbonaceous material is 50 to 84 cm −1 ,
[12] The nonaqueous electrolyte according to [11], wherein the half-value width of a peak near 1360 cm −1 of the non-graphitizable carbonaceous material observed in the Raman spectrum is in the range of 175 to 190 cm −1. Mixed negative electrode materials for secondary batteries,
[13] The value of the half width of the peak near 1360 cm −1 of the carbon precursor of the non-graphitizable carbonaceous material observed in the Raman spectrum is in the range of 230 to 260 cm −1 [11] or [ [12] The mixed negative electrode material for a non-aqueous electrolyte secondary battery according to [12] or [14] the carbon source of the non-graphitizable carbonaceous material according to any one of [11] to [13] Mixed negative electrode material for non-aqueous electrolyte secondary battery,
Is disclosed.
本発明の混合負極材料を用いた非水電解質二次電池は、従来の難黒鉛化性炭素質材料を含む混合負極材料を用いた非水電解質二次電池と比較して、保存後であっても不可逆容量が小さく、従って直流抵抗値が低い。すなわち、本発明の混合負極材料を用いた非水電解質二次電池は、優れたエネルギー密度及び入出力特性を示す。換言すると、本発明の混合負極材料は、優れた保存特性を有しており、粉体での保存又は電極作成後の保存後に、二次電池を作製した場合であっても、不可逆容量の上昇及び直流抵抗値の上昇が見られない。すなわち、本発明の混合負極材料は、Li金属の析出が生じやすい易黒鉛化性炭素質材料及び/又は黒鉛質材料への負担を軽減できるものである。
また、本発明の混合負極材料によれば、難黒鉛化性炭素質材料のみを用いた負極を含む非水電解質二次電池と比較して優れたエネルギー密度及び入出力特性を示す。また、易黒鉛化性炭素質材料又は黒鉛質材料のみを用いた負極を含む非水電解質二次電池と比較して、優れたサイクル特性を示す。The non-aqueous electrolyte secondary battery using the mixed negative electrode material of the present invention is after storage as compared with a non-aqueous electrolyte secondary battery using a mixed negative electrode material containing a conventional non-graphitizable carbonaceous material. However, the irreversible capacity is small and the DC resistance value is low. That is, the nonaqueous electrolyte secondary battery using the mixed negative electrode material of the present invention exhibits excellent energy density and input / output characteristics. In other words, the mixed negative electrode material of the present invention has excellent storage characteristics, and the increase in irreversible capacity even when a secondary battery is manufactured after storage in powder or storage after electrode preparation. No increase in DC resistance is observed. That is, the mixed negative electrode material of the present invention can reduce the burden on the graphitizable carbonaceous material and / or the graphitic material in which Li metal is likely to precipitate.
Moreover, according to the mixed negative electrode material of this invention, the energy density and input-output characteristic which were excellent compared with the nonaqueous electrolyte secondary battery containing the negative electrode using only a non-graphitizable carbonaceous material are shown. In addition, it exhibits excellent cycle characteristics as compared with a non-aqueous electrolyte secondary battery including a negative electrode using only a graphitizable carbonaceous material or a graphite material.
[1]非水電解質二次電池用混合負極材料の製造方法
本発明の非水電解質二次電池用混合負極材料の製造方法は、(1)難黒鉛化性炭素前駆体と揮発性有機物とを800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む非水電解質二次電池用混合負極材料の製造方法であって、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である製造方法(以下、本発明の「非水電解質二次電池用混合負極材料の製造方法(A)」と称することがある)であってもよい。
また、本発明の非水電解質二次電池用混合負極材料の製造方法は、(1)比表面積100〜500m2/gの難黒鉛化性炭素前駆体と揮発性有機物との混合物を800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む製造方法(以下、本発明の「非水電解質二次電池用混合負極材料の製造方法(B)」と称することがある)であってもよい。
以下に、非水電解質二次電池用混合負極材料の製造方法(A)を説明し、続いて非水電解質二次電池用混合負極材料の製造方法(B)を説明する。[1] Method for producing mixed negative electrode material for nonaqueous electrolyte secondary battery The method for producing a mixed negative electrode material for nonaqueous electrolyte secondary battery according to the present invention comprises (1) a non-graphitizable carbon precursor and a volatile organic substance. A step of obtaining a non-graphitizable carbonaceous material by firing in an inert gas atmosphere at 800 to 1400 ° C., and (2) the non-graphitizable carbonaceous material, the graphitizable carbonaceous material and / or graphite. And a non-graphitizable carbonaceous material calculated using the Bragg equation in a wide-angle X-ray diffraction method. The (002) plane average plane distance d 002 is in the range of 0.38 to 0.40 nm, and the specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is 1 to 10 m 2 / g. And is observed in the Raman spectrum The value of the half width of the peak in the vicinity of the flame-graphitizable carbon precursor 1360 cm -1, which is the difference between the value of the half width of the peak around 1360 cm -1 of the flame graphitizable carbonaceous material is 50~84cm -1 (hereinafter may be referred to as “manufacturing method (A) of mixed negative electrode material for nonaqueous electrolyte secondary battery” of the present invention) of the present invention).
Moreover, the manufacturing method of the mixed negative electrode material for nonaqueous electrolyte secondary batteries of this invention is (800) 1400. The mixture of the non-graphitizable carbon precursor and volatile organic substance with a specific surface area of 100-500 m < 2 > / g. A step of obtaining a non-graphitizable carbonaceous material by firing in an inert gas atmosphere at 0 ° C., and (2) the non-graphitizable carbonaceous material, the graphitizable carbonaceous material and / or the graphitic material, (Hereinafter, may be referred to as “a method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery (B)” of the present invention).
Below, the manufacturing method (A) of the mixed negative electrode material for nonaqueous electrolyte secondary batteries is demonstrated, and the manufacturing method (B) of the mixed negative electrode material for nonaqueous electrolyte secondary batteries is demonstrated.
(1−1)非水電解質二次電池用混合負極材料の製造方法(A)
《焼成工程(1)》
焼成工程(1)においては、難黒鉛化性炭素前駆体と揮発性有機物とを800〜1400℃の不活性ガス雰囲気下で焼成する。(1-1) Method for producing mixed negative electrode material for nonaqueous electrolyte secondary battery (A)
<< Baking process (1) >>
In the firing step (1), the non-graphitizable carbon precursor and the volatile organic material are fired in an inert gas atmosphere at 800 to 1400 ° C.
《難黒鉛化性炭素前駆体》
(炭素源)
難黒鉛化性炭素前駆体は、難黒鉛化性炭素質材料を製造する際に炭素成分を供給する難黒鉛化性炭素質材料の前駆体であり、植物由来の炭素材(以下、「植物由来のチャー」と称することがある)を原料に用いて製造することができる。なお、チャーとは、一般的には、石炭を加熱した際に得られる溶融軟化しない炭素分に富む粉末状の固体を示すが、ここでは有機物を加熱して得られる溶融軟化しない炭素分に富む粉末状の固体も示す。<Non-graphitizable carbon precursor>
(Carbon source)
A non-graphitizable carbon precursor is a precursor of a non-graphitizable carbonaceous material that supplies a carbon component when producing a non-graphitizable carbonaceous material. Can be used as a raw material. In addition, char generally indicates a powder-like solid rich in carbon that is not melt-softened, which is obtained when coal is heated, but here it is rich in carbon that is not melt-softened obtained by heating organic matter. Also shown is a powdered solid.
植物由来のチャーの原料となる植物(以下、「植物原料」と称することがある)には、特に制限はない。例えば、椰子殻、珈琲豆、茶葉、サトウキビ、果実(例えば、みかん、バナナ)、藁、・殻、広葉樹、針葉樹、竹を例示できる。この例示は、本来の用途に供した後の廃棄物(例えば、使用済みの茶葉)、あるいは植物原料の一部(例えば、バナナやみかんの皮)を包含する。これらの植物は、単独で又は2種以上組み合わせて使用することができる。これらの植物の中でも、大量入手が容易な椰子殻が好ましい。 There are no particular restrictions on the plant (hereinafter sometimes referred to as “plant material”) that is the raw material for plant-derived char. For example, coconut husks, coconut beans, tea leaves, sugar cane, fruits (for example, mandarin oranges, bananas), cocoons, shells, hardwoods, conifers, and bamboo can be exemplified. Examples of this include waste (for example, used tea leaves) after being used for the original use, or part of plant materials (for example, bananas and tangerine peels). These plants can be used alone or in combination of two or more. Among these plants, coconut shells that are easily available in large quantities are preferred.
椰子殻としては、特に限定されるものではなく、例えばパームヤシ(アブラヤシ)、ココヤシ、サラク、オオミヤシの椰子殻を挙げることができる。これらの椰子殻は、単独又は組み合わせて使用することができる。食品、洗剤原料、バイオディーゼル油原料等として利用され、大量に発生するバイオマス廃棄物である、ココヤシ及びパームヤシの椰子殻が特に好ましい。 The coconut shell is not particularly limited, and examples thereof include palm palm (oil palm), coconut palm, salak, and palm palm. These coconut shells can be used alone or in combination. Coconut palm and palm palm coconut shells, which are biomass wastes used as foods, detergent raw materials, biodiesel oil raw materials and the like and generated in large quantities, are particularly preferable.
植物原料からチャーを製造する方法は特に限定されるものではないが、例えば植物原料を、300℃以上の不活性ガス雰囲気下で、熱処理(以下、「仮焼成」と称することがある)することによって製造することができる。また、チャー(例えば、椰子殻チャー)の形態で入手することも可能である。 The method for producing char from the plant raw material is not particularly limited. For example, the plant raw material is heat-treated (hereinafter sometimes referred to as “temporary firing”) in an inert gas atmosphere of 300 ° C. or higher. Can be manufactured by. It can also be obtained in the form of char (eg, coconut shell char).
(脱灰)
植物由来のチャーから製造された難黒鉛化性炭素質材料は、多量の活物質をドープ可能であることから、非水電解質二次電池の負極材料として基本的には適している。しかし、植物由来のチャーには、植物に含まれていた金属元素が多く含有されている。例えば、椰子殻チャーでは、カリウムを0.3%程度、鉄元素を0.1%程度含んでいる。このような金属元素を多く含んだ難黒鉛化性炭素質材料を負極として用いると、非水電解質二次電池の電気化学的な特性や安全性に好ましくない影響を与えることがある。(Decalcification)
The non-graphitizable carbonaceous material produced from plant-derived char can be doped with a large amount of active material, and thus is basically suitable as a negative electrode material for non-aqueous electrolyte secondary batteries. However, plant-derived char contains a large amount of metal elements contained in plants. For example, coconut shell char contains about 0.3% potassium and about 0.1% iron element. If such a non-graphitizable carbonaceous material containing a lot of metal elements is used as the negative electrode, it may adversely affect the electrochemical characteristics and safety of the non-aqueous electrolyte secondary battery.
また、植物由来のチャーは、カリウム以外のアルカリ金属(例えば、ナトリウム)、アルカリ土類金属(例えば、マグネシウム、カルシウム)、遷移金属(例えば、鉄、銅)及びその他の金属類も含んでいる。難黒鉛化性炭素質材料がこれらの金属類を含むと、非水電解質二次電池の負極からの脱ドープ時に不純物が電解液中に溶出し、電池性能に好ましくない影響を与え、安全性を害する可能性がある。 The plant-derived char also contains alkali metals other than potassium (for example, sodium), alkaline earth metals (for example, magnesium, calcium), transition metals (for example, iron, copper), and other metals. If the non-graphitizable carbonaceous material contains these metals, impurities will elute into the electrolyte during de-doping from the negative electrode of the non-aqueous electrolyte secondary battery, adversely affecting the battery performance and improving safety. There is a possibility of harm.
更に、本発明者等の検討により、灰分により難黒鉛化性炭素質材料の細孔が閉塞され、電池の充放電容量に悪影響を及ぼすことがあると確認されている。 Furthermore, it has been confirmed by the inventors that the pores of the non-graphitizable carbonaceous material are blocked by ash, which may adversely affect the charge / discharge capacity of the battery.
従って、植物由来のチャーに含まれているこのような灰分(アルカリ金属、アルカリ土類金属、遷移金属、及びその他の元素類)は、難黒鉛化性炭素質材料を得るために焼成する前に、脱灰処理によって灰分を減少させておくことが望ましい。脱灰方法は特に制限されないが、例えば塩酸、硫酸等の鉱酸、酢酸、蟻酸等の有機酸等を含む酸性水を用いて金属分を抽出脱灰する方法(液相脱灰)、塩化水素などのハロゲン化合物を含有した高温の気相に暴露させて脱灰する方法(気相脱灰)を用いることができる。適用する脱灰方法を限定する趣旨ではないが、以下では、脱灰後に乾燥処理の必要が無い点で好ましい気相脱灰について説明する。 Therefore, such ash (alkali metal, alkaline earth metal, transition metal, and other elements) contained in plant-derived char must be baked to obtain a non-graphitizable carbonaceous material. It is desirable to reduce the ash content by deashing treatment. The deashing method is not particularly limited. For example, a method (liquid phase deashing) in which a metal component is extracted and deashed using acid water containing a mineral acid such as hydrochloric acid or sulfuric acid, or an organic acid such as acetic acid or formic acid, hydrogen chloride A method of deashing by exposing to a high temperature gas phase containing a halogen compound such as (gas phase deashing) can be used. Although not intended to limit the deashing method to be applied, gas phase deashing that is preferable in that no drying process is required after deashing will be described below.
気相脱灰としては、植物由来のチャーを、ハロゲン化合物を含む気相中で熱処理することが好ましい。ハロゲン化合物は特に制限されないが、例えば、フッ素、塩素、臭素、ヨウ素、フッ化水素、塩化水素、臭化水素、フッ化塩素(ClF)、塩化ヨウ素(ICl)、臭化ヨウ素(IBr)、塩化臭素(BrCl)等を挙げることができる。熱分解によりこれらのハロゲン化合物を発生する化合物、又はこれらの混合物を用いることもできる。好ましくは塩化水素である。 As the gas phase decalcification, it is preferable to heat-treat the plant-derived char in a gas phase containing a halogen compound. The halogen compound is not particularly limited, and examples thereof include fluorine, chlorine, bromine, iodine, hydrogen fluoride, hydrogen chloride, hydrogen bromide, chlorine fluoride (ClF), iodine chloride (ICl), iodine bromide (IBr), and chloride. Examples include bromine (BrCl). A compound that generates these halogen compounds by thermal decomposition, or a mixture thereof can also be used. Hydrogen chloride is preferred.
気相脱灰は、ハロゲン化合物と不活性ガスとを混合して使用してもよい。不活性ガスは、植物由来のチャーを構成する炭素成分と反応しないガスであれば特に制限されない。例えば、窒素、ヘリウム、アルゴン、クリプトン、又はそれらの混合ガスを挙げることができる。好ましくは窒素である。 The vapor phase deashing may be used by mixing a halogen compound and an inert gas. The inert gas is not particularly limited as long as it is a gas that does not react with the carbon component constituting the plant-derived char. For example, nitrogen, helium, argon, krypton, or a mixed gas thereof can be given. Nitrogen is preferred.
気相脱灰において、ハロゲン化合物と不活性ガスとの混合比は、十分な脱灰が達成できる限り、限定されるものではないが、例えば不活性ガスに対するハロゲン化合物の量は0.01〜10.0体積%であり、好ましくは0.05〜8.0体積%であり、更に好ましくは0.1〜5.0体積%である。 In the gas phase deashing, the mixing ratio of the halogen compound and the inert gas is not limited as long as sufficient deashing can be achieved. For example, the amount of the halogen compound with respect to the inert gas is 0.01 to 10%. It is 0.0 volume%, Preferably it is 0.05-8.0 volume%, More preferably, it is 0.1-5.0 volume%.
気相脱灰の温度は、脱灰の対象物である植物由来のチャーにより変えることが好ましいが、例えば500〜950℃、好ましくは600〜940℃、より好ましくは650〜940℃、更に好ましくは850〜930℃で実施することができる。脱灰温度が低すぎると、脱灰効率が低下し、十分に脱灰できないことがある。脱灰温度が高くなりすぎると、ハロゲン化合物による賦活が起きることがある。 The temperature of the vapor phase demineralization is preferably changed depending on the plant-derived char that is the object of demineralization, for example, 500 to 950 ° C, preferably 600 to 940 ° C, more preferably 650 to 940 ° C, and still more preferably. It can implement at 850-930 degreeC. When the deashing temperature is too low, the deashing efficiency is lowered and the deashing may not be sufficiently performed. If the deashing temperature is too high, activation by a halogen compound may occur.
気相脱灰の時間は、特に制限されるものではないが、例えば5〜300分であり、好ましくは10〜200分であり、より好ましくは20〜150分である。 The time for vapor phase decalcification is not particularly limited, but is, for example, 5 to 300 minutes, preferably 10 to 200 minutes, and more preferably 20 to 150 minutes.
本発明の製造方法における気相脱灰は、植物由来のチャーに含まれているカリウム、鉄等を除去するものである。気相脱灰処理後に得られる難黒鉛化性炭素前駆体に含まれるカリウム含有量は0.1重量%以下が好ましく、0.05重量%以下がより好ましく、0.03重量%以下が更に好ましい。気相脱灰処理後に得られる難黒鉛化性炭素前駆体に含まれる鉄含有量は0.02重量%以下が好ましく、0.015重量%以下がより好ましく、0.01重量%以下が更に好ましい。難黒鉛化性炭素前駆体に含まれるカリウムや鉄の含有量が多くなると、得られる難黒鉛化性炭素質材料を用いた非水電解質二次電池において、脱ドープ容量が小さくなることがある。また、非脱ドープ容量が大きくなることがある。更に、これらの金属元素が電解液中に溶出し、再析出した際に短絡が生じ、非水電解質二次電池の安全性に大きな問題が生じることがある。 The gas phase decalcification in the production method of the present invention is to remove potassium, iron and the like contained in plant-derived char. The potassium content contained in the non-graphitizable carbon precursor obtained after the vapor phase deashing treatment is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and further preferably 0.03% by weight or less. . The iron content contained in the non-graphitizable carbon precursor obtained after the vapor phase deashing treatment is preferably 0.02% by weight or less, more preferably 0.015% by weight or less, and still more preferably 0.01% by weight or less. . If the content of potassium or iron contained in the non-graphitizable carbon precursor is increased, the dedoping capacity may be reduced in the nonaqueous electrolyte secondary battery using the obtained non-graphitizable carbonaceous material. Also, the undedoped capacity may increase. Furthermore, a short circuit may occur when these metal elements are eluted and re-deposited in the electrolytic solution, which may cause a serious problem in the safety of the nonaqueous electrolyte secondary battery.
気相脱灰の対象となる植物由来のチャーの粒子径は、特に限定されるものではないが、粒子径が小さすぎる場合、除去されたカリウム等を含む気相と、植物由来のチャーとを分離することが困難になり得ることから、粒子径の平均値の下限は100μm以上が好ましく、300μm以上がより好ましく、500μm以上が更に好ましい。また、粒子径の平均値の上限は10000μm以下が好ましく、8000μm以下がより好ましく、5000μm以下が更に好ましい。 The particle diameter of the plant-derived char that is subject to vapor phase demineralization is not particularly limited. However, if the particle diameter is too small, the gas phase containing removed potassium and the like and the plant-derived char Since it may be difficult to separate, the lower limit of the average particle diameter is preferably 100 μm or more, more preferably 300 μm or more, and even more preferably 500 μm or more. Further, the upper limit of the average particle diameter is preferably 10,000 μm or less, more preferably 8000 μm or less, and still more preferably 5000 μm or less.
