JP2011175842A - Negative electrode material for lithium battery, negative electrode for lithium secondary battery, and lithium battery - Google Patents
Negative electrode material for lithium battery, negative electrode for lithium secondary battery, and lithium battery Download PDFInfo
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Abstract
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本発明は、リチウム二次電池用負極材、該負極材を用いたリチウム二次電池用負極及びリチウム二次電池に関する。 The present invention relates to a negative electrode material for a lithium secondary battery, a negative electrode for a lithium secondary battery using the negative electrode material, and a lithium secondary battery.
更に詳しくは、ポータブル電子機器用、電気自動車用、電力貯蔵用等に好適なリチウム二次電池とそれを得るためのリチウム二次電池用負極材及び該負極材を用いたリチウム二次電池用負極に関する。 More specifically, a lithium secondary battery suitable for portable electronic devices, electric vehicles, power storage, and the like, a negative electrode material for lithium secondary battery for obtaining the same, and a negative electrode for lithium secondary battery using the negative electrode material About.
携帯電話、ノート型パソコン等の電子機器の小型軽量化に伴い、リチウムイオン二次電池等のリチウム二次電池には、高電極密度化が要求されている。現在のリチウム二次電池は、一般に、正極活物質（正極材）としてリチウム酸化物、負極活物質（負極材）として炭素粒子が用いられているが、電池性能を向上させるためには、これら正極材及び負極材の特性を向上させることが重要である。 With the reduction in size and weight of electronic devices such as mobile phones and notebook computers, lithium secondary batteries such as lithium ion secondary batteries are required to have higher electrode density. Current lithium secondary batteries generally use lithium oxide as a positive electrode active material (positive electrode material) and carbon particles as a negative electrode active material (negative electrode material). In order to improve battery performance, these positive electrodes are used. It is important to improve the properties of the material and the negative electrode material.
現在、リチウムイオン二次電池用負極材に用いられるているのは、主に、炭素粒子であり、炭素粒子は大きく２種類に分けられる。１つは結晶化度の低い非晶質炭素粒子であり、もう一つは結晶化度の高い黒鉛粒子である。現在、携帯電話やノート型パソコンには、黒鉛粒子が主として用いられている。 At present, carbon particles are mainly used for negative electrode materials for lithium ion secondary batteries, and the carbon particles are roughly classified into two types. One is amorphous carbon particles with low crystallinity, and the other is graphite particles with high crystallinity. At present, graphite particles are mainly used in mobile phones and notebook computers.
負極材に黒鉛を用いた例として、天然黒鉛粒子、コークスを黒鉛化した人造黒鉛粒子、有機系高分子材料やピッチ等を黒鉛化した人造黒鉛粒子、これらを粉砕した黒鉛粒子等がある。これらの黒鉛粒子は、有機系結着剤及び有機溶剤と混合して黒鉛ペーストとし、この黒鉛ペーストを銅箔の表面に塗布し、溶剤を乾燥、成形して、リチウムイオン二次電池用負極として使用している。負極に黒鉛を使用することでリチウムのデンドライトによる内容短絡の問題を解消し、充放電特性の改良を図っている（例えば、特許文献１参照）。 Examples of the negative electrode material using graphite include natural graphite particles, artificial graphite particles obtained by graphitizing coke, artificial graphite particles obtained by graphitizing organic polymer materials and pitches, and graphite particles obtained by pulverizing these. These graphite particles are mixed with an organic binder and an organic solvent to form a graphite paste. The graphite paste is applied to the surface of the copper foil, and the solvent is dried and molded to form a negative electrode for a lithium ion secondary battery. I use it. By using graphite for the negative electrode, the problem of content short circuit due to lithium dendrite is solved, and the charge / discharge characteristics are improved (for example, see Patent Document 1).
しかしながら