気相脱灰に用いる装置は、植物由来のチャーとハロゲン化合物を含む気相とを混合しながら加熱できる装置であれば、特に限定されない。例えば、流動炉を用い、流動床等による連続式又はバッチ式の層内流通方式を用いることができる。気相の供給量(流動量)は特に限定されないが、例えば植物由来のチャー1g当たり1mL/分以上、好ましくは5mL/分以上、更に好ましくは10mL/分以上の気相を供給する。 The apparatus used for vapor phase demineralization is not particularly limited as long as it can be heated while mixing plant-derived char and a vapor phase containing a halogen compound. For example, using a fluidized furnace, a continuous or batch type in-bed flow system using a fluidized bed or the like can be used. The supply amount (flow amount) of the gas phase is not particularly limited, but, for example, 1 mL / min or more, preferably 5 mL / min or more, more preferably 10 mL / min or more is supplied per 1 g of plant-derived char.
前記の通り、気相脱灰におけるハロゲン化合物の濃度、脱灰温度、及び脱灰時間等は、十分な脱灰が達成できる限り限定されるものではないが、例えば得られる難黒鉛化性炭素質材料のカリウム元素含有量が0.1重量%以下及び/又は鉄元素含有量が0.02重量%以下となるように熱処理すればよい。例えば、ハロゲン化合物の濃度が高いほど、脱灰温度が長いほど、そして脱灰時間が長いほど、脱灰が進行し、カリウム元素及び鉄元素の含有量が減少する。従って、当業者であれば、これらの条件を適当に制御することによって、難黒鉛化性炭素質材料のカリウム元素含有量が0.1重量%以下及び/又は鉄元素含有量が0.02重量%以下となるように熱処理することができる。 As described above, the concentration of the halogen compound in the vapor phase deashing, the deashing temperature, the deashing time, and the like are not limited as long as sufficient deashing can be achieved. For example, the obtained non-graphitizable carbonaceous material What is necessary is just to heat-process so that potassium element content of a material may be 0.1 weight% or less and / or iron element content may be 0.02 weight% or less. For example, the higher the concentration of the halogen compound, the longer the deashing temperature, and the longer the deashing time, the more the deashing proceeds and the contents of potassium element and iron element decrease. Accordingly, those skilled in the art can appropriately control these conditions so that the non-graphitizable carbonaceous material has a potassium element content of 0.1% by weight or less and / or an iron element content of 0.02% by weight. % Can be heat-treated.
レーザーラマン分光法により観測されるラマンスペクトルにおいて、気相脱灰後に得られる難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値は230〜260cm−1の範囲にあることが好ましく、235〜250cm−1の範囲にあることがより好ましい。ラマンスペクトルの1360cm−1付近のピークの半値幅は、難黒鉛化性炭素質材料の非晶質の量を表すと考えられる。ピークの半値幅の値が小さすぎる場合には、非晶質の量が少ないため、その後の焼成工程により収束することのできる構造が少なく、難黒鉛化性炭素前駆体の有する微細欠陥を収束により軽減できないことがある。一方、半値幅の値が大きすぎる場合には、その後の焼成工程により収束することのできる非晶質の量が多すぎて、その結果、得られた難黒鉛化性炭素質材料を用いた非水電解質二次電池の電気抵抗が大きくなることがある。In the Raman spectrum observed by laser Raman spectroscopy, the half-width value of the peak around 1360 cm -1 in the gas phase decalcification later obtained non-graphitizable carbon precursor to be in the range of 230~260Cm -1 Preferably, it exists in the range of 235-250 cm < -1 >. The half width of the peak near 1360 cm −1 of the Raman spectrum is considered to represent the amorphous amount of the non-graphitizable carbonaceous material. When the half width of the peak is too small, the amount of amorphous material is small, so there are few structures that can be converged by the subsequent firing step, and fine defects possessed by the non-graphitizable carbon precursor are converged. It may not be possible to mitigate. On the other hand, when the value of the half width is too large, the amount of amorphous that can be converged by the subsequent firing step is too large, and as a result, the non-graphitizable carbonaceous material obtained is not used. The electric resistance of the water electrolyte secondary battery may increase.
なお、ラマンスペクトルは後述する方法を用いて測定することができる。本明細書において、半値幅とは、半値全幅(FWHM)を示す。1360cm−1付近のピークは、Dバンドと呼ばれ、炭素材料における非弾性散乱を伴う二重共鳴効果によってラマンスペクトルに現れるピークである。The Raman spectrum can be measured using a method described later. In this specification, the half width indicates the full width at half maximum (FWHM). A peak near 1360 cm −1 is called a D band, and is a peak that appears in a Raman spectrum due to a double resonance effect accompanied by inelastic scattering in a carbon material.
前記難黒鉛化性炭素前駆体は、平均粒子径100〜10000μmの植物由来のチャーを、ハロゲン化合物を含む不活性ガス雰囲気中で500〜950℃、好ましくは600〜940℃、より好ましくは650〜940℃、更に好ましくは850〜930℃で熱処理することによって得られる難黒鉛化性炭素前駆体でもよい。すなわち、本発明の非水電解質二次電池用混合負極材料の製造方法は、平均粒子径100〜10000μmの植物由来のチャーを、ハロゲン化合物を含む不活性ガス雰囲気中で500〜950℃、好ましくは600〜940℃、より好ましくは650〜940℃、更に好ましくは810〜970℃、更に好ましくは850〜930℃で熱処理し、難黒鉛化性炭素前駆体を得る、気相脱灰工程、(1)前記難黒鉛化性炭素前駆体と揮発性有機物とを800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む非水電解質二次電池用混合負極材料の製造方法であってもよい。
前記の気相脱灰工程及び焼成工程により、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である、難黒鉛化性炭素質材料を得ることができる。The non-graphitizable carbon precursor contains plant-derived char having an average particle size of 100 to 10000 μm in an inert gas atmosphere containing a halogen compound at 500 to 950 ° C., preferably 600 to 940 ° C., more preferably 650 to 650 ° C. It may be a non-graphitizable carbon precursor obtained by heat treatment at 940 ° C, more preferably 850-930 ° C. That is, the method for producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery according to the present invention is characterized in that a plant-derived char having an average particle size of 100 to 10000 μm is heated to 500 to 950 ° C. in an inert gas atmosphere containing a halogen compound, preferably A gas phase deashing step wherein heat treatment is performed at 600 to 940 ° C., more preferably 650 to 940 ° C., further preferably 810 to 970 ° C., more preferably 850 to 930 ° C. to obtain a non-graphitizable carbon precursor, (1 ) Firing the non-graphitizable carbon precursor and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a non-graphitizable carbonaceous material; and (2) the non-graphitizable carbon. The manufacturing method of the mixed negative electrode material for nonaqueous electrolyte secondary batteries including the process of mixing a porous material, an easily graphitizable carbonaceous material, and / or a graphite material may be sufficient.
The average interplanar spacing d 002 of the (002) plane of the non-graphitizable carbonaceous material calculated using the Bragg equation in the wide-angle X-ray diffraction method by the vapor phase decalcification step and the firing step is 0.38. The non-graphite that is in the range of ˜0.40 nm, the specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g, and is observed in the Raman spectrum The difference between the half-width value of the peak near 1360 cm −1 of the graphitizable carbon precursor and the half-width value of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material is 50 to 84 cm −1 . A non-graphitizable carbonaceous material can be obtained.
(粉砕及び分級)
難黒鉛化性炭素前駆体は、必要に応じて粉砕工程、分級工程を経て、平均粒子径を調製される。粉砕工程、分級工程は、脱灰処理の後、実施することが好ましい。(Crushing and classification)
The non-graphitizable carbon precursor is adjusted in average particle size through a pulverization step and a classification step as necessary. The pulverization step and the classification step are preferably performed after the decalcification treatment.
粉砕工程では、難黒鉛化性炭素前駆体を、焼成工程後の平均粒子径が例えば1〜30μmの範囲になるように粉砕する。すなわち、本発明の製造方法で用いる難黒鉛化性炭素質材料の平均粒子径を、例えば1〜30μmの範囲になるように調製する。 In the pulverization step, the non-graphitizable carbon precursor is pulverized so that the average particle size after the firing step is in the range of, for example, 1 to 30 μm. That is, the average particle diameter of the non-graphitizable carbonaceous material used in the production method of the present invention is prepared to be in the range of 1 to 30 μm, for example.
難黒鉛化性炭素前駆体は、後述する熱処理工程を実施しても溶解しないため、粉砕工程の順番は、脱灰工程後であれば特に限定されない。難黒鉛化性炭素質材料の比表面積の低減の観点から、焼成工程の前に実施することが好ましい。しかしながら、焼成工程後に粉砕工程を実施することを排除するものではない。 Since the non-graphitizable carbon precursor does not dissolve even when the heat treatment step described below is performed, the order of the pulverization step is not particularly limited as long as it is after the deashing step. From the viewpoint of reducing the specific surface area of the non-graphitizable carbonaceous material, it is preferably performed before the firing step. However, it does not exclude performing the pulverization step after the firing step.
粉砕工程に用いる粉砕機は特に限定されるものではなく、例えばジェットミル、ボールミル、ハンマーミル、又はロッドミルなどを使用することができる。微粉の発生が少ない観点からは、分級機能を備えたジェットミルが好ましい。ボールミル、ハンマーミル、又はロッドミルなどを用いる場合は、粉砕工程後に分級を行うことで微粉を取り除くことができる。 The pulverizer used in the pulverization step is not particularly limited, and for example, a jet mill, a ball mill, a hammer mill, or a rod mill can be used. From the viewpoint of generating less fine powder, a jet mill having a classification function is preferable. When using a ball mill, a hammer mill, a rod mill or the like, fine powder can be removed by classification after the pulverization step.
分級工程によって、難黒鉛化性炭素質材料の平均粒子径をより正確に調製することが可能となる。例えば、粒子径が1μm以下の粒子を除くことが可能となる。 By the classification step, the average particle diameter of the non-graphitizable carbonaceous material can be more accurately prepared. For example, particles having a particle diameter of 1 μm or less can be removed.
分級方法は、特に制限されないが、例えば篩を用いた分級、湿式分級、乾式分級を挙げることができる。湿式分級機としては、例えば重力分級、慣性分級、水力分級、遠心分級等の原理を利用した分級機を挙げることができる。乾式分級機としては、沈降分級、機械的分級、遠心分級等の原理を利用した分級機を挙げることができる。 The classification method is not particularly limited, and examples thereof include classification using a sieve, wet classification, and dry classification. As the wet classifier, for example, a classifier using principles such as gravity classification, inertia classification, hydraulic classification, centrifugal classification, and the like can be given. Examples of the dry classifier include a classifier using a principle such as sedimentation classification, mechanical classification, and centrifugal classification.
粉砕工程と分級工程は、1つの装置を用いて実施することもできる。例えば、乾式の分級機能を備えたジェットミルを用いて、粉砕工程と分級工程を実施することができる。更に、粉砕機と分級機とが独立した装置を用いることもできる。この場合、粉砕と分級とを連続して行うこともできるが、粉砕と分級とを不連続に行うこともできる。 The pulverization step and the classification step can be performed using one apparatus. For example, the pulverization step and the classification step can be performed using a jet mill having a dry classification function. Furthermore, an apparatus in which the pulverizer and the classifier are independent can be used. In this case, pulverization and classification can be performed continuously, but pulverization and classification can also be performed discontinuously.
《揮発性有機物》
難黒鉛化性炭素前駆体と揮発性有機物との混合物を焼成することによって、本発明の製造方法で用いる難黒鉛化性炭素質材料が得られる。難黒鉛化性炭素前駆体と揮発性有機物とを混合して焼成することにより、得られる難黒鉛化性炭素質材料の比表面積を低減させることができ、非水電解質二次電池用の負極材として好適な比表面積とすることができる。更に、難黒鉛化性炭素質材料への二酸化炭素の吸着量を調整することができる。《Volatile organic matter》
By baking a mixture of a non-graphitizable carbon precursor and a volatile organic material, a non-graphitizable carbonaceous material used in the production method of the present invention is obtained. By mixing and baking a non-graphitizable carbon precursor and a volatile organic substance, the specific surface area of the obtained non-graphitizable carbonaceous material can be reduced, and a negative electrode material for a non-aqueous electrolyte secondary battery It can be set as a suitable specific surface area. Furthermore, the amount of carbon dioxide adsorbed on the non-graphitizable carbonaceous material can be adjusted.
揮発性有機物は、常温で固体状態であり、残炭率が5%未満である有機物であることが好ましい。揮発性有機物は、植物由来のチャーから製造される難黒鉛化性炭素前駆体の比表面積を低減させることのできる揮発物質(例えば、炭化水素系ガスやタール)を発生させるものが好ましい。なお、揮発性有機物において、比表面積を低減させることのできる揮発物質(例えば、炭化水素系ガス、又はタール成分)の含量は特に限定されるものではない。 The volatile organic substance is preferably an organic substance that is in a solid state at room temperature and has a residual carbon ratio of less than 5%. The volatile organic substance is preferably one that generates a volatile substance (for example, hydrocarbon gas or tar) that can reduce the specific surface area of the non-graphitizable carbon precursor produced from plant-derived char. In the volatile organic substance, the content of the volatile substance (for example, hydrocarbon gas or tar component) that can reduce the specific surface area is not particularly limited.
揮発性有機物としては、例えば熱可塑性樹脂、又は低分子有機化合物が挙げられる。具体的には、熱可塑性樹脂としては、ポリスチレン、ポリエチレン、ポリプロピレン、ポリ(メタ)アクリル酸、ポリ(メタ)アクリル酸エステル等を挙げることができる。なお、この明細書において、(メタ)アクリルとは、メタクリルとメタアクリルの総称である。低分子有機化合物としては、トルエン、キシレン、メシチレン、スチレン、ナフタレン、フェナントレン、アントラセン、ピレン等を挙げることができる。焼成温度下で揮発し、熱分解した場合に難黒鉛化性炭素前駆体の表面を酸化賦活しないものが好ましいことから、熱可塑性樹脂としてはポリスチレン、ポリエチレン、ポリプロピレンが好ましい。低分子有機化合物としては、更に安全上の観点から常温下において揮発性が小さいことが好ましく、ナフタレン、フェナントレン、アントラセン、ピレン等が好ましい。 As a volatile organic substance, a thermoplastic resin or a low molecular organic compound is mentioned, for example. Specifically, examples of the thermoplastic resin include polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, and the like. In this specification, (meth) acryl is a general term for methacryl and methacryl. Examples of the low molecular organic compound include toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, and pyrene. Since those which do not oxidize and activate the surface of the non-graphitizable carbon precursor when volatilized at the firing temperature and thermally decomposed are preferred, polystyrene, polyethylene and polypropylene are preferred as the thermoplastic resin. The low molecular weight organic compound preferably has low volatility at room temperature from the viewpoint of safety, and naphthalene, phenanthrene, anthracene, pyrene and the like are preferable.
残炭率は、試料を不活性ガス中で強熱した後の強熱残分の炭素量を定量することにより測定する。強熱とは、揮発性有機物およそ1g(この正確な重量をW1(g)とする)を坩堝に入れ、1分間に20Lの窒素を流しながら坩堝を電気炉にて、10℃/分の昇温速度で常温から800℃まで昇温、その後800℃で1時間強熱する。このときの残存物を強熱残分とし、その重量をW2(g)とする。 The residual carbon ratio is measured by quantifying the carbon content of the ignition residue after the sample is ignited in an inert gas. Ignition is about 1 g of volatile organic matter (this exact weight is set to W1 (g)) in a crucible, and the temperature of the crucible is increased by 10 ° C./min in an electric furnace while flowing 20 L of nitrogen per minute. The temperature is raised from room temperature to 800 ° C. at a temperature rate, and then ignited at 800 ° C. for 1 hour. The residue at this time is regarded as an ignition residue, and its weight is defined as W2 (g).
次いで上記強熱残分について、JIS M8819に定められた方法に準拠して元素分析を行い、炭素の重量割合P1(%)を測定し、残炭率P2(%)を算出することができる。 Subsequently, the ignition residue can be subjected to elemental analysis in accordance with the method defined in JIS M8819, the carbon weight ratio P1 (%) can be measured, and the residual coal ratio P2 (%) can be calculated.
本発明の製造方法において焼成される混合物は、特に限定されるものではないが、好ましくは難黒鉛化性炭素前駆体と揮発性有機物とを97:3〜40:60の重量比で含む混合物である。難黒鉛化性炭素前駆体と揮発性有機物との混合量は、より好ましくは95:5〜60:40、更に好ましくは93:7〜80:20である。例えば、揮発性有機物が3重量部以上であると比表面積を十分に低減させることができる。一方、揮発性有機物が多すぎると、比表面積の低減効果が飽和し、揮発性有機物を無駄に消費してしまうことがあるため好ましくない。 The mixture baked in the production method of the present invention is not particularly limited, but is preferably a mixture containing a non-graphitizable carbon precursor and a volatile organic substance in a weight ratio of 97: 3 to 40:60. is there. The mixing amount of the non-graphitizable carbon precursor and the volatile organic substance is more preferably 95: 5 to 60:40, still more preferably 93: 7 to 80:20. For example, when the volatile organic substance is 3 parts by weight or more, the specific surface area can be sufficiently reduced. On the other hand, if there are too many volatile organic substances, the effect of reducing the specific surface area is saturated, and the volatile organic substances may be consumed in vain, which is not preferable.
難黒鉛化性炭素前駆体と揮発性有機物との混合は、粉砕工程の前あるいは粉砕工程の後のいずれの段階で行ってもよい。 Mixing of the non-graphitizable carbon precursor and the volatile organic material may be performed at any stage before the pulverization process or after the pulverization process.
粉砕工程の前に混合する場合には、難黒鉛化性炭素前駆体と揮発性有機物とを計量しながら、粉砕装置に同時に供給することにより粉砕と混合を同時に行うことができる。 In the case of mixing before the pulverization step, the non-graphitizable carbon precursor and the volatile organic substance can be measured and simultaneously supplied to the pulverizer to simultaneously pulverize and mix.
粉砕工程の後に混合する場合には、混合方法は両者が均一に混合される手法であれば、公知の混合方法を用いることができる。揮発性有機物は、粒子の形状で混合されることが好ましいが、粒子の形や粒子径は特に限定されない。揮発性有機物を粉砕された難黒鉛化性炭素前駆体に均一に分散させる観点からは、揮発性有機物の平均粒子径は好ましくは0.1〜2000μm、より好ましくは1〜1000μm、更に好ましくは2〜600μmである。 In the case of mixing after the pulverization step, a known mixing method can be used as long as the mixing method is a method in which both are uniformly mixed. The volatile organic substance is preferably mixed in the form of particles, but the shape and particle diameter of the particles are not particularly limited. From the viewpoint of uniformly dispersing the volatile organic substance in the pulverized non-graphitizable carbon precursor, the average particle size of the volatile organic substance is preferably 0.1 to 2000 μm, more preferably 1 to 1000 μm, and still more preferably 2 ~ 600 μm.
上述した混合物は、難黒鉛化性炭素前駆体及び揮発性有機物以外の他の成分を含んでいてもよい。例えば、天然黒鉛、人造黒鉛、金属系材料、合金系材料、又は酸化物系材料を含むことができる。他の成分の含有量は、特に限定されるものではないが、好ましくは難黒鉛化性炭素前駆体と揮発性有機物との混合物100重量部に対して、50重量部以下であり、より好ましくは30重量部以下であり、更に好ましくは20重量部以下であり、最も好ましくは10重量部以下である。 The mixture mentioned above may contain other components other than the non-graphitizable carbon precursor and the volatile organic substance. For example, natural graphite, artificial graphite, metal-based material, alloy-based material, or oxide-based material can be included. The content of other components is not particularly limited, but is preferably 50 parts by weight or less with respect to 100 parts by weight of the mixture of the non-graphitizable carbon precursor and the volatile organic substance, and more preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and most preferably 10 parts by weight or less.
《焼成》
本発明の製造方法における焼成工程は、難黒鉛化性炭素前駆体と揮発性有機物との混合物を800〜1400℃で焼成する。<Baking>
In the firing step in the production method of the present invention, a mixture of the non-graphitizable carbon precursor and the volatile organic material is fired at 800 to 1400 ° C.
焼成工程は、(a)粉砕された混合物を、800〜1400℃で焼成し、本焼成を行う焼成工程、でもよく、(b)粉砕された混合物を、350℃以上800℃未満で予備焼成し、その後800〜1400℃で本焼成を行う焼成工程、でもよい。 The firing step may be a firing step in which (a) the pulverized mixture is baked at 800 to 1400 ° C. and main firing is performed, and (b) the pulverized mixture is pre-fired at 350 ° C. or higher and lower than 800 ° C. Then, a baking step of performing main baking at 800 to 1400 ° C. may be used.
焼成工程(a)を実施する場合、本焼成の工程で難黒鉛化性炭素前駆体へのタール成分及び炭化水素系ガスの被覆が起こると考えられる。焼成工程(b)を実施する場合には、予備焼成の工程で難黒鉛化性炭素前駆体へのタール成分及び炭化水素系ガスの被覆が起こると考えられる。 When the firing step (a) is performed, it is considered that the tar-component and the hydrocarbon-based gas are coated on the non-graphitizable carbon precursor in the main firing step. When the firing step (b) is performed, it is considered that the tar-component and hydrocarbon gas are coated on the non-graphitizable carbon precursor in the preliminary firing step.
以下に、本発明の一実施形態として、予備焼成及び本焼成の手順の一例を説明するが、本発明はこれに制限されるものではない。 Hereinafter, as an embodiment of the present invention, an example of the pre-baking and main baking procedures will be described, but the present invention is not limited thereto.
(予備焼成)
本発明の製造方法における予備焼成工程は、例えば粉砕された混合物を350℃以上800℃未満で焼成することによって行うことができる。予備焼成工程によって、揮発分(例えばCO2、CO、CH4、H2等)とタール分とを除去できる。予備焼成工程後に実施する本焼成工程における揮発分やタール分の発生を軽減でき、焼成機の負担を軽減することができる。(Preliminary firing)
The preliminary baking step in the production method of the present invention can be performed, for example, by baking the pulverized mixture at 350 ° C. or higher and lower than 800 ° C. Volatile components (for example, CO 2 , CO, CH 4 , H 2, etc.) and tar components can be removed by the preliminary firing step. Generation | occurrence | production of the volatile matter and tar part in the main baking process implemented after a preliminary baking process can be reduced, and the burden of a baking machine can be reduced.
予備焼成工程は、350℃以上で実施することが好ましく、400℃以上で実施することがより好ましい。予備焼成工程は、通常の予備焼成の手順に従って実施することができる。具体的には、予備焼成は、不活性ガス雰囲気中で行うことができる。不活性ガスとしては、窒素、アルゴン等を挙げることができる。また、予備焼成は、減圧下で実施してもよく、例えば、10kPa以下で行うことができる。予備焼成の時間も特に限定されるものではないが、例えば0.5〜10時間の範囲で実施することができ、1〜5時間がより好ましい。 The pre-baking step is preferably performed at 350 ° C. or higher, more preferably 400 ° C. or higher. The pre-baking step can be performed according to a normal pre-baking procedure. Specifically, the pre-baking can be performed in an inert gas atmosphere. Examples of the inert gas include nitrogen and argon. Further, the pre-baking may be performed under reduced pressure, for example, 10 kPa or less. The pre-baking time is not particularly limited, but can be carried out in the range of 0.5 to 10 hours, for example, and more preferably 1 to 5 hours.
(本焼成)
本焼成工程は、通常の本焼成の手順に従って行うことができる。本焼成を行うことにより、非水電解質二次電池用の難黒鉛化性炭素質材料を得ることができる。(Main firing)
The main baking step can be performed according to a normal main baking procedure. By performing the main firing, a non-graphitizable carbonaceous material for a non-aqueous electrolyte secondary battery can be obtained.
具体的な本焼成工程の温度は、800〜1400℃であり、好ましくは1000〜1350℃であり、より好ましくは1100〜1300℃である。本焼成は、不活性ガス雰囲気下で実施する。不活性ガスとしては、窒素、アルゴン等を挙げることができ、ハロゲンガスを含有する不活性ガス中で本焼成を行うことも可能である。また、本焼成工程は、減圧下で行うこともでき、例えば、10kPa以下で実施することも可能である。本焼成工程を実施する時間は特に限定されるものではないが、例えば0.05〜10時間で行うことができ、0.05〜8時間が好ましく、0.05〜6時間がより好ましい。 The specific temperature of the main firing step is 800 to 1400 ° C, preferably 1000 to 1350 ° C, and more preferably 1100 to 1300 ° C. The main firing is performed in an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, and the like, and the main calcination can be performed in an inert gas containing a halogen gas. Moreover, this baking process can also be performed under reduced pressure, for example, it is also possible to implement at 10 kPa or less. Although the time which implements this baking process is not specifically limited, For example, it can carry out in 0.05 to 10 hours, 0.05 to 8 hours are preferable and 0.05 to 6 hours are more preferable.
《難黒鉛化性炭素質材料》
本発明の負極材料に含まれる難黒鉛化性炭素質材料は、限定されるものではないが、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、ラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である。《Non-graphitizable carbonaceous material》
The non-graphitizable carbonaceous material contained in the negative electrode material of the present invention is not limited, but the non-graphitizable carbonaceous material of the non-graphitizable carbonaceous material calculated using the Bragg equation in the wide angle X-ray diffraction method ( 002) The average interplanar spacing d 002 is in the range of 0.38 to 0.40 nm, and the specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g. to Yes, and the value of the half-value width of the peak around 1360 cm -1 of the flame-graphitizable carbon precursor observed in the Raman spectrum, the peak around 1360 cm -1 of the flame graphitizable carbonaceous material of the half-value width The difference from the value is 50 to 84 cm −1 .
本発明の製造方法において使用される非水電解質二次電池用難黒鉛化性炭素質材料は、窒素吸着BET3点法により求められる比表面積が、1m2/g〜10m2/gであり、好ましくは1.2m2/g〜9.5m2/gであり、より好ましくは1.4m2/g〜9.0m2/gである。小さすぎる比表面積では、難黒鉛化性炭素質材料へのリチウムイオンの吸着量が少なくなり、非水電解質二次電池の充電容量が少なくなることがある。高すぎる比表面積では、リチウムイオンが難黒鉛化性炭素質材料の表面で反応し、リチウムイオンの利用効率が低くなることがある。The non-aqueous electrolyte secondary battery flame graphitizable carbonaceous material used in the production process of the present invention, the specific surface area determined by nitrogen adsorption BET3 point method is a 1m 2 / g~10m 2 / g, preferably is 1.2m 2 /g~9.5m 2 / g, more preferably 1.4m 2 /g~9.0m 2 / g. When the specific surface area is too small, the amount of lithium ions adsorbed on the non-graphitizable carbonaceous material is decreased, and the charge capacity of the nonaqueous electrolyte secondary battery may be decreased. When the specific surface area is too high, lithium ions may react on the surface of the non-graphitizable carbonaceous material, and the utilization efficiency of lithium ions may be lowered.
本発明の製造方法において使用される難黒鉛化性炭素質材料は、広角X線回折法からBragg式を用いて算出される(002)面の平均面間隔d002が、0.375nm以上0.40nm以下の範囲にあり、好ましくは0.380以上0.400nm以下の範囲であり、更に好ましくは0.381nm以上0.389nm以下の範囲である。(002)面の平均面間隔d002が小さすぎる場合には、リチウムイオンが難黒鉛化性炭素質材料に挿入される際の抵抗が大きくなることがあり、出力時の抵抗が大きくなることがあり、リチウムイオン電池としての入出力特性が低下することがある。また、難黒鉛化性炭素質材料が膨張収縮を繰り返すため、電池材料としての安定性を損なうことがある。平均面間隔d002が大きすぎる場合には、リチウムイオンの拡散抵抗は小さくなるものの、難黒鉛化性炭素質材料の体積が大きくなり、体積あたりの実行容量が小さくなることがある。The non-graphitizable carbonaceous material used in the production method of the present invention has an average interplanar spacing d 002 of (002) plane calculated from the wide-angle X-ray diffraction method using the Bragg equation is 0.375 nm or more and 0.00. It is in the range of 40 nm or less, preferably in the range of 0.380 to 0.400 nm, more preferably in the range of 0.381 nm to 0.389 nm. If the average interplanar spacing d002 of (002) plane is too small, the resistance when lithium ions are inserted into the non-graphitizable carbonaceous material may increase, and the resistance during output may increase. In some cases, the input / output characteristics of the lithium ion battery may deteriorate. Further, since the non-graphitizable carbonaceous material repeatedly expands and contracts, the stability as a battery material may be impaired. When the average interplanar distance d 002 is too large, the diffusion resistance of lithium ions decreases, but the volume of the non-graphitizable carbonaceous material increases, and the effective capacity per volume may decrease.
本発明の製造方法において使用される難黒鉛化性炭素質材料が含む窒素原子量は、少ないほどよいが、通常、元素分析によって得られた分析値より、0.5重量%以下であることが好ましい。窒素原子量が多すぎると、リチウムイオンと窒素とが反応し、リチウムイオン効率を低下させるだけでなく、保存中に空気中の酸素と反応することがある。 The amount of nitrogen atoms contained in the non-graphitizable carbonaceous material used in the production method of the present invention is preferably as small as possible, but is usually preferably 0.5% by weight or less from the analytical value obtained by elemental analysis. . When the amount of nitrogen atoms is too large, lithium ions and nitrogen react to reduce lithium ion efficiency, and may react with oxygen in the air during storage.
本発明の製造方法において使用される難黒鉛化性炭素質材料が含む酸素原子量は、少ないほどよいが、通常、元素分析によって得られた分析値より、0.25重量%以下であることが好ましい。酸素原子量が多すぎると、リチウムイオンと酸素とが反応し、リチウムイオン効率を低下させるだけでなく、空気中の酸素、水分を誘引し、難黒鉛化性炭素質材料と反応する確率を高めるだけでなく、水を吸着したとき、容易に脱離させないなど、リチウム効率が低下することがある。 The amount of oxygen atoms contained in the non-graphitizable carbonaceous material used in the production method of the present invention is preferably as small as possible, but is usually preferably 0.25% by weight or less from the analytical value obtained by elemental analysis. . If the amount of oxygen atoms is too large, lithium ions react with oxygen, not only lowering the lithium ion efficiency, but also attracting oxygen and moisture in the air and increasing the probability of reacting with non-graphitizable carbonaceous materials. In addition, when water is adsorbed, the lithium efficiency may decrease, for example, it may not be easily desorbed.
レーザーラマン分光法により観測されるラマンスペクトルにおいて、焼成工程後に得られる難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値は、175〜190cm−1の範囲にあることが好ましく、175〜180cm−1の範囲にあることがより好ましい。難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅が上記の範囲にあることによって、リチウムクラスターが形成されやすくなり、導電性を確保できやすくなり、実効容量として十分な放電特性を発揮しやすくなる。なお、リチウムクラスターとは、リチウムイオン間の相互作用によりリチウムイオンが集合し、ひとつの塊となった状態を示し、リチウムイオンはリチウムクラスターを形成しつつ吸蔵される。リチウムイオンは、リチウムイオン及びリチウムクラスターの状態で吸蔵されるが、リチウムクラスターを形成することによってより高い電池特性を得ることができると考えられる。In the Raman spectrum observed by laser Raman spectroscopy, the half-value width of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material obtained after the firing step is preferably in the range of 175 to 190 cm −1. More preferably, it is in the range of 175 to 180 cm −1 . When the full width at half maximum of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material is in the above range, lithium clusters are easily formed, conductivity can be easily secured, and sufficient discharge characteristics as effective capacity can be obtained. It becomes easy to demonstrate. In addition, a lithium cluster shows the state which lithium ion gathered by the interaction between lithium ions, and became one lump, and lithium ion is occluded forming a lithium cluster. Lithium ions are occluded in the form of lithium ions and lithium clusters, but it is considered that higher battery characteristics can be obtained by forming lithium clusters.
焼成前の難黒鉛化性炭素前駆体のレーザーラマン分光法により観測されるラマンスペクトルの1360cm−1付近のピークの半値幅の値と、焼成後に得られる難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差は、50cm−1以上84cm−1以下である。半値幅の値は55cm−1以上83cm−1以下であることがより好ましく、60cm−1以上80cm−1以下であることが更に好ましい。半値幅の値の差が50cm−1以上であると、焼成による炭素の構造収束により、結晶が発達し、充放電における効率が高くなりやすい。更に、難黒鉛化性炭素質材料の微細孔が閉塞されやすく、難黒鉛化性炭素質材料の吸湿性が低下しやすくなる。従って、本発明の製造方法に用いる難黒鉛化性炭素質材料は、非水電解質二次電池用難黒鉛化性炭素質材料として好ましい。一方、焼成前後の半値幅の差が大きくなりすぎると、炭素の構造の収束により、新たな欠陥が発生することがあり、充放電の効率が低下することがある。更に、難黒鉛化性炭素質材料の吸湿性が高まり、電解液の加水分解に伴う酸の発生や水の電気分解によるガスの発生が問題を引き起こすことがあり、難黒鉛化性炭素質材料の劣化が生じることがあり、電極材料としての保存安定性が低下することがある。The value of the half width of the peak around 1360 cm -1 of the Raman spectrum observed by the pre-firing laser Raman spectroscopy non-graphitizable carbon precursor, 1360 cm of non-graphitizable carbonaceous material obtained after calcination -1 The difference from the value of the half width of the nearby peak is 50 cm −1 or more and 84 cm −1 or less. The half-value width is more preferably 55 cm −1 or more and 83 cm −1 or less, and further preferably 60 cm −1 or more and 80 cm −1 or less. When the difference between the half-value width values is 50 cm −1 or more, a crystal develops due to the structural convergence of carbon by firing, and the efficiency in charge and discharge tends to increase. Furthermore, the micropores of the non-graphitizable carbonaceous material are likely to be clogged, and the hygroscopicity of the non-graphitizable carbonaceous material is likely to decrease. Therefore, the non-graphitizable carbonaceous material used in the production method of the present invention is preferable as the non-graphitizable carbonaceous material for non-aqueous electrolyte secondary batteries. On the other hand, if the difference between the half widths before and after firing becomes too large, new defects may occur due to the convergence of the carbon structure, and the charge / discharge efficiency may decrease. Furthermore, the hygroscopicity of the non-graphitizable carbonaceous material increases, and the generation of acid due to the hydrolysis of the electrolyte and the generation of gas due to water electrolysis may cause problems. Deterioration may occur and storage stability as an electrode material may be reduced.
本発明の製造方法において使用される難黒鉛化性炭素質材料の平均粒子径(Dv50)は、好ましくは1〜30μmである。平均粒子径が小さすぎると、微粉が増加し、難黒鉛化性炭素質材料の比表面積が増加する。その結果、難黒鉛化性炭素質材料と電解液との反応性が高くなり、不可逆容量が増加し、正極の容量が無駄になる割合が増加することがある。ここで不可逆容量とは、非電解質二次電池に充電した容量のうち、放電しない容量である。平均粒子径が小さすぎる難黒鉛化性炭素質材料を用いて負極電極を製造した場合、難黒鉛化性炭素質材料間に形成される空隙が小さくなり、電解液中のリチウムの移動が制限されることがあるため、好ましくない。難黒鉛化性炭素質材料の平均粒子径は、より好ましくは2μm以上、特に好ましくは3μm以上である。平均粒子径が30μm以下の場合、粒子内でのリチウムの拡散自由行程が少なく、急速な充放電が可能となり好ましい。更に、リチウムイオン二次電池では、入出力特性の向上には電極面積を大きくすることが重要であり、そのため電極調製時に集電板への活物質の塗工厚みを薄くする必要がある。塗工厚みを薄くするには、活物質の粒子径を小さくする必要がある。このような観点から、平均粒子径の上限としては30μm以下が好ましいが、より好ましくは19μm以下であり、更に好ましくは17μm以下であり、更に好ましくは16μm以下、最も好ましくは15μm以下である。The average particle diameter (D v50 ) of the non- graphitizable carbonaceous material used in the production method of the present invention is preferably 1 to 30 μm. When the average particle diameter is too small, fine powder increases and the specific surface area of the non-graphitizable carbonaceous material increases. As a result, the reactivity between the non-graphitizable carbonaceous material and the electrolytic solution is increased, the irreversible capacity is increased, and the proportion of wasted capacity of the positive electrode may be increased. Here, the irreversible capacity is a capacity that does not discharge among the capacity charged in the non-electrolyte secondary battery. When a negative electrode is produced using a non-graphitizable carbonaceous material having an average particle size that is too small, voids formed between the non-graphitizable carbonaceous materials are reduced, and movement of lithium in the electrolyte is restricted. This is not preferable. The average particle size of the non-graphitizable carbonaceous material is more preferably 2 μm or more, and particularly preferably 3 μm or more. When the average particle size is 30 μm or less, the lithium free diffusion process in the particles is small, and rapid charge / discharge is possible, which is preferable. Further, in the lithium ion secondary battery, it is important to increase the electrode area for improving the input / output characteristics. For this reason, it is necessary to reduce the coating thickness of the active material on the current collector plate during electrode preparation. In order to reduce the coating thickness, it is necessary to reduce the particle diameter of the active material. From such a viewpoint, the upper limit of the average particle diameter is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, still more preferably 16 μm or less, and most preferably 15 μm or less.
本発明の製造方法において使用される難黒鉛化性炭素質材料の真密度の範囲は、特に限定されるものではないが、好ましくは1.45〜1.70g/cm3の範囲にあり、より好ましくは1.45〜1.65g/cm3、更に好ましくは1.45〜1.60g/cm3の範囲にある。1.45g/cm3未満であると単位体積当たりのドープ容量、および脱ドープ容量が小さくなり好ましくない。The true density range of the non-graphitizable carbonaceous material used in the production method of the present invention is not particularly limited, but is preferably in the range of 1.45 to 1.70 g / cm 3 , more Preferably it is 1.45 to 1.65 g / cm 3 , more preferably 1.45 to 1.60 g / cm 3 . If it is less than 1.45 g / cm 3 , the doping capacity per unit volume and the dedoping capacity are undesirably small.
《混合工程(2)》
本発明の製造方法における混合工程(2)は、前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程である。<< Mixing process (2) >>
The mixing step (2) in the production method of the present invention is a step of mixing the non-graphitizable carbonaceous material, the graphitizable carbonaceous material and / or the graphite material.
(易黒鉛化性炭素質材料)
易黒鉛化性炭素とは、2000℃以上の高温で熱処理することにより黒鉛構造に変化する非黒鉛質炭素の総称であるが、本明細書においては、真密度が1.70g/cm3以上2.2g/cm3以下の非黒鉛質炭素を易黒鉛化性炭素と称する。易黒鉛化性炭素質材料の真密度は、特に限定されるものではないが、好ましくは1.80〜2.18g/cm3の範囲にあり、より好ましくは1.90〜2.15g/cm3の範囲である。(Easily graphitizable carbonaceous material)
Graphitizable carbon is a general term for non-graphitic carbon that changes to a graphite structure by heat treatment at a high temperature of 2000 ° C. or higher. In this specification, the true density is 1.70 g / cm 3 or more 2 Non-graphitic carbon of 2 g / cm 3 or less is referred to as graphitizable carbon. The true density of the graphitizable carbonaceous material is not particularly limited, but is preferably in the range of 1.80 to 2.18 g / cm 3 , more preferably 1.90 to 2.15 g / cm. 3 range.
本発明の混合負極材料に含まれる易黒鉛化性炭素質材料は、限定されるものではないが、ピッチ又は熱可塑性樹脂などの易黒鉛化性炭素前駆体を焼成することによって得られるものである。すなわち、前記混合負極材料に含まれる易黒鉛化性炭素質材料の炭素源は、易黒鉛化性炭素質材料が製造できる限りにおいて限定されるものではないが、例えば石油系ピッチ若しくはタール、石炭系ピッチ若しくはタール、石油コークス、石炭コークス、中間相ピッチ、メゾカーボンマイクロビーズ、塩化ビニル系樹脂、熱可塑性樹脂(例えば、ケトン樹脂、ポリビニルアルコール、ポリエチレンテレフタレート、ポリアセタール、ポリアクリロニトリル、スチレン/ジビニルベンゼン共重合体、ポリイミド、ポリカーボネート、変性ポリフェニレンエーテル、ポリブチレンテレフタレート、ポリアリレート、ポリスルホン、ポリフェニレンスルフィド、ポリエーテルエーテルケトン、ポリイミド樹脂、フッ素樹脂、アラミド樹脂、又はポリアミドイミド)、を挙げることができる。なお、これらの炭素源は、酸化処理により不融化されていないものである。 The graphitizable carbonaceous material contained in the mixed negative electrode material of the present invention is not limited, but is obtained by firing a graphitizable carbon precursor such as pitch or thermoplastic resin. . That is, the carbon source of the graphitizable carbonaceous material contained in the mixed negative electrode material is not limited as long as the graphitizable carbonaceous material can be produced. For example, petroleum-based pitch or tar, coal-based Pitch or tar, petroleum coke, coal coke, mesophase pitch, mesocarbon microbead, vinyl chloride resin, thermoplastic resin (for example, ketone resin, polyvinyl alcohol, polyethylene terephthalate, polyacetal, polyacrylonitrile, styrene / divinylbenzene copolymer) Coalesced, polyimide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyarylate, polysulfone, polyphenylene sulfide, polyether ether ketone, polyimide resin, fluorine resin, aramid resin, or poly Midoimido), it can be mentioned. These carbon sources are not infusible by oxidation treatment.
易黒鉛化性炭素質材料は、前記易黒鉛化性炭素前駆体を、通常の焼成の手順に従って焼成することにより得ることができる。
焼成は、(a)易黒鉛化性炭素前駆体を、800℃以上2500℃未満で焼成し、本焼成を行う焼成工程、でもよく、(b)易黒鉛化性炭素前駆体、300℃以上800℃未満で予備焼成し、その後800℃以上2500℃未満で本焼成を行う焼成工程、でもよい。
温度以外の条件は、前記「《焼成》」の欄に記載の条件で行うことができる。The graphitizable carbonaceous material can be obtained by firing the graphitizable carbon precursor according to a normal firing procedure.
The firing may be a firing step in which (a) an easily graphitizable carbon precursor is fired at 800 ° C. or more and less than 2500 ° C. to perform main firing, and (b) an easily graphitizable carbon precursor, 300 ° C. or more and 800 ° C. or more. It may be a baking step in which preliminary baking is performed at a temperature lower than ℃, and then main baking is performed at 800 ° C. or higher and lower than 2500 ° C.
Conditions other than temperature can be performed under the conditions described in the column “<< Firing”.
前記易黒鉛化性炭素質材料の物性は、特に限定されるものではないが、以下の物性を有するものが好ましい。
前記易黒鉛化性炭素質材料の、広角X線回折法からBragg式を用いて算出される(002)面の平均面間隔d002は、好ましくは0.345nm以上0.375nm未満であり、更に好ましくは0.345nm〜0.360nmである。The physical properties of the graphitizable carbonaceous material are not particularly limited, but those having the following physical properties are preferable.
The average plane distance d 002 of the (002) plane calculated from the graphitizable carbonaceous material using the Bragg equation from a wide-angle X-ray diffraction method is preferably 0.345 nm or more and less than 0.375 nm, Preferably it is 0.345 nm-0.360 nm.
易黒鉛化性炭素質材料の、窒素吸着BET3点法により求められる比表面積は、1m2/g〜10m2/gであり、好ましくは1.2m2/g〜9.5m2/gであり、より好ましくは1.4m2/g〜9.0m2/gである。小さすぎる比表面積では、炭素質材料へのリチウムイオンの吸着量が少なくなり、非水電解質二次電池の充電容量が少なくなることがある。高すぎる比表面積では、リチウムイオンが炭素質材料の表面で反応し、リチウムイオンの利用効率が低くなることがある。The graphitizable carbonaceous material, specific surface area determined by nitrogen adsorption BET3 point method is a 1m 2 / g~10m 2 / g, there preferably 1.2m 2 /g~9.5m 2 / g , more preferably 1.4m 2 /g~9.0m 2 / g. When the specific surface area is too small, the amount of lithium ions adsorbed on the carbonaceous material is decreased, and the charge capacity of the nonaqueous electrolyte secondary battery may be decreased. When the specific surface area is too high, lithium ions may react on the surface of the carbonaceous material, and the utilization efficiency of lithium ions may be reduced.
易黒鉛化性炭素質材料の窒素原子量は、少ないほどよいが、通常、元素分析によって得られた分析値より、0.5重量%以下であることが好ましい。窒素原子量が多すぎると、リチウムイオンと窒素とが反応し、リチウムイオン効率を低下させるだけでなく、保存中に空気中の酸素と反応することがある。 Although the amount of nitrogen atoms in the graphitizable carbonaceous material is preferably as small as possible, it is usually preferably 0.5% by weight or less from the analytical value obtained by elemental analysis. When the amount of nitrogen atoms is too large, lithium ions and nitrogen react to reduce lithium ion efficiency, and may react with oxygen in the air during storage.
易黒鉛化性炭素質材料の酸素原子量は、少ないほどよいが、通常、元素分析によって得られた分析値より、0.25重量%以下であることが好ましい。酸素原子量が多すぎると、リチウムイオンと酸素とが反応し、リチウムイオン効率を低下させるだけでなく、空気中の酸素、水分を誘引し、易黒鉛化性炭素質材料と反応する確率を高めるだけでなく、水を吸着したとき、容易に脱離させないなど、リチウム効率が低下することがある。 The amount of oxygen atoms in the graphitizable carbonaceous material is preferably as small as possible, but is usually preferably 0.25% by weight or less from the analytical value obtained by elemental analysis. If the amount of oxygen atoms is too large, lithium ions and oxygen react to reduce lithium ion efficiency, but also attract oxygen and moisture in the air and increase the probability of reacting with graphitizable carbonaceous materials. In addition, when water is adsorbed, the lithium efficiency may decrease, for example, it may not be easily desorbed.
易黒鉛化性炭素質材料の平均粒子径(Dv50)は、好ましくは3〜30μmである。平均粒子径が小さすぎると、微粉が増加し、易黒鉛化性炭素質材料の比表面積が増加する。その結果、易黒鉛化性炭素質材料と電解液との反応性が高くなり、不可逆容量が増加し、正極の容量が無駄になる割合が増加することがある。易黒鉛化性炭素質材料の平均粒子径は、より好ましくは4μm以上、特に好ましくは5μm以上である。平均粒子径が30μm以下の場合、粒子内でのリチウムの拡散自由行程が少なく、急速な充放電が可能となり好ましい。平均粒子径の上限としては30μm以下が好ましいが、より好ましくは19μm以下であり、更に好ましくは17μm以下であり、更に好ましくは16μm以下、最も好ましくは15μm以下である。The average particle diameter (D v50 ) of the graphitizable carbonaceous material is preferably 3 to 30 μm. If the average particle size is too small, fine powder increases and the specific surface area of the graphitizable carbonaceous material increases. As a result, the reactivity between the graphitizable carbonaceous material and the electrolytic solution is increased, the irreversible capacity is increased, and the proportion of wasted capacity of the positive electrode may be increased. The average particle diameter of the graphitizable carbonaceous material is more preferably 4 μm or more, and particularly preferably 5 μm or more. When the average particle size is 30 μm or less, the lithium free diffusion process in the particles is small, and rapid charge / discharge is possible, which is preferable. The upper limit of the average particle diameter is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, still more preferably 16 μm or less, and most preferably 15 μm or less.
(黒鉛質材料)
本発明の混合負極材料に含まれる黒鉛質材料は、限定されるものではないが、天然黒鉛又は人造黒鉛を挙げることができる。(Graphite material)
Although the graphite material contained in the mixed negative electrode material of the present invention is not limited, natural graphite or artificial graphite can be mentioned.
人造黒鉛は、限定されるものではないが、前記易黒鉛化性炭素前駆体を、不活性ガス雰囲気中で2500〜3000℃で、焼成(黒鉛化処理)することによって製造することができる。
黒鉛化処理は、炭素前駆体を連続して黒鉛化処理温度(2500〜3000℃)まで昇温して炭素化と黒鉛化処理を連続して行うことも可能であるが、一旦黒鉛化処理温度より低い温度で、例えば500〜1500℃で炭素化(焼成)した後、黒鉛化処理することが工業的に実施する場合は装置の材質、構造、加熱方法等の設計の容易さ等の点から好ましい場合が多い。
黒鉛化処理は不活性ガス雰囲気中又は減圧下に2500〜3000℃の温度に数分〜数時間程度保持することによって行う。黒鉛化温度とは被処理物が受ける最高の処理温度をいう。黒鉛化は減圧下又は不活性ガス雰囲気中で行うが、これは黒鉛化時に原料が雰囲気ガスと反応することを防止するものである。不活性ガスとしてはアルゴンガス、ヘリウムガス等を挙げることができる。又減圧下の黒鉛化においては上記不活性ガス共存下の雰囲気が好ましい。Although artificial graphite is not limited, it can be produced by firing (graphitizing) the graphitizable carbon precursor at 2500 to 3000 ° C. in an inert gas atmosphere.
In the graphitization treatment, it is possible to continuously raise the carbon precursor to the graphitization treatment temperature (2500 to 3000 ° C.) and continuously perform the carbonization and the graphitization treatment. In the case where carbonization (firing) is performed at a lower temperature, for example, at 500 to 1500 ° C., and then graphitization is performed industrially, the material, structure, heating method, etc. of the apparatus are easy to design. Often preferred.
The graphitization treatment is performed by maintaining the temperature at 2500 to 3000 ° C. for about several minutes to several hours in an inert gas atmosphere or under reduced pressure. The graphitization temperature refers to the highest processing temperature that the workpiece is subjected to. Graphitization is carried out under reduced pressure or in an inert gas atmosphere, which prevents the raw material from reacting with the atmospheric gas during graphitization. Examples of the inert gas include argon gas and helium gas. In graphitization under reduced pressure, an atmosphere in the presence of the above inert gas is preferable.
黒鉛質材料の物性は、特に限定されるものではないが、以下の物性を有するものが好ましい。
黒鉛の理論密度は、2.27g/cm3であるが、本発明の製造方法において使用される黒鉛質材料の真密度は、2.15g/cm3以上であり、好ましくは2.17g/cm3以上であり、更に好ましくは2.20g/cm3以上である。真密度が大きい場合、電池容積当たりのエネルギー密度を高くすることができるからである。
黒鉛質材料の、広角X線回折法からBragg式を用いて算出される(002)面の平均面間隔d002は、好ましくは0.336〜0.345nmであり、より好ましくは0.336〜0.344nmであり、更に好ましくは0.337〜0.342nmである。d002が0.350nmを超える黒鉛質材料は、放電曲線の平坦性が悪化することがある。
黒鉛質材料の、c軸方向の結晶子の大きさLc(002)は、好ましくは15nmを超え50nm以下であり、より好ましくは15nmを超え40nm以下であり、更に好ましくは20〜40nmである。Lc(002)が50nmを超えるような黒鉛構造の発達した黒鉛質材料を負極材料として用いた二次電池においては、活物質のドープ及び脱ドープによる黒鉛質物質の崩壊や電解液の分解が起り易く、好ましくない。The physical properties of the graphite material are not particularly limited, but those having the following physical properties are preferable.
The theoretical density of graphite is 2.27 g / cm 3 , but the true density of the graphite material used in the production method of the present invention is 2.15 g / cm 3 or more, preferably 2.17 g / cm 3. 3 or more, more preferably 2.20 g / cm 3 or more. This is because when the true density is large, the energy density per battery volume can be increased.
The average interplanar spacing d 002 of the (002) plane calculated from the wide-angle X-ray diffraction method of the graphite material using the Bragg equation is preferably 0.336 to 0.345 nm, more preferably 0.336 to It is 0.344 nm, and more preferably 0.337 to 0.342 nm. A graphite material having d 002 exceeding 0.350 nm may deteriorate the flatness of the discharge curve.
The crystallite size Lc (002) in the c-axis direction of the graphite material is preferably more than 15 nm and 50 nm or less, more preferably more than 15 nm and 40 nm or less, and further preferably 20 to 40 nm. In a secondary battery using a graphite material having a graphite structure with an Lc (002) exceeding 50 nm as a negative electrode material, the graphite material collapses or the electrolyte solution decomposes due to doping and dedoping of the active material. It is easy and not preferable.
黒鉛質材料の、窒素吸着BET3点法により求められる比表面積は、0.5m2/g〜10m2/gであり、好ましくは0.7m2/g〜9.5m2/gであり、より好ましくは1.0m2/g〜9.0m2/gである。小さすぎる比表面積では、炭素質材料へのリチウムイオンの吸着量が少なくなり、非水電解質二次電池の充電容量が少なくなることがある。高すぎる比表面積では、リチウムイオンが炭素質材料の表面で反応し、リチウムイオンの利用効率が低くなることがある。Of graphitized material, specific surface area determined by nitrogen adsorption BET3 point method is 0.5m 2 / g~10m 2 / g, preferably 0.7m 2 /g~9.5m 2 / g, more preferably from 1.0m 2 /g~9.0m 2 / g. When the specific surface area is too small, the amount of lithium ions adsorbed on the carbonaceous material is decreased, and the charge capacity of the nonaqueous electrolyte secondary battery may be decreased. When the specific surface area is too high, lithium ions may react on the surface of the carbonaceous material, and the utilization efficiency of lithium ions may be reduced.
黒鉛質材料の平均粒子径(Dv50)は、好ましくは3〜30μmである。平均粒子径が小さすぎると、微粉が増加し、黒鉛質材料の比表面積が増加する。その結果、黒鉛質材料と電解液との反応性が高くなり、不可逆容量が増加し、正極の容量が無駄になる割合が増加することがある。黒鉛質材料の平均粒子径は、より好ましくは4μm以上、特に好ましくは5μm以上である。平均粒子径が30μm以下の場合、粒子内でのリチウムの拡散自由行程が少なく、急速な充放電が可能となり好ましい。平均粒子径の上限としては30μm以下が好ましいが、より好ましくは19μm以下であり、更に好ましくは17μm以下であり、更に好ましくは16μm以下、最も好ましくは15μm以下である。The average particle diameter (D v50 ) of the graphite material is preferably 3 to 30 μm. If the average particle size is too small, fine powder increases and the specific surface area of the graphite material increases. As a result, the reactivity between the graphite material and the electrolytic solution is increased, the irreversible capacity is increased, and the proportion of wasted capacity of the positive electrode may be increased. The average particle diameter of the graphite material is more preferably 4 μm or more, and particularly preferably 5 μm or more. When the average particle size is 30 μm or less, the lithium free diffusion process in the particles is small, and rapid charge / discharge is possible, which is preferable. The upper limit of the average particle diameter is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, still more preferably 16 μm or less, and most preferably 15 μm or less.
(混合比)
本発明の混合工程における前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料との混合比は、本発明の効果が得られる限りにおいて、限定されるものではないが、難黒鉛化性炭素質材料は、得られる混合負極材料の総質量に対して20質量%〜80質量%であり、好ましくは25質量%〜75質量%であり、更に好ましくは、30質量%〜70質量%である。易黒鉛化性炭素質材料は、得られる混合負極材料の総質量に対して20質量%〜80質量%であり、好ましくは25質量%〜75質量%であり、更に好ましくは、30質量%〜70質量%である。黒鉛質材料は、得られる混合負極材料の総質量に対して20質量%〜80質量%であり、好ましくは25質量%〜75質量%であり、更に好ましくは、30質量%〜70質量%である。(mixing ratio)
The mixing ratio of the non-graphitizable carbonaceous material and the graphitizable carbonaceous material and / or the graphite material in the mixing step of the present invention is not limited as long as the effect of the present invention is obtained. Although the non-graphitizable carbonaceous material is 20% by mass to 80% by mass, preferably 25% by mass to 75% by mass, and more preferably 30% by mass with respect to the total mass of the obtained mixed negative electrode material. It is mass%-70 mass%. The graphitizable carbonaceous material is 20% by mass to 80% by mass with respect to the total mass of the obtained mixed negative electrode material, preferably 25% by mass to 75% by mass, and more preferably 30% by mass to 70% by mass. The graphite material is 20% by mass to 80% by mass, preferably 25% by mass to 75% by mass, and more preferably 30% by mass to 70% by mass with respect to the total mass of the obtained mixed negative electrode material. is there.
(1−2)非水電解質二次電池用混合負極材料の製造方法(B)
《焼成工程(1)》
前記製造方法(B)における焼成工程(1)においては、比表面積100〜500m2/gの難黒鉛化性炭素前駆体と揮発性有機物との混合物を800〜1400℃の不活性ガス雰囲気下で焼成する。(1-2) Manufacturing method of mixed negative electrode material for non-aqueous electrolyte secondary battery (B)
<< Baking process (1) >>
In the firing step (1) in the production method (B), a mixture of a non-graphitizable carbon precursor having a specific surface area of 100 to 500 m 2 / g and a volatile organic substance is placed in an inert gas atmosphere at 800 to 1400 ° C. Bake.
《難黒鉛化性炭素前駆体》
本発明の製造方法(B)において、粉砕後の難黒鉛化性炭素前駆体の比表面積は、100〜500m2/gであり、好ましくは200〜500m2/gであり、例えば200〜400m2/gである。比表面積が小さすぎると、後述する焼成工程を経ても、難黒鉛化性炭素質材料の微細孔を十分に低減することができないことがあり、難黒鉛化性炭素質材料の吸湿性が低下しにくくなることがある。難黒鉛化性炭素質材料に水分が存在すると、電解液の加水分解に伴う酸の発生や水の電気分解によるガスの発生が問題を引き起こすことがある。また、空気雰囲気下で難黒鉛化性炭素質材料の酸化が進み、電池性能が大きく変化することもある。比表面積が大きくなりすぎると、後述する焼成工程を経ても炭素質材料の比表面積が小さくならず、非水電解質二次電池のリチウムイオンの利用効率が低下することがある。難黒鉛化性炭素前駆体の比表面積は、気相脱灰の温度の制御によって調製することが可能である。なお、本明細書において、比表面積はBET法(窒素吸着BET3点法)により定まる比表面積(BET比表面積)を意味する。具体的には後述する方法を用いて測定することができる。
非水電解質二次電池用混合負極材料の製造方法(B)で使用する難黒鉛化性炭素前駆体は、前記の通り、比表面積100〜500m2/gである。それ以外の難黒鉛化性炭素前駆体の特徴及び調整方法などは、限定されるものではないが、実質的に非水電解質二次電池用混合負極材料の製造方法(A)の「《難黒鉛化性炭素質前駆体》」の欄に記載の難黒鉛化性炭素前駆体と同様であってもよい。<Non-graphitizable carbon precursor>
In the production method of the present invention (B), a specific surface area of the non-graphitizable carbon precursor after the pulverization is 100 to 500 m 2 / g, preferably 200 to 500 m 2 / g, for example 200 to 400 m 2 / G. If the specific surface area is too small, the micropores of the non-graphitizable carbonaceous material may not be sufficiently reduced even after the firing step described later, and the hygroscopicity of the non-graphitizable carbonaceous material is reduced. It may be difficult. If moisture is present in the non-graphitizable carbonaceous material, the generation of acid accompanying the hydrolysis of the electrolytic solution and the generation of gas due to the electrolysis of water may cause problems. Further, the oxidation of the non-graphitizable carbonaceous material progresses in an air atmosphere, and the battery performance may change greatly. If the specific surface area becomes too large, the specific surface area of the carbonaceous material will not be reduced even after the firing step described later, and the utilization efficiency of lithium ions in the nonaqueous electrolyte secondary battery may be reduced. The specific surface area of the non-graphitizable carbon precursor can be prepared by controlling the temperature of vapor phase decalcification. In the present specification, the specific surface area means a specific surface area (BET specific surface area) determined by a BET method (nitrogen adsorption BET three-point method). Specifically, it can measure using the method mentioned later.
As described above, the non-graphitizable carbon precursor used in the method (B) for producing the mixed negative electrode material for a nonaqueous electrolyte secondary battery has a specific surface area of 100 to 500 m 2 / g. The other features of the non-graphitizable carbon precursor and the adjustment method thereof are not limited, but are substantially “" Non-graphite graphite "in the method (A) for producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery. It may be the same as the non-graphitizable carbon precursor described in the column of “graphitizable carbonaceous precursor” ”.
《揮発性有機物》
本発明の製造方法(B)において使用される揮発性有機物は、実質的に前記非水電解質二次電池用混合負極材料の製造方法(A)の「《揮発性有機物》」の欄に記載の揮発性有機物を用いることができる。《Volatile organic matter》
The volatile organic substance used in the production method (B) of the present invention is substantially the same as that described in the column “<< Volatile organic substance” in the production method (A) of the mixed negative electrode material for a nonaqueous electrolyte secondary battery. Volatile organic materials can be used.
《焼成》
本発明の製造方法(B)における焼成は、比表面積100〜500m2/gの難黒鉛化性炭素前駆体を用いる限りにおいて、実質的に前記非水電解質二次電池用混合負極材料の製造方法(A)の「《焼成》」の欄に記載に従って、行うことができる。<Baking>
As long as the non-graphitizable carbon precursor having a specific surface area of 100 to 500 m 2 / g is used for the firing in the production method (B) of the present invention, the method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery is substantially used. It can be carried out according to the description in the column “<< Firing” in (A).
《難黒鉛化性炭素質材料》
本発明の製造方法(B)において使用される難黒鉛化性炭素質材料は、比表面積100〜500m2/gの難黒鉛化性炭素前駆体を焼成して得られたものである限り、実質的に前記非水電解質二次電池用混合負極材料の製造方法(A)の「《難黒鉛化性炭素質材料》」の欄に記載の難黒鉛化性炭素質材料と同様のものでもよい。《Non-graphitizable carbonaceous material》
The non-graphitizable carbonaceous material used in the production method (B) of the present invention is substantially as long as it is obtained by firing a non-graphitizable carbon precursor having a specific surface area of 100 to 500 m 2 / g. In particular, it may be the same as the non-graphitizable carbonaceous material described in the column “<< Non-graphitizable carbonaceous material >>” in the manufacturing method (A) of the mixed negative electrode material for nonaqueous electrolyte secondary batteries.
《混合工程(2)》
本発明の製造方法(B)における混合工程(2)は、実質的に前記非水電解質二次電池用混合負極材料の製造方法(A)の「《混合工程(2)》」の欄の記載に従って、行うことができる。<< Mixing process (2) >>
The mixing step (2) in the production method (B) of the present invention is substantially the description in the column “<< Mixing step (2) >>” of the production method (A) of the mixed negative electrode material for a nonaqueous electrolyte secondary battery. Can be done according to.
[2]非水電解質二次電池用混合負極材料
本発明の非水電解質二次電池用混合負極材料は、難黒鉛化性炭素質材料と易黒鉛化性炭素質材料及び/又は黒鉛質材料とを含む非水電解質二次電池用混合負極材料であって、広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される難黒鉛化性炭素質材料の炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である。本発明の非水電解質二次電池用混合負極材料は、限定されるものではないが、例えば本発明の非水電解質二次電池用混合負極材料の製造方法(A)又は(B)によって、製造することができる。[2] Mixed negative electrode material for nonaqueous electrolyte secondary battery The mixed negative electrode material for nonaqueous electrolyte secondary battery of the present invention comprises a non-graphitizable carbonaceous material, an easily graphitizable carbonaceous material and / or a graphite material. A non-aqueous electrolyte secondary battery mixed negative electrode material containing an average interplanar spacing d 002 of the (002) plane of the non-graphitizable carbonaceous material calculated using the Bragg equation in a wide-angle X-ray diffraction method Is in the range of 0.38 to 0.40 nm, the specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g, and is observed in the Raman spectrum. The difference between the half width of the peak near 1360 cm −1 of the carbon precursor of the non-graphitizable carbonaceous material and the half width of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material is 50-84 cm −1 . The mixed negative electrode material for a nonaqueous electrolyte secondary battery of the present invention is not limited. For example, the mixed negative electrode material for a nonaqueous electrolyte secondary battery of the present invention is manufactured by the manufacturing method (A) or (B). can do.
本発明の非水電解質二次電池用混合負極材料の、窒素吸着BET3点法により求められる比表面積は、特に限定されるものではないが、1m2/g〜10m2/gであり、好ましくは1.2m2/g〜9.5m2/gであり、より好ましくは1.4m2/g〜9.0m2/gである。The non-aqueous electrolyte secondary battery mixing a negative electrode material of the present invention, the specific surface area determined by nitrogen adsorption BET3 point method is not particularly limited, a 1m 2 / g~10m 2 / g, preferably a 1.2m 2 /g~9.5m 2 / g, more preferably 1.4m 2 /g~9.0m 2 / g.
本発明の非水電解質二次電池用混合負極材料の真密度は、特に限定されるものではないが、好ましくは1.45〜2.10g/cm3であり、より好ましくは1.50〜2.05g/cm3であり、更に好ましくは1.50〜2.00g/cm3である。The true density of the mixed negative electrode material for a non-aqueous electrolyte secondary battery of the present invention is not particularly limited, but is preferably 1.45 to 2.10 g / cm 3 , more preferably 1.50 to 2. 0.05 g / cm 3 , more preferably 1.50 to 2.00 g / cm 3 .
本発明の非水電解質二次電池用混合負極材料の平均粒子径(Dv50)は、特に限定されるものではないが、好ましくは3〜30μmである。平均粒子径の下限は、より好ましくは4μm以上、特に好ましくは5μm以上である。平均粒子径の上限は、より好ましくは19μm以下であり、更に好ましくは17μm以下であり、更に好ましくは16μm以下、最も好ましくは15μm以下である。Although the average particle diameter ( Dv50 ) of the mixed negative electrode material for nonaqueous electrolyte secondary batteries of this invention is not specifically limited, Preferably it is 3-30 micrometers. The lower limit of the average particle diameter is more preferably 4 μm or more, and particularly preferably 5 μm or more. The upper limit of the average particle diameter is more preferably 19 μm or less, further preferably 17 μm or less, further preferably 16 μm or less, and most preferably 15 μm or less.
(難黒鉛化性炭素質材料)
本発明の非水電解質二次電池用混合負極材料に含まれる難黒鉛化性炭素質材料の(002)面の平均面間隔d002は、広角X線回折法においてBragg式を用いて算出され、0.38〜0.40nmの範囲にある。前記難黒鉛化性炭素質材料の窒素吸着BET3点法により求めた比表面積は1〜10m2/gの範囲にある。前記難黒鉛化性炭素質材料の難黒鉛化性炭素前駆体のラマンスペクトルにおいて観察される1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1であり、より好ましくは55cm−1〜83cm−1であり、更に好ましくは60cm−1〜80cm−1である。(Non-graphitizable carbonaceous material)
The average interplanar spacing d 002 of the (002) plane of the non-graphitizable carbonaceous material contained in the mixed negative electrode material for a nonaqueous electrolyte secondary battery of the present invention is calculated using the Bragg equation in the wide angle X-ray diffraction method, It exists in the range of 0.38-0.40 nm. The specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g. The half-width value of the peak near 1360 cm −1 observed in the Raman spectrum of the non-graphitizable carbon precursor of the non-graphitizable carbonaceous material, and the value near 1360 cm −1 of the non-graphitizable carbonaceous material. the difference between the value of the half width of the peak is 50~84cm -1, more preferably from 55cm -1 ~83cm -1, more preferably from 60cm -1 ~80cm -1.
(密度こう配管法による真密度による炭素質材料の分離)
本発明の混合負極材料(炭素材混合物)に含まれる難黒鉛化性炭素質材料、易黒鉛化性炭素質材料、及び黒鉛質材料は、密度こう配管法による真密度によって分離することができる。具体的には、炭素繊維−密度の試験方法(JISR7603−1999)の密度こう配管法に準拠して操作を行い、炭素材混合物に含まれる非黒鉛性炭素(易黒鉛化性炭素質材料、及び黒鉛質材料)を分離し、測定された真密度から、それらを同定することができる。
更に、バインダー等を含み成形された非水電解質二次電池用負極から、炭素質材料を分離し、同じように密度こう配管法による真密度によって、難黒鉛化性炭素質材料、易黒鉛化性炭素質材料、及び黒鉛質材料を分離することが可能である。(Separation of carbonaceous material by true density by density pipe method)
The non-graphitizable carbonaceous material, the graphitizable carbonaceous material, and the graphite material contained in the mixed negative electrode material (carbon material mixture) of the present invention can be separated by the true density by the density pipe method. Specifically, the carbon fiber-density test method (JIS R7603-1999) is operated in accordance with the density piping method, and non-graphitizable carbon contained in the carbon material mixture (easily graphitizable carbonaceous material, and Graphite materials) can be separated and identified from the measured true density.
Furthermore, the carbonaceous material is separated from the negative electrode for the non-aqueous electrolyte secondary battery that is formed including a binder, and the non-graphitizable carbonaceous material and graphitizable property are similarly obtained by the true density by the density pipe method. It is possible to separate the carbonaceous material and the graphite material.
[3]非水電解質二次電池用負極
《負極電極の製造》
本発明の混合負極材料を用いる負極電極は、炭素質材料に結合剤(バインダー)を添加し適当な溶媒を適量添加、混練し、電極合剤とした後に、金属板等からなる集電板に塗布・乾燥後、加圧成形することにより製造することができる。本発明の混合負極材料を用いることにより特に導電助剤を添加しなくとも高い導電性を有する電極を製造することができるが、更に高い導電性を賦与することを目的に必要に応じて電極合剤を調製時に、導電助剤を添加することができる。導電助剤としては、アセチレンブラック、ケッチェンブラック、カーボンナノファイバー、カーボンナノチューブ、又はカーボンファイバーなどを用いることができ、添加量は使用する導電助剤の種類によっても異なるが、添加する量が少なすぎると期待する導電性が得られないので好ましくなく、多すぎると電極合剤中の分散が悪くなるので好ましくない。このような観点から、添加する導電助剤の好ましい割合は0.5〜15重量%(ここで、活物質(混合負極材料)量+バインダー量+導電助剤量=100重量%とする)であり、更に好ましくは0.5〜7重量%、特に好ましくは0.5〜5重量%である。結合剤としては、PVDF(ポリフッ化ビニリデン)、ポリテトラフルオロエチレン、およびSBR(スチレン・ブタジエン・ラバー)とCMC(カルボキシメチルセルロース)との混合物等の電解液と反応しないものであれば特に限定されない。中でもPVDFは、活物質表面に付着したPVDFがリチウムイオン移動を阻害することが少なく、良好な入出力特性を得るために好ましい。PVDFを溶解しスラリーを形成するためにN−メチルピロリドン(NMP)などの極性溶媒が好ましく用いられるが、SBRなどの水性エマルジョンやCMCを水に溶解して用いることもできる。結合剤の添加量が多すぎると、得られる電極の抵抗が大きくなるため、電池の内部抵抗が大きくなり電池特性を低下させるので好ましくない。また、結合剤の添加量が少なすぎると、負極材料粒子相互および集電材との結合が不十分となり好ましくない。結合剤の好ましい添加量は、使用するバインダーの種類によっても異なるが、PVDF系のバインダーでは好ましくは3〜13重量%であり、更に好ましくは3〜10重量%である。一方、溶媒に水を使用するバインダーでは、SBRとCMCとの混合物など、複数のバインダーを混合して使用することが多く、使用する全バインダーの総量として0.5〜5重量%が好ましく、更に好ましくは1〜4重量%である。電極活物質層は集電板の両面に形成するのが基本であるが、必要に応じて片面でもよい。電極活物質層が厚いほど、集電板やセパレータなどが少なくて済むため高容量化には好ましいが、対極と対向する電極面積が広いほど入出力特性の向上に有利なため活物質層が厚すぎると入出力特性が低下するため好ましくない。好ましい活物質層(片面当たり)の厚みは、限定されるものではなく10〜1000μmの範囲内であるが、好ましくは10〜80μmであり、更に好ましくは20〜75μm、特に好ましくは20〜60μmである。
負極電極は、通常集電体を有する。負極集電体としては、例えば、SUS、銅、ニッケル又はカーボンを用いるができ、中でも、銅又はSUSが好ましい。[3] Negative electrode for nonaqueous electrolyte secondary battery << Manufacture of negative electrode >>
In the negative electrode using the mixed negative electrode material of the present invention, a binder (binder) is added to a carbonaceous material, an appropriate amount of an appropriate solvent is added and kneaded to form an electrode mixture, and then a current collector plate made of a metal plate or the like It can be produced by pressure molding after coating and drying. By using the mixed negative electrode material of the present invention, an electrode having high conductivity can be produced without particularly adding a conductive auxiliary agent. However, the electrode combination is necessary for the purpose of imparting higher conductivity. When preparing the agent, a conductive aid can be added. As the conductive auxiliary agent, acetylene black, ketjen black, carbon nanofiber, carbon nanotube, carbon fiber or the like can be used, and the addition amount varies depending on the type of conductive auxiliary agent used, but the added amount is small. If the amount is too large, the expected conductivity cannot be obtained, and this is not preferable. If the amount is too large, the dispersion in the electrode mixture deteriorates. From such a viewpoint, the preferable ratio of the conductive auxiliary agent to be added is 0.5 to 15% by weight (where the amount of active material (mixed negative electrode material) + the amount of binder + the amount of conductive auxiliary agent = 100% by weight). More preferably 0.5 to 7% by weight, particularly preferably 0.5 to 5% by weight. The binder is not particularly limited as long as it does not react with an electrolytic solution such as PVDF (polyvinylidene fluoride), polytetrafluoroethylene, and a mixture of SBR (styrene-butadiene rubber) and CMC (carboxymethylcellulose). Among them, PVDF is preferable because PVDF attached to the surface of the active material hardly inhibits lithium ion migration and obtains favorable input / output characteristics. In order to dissolve PVDF and form a slurry, a polar solvent such as N-methylpyrrolidone (NMP) is preferably used, but an aqueous emulsion such as SBR or CMC can also be used by dissolving in water. When the amount of the binder added is too large, the resistance of the obtained electrode is increased, which is not preferable because the internal resistance of the battery is increased and the battery characteristics are deteriorated. Moreover, when there is too little addition amount of a binder, the coupling | bonding with negative electrode material particle | grains and a collector is insufficient, and it is unpreferable. Although the preferable addition amount of a binder changes also with kinds of binder to be used, it is preferably 3 to 13% by weight, more preferably 3 to 10% by weight in the case of a PVDF type binder. On the other hand, in a binder using water as a solvent, a mixture of a plurality of binders such as a mixture of SBR and CMC is often used, and the total amount of all binders used is preferably 0.5 to 5% by weight. Preferably it is 1-4 weight%. The electrode active material layer is basically formed on both sides of the current collector plate, but may be on one side if necessary. A thicker electrode active material layer is preferable for increasing the capacity because fewer current collector plates and separators are required. However, the larger the electrode area facing the counter electrode, the better the input / output characteristics, and the thicker the active material layer. Too much is not preferable because the input / output characteristics deteriorate. The thickness of the active material layer (per one side) is not limited and is in the range of 10 to 1000 μm, preferably 10 to 80 μm, more preferably 20 to 75 μm, and particularly preferably 20 to 60 μm. is there.
The negative electrode usually has a current collector. As the negative electrode current collector, for example, SUS, copper, nickel, or carbon can be used, and among them, copper or SUS is preferable.
[4]非水電解質二次電池
本発明の混合負極材料を用いて、非水電解質二次電池の負極を形成した場合、正極材料、セパレータ、電解液など電池を構成する他の材料は特に限定されることなく、非水溶媒二次電池として従来使用され、あるいは提案されている種々の材料を使用することが可能である。[4] Non-aqueous electrolyte secondary battery When the negative electrode of the non-aqueous electrolyte secondary battery is formed using the mixed negative electrode material of the present invention, other materials constituting the battery such as a positive electrode material, a separator, and an electrolytic solution are particularly limited. It is possible to use various materials conventionally used or proposed as a nonaqueous solvent secondary battery.
(正極電極)
正極電極は、正極活物質を含み、更に導電助剤、バインダー、又はその両方を含んでもよい。正極活物質層における正極活物質と、他の材料との混合比は、本発明の効果が得られる限りにおいて、限定されるものではなく、適宜決定することができる。
正極活物質は、正極活物質を限定せずに用いることができる。例えば、層状酸化物系(LiMO2と表されるもので、Mは金属:例えばLiCoO2、LiNiO2、LiMnO2、又はLiNixCoyMnzO2(ここでx、y、zは組成比を表す))、オリビン系(LiMPO4で表され、Mは金属:例えばLiFePO4など)、スピネル系(LiM2O4で表され、Mは金属:例えばLiMn2O4など)の複合金属カルコゲン化合物を挙げることができ、これらのカルコゲン化合物を必要に応じて混合してもよい。
また、コバルト酸リチウムのコバルトの一部をニッケルとマンガンで置換し、コバルト、ニッケル、マンガンの3つを使用することで材料の安定性を高めた三元系〔Li(Ni−Mn−Co)O2〕や前記三元系のマンガンの代わりにアルミニウムを使用するNCA系材料〔Li(Ni−Co−Al)O2〕が知られており、これらの材料を使用することができる。(Positive electrode)
The positive electrode includes a positive electrode active material, and may further include a conductive additive, a binder, or both. The mixing ratio of the positive electrode active material and other materials in the positive electrode active material layer is not limited as long as the effect of the present invention is obtained, and can be determined as appropriate.
The positive electrode active material can be used without limiting the positive electrode active material. For example, a layered oxide system (expressed as LiMO 2 , where M is a metal: for example, LiCoO 2 , LiNiO 2 , LiMnO 2 , or LiNi x Co y Mn z O 2 (where x, y, z are composition ratios) ), Olivine-based (represented by LiMPO 4 , M is a metal: for example LiFePO 4 ), spinel-based (represented by LiM 2 O 4 , M is a metal: for example LiMn 2 O 4 ) Compounds may be mentioned, and these chalcogen compounds may be mixed as necessary.
In addition, a ternary system [Li (Ni-Mn-Co) in which a part of cobalt of lithium cobaltate is replaced with nickel and manganese, and the stability of the material is improved by using three of cobalt, nickel, and manganese. NCA-based materials [Li (Ni—Co—Al) O 2 ] using aluminum instead of O 2 ] and the ternary manganese are known, and these materials can be used.
正極電極は、更に導電助剤及び/又はバインダーを含むことができる。導電助剤としては、例えば、アセチレンブラック、ケッチェンブラック、又はカーボンファイバーを挙げることができる。導電助剤の含有量は、限定されるものではないが、例えば0.5〜15重量%である。また、バインダーとしては、例えば、PTFE又はPVDF等のフッ素含有バインダーを挙げることができる。導電助剤の含有量は、限定されるものではないが、例えば0.5〜15重量%である。また、正極活物質層の厚さは、限定されないが、例えば10〜1000μmの範囲内である。
正極活物質層は、通常集電体を有する。負極集電体としては、例えば、SUS、アルミニウム、ニッケル、鉄、チタンおよびカーボンを用いるができ、中でも、アルミニウム又はSUSが好ましい。The positive electrode can further contain a conductive additive and / or a binder. As a conductive support agent, acetylene black, ketjen black, or carbon fiber can be mentioned, for example. Although content of a conductive support agent is not limited, For example, it is 0.5 to 15 weight%. Moreover, as a binder, fluorine-containing binders, such as PTFE or PVDF, can be mentioned, for example. Although content of a conductive support agent is not limited, For example, it is 0.5 to 15 weight%. Moreover, although the thickness of a positive electrode active material layer is not limited, For example, it exists in the range of 10-1000 micrometers.
The positive electrode active material layer usually has a current collector. As the negative electrode current collector, for example, SUS, aluminum, nickel, iron, titanium, and carbon can be used, and among these, aluminum or SUS is preferable.
(電解液)
これら正極と負極との組み合わせで用いられる非水溶媒型電解液は、一般に非水溶媒に電解質を溶解することにより形成される。非水溶媒としては、例えばプロピレンカーボネート、エチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、ジメトキシエタン、ジエトキシエタン、γ−ブチルラクトン、テトラヒドロフラン、2−メチルテトラヒドロフラン、スルホラン、又は1,3−ジオキソランなどの有機溶媒の一種又は二種以上を組み合わせて用いることができる。また、電解質としては、LiClO4、LiPF6、LiBF4、LiCF3SO3、LiAsF6、LiCl、LiBr、LiB(C6H5)4、又はLiN(SO3CF3)2などが用いられる。二次電池は、一般に上記のようにして形成した正極層と負極層とを必要に応じて不織布、その他の多孔質材料などからなる透液性セパレータを介して対向させ電解液中に浸漬させることにより形成される。セパレータとしては、二次電池に通常用いられる不織布、その他の多孔質材料からなる透過性セパレータを用いることができる。あるいはセパレータの代わりに、もしくはセパレータと一緒に、電解液を含浸させたポリマーゲルからなる固体電解質を用いることもできる。(Electrolyte)
The nonaqueous solvent electrolyte used in combination of these positive electrode and negative electrode is generally formed by dissolving an electrolyte in a nonaqueous solvent. Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, diethoxyethane, γ-butyllactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane. These can be used alone or in combination of two or more. As the electrolyte, LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiAsF 6 , LiCl, LiBr, LiB (C 6 H 5 ) 4 , or LiN (SO 3 CF 3 ) 2 is used. In secondary batteries, the positive electrode layer and the negative electrode layer formed as described above are generally immersed in an electrolytic solution with a liquid-permeable separator made of nonwoven fabric or other porous material facing each other as necessary. It is formed by. As the separator, a non-woven fabric usually used for a secondary battery or a permeable separator made of another porous material can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolytic solution can be used instead of or together with the separator.
以下、実施例によって本発明を具体的に説明するが、これらは本発明の範囲を限定するものではない。
なお、以下に炭素前駆体、揮発性有機物、炭素質材料、及び混合負極材料等の物性値の測定法を記載するが、実施例を含めて、本明細書中に記載する物性値は、以下の方法により求めた値に基づくものである。EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.
In addition, although the measuring method of physical property values, such as a carbon precursor, a volatile organic substance, a carbonaceous material, and a mixed negative electrode material, is described below, the physical property values described in this specification including the examples are as follows: This is based on the value obtained by the above method.
(窒素吸着法による比表面積測定)
以下にBETの式から誘導された近似式を記す。(Specific surface area measurement by nitrogen adsorption method)
An approximate expression derived from the BET expression is described below.
上記の近似式を用いて、液体窒素温度における、窒素吸着による3点法によりvmを求め、次式により試料の比表面積を計算した。Using the above approximate equation, vm was determined by a three-point method by nitrogen adsorption at liquid nitrogen temperature, and the specific surface area of the sample was calculated by the following equation.
このとき、vmは試料表面に単分子層を形成するに必要な吸着量(cm3/g)、vは実測される吸着量(cm3/g)、p0は飽和蒸気圧、pは絶対圧、cは定数(吸着熱を反映)、Nはアボガドロ数6.022×1023、a(nm2)は吸着質分子が試料表面で占める面積(分子占有断面積)である。In this case, v m adsorption amount necessary to form a monomolecular layer on the surface of the sample (cm 3 / g), v adsorption amount is measured (cm 3 / g), p 0 is saturation vapor pressure, p is Absolute pressure, c is a constant (reflecting the heat of adsorption), N is Avogadro's number 6.022 × 1023, and a (nm 2 ) is an area occupied by the adsorbate molecule on the sample surface (molecular occupation cross section).
具体的には、日本BELL社製「BELL Sorb Mini」を用いて、以下のようにして液体窒素温度における炭素材料への窒素の吸着量を測定した。粒子径約5〜50μmに粉砕した炭素材料を試料管に充填し、試料管を−196℃に冷却した状態で、一旦減圧し、その後所望の相対圧にて炭素材料に窒素(純度99.999%)を吸着させる。各所望の相対圧にて平衡圧に達した時の試料に吸着した窒素量を吸着ガス量vとした。 Specifically, the amount of nitrogen adsorbed on the carbon material at the liquid nitrogen temperature was measured as follows using “BELL Sorb Mini” manufactured by BELL JAPAN. A carbon material pulverized to a particle diameter of about 5 to 50 μm is filled in a sample tube, and the sample tube is cooled to −196 ° C., and then once depressurized. %) Is adsorbed. The amount of nitrogen adsorbed on the sample when the equilibrium pressure was reached at each desired relative pressure was defined as the amount of adsorbed gas v.
(X線回折法による平均層面間隔d002測定)
「株式会社リガク製MiniFlexII」を用い、炭素質材料粉末を試料ホルダーに充填し、Niフィルターにより単色化したCuKα線を線源とし、X線回折図形を得た。回折図形のピーク位置は重心法(回折線の重心位置を求め、これに対応する2θ値でピーク位置を求める方法)により求め、標準物質用高純度シリコン粉末の(111)面の回折ピークを用いて補正した。CuKα線の波長を0.15418nmとし、以下に記すBraggの公式によりd002を算出した。(Measurement of average layer spacing d002 by X-ray diffraction method)
Using “MiniFlexII manufactured by Rigaku Corporation”, an X-ray diffraction pattern was obtained using a CuKα ray filled with a carbonaceous material powder in a sample holder and monochromated by a Ni filter as a radiation source. The peak position of the diffraction pattern is obtained by the barycentric method (a method of obtaining the barycentric position of the diffraction line and obtaining the peak position by the corresponding 2θ value), and using the diffraction peak on the (111) plane of the high-purity silicon powder for standard materials. Corrected. The wavelength of the CuKα ray was 0.15418 nm, and d002 was calculated according to the Bragg formula described below.
(ラマンスペクトル)
株式会社堀場製作所製、LabRAM ARAMISを用い、レーザー波長532nmの光源を用いて、ラマンスペクトルを測定した。試験は、各サンプルにおいて無作為に3箇所の粒子をサンプリングし、更にサンプリングした各粒子内から2箇所について測定した。測定条件は、波長範囲50〜2000cm−1、積算回数1000回であり、計6箇所の平均値を計測値として算出した。
半値幅は、上記測定条件にて得られたスペクトルに対し、Dバンド(1360cm−1付近)とGバンド(1590cm−1付近)とのピーク分離を、ガウス関数でフィッティングして実施した後、測定した。(Raman spectrum)
Using a LabRAM ARAMIS manufactured by HORIBA, Ltd., a Raman spectrum was measured using a light source having a laser wavelength of 532 nm. In the test, three particles were randomly sampled in each sample, and two samples were measured from within each sampled particle. The measurement conditions were a wavelength range of 50 to 2000 cm −1 , an integration count of 1000 times, and a total of 6 average values were calculated as measurement values.
The full width at half maximum is measured after fitting a peak separation of the D band (near 1360 cm −1 ) and the G band (near 1590 cm −1 ) with a Gaussian function to the spectrum obtained under the above measurement conditions. did.
(残炭率の測定)
残炭率は、試料を不活性ガス中で強熱した後の強熱残分の炭素量を定量することにより測定した。強熱は、揮発性有機物およそ1g(この正確な重量をW1(g)とする)を坩堝にいれ、1分間に20Lの窒素を流しながら坩堝を電気炉にて、10℃/分の昇温速度で常温から800℃まで昇温、その後800℃で1時間強熱した。このときの残存物を強熱残分とし、その重量をW2(g)とした。
次いで上記強熱残分について、JIS M8819に定められた方法に準拠して元素分析を行い、炭素の重量割合P1(%)を測定した。残炭率P2(%)は以下の式により算出した。(Measurement of residual coal rate)
The residual carbon ratio was measured by quantifying the carbon content of the ignition residue after the sample was ignited in an inert gas. Ignition is about 1 g of volatile organic matter (this exact weight is W 1 (g)) in a crucible, and the crucible is heated at 10 ° C./min in an electric furnace while flowing 20 L of nitrogen per minute. The temperature was raised from room temperature to 800 ° C at a temperature rate, and then ignited at 800 ° C for 1 hour. The residue at this time was regarded as an ignition residue, and its weight was defined as W 2 (g).
Next, the ignition residue was subjected to elemental analysis in accordance with the method defined in JIS M8819, and the carbon weight ratio P 1 (%) was measured. The residual coal rate P 2 (%) was calculated by the following formula.
(ブタノール法による真密度)
JIS R7212に定められた方法に準拠し、ブタノールを用いて測定した。概要を以下に記す。
内容積約40mLの側管付比重びんの質量(m1)を正確に量る。次に、その底部に試料を約10mmの厚さになるように平らに入れた後、その質量(m2)を正確に量る。これに1−ブタノールを静かに加えて、底から20mm程度の深さにする。次に比重びんに軽い振動を加えて、大きな気泡の発生がなくなったのを確かめた後、真空デシケーター中に入れ、徐々に排気して2.0〜2.7kPaとする。その圧力に20分間以上保ち、気泡の発生が止まった後取り出して、更に1−ブタノールで満たし、栓をして恒温水槽(30±0.03℃に調節してあるもの)に15分間以上浸し、1−ブタノールの液面を標線に合わせる。次に、これを取り出して外部をよくぬぐって室温まで冷却した後、質量(m4)を正確に量る。次に同じ比重びんに1−ブタノールだけを満たし、前記と同じようにして恒温水槽に浸し、標線を合わせた後、質量(m3)を量る。また、使用直前に沸騰させて溶解した気体を除いた蒸留水を比重びんにとり、前と同様に恒温水槽に浸し、標線を合わせた後質量(m5)を量る。真密度(ρBt)は次の式により計算する。
In accordance with the method defined in JIS R7212, measurement was performed using butanol. The outline is described below.
The mass (m 1 ) of a specific gravity bottle with a side tube having an internal volume of about 40 mL is accurately measured. Next, the sample is put flat on the bottom so as to have a thickness of about 10 mm, and then its mass (m 2 ) is accurately measured. Gently add 1-butanol to this to a depth of about 20 mm from the bottom. Next, light vibration is applied to the specific gravity bottle, and it is confirmed that large bubbles are not generated. Then, the bottle is placed in a vacuum desiccator and gradually evacuated to 2.0 to 2.7 kPa. Keep at that pressure for 20 minutes or more, take out after bubble generation stops, fill with 1-butanol, plug and immerse in a constant temperature water bath (adjusted to 30 ± 0.03 ° C) for 15 minutes or more. Align the liquid level of 1-butanol with the marked line. Next, this is taken out, the outside is well wiped off and cooled to room temperature, and then the mass (m 4 ) is accurately measured. Next, the same specific gravity bottle is filled with only 1-butanol, immersed in a constant temperature water bath in the same manner as described above, and after aligning the marked lines, the mass (m 3 ) is measured. Moreover, distilled water excluding the gas that has been boiled and dissolved immediately before use is placed in a specific gravity bottle, immersed in a constant temperature water bath as before, and the mass (m 5 ) is measured after aligning the marked lines. The true density (ρ Bt ) is calculated by the following formula.
(平均粒子径)
試料約0.1gに対し、分散剤(カチオン系界面活性剤「SNウェット366」(サンノプコ社製))を3滴加え、試料に分散剤を馴染ませる。次に、純水30mLを加え、超音波洗浄機で約2分間分散させたのち、粒径分布測定器(島津製作所製「SALD−3000J」)で、粒径0.05〜3000μmの範囲の粒径分布を求めた。
得られた粒径分布から、累積容積が50%となる粒径をもって平均粒径Dv50(μm)とした。(Average particle size)
Three drops of a dispersing agent (cationic surfactant “SN Wet 366” (manufactured by San Nopco)) are added to about 0.1 g of the sample, and the sample is made to conform to the dispersing agent. Next, after adding 30 mL of pure water and dispersing for about 2 minutes with an ultrasonic cleaner, particles having a particle size in the range of 0.05 to 3000 μm are measured with a particle size distribution analyzer (“SALD-3000J” manufactured by Shimadzu Corporation). The diameter distribution was determined.
From the obtained particle size distribution, the average particle size D v50 (μm) was defined as the particle size with a cumulative volume of 50%.
(吸湿量の測定)
測定前に、負極材料を200℃で12時間、真空乾燥させ、その後、この負極材料1gを直径8.5cm、高さ1.5cmのシャーレに、できる限り薄い厚みとなるように広げた。温度25℃、湿度50%の一定雰囲気に制御した恒温恒湿槽内に、100時間、放置した後、恒温恒湿槽からシャーレを取り出し、カールフィッシャ水分計(三菱化学アナリテック/CA−200)を用いて吸湿量を測定した。気化室(VA−200)の温度は200℃とした。(Measurement of moisture absorption)
Before the measurement, the negative electrode material was vacuum-dried at 200 ° C. for 12 hours, and then 1 g of this negative electrode material was spread on a petri dish having a diameter of 8.5 cm and a height of 1.5 cm so as to be as thin as possible. After leaving in a constant temperature and humidity chamber controlled at a constant temperature of 25 ° C. and a humidity of 50% for 100 hours, the petri dish is taken out of the constant temperature and humidity chamber and the Karl Fischer moisture meter (Mitsubishi Chemical Analytech / CA-200). The moisture absorption was measured using The temperature of the vaporization chamber (VA-200) was 200 ° C.
(活物質の電極性能および電池性能試験)
炭素質材料又は炭素材混合物を用いて、以下の(a)〜(g)の操作を行い、負極電極及び非水電解質二次電池を作製し、そして電極性能の評価を行った。
(a)負極電極の作製
炭素質材料94重量部、ポリフッ化ビニリデン(株式会社クレハ製「KF#9100」)6重量部にNMPを加えてペースト状にし、銅箔上に均一に塗布した。乾燥した後、銅箔より直径15mmの円板状に打ち抜き、これをプレスして電極とした。なお、電極中の炭素質材料の量は約10mgになるように調整した。(Active material electrode performance and battery performance test)
Using the carbonaceous material or the carbonaceous material mixture, the following operations (a) to (g) were performed to produce a negative electrode and a nonaqueous electrolyte secondary battery, and the electrode performance was evaluated.
(A) Production of negative electrode NMP was added to 94 parts by weight of a carbonaceous material and 6 parts by weight of polyvinylidene fluoride (“KF # 9100” manufactured by Kureha Co., Ltd.) to form a paste, which was uniformly applied on a copper foil. After drying, it was punched out from a copper foil into a disk shape having a diameter of 15 mm and pressed to obtain an electrode. The amount of carbonaceous material in the electrode was adjusted to about 10 mg.
(b)試験電池の作製
本発明の炭素材混合物は、非水電解質二次電池の負極電極を構成するのに適しているが、電池活物質の放電容量(脱ドープ量)及び不可逆容量(非脱ドープ量)を、対極の性能のバラツキに影響されることなく精度良く評価するために、特性の安定したリチウム金属を対極として、上記で得られた電極を用いてリチウム二次電池を構成し、その特性を評価した。
リチウム極の調製は、Ar雰囲気中のグローブボックス内で行った。予めCR2016サイズのコイン型電池用缶の外蓋に直径16mmのステンレススチール網円盤をスポット溶接した後、厚さ0.8mmの金属リチウム薄板を直径15mmの円盤状に打ち抜いたものをステンレススチール網円盤に圧着し、電極(対極)とした。
このようにして製造した電極の対を用い、電解液としてはエチレンカーボネートとメチルエチルカーボネートを容量比で3:7で混合した混合溶媒に1.2mol/Lの割合でLiPF6を加えたものを使用し、直径19mmの硼珪酸塩ガラス繊維製微細細孔膜のセパレータとして、ポリエチレン製のガスケットを用いて、Arグローブボックス中で、2016サイズのコイン型非水電解質系リチウム二次電池を組み立てた。(B) Preparation of test battery The carbon material mixture of the present invention is suitable for constituting the negative electrode of a non-aqueous electrolyte secondary battery, but the discharge capacity (de-doping amount) and irreversible capacity (non-reduction capacity) of the battery active material. In order to accurately evaluate (de-doping amount) without being affected by variations in the performance of the counter electrode, a lithium secondary battery is constructed using the electrode obtained above with lithium metal having stable characteristics as the counter electrode. The characteristics were evaluated.
The lithium electrode was prepared in a glove box in an Ar atmosphere. A 16 mm diameter stainless steel mesh disk was spot welded to the outer lid of a CR2016 size coin-shaped battery can beforehand, and then a 0.8 mm thick metal lithium sheet was punched into a 15 mm diameter disk shape. To be an electrode (counter electrode).
A pair of electrodes manufactured in this manner was used, and an electrolyte solution was obtained by adding LiPF 6 at a rate of 1.2 mol / L to a mixed solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 3: 7. A 2016-size coin-type non-aqueous electrolyte lithium secondary battery was assembled in an Ar glove box using a polyethylene gasket as a separator of a microporous membrane made of borosilicate glass fiber having a diameter of 19 mm. .
(c)電池容量の測定
上記構成のリチウム二次電池について、充放電試験装置(東洋システム製「TOSCAT」)を用いて充放電試験を行った。炭素極へのリチウムのドープ反応を定電流定電圧法により行い、脱ドープ反応を定電流法で行った。ここで、正極にリチウムカルコゲン化合物を使用した電池では、炭素極へのリチウムのドープ反応が「充電」であり、本発明の(a)〜(b)で作製した試験電池のように対極にリチウム金属を使用した電池では、炭素極へのドープ反応が「放電」と呼ぶことになり、用いる対極により同じ炭素極へのリチウムのドープ反応の呼び方が異なる。そこでここでは、便宜上炭素極へのリチウムのドープ反応を「充電」と記述することにする。逆に「放電」とは(a)〜(b)で作製した試験電池では充電反応であるが、炭素質材料からのリチウムの脱ドープ反応であるため便宜上「放電」と記述することにする。
ここで採用した充電方法は、定電流定電圧法であり、具体的には端子電圧が50mVに達するまで0.5mA/cm2の電流密度で定電流充電を行い、50mVに達した時点で一定電圧のまま充電を行い、電流値が20μAに達するまで充電を継続した。
充電終了後、30分間電池回路を開放し、その後放電を行った。放電は0.5mA/cm2で定電流放電を行い、終止電圧を1.5Vとした。このときの放電した電気量を放電容量と定義し、炭素質材料電極の体積(集電体の体積を除く)で除したmAh/cm3を単位として、体積当たりの放電容量を示した。特性測定は25℃で行った。同一試料を用いて作製した試験電池について、n=3の測定値を平均して放電容量を決定した。(C) Measurement of battery capacity About the lithium secondary battery of the said structure, the charge / discharge test was done using the charge / discharge test apparatus ("TOSCAT" by Toyo System). Lithium doping reaction on the carbon electrode was performed by the constant current constant voltage method, and dedoping reaction was performed by the constant current method. Here, in a battery using a lithium chalcogen compound for the positive electrode, the lithium doping reaction to the carbon electrode is “charging”, and the lithium is used for the counter electrode as in the test battery prepared in (a) to (b) of the present invention. In a battery using a metal, the doping reaction to the carbon electrode is referred to as “discharge”, and the naming of the lithium doping reaction to the same carbon electrode differs depending on the counter electrode used. Therefore, for the sake of convenience, the lithium doping reaction on the carbon electrode will be described as “charging”. Conversely, “discharge” is a charging reaction in the test batteries prepared in (a) to (b), but it is described as “discharge” for convenience because it is a dedoping reaction of lithium from a carbonaceous material.
The charging method adopted here is a constant current / constant voltage method. Specifically, constant current charging is performed at a current density of 0.5 mA / cm 2 until the terminal voltage reaches 50 mV, and constant when the voltage reaches 50 mV. Charging was continued with the voltage maintained until the current value reached 20 μA.
After completion of charging, the battery circuit was opened for 30 minutes and then discharged. The discharge was a constant current discharge at 0.5 mA / cm 2 and the final voltage was 1.5V. The amount of electricity discharged at this time was defined as the discharge capacity, and the discharge capacity per volume was shown in units of mAh / cm 3 divided by the volume of the carbonaceous material electrode (excluding the volume of the current collector). Characteristic measurements were performed at 25 ° C. About the test battery produced using the same sample, the discharge capacity was determined by averaging the measured values of n = 3.
(d)入出力特性試験およびサイクル特性試験用電池の作製
正極は、LiNi1/3Co1/3Mn1/3O2(UMICORE製Cellcore MX6)94重量部、カーボンブラック(TIMCAL製Super P)3重量部、ポリフッ化ビニリデン(クレハ製KF#7200)3重量部にNMPを加えてペースト状にし、アルミニウム箔上に均一に塗布した。乾燥した後、塗工電極を直径14mmの円板上に打ち抜き、これをプレスし電極とした。なお、電極中のLiNi1/3Co1/3Mn1/3O2の量は約15mgになるように調整した。
負極は、負極活物質の充電容量の95%となるよう負極電極中の炭素質材料の重量を調整した以外、上記(a)と同様の手順で負極電極を作製した。なお、LiNi1/3Co1/3Mn1/3O2の容量を165mAh/gとして計算し、1C(Cは時間率を表す)を2.475mAとした。
このようにして調製した電極の対を用い、電解液としてはエチレンカーボネートとメチルエチルカーボネートを容量比で3:7で混合した混合溶媒に1.2mol/Lの割合でLiPF6を加えたものを使用し、直径17mmの硼珪酸塩ガラス繊維製微細細孔膜のセパレータとして、ポリエチレン製のガスケットを用いて、Arグローブボックス中で、2032サイズのコイン型非水電解質系リチウム二次電池を組み立てた。(D) Production of battery for input / output characteristic test and cycle characteristic test The positive electrode was 94 parts by weight of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (Cumcore MX6 manufactured by umicore), carbon black (Supercal manufactured by TIMCAL). NMP was added to 3 parts by weight and 3 parts by weight of polyvinylidene fluoride (Kureha KF # 7200) to form a paste, which was uniformly coated on the aluminum foil. After drying, the coated electrode was punched onto a disk having a diameter of 14 mm and pressed to obtain an electrode. The amount of LiNi 1/3 Co 1/3 Mn 1/3 O 2 in the electrode was adjusted to about 15 mg.
For the negative electrode, a negative electrode was produced in the same procedure as in the above (a), except that the weight of the carbonaceous material in the negative electrode was adjusted to 95% of the charge capacity of the negative electrode active material. Note that the capacity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 was calculated as 165 mAh / g, and 1C (C represents a time rate) was 2.475 mA.
Using the pair of electrodes prepared in this manner, an electrolytic solution obtained by adding LiPF 6 at a ratio of 1.2 mol / L to a mixed solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 3: 7 was used. A 2032 size coin-type non-aqueous electrolyte lithium secondary battery was assembled in an Ar glove box using a polyethylene gasket as a separator for a microporous membrane made of borosilicate glass fiber having a diameter of 17 mm. .
(e)50%充電状態の入出力試験および直流抵抗値試験
上記(d)の構成の非水電解質二次電池について、充放電試験機(東洋システム製「TOSCAT」)を用いて電池試験を行った。はじめにエージングを行った後、50%充電状態で入出力試験および直流抵抗値試験を開始した。以下にエージング手順(e−1)〜(e−3)を示す。(E) 50% charged state input / output test and direct current resistance value test The non-aqueous electrolyte secondary battery having the configuration of (d) above was subjected to a battery test using a charge / discharge tester (“TOSCAT” manufactured by Toyo System). It was. After aging first, an input / output test and a direct current resistance test were started in a 50% state of charge. Aging procedures (e-1) to (e-3) are shown below.
エージング手順(e−1)
定電流定電圧法を用いて、電池電圧が4.2VになるまではC/10の電流値で定電流充電を行い、その後、電池電圧を4.2Vに保持するように(定電圧に保持しながら)電流値を減衰させて電流値がC/100以下になるまで充電を継続した。充電終了後、30分間電池回路を開放した。
エージング手順(e−2)
電池電圧が2.75Vに達するまでC/10の定電流値で放電を行った。充電終了後、30分間電池回路を開放した。
不可逆容量は、前記エージング手順(e−1)の充電容量とエージング手順(e−2)の放電容量との差から計算した。
エージング手順(e−3)
エージング手順(e−1)〜(e−2)を更に2回繰り返した。Aging procedure (e-1)
Using the constant current constant voltage method, constant current charging is performed at a current value of C / 10 until the battery voltage reaches 4.2 V, and then the battery voltage is maintained at 4.2 V (held at a constant voltage). While) the current value was attenuated and charging was continued until the current value became C / 100 or less. After completion of charging, the battery circuit was opened for 30 minutes.
Aging procedure (e-2)
The battery was discharged at a constant current value of C / 10 until the battery voltage reached 2.75V. After completion of charging, the battery circuit was opened for 30 minutes.
The irreversible capacity was calculated from the difference between the charge capacity of the aging procedure (e-1) and the discharge capacity of the aging procedure (e-2).
Aging procedure (e-3)
Aging procedures (e-1) to (e-2) were repeated two more times.
エージング終了後、定電流定電圧法を用いて電池電圧が4.2Vになるまでは1Cの電流値で定電流充電を行い、その後、電池電圧を4.2Vに保持するように(定電圧に保持しながら)電流値を減衰させて電流値がC/100以下になるまで充電を継続した。放電は電池電圧が2.75Vに達するまで電流値を1Cで1回行った。充電終了後、30分間電池回路を開放した。その後、電池電圧が2.75Vに達するまで1Cの定電流値で放電を行い、このときの放電容量を放電容量100%とした。 After the end of aging, constant current charging is performed at a current value of 1 C until the battery voltage reaches 4.2 V using the constant current constant voltage method, and then the battery voltage is maintained at 4.2 V (to a constant voltage). Charging was continued until the current value was reduced to C / 100 or less while the current value was attenuated. Discharging was performed once at a current value of 1C until the battery voltage reached 2.75V. After completion of charging, the battery circuit was opened for 30 minutes. Thereafter, discharging was performed at a constant current value of 1 C until the battery voltage reached 2.75 V, and the discharging capacity at this time was set to 100% discharging capacity.
入出力試験および直流抵抗値試験は、松下電池工業 平成17年度〜平成18年度 NEDO成果報告書 燃料電池自動車等用リチウム電池技術開発 車載用リチウム電池技術開発(高入出力・長寿命リチウムイオン電池の技術開発)の3)−1を参考に行った。以下に入出力試験および直流抵抗値試験手順(e−4)〜(e−7)を示す。
入出力試験および直流抵抗値試験手順(e−4)
上記放電容量に対する50%の充電状態において、1Cの電流値で放電を10秒間行った後、10分間電池回路を開放した。
入出力試験および直流抵抗値試験手順(e−5)
1Cの電流値で充電を10秒間行った後、10分間電池回路を開放した。
入出力試験および直流抵抗値試験手順(e−6)
入出力試験手順(e−4)と(e−5)における充放電の電流値を、2C、3Cに変更して、同様に入出力試験手順(e−4)〜(e−5)を行った。
入出力試験および直流抵抗値試験手順(e−7)
充電側において10秒目の電圧を各電流値に対してプロットし、最小二乗法によって近似直線を得た。この近似直線を外挿して充電側の上限電圧を4.2Vとした際の電流値を算出した。
入出力試験および直流抵抗値試験手順(e−8)
得られた電流値(A)と上限電圧(V)との積を入力値(W)とし、正極および負極の体積(両方の集電体の体積を除く)で除したW/cm3を単位として、体積当たりの入力値を示した。
入出力試験および直流抵抗値試験手順(e−9)
同様に、放電側において10秒目の電圧を各電流値に対してプロットし、最小二乗法によって近似直線を得た。この近似直線を外挿して放電側の下限電圧を2.75Vとした際の電流値を算出した。
入出力試験および直流抵抗値試験手順(e−10)
得られた電流値(A)と下限電圧(V)との積を出力値(W)とし、正極および負極の体積(両方の集電体の体積を除く)で除したW/cm3を単位として、体積当たりの出力値を示した。
入出力試験および直流抵抗値試験手順(e−11)
放電側において電流印加停止から10分後までの電圧差を各電流値に対してプロットし、最小二乗法によって近似直線を得た。この近似直線の傾きを直流抵抗値(Ω)とした。The I / O test and DC resistance test were conducted in Matsushita Battery Industry 2005-2006 NEDO Results Report. Lithium Battery Technology Development for Fuel Cell Vehicles, etc. Automotive Lithium Battery Technology Development (High I / O / Long Life Lithium Ion Battery) (Technology Development) 3) -1 was conducted as a reference. The input / output test and DC resistance value test procedures (e-4) to (e-7) are shown below.
Input / output test and DC resistance test procedure (e-4)
In a charged state of 50% with respect to the discharge capacity, discharging was performed at a current value of 1 C for 10 seconds, and then the battery circuit was opened for 10 minutes.
Input / output test and DC resistance test procedure (e-5)
After charging at a current value of 1 C for 10 seconds, the battery circuit was opened for 10 minutes.
Input / output test and DC resistance test procedure (e-6)
Change the charge / discharge current values in the input / output test procedures (e-4) and (e-5) to 2C and 3C, and perform the input / output test procedures (e-4) to (e-5) in the same manner. It was.
Input / output test and DC resistance test procedure (e-7)
On the charge side, the voltage at 10 seconds was plotted against each current value, and an approximate straight line was obtained by the method of least squares. By extrapolating this approximate straight line, the current value when the upper limit voltage on the charging side was 4.2 V was calculated.
Input / output test and DC resistance test procedure (e-8)
The product of the obtained current value (A) and the upper limit voltage (V) is the input value (W), and the unit is W / cm 3 divided by the volume of the positive electrode and the negative electrode (excluding the volume of both current collectors). As shown, input values per volume are shown.
Input / output test and DC resistance test procedure (e-9)
Similarly, the voltage at 10 seconds on the discharge side was plotted against each current value, and an approximate straight line was obtained by the least square method. By extrapolating this approximate straight line, the current value when the lower limit voltage on the discharge side was 2.75 V was calculated.
Input / output test and DC resistance test procedure (e-10)
The product of the obtained current value (A) and the lower limit voltage (V) is the output value (W), and the unit is W / cm 3 divided by the volume of the positive electrode and the negative electrode (excluding the volume of both current collectors). The output value per volume is shown.
Input / output test and DC resistance test procedure (e-11)
On the discharge side, the voltage difference from the current application stop to 10 minutes after the current application was plotted against each current value, and an approximate straight line was obtained by the least square method. The slope of this approximate straight line was defined as the DC resistance value (Ω).
(f)保存前後の不可逆容量及び直流抵抗値変化率の測定
上記(d)で作製した負極を温度25℃、湿度50%の一定雰囲気に制御した恒温恒湿槽内に、7日間(168時間)、放置した後、恒温恒湿槽から取り出し、上記(d)〜(e)と同様の手順で評価用電池の作製および直流抵抗値試験を行った。保存後の直流抵抗値を保存前の直流抵抗値で除し、保存前後の直流抵抗変化率(%)とした。また、(e−1)及び(e−2)から得られた充電容量と放電容量の差から、不可逆容量を計算した。保存後の不可逆容量を保存前の不可逆容量で除し、保存前後の不可逆容量変化率(%)とした。(F) Measurement of irreversible capacity before and after storage and rate of change in DC resistance value The negative electrode produced in (d) above was placed in a constant temperature and humidity chamber controlled to a constant atmosphere at a temperature of 25 ° C. and a humidity of 50% for 7 days (168 hours). ) After leaving, it was taken out from the constant temperature and humidity chamber, and the battery for evaluation and the direct current resistance test were performed in the same procedure as the above (d) to (e). The DC resistance value after storage was divided by the DC resistance value before storage to obtain the DC resistance change rate (%) before and after storage. Further, the irreversible capacity was calculated from the difference between the charge capacity and the discharge capacity obtained from (e-1) and (e-2). The irreversible capacity after storage was divided by the irreversible capacity before storage to obtain the irreversible capacity change rate (%) before and after storage.
(g)サイクル特性の評価
LiNi1/3Co1/3Mn1/3O2正極との組み合わせ電池における、50℃で100サイクル後の初回放電量に対する容量維持率(%)として求めた。
評価用電池は、上記(d)と同様の手順で作製した。
上記(d)の構成の非水電解質二次電池について、充放電試験機(東洋システム製「TOSCAT」)を用いて電池試験を行った。はじめにエージングを行った後、サイクル特性試験を開始した。以下にエージング手順(g−1)〜(g−5)を示す。In combination battery and evaluation LiNi 1/3 Co 1/3 Mn 1/3 O 2 positive electrode (g) Cycle characteristics were determined as the capacity retention rate to the initial discharge amount after 100 cycles at 50 ℃ (%).
The evaluation battery was produced in the same procedure as in the above (d).
About the nonaqueous electrolyte secondary battery of the said (d) structure, the battery test was done using the charging / discharging tester ("TOSCAT" by Toyo System). After aging first, a cycle characteristic test was started. Aging procedures (g-1) to (g-5) are shown below.
エージング手順(g−1)
定電流定電圧法を用いて、電池電圧が4.1VになるまではC/20の電流値で定電流充電を行い、その後、電池電圧を4.1Vに保持するように(定電圧に保持しながら)電流値を減衰させて電流値がC/100以下になるまで充電を継続した。充電終了後、30分間電池回路を開放した。
エージング手順(g−2)
電池電圧が2.75Vに達するまでC/20の定電流値で放電を行った。充電終了後、30分間電池回路を開放した。
エージング手順(g−3)
エージング手順(g−1)の電池電圧を4.2Vに、(g−1)と(g−2)の電流値をC/20からC/5に変更して、(g−1)〜(g−2)を2回繰り返した。Aging procedure (g-1)
Using the constant current constant voltage method, constant current charging is performed at a current value of C / 20 until the battery voltage reaches 4.1 V, and then the battery voltage is maintained at 4.1 V (held at a constant voltage). While) the current value was attenuated and charging was continued until the current value became C / 100 or less. After completion of charging, the battery circuit was opened for 30 minutes.
Aging procedure (g-2)
The battery was discharged at a constant current value of C / 20 until the battery voltage reached 2.75V. After completion of charging, the battery circuit was opened for 30 minutes.
Aging procedure (g-3)
The battery voltage of the aging procedure (g-1) is changed to 4.2 V, the current values of (g-1) and (g-2) are changed from C / 20 to C / 5, and (g-1) to (g-1) g-2) was repeated twice.
エージング終了後、定電流定電圧法を用いて電池電圧が4.2Vになるまでは1Cの電流値で定電流充電を行い、その後、電池電圧を4.2Vに保持するように(定電圧に保持しながら)電流値を減衰させて電流値がC/100以下になるまで充電を継続した。放電は電池電圧が2.75Vに達するまで電流値を1Cで1回行った。充電終了後、30分間電池回路を開放した。その後、電池電圧が2.75Vに達するまで1Cの定電流値で放電を行った。
この充放電方法を50℃で100サイクル繰り返した。100サイクル目の放電容量を1サイクル目の放電容量で除し、容量維持率(%)とした。After the end of aging, constant current charging is performed at a current value of 1 C until the battery voltage reaches 4.2 V using the constant current constant voltage method, and then the battery voltage is maintained at 4.2 V (to a constant voltage). Charging was continued until the current value was reduced to C / 100 or less while the current value was attenuated. Discharging was performed once at a current value of 1C until the battery voltage reached 2.75V. After completion of charging, the battery circuit was opened for 30 minutes. Thereafter, discharging was performed at a constant current value of 1 C until the battery voltage reached 2.75V.
This charge / discharge method was repeated 100 cycles at 50 ° C. The discharge capacity at the 100th cycle was divided by the discharge capacity at the 1st cycle to obtain a capacity retention rate (%).
(調製例1)
椰子殻を破砕し、500℃で乾留して、粒径2.360〜0.850mmの椰子殻チャー(粒径2.360〜0.850mmの粒子を98重量%含有)を得た。この椰子殻チャー100gに対して、塩化水素ガスを1体積%含む窒素ガスを10L/分の流量で供給しながら870℃で50分間気相脱灰処理を実施した。その後、塩化水素ガスの供給のみを停止し、窒素ガスを10L/分の流量で供給しながら、更に870℃で30分間気相脱酸処理を実施し、炭素前駆体を得た。
得られた炭素前駆体を、ボールミルを用いて平均粒子径10μmに粗粉砕した後、コンパクトジェットミル(株式会社セイシン企業製、コジェットシステムα−mkIII)を用いて粉砕及び分級し、平均粒径約6μmの炭素前駆体を得た。得られた炭素前駆体の比表面積は、350m2/gであった。
調製した炭素前駆体9.1gと、ポリスチレン0.9g(積水化成品工業株式会社製、平均粒径400μm、残炭率1.2%)とを混合した。この混合物10gを黒鉛製容器(縦100mm、横100mm、高さ50mm)に入れ、株式会社モトヤマ製高速昇温炉中、毎分5Lの窒素流量下、毎分60℃の昇温速度で1290℃まで昇温した後、24分間保持し、自然冷却した。炉内温度が200℃以下に低下したことを確認し、炉内から炭素質材料1を取り出した。回収された炭素質材料1は8.1gであり、炭素前駆体に対する回収率は89%であった。(Preparation Example 1)
The coconut shell was crushed and dry-distilled at 500 ° C. to obtain coconut shell char having a particle size of 2.360 to 0.850 mm (containing 98 wt% of particles having a particle size of 2.360 to 0.850 mm). A vapor phase deashing process was performed for 50 minutes at 870 ° C. while supplying nitrogen gas containing 1% by volume of hydrogen chloride gas at a flow rate of 10 L / min to 100 g of this coconut shell char. Thereafter, only the supply of hydrogen chloride gas was stopped, and while supplying nitrogen gas at a flow rate of 10 L / min, vapor phase deoxidation treatment was further performed at 870 ° C. for 30 minutes to obtain a carbon precursor.
The obtained carbon precursor was roughly pulverized to an average particle size of 10 μm using a ball mill, and then pulverized and classified using a compact jet mill (manufactured by Seishin Enterprise Co., Ltd., Kodget System α-mkIII) to obtain an average particle size. About 6 μm of carbon precursor was obtained. The specific surface area of the obtained carbon precursor was 350 m 2 / g.
The prepared carbon precursor 9.1 g and 0.9 g of polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle size 400 μm, residual carbon ratio 1.2%) were mixed. 10 g of this mixture was placed in a graphite container (length 100 mm, width 100 mm, height 50 mm), and 1290 ° C. at a temperature increase rate of 60 ° C. per minute under a 5 L / min nitrogen flow rate in a high-speed heating furnace manufactured by Motoyama Co., Ltd. After being heated up to 24 hours, it was kept for 24 minutes and naturally cooled. After confirming that the furnace temperature had dropped to 200 ° C. or less, the carbonaceous material 1 was taken out from the furnace. The recovered carbonaceous material 1 was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%.
(調整例2)
本調整例では、易黒鉛化性炭素質材料の調製を行った。
軟化点205℃、H/C原子比0.65の石油系ピッチ70kgと、ナフタレン30kgとを、撹拌翼および出口ノズルのついた内容積300Lの耐圧容器に仕込み、190℃で加熱溶融混合を行った後、80〜90℃に冷却し、耐圧容器内を窒素ガスにより加圧して、内容物を出口ノズルから押出し、直径約500μmの紐状成型体を得た。次いで、この紐状成型体を直径(D)と長さ(L)の比(L/D)が約1.5になるように粉砕し、得られた破砕物を93℃に加熱した0.53重量%のポリビニルアルコール(ケン化度88%)を溶解した水溶液中に投入し、撹拌分散し、冷却して球状ピッチ成型体スラリーを得た。大部分の水をろ過により取り除いた後、球状ピッチ成形体の約6倍量の重量のn−ヘキサンでピッチ成形体中のナフタレンを抽出除去した。このようにして得た多孔性球状ピッチを、流動床を用いて、加熱空気を通じながら、150℃まで昇温し、150℃に1時間保持して酸化し、多孔性球状酸化ピッチを得た。
次に酸化ピッチを窒素ガス雰囲気中(常圧)で650℃まで昇温し、650℃で1時間保持して予備炭素化を実施し、炭素前駆体を得た。得られた炭素前駆体を粉砕し、平均粒子径約4μmの粉末状炭素前駆体とした。
この粉末状炭素前駆体10gを黒鉛ボードに堆積し、直径100mmの横型管状炉に入れ、250℃/hの速度で1200℃まで昇温し、1200℃で1時間保持して、易黒鉛化性炭素質材料を得た。なお、本焼成は、流量10L/minの窒素雰囲気下で行った。
焼成前及び焼成後のラマンスペクトル測定による1360cm−1付近の半値幅及びそれらの差を表1に示す。(Adjustment example 2)
In this adjustment example, an easily graphitizable carbonaceous material was prepared.
A 70 kg petroleum pitch with a softening point of 205 ° C. and an H / C atomic ratio of 0.65 and 30 kg of naphthalene are charged into a 300 L internal pressure vessel equipped with stirring blades and outlet nozzles, and heated, melted and mixed at 190 ° C. After cooling to 80 to 90 ° C., the inside of the pressure vessel was pressurized with nitrogen gas, and the contents were extruded from the outlet nozzle to obtain a string-like molded body having a diameter of about 500 μm. Subsequently, this string-like molded body was pulverized so that the ratio (L / D) of the diameter (D) to the length (L) was about 1.5, and the obtained crushed material was heated to 93 ° C. The solution was poured into an aqueous solution in which 53% by weight of polyvinyl alcohol (saponification degree: 88%) was dissolved, stirred and dispersed, and cooled to obtain a spherical pitch molded body slurry. After most of the water was removed by filtration, naphthalene in the pitch molded body was extracted and removed with n-hexane having a weight about 6 times that of the spherical pitch molded body. The porous spherical pitch obtained in this manner was heated to 150 ° C. while passing through heated air using a fluidized bed, and was maintained at 150 ° C. for 1 hour for oxidation to obtain a porous spherical oxidized pitch.
Next, the oxidation pitch was raised to 650 ° C. in a nitrogen gas atmosphere (normal pressure), and kept at 650 ° C. for 1 hour to carry out preliminary carbonization to obtain a carbon precursor. The obtained carbon precursor was pulverized to obtain a powdery carbon precursor having an average particle size of about 4 μm.
10 g of this powdery carbon precursor is deposited on a graphite board, placed in a horizontal tubular furnace having a diameter of 100 mm, heated to 1200 ° C. at a rate of 250 ° C./h, and held at 1200 ° C. for 1 hour to facilitate graphitization. A carbonaceous material was obtained. The main firing was performed in a nitrogen atmosphere with a flow rate of 10 L / min.
Table 1 shows the full width at half maximum around 1360 cm −1 and the difference between them measured by Raman spectrum measurement before and after baking.
(調整例3)
人造黒鉛(上海杉杉製CMS−G10)を黒鉛質材料とした。(Adjustment Example 3)
Artificial graphite (CMS-G10 manufactured by Shanghai Sugisugi) was used as the graphite material.
(調整例4)
気相脱灰処理の温度を870℃に代えて980℃で行った以外は調整例1の操作を繰り返して、炭素質材料4を得た。焼成前及び焼成後のラマンスペクトル測定による1360cm−1付近の半値幅及びそれらの差を表1に示す。(Adjustment example 4)
The carbonaceous material 4 was obtained by repeating the operation of Adjustment Example 1 except that the temperature of the vapor phase decalcification treatment was changed to 980 ° C. instead of 870 ° C. Table 1 shows the full width at half maximum around 1360 cm −1 and the difference between them measured by Raman spectrum measurement before and after baking.
(調整例5)
気相脱灰処理の温度を870℃に代えて800℃で行った以外は調整例1の操作を繰り返して、炭素質材料5を得た。焼成前及び焼成後のラマンスペクトル測定による1360cm−1付近の半値幅及びそれらの差を表1に示す。(Adjustment Example 5)
The carbonaceous material 5 was obtained by repeating the operation of Adjustment Example 1 except that the temperature of the vapor phase decalcification treatment was changed to 800 ° C. instead of 870 ° C. Table 1 shows the full width at half maximum around 1360 cm −1 and the difference between them measured by Raman spectrum measurement before and after baking.
《実施例1》
調製例1で得られた60質量%の炭素質材料1、及び調製例2で得られた40質量%の易黒鉛化性炭素質材料を遊星型混練機によって混合した。得られた炭素材混合物1を、負極活物質として用いた試験電池を作製した。Example 1
60% by mass of the carbonaceous material 1 obtained in Preparation Example 1 and 40% by mass of the graphitizable carbonaceous material obtained in Preparation Example 2 were mixed using a planetary kneader. A test battery using the obtained carbon material mixture 1 as a negative electrode active material was produced.
《実施例2》
調製例1で得られた80質量%の炭素質材料1及び調製例2で得られた20質量%の易黒鉛化性炭素質材料を用いたことを除いては、実施例1の操作を繰り返して、炭素材混合物2を調製し、試験電池を作製した。Example 2
The procedure of Example 1 was repeated except that 80% by mass of the carbonaceous material 1 obtained in Preparation Example 1 and 20% by mass of the graphitizable carbonaceous material obtained in Preparation Example 2 were used. Then, a carbon material mixture 2 was prepared, and a test battery was produced.
《実施例3》
調製例1で得られた60質量%の炭素質材料1、及び調製例3で得られた40質量%の黒鉛質材料を遊星型混練機によって混合した。得られた炭素材混合物3を、負極活物質として用いた試験電池を作製した。Example 3
60% by mass of the carbonaceous material 1 obtained in Preparation Example 1 and 40% by mass of the graphite material obtained in Preparation Example 3 were mixed using a planetary kneader. A test battery using the obtained carbon material mixture 3 as a negative electrode active material was produced.
《実施例4》
調製例1で得られた80質量%の炭素質材料1及び調製例3で得られた20質量%の黒鉛質材料を用いたことを除いては、実施例3の操作を繰り返して、炭素材混合物4を調製し、試験電池を作製した。Example 4
The procedure of Example 3 was repeated except that 80% by mass of the carbonaceous material 1 obtained in Preparation Example 1 and 20% by mass of the graphite material obtained in Preparation Example 3 were used. Mixture 4 was prepared to produce a test battery.
《比較例1》
調製例4で得られた60質量%の炭素質材料4及び調製例2で得られた40質量%の易黒鉛化性炭素質材料を用いたことを除いては、実施例1の操作を繰り返して、炭素材混合物を調製し、試験電池を作製した。<< Comparative Example 1 >>
The procedure of Example 1 was repeated except that 60% by mass of the carbonaceous material 4 obtained in Preparation Example 4 and 40% by mass of the graphitizable carbonaceous material obtained in Preparation Example 2 were used. Thus, a carbon material mixture was prepared to prepare a test battery.
《比較例2》
調製例5で得られた80質量%の炭素質材料5及び調製例3で得られた20質量%の黒鉛質材料を用いたことを除いては、実施例1の操作を繰り返して、炭素材混合物を調製し、試験電池を作製した。<< Comparative Example 2 >>
The procedure of Example 1 was repeated except that 80% by mass of the carbonaceous material 5 obtained in Preparation Example 5 and 20% by mass of the graphite material obtained in Preparation Example 3 were used. A mixture was prepared and a test battery was made.
実施例1〜4で得られた炭素材混合物の負極電極を用いた二次電池は、電極保存後の不可逆容量が小さく、そして直流抵抗値も低かった。すなわち、優れたエネルギー密度及び入出力特性を示した。また、実施例1〜4で得られた炭素材混合物の吸湿量は、非常に低く、優れたものであった。更に、炭素材混合物の負極電極を用いた二次電池は、優れたサイクル特性を示した。これに対して、炭素前駆体と炭素質材料との1360cm−1付近のピークの半値幅の値との差が50〜84cm−1に含まれない調整例4及び5の炭素質材料と用いた比較例1及び2で得られた炭素材混合物の吸湿量は高く、電極保存後の不可逆容量が大きく、そして直流抵抗値も高かった。The secondary batteries using the negative electrode of the carbon material mixture obtained in Examples 1 to 4 had a small irreversible capacity after electrode storage and a low DC resistance value. That is, it showed excellent energy density and input / output characteristics. Moreover, the moisture absorption amount of the carbon material mixture obtained in Examples 1 to 4 was very low and excellent. Furthermore, the secondary battery using the negative electrode of the carbon material mixture showed excellent cycle characteristics. In contrast, the carbonaceous materials of Preparation Examples 4 and 5 in which the difference between the half-width value of the peak near 1360 cm −1 between the carbon precursor and the carbonaceous material was not included in 50 to 84 cm −1 were used. The carbon material mixture obtained in Comparative Examples 1 and 2 had a high moisture absorption, a large irreversible capacity after electrode storage, and a high DC resistance value.
本発明の炭素質材料を用いた非水電解質二次電池は、良好な充放電容量とともに、酸化劣化に対する良好な耐性を有する。従って、長寿命が求められるハイブリッド自動車(HEV)及び電気自動車(EV)等の車載用途に特に用いることができる。
以上、本発明を特定の態様に沿って説明したが、当業者に自明の変形や改良は本発明の範囲に含まれる。The non-aqueous electrolyte secondary battery using the carbonaceous material of the present invention has a good resistance to oxidative degradation as well as a good charge / discharge capacity. Therefore, it can be used particularly for in-vehicle applications such as hybrid vehicles (HEV) and electric vehicles (EV) that require a long life.
As mentioned above, although this invention was demonstrated along the specific aspect, the deformation | transformation and improvement obvious to those skilled in the art are included in the scope of the present invention.
Claims (14)
(2)前記難黒鉛化性炭素前駆体と揮発性有機物とを800〜1400℃の不活性ガス雰囲気下で焼成し、難黒鉛化性炭素質材料を得る工程、及び
(3)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含み、前記揮発性有機物が、常温で固体状態であり、以下に示す算出方法により求められる残炭率が5重量%未満である、非水電解質二次電池用混合負極材料の製造方法であって、
広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、
窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そして
ラマンスペクトルにおいて観察される前記難黒鉛化性炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である、
非水電解質二次電池用混合負極材料の製造方法。
(残炭率の算出方法)
前記揮発性有機物1gを、不活性ガス中で常温から10℃/分の昇温速度で800℃まで昇温した後、800℃で1時間灰化して得た残存物の重量と前記残存物の炭素含有率との積を残炭率とする。 (1) A step of producing a non-graphitizable carbon precursor by heating while mixing a plant-derived char and a gas phase containing a halogen compound at 850 to 940 ° C.,
(2) the flame-graphitizable carbon precursor and the volatile organics were fired in an inert gas atmosphere of 800 to 1400 ° C., obtaining a non-graphitizable carbonaceous material, and (3) the flame-graphitizable see containing and sex carbonaceous material, mixing the graphitizable carbonaceous material and / or graphitic material, and, the volatile organic material is a solid state at room temperature, determined by the calculation method shown below A method for producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery, wherein the residual carbon ratio is less than 5% by weight ,
Is calculated using the Bragg equation at the wide-angle X-ray diffraction method, the average spacing d 002 of (002) plane of the flame graphitizable carbonaceous material is in the range of 0.38~0.40Nm,
The specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g, and 1360 cm −1 of the non-graphitizable carbon precursor observed in the Raman spectrum. The difference between the half-width value of the nearby peak and the half-width value of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material is 50 to 84 cm −1 .
A method for producing a mixed negative electrode material for a nonaqueous electrolyte secondary battery.
(Calculation method of residual coal rate)
1 g of the volatile organic substance was heated from an ordinary temperature to 800 ° C. at a temperature increase rate of 10 ° C./min in an inert gas, and then incinerated at 800 ° C. for 1 hour, and the weight of the residue and The product of carbon content is the residual coal rate.
請求項1に記載の非水電解質二次電池用混合負極材料の製造方法。 The half-width value of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material observed in the Raman spectrum is in the range of 175 to 190 cm −1 .
The manufacturing method of the mixed negative electrode material for nonaqueous electrolyte secondary batteries of Claim 1.
請求項1又は2に記載の非水電解質二次電池用混合負極材料の製造方法。 The half-width value of the peak near 1360 cm −1 of the non-graphitizable carbon precursor observed in the Raman spectrum is in the range of 230 to 260 cm −1 .
The manufacturing method of the mixed negative electrode material for nonaqueous electrolyte secondary batteries of Claim 1 or 2.
(2)前記難黒鉛化性炭素質材料と、易黒鉛化性炭素質材料及び/又は黒鉛質材料とを混合する工程、を含む非水電解質二次電池用混合負極材料の製造方法。 (1) A mixture of a non-graphitizable carbon precursor having a specific surface area of 100 to 500 m 2 / g and a volatile organic substance is fired in an inert gas atmosphere at 800 to 1400 ° C. to obtain a non-graphitizable carbonaceous material. And (2) a method of producing a mixed negative electrode material for a non-aqueous electrolyte secondary battery, comprising the step of mixing the non-graphitizable carbonaceous material with the graphitizable carbonaceous material and / or the graphite material. .
窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にある、
請求項4に記載の非水電解質二次電池用混合負極材料の製造方法。 Is calculated using the Bragg equation at the wide-angle X-ray diffraction method, the average spacing d 002 of (002) plane of the flame graphitizable carbonaceous material is in the range of 0.38~0.40Nm, and nitrogen adsorption The specific surface area of the non-graphitizable carbonaceous material determined by the BET three-point method is in the range of 1 to 10 m 2 / g.
The manufacturing method of the mixed negative electrode material for nonaqueous electrolyte secondary batteries of Claim 4.
広角X線回折法においてBragg式を用いて算出される、前記難黒鉛化性炭素質材料の(002)面の平均面間隔d002が0.38〜0.40nmの範囲にあり、
窒素吸着BET3点法により求めた前記難黒鉛化性炭素質材料の比表面積が1〜10m2/gの範囲にあり、そしてラマンスペクトルにおいて観察される難黒鉛化性炭素質材料の炭素前駆体の1360cm−1付近のピークの半値幅の値と、前記難黒鉛化性炭素質材料の1360cm−1付近のピークの半値幅の値との差が50〜84cm−1である、非水電解質二次電池用混合負極材料。 A mixed negative electrode material for a nonaqueous electrolyte secondary battery comprising a non-graphitizable carbonaceous material and an easily graphitizable carbonaceous material and / or a graphite material,
Is calculated using the Bragg equation at the wide-angle X-ray diffraction method, the average spacing d 002 of (002) plane of the flame graphitizable carbonaceous material is in the range of 0.38~0.40Nm,
The specific surface area of the non-graphitizable carbonaceous material determined by the nitrogen adsorption BET three-point method is in the range of 1 to 10 m 2 / g, and the carbon precursor of the non-graphitizable carbonaceous material observed in the Raman spectrum the value of the half width of the peak of 1360cm around -1, the difference between the value of the half width of the peak near 1360cm -1 in the flame graphitizable carbonaceous material is 50~84Cm -1, the non-aqueous electrolyte secondary Mixed negative electrode material for batteries.
請求項7に記載の非水電解質二次電池用混合負極材料。 The half-width value of the peak near 1360 cm −1 of the non-graphitizable carbonaceous material observed in the Raman spectrum is in the range of 175 to 190 cm −1 .
The mixed negative electrode material for nonaqueous electrolyte secondary batteries according to claim 7 .
請求項7又は8に記載の非水電解質二次電池用混合負極材料。 The half-width value of the peak near 1360 cm −1 of the non-graphitizable carbon precursor observed in the Raman spectrum is in the range of 230 to 260 cm −1 .
The mixed negative electrode material for a nonaqueous electrolyte secondary battery according to claim 7 or 8 .
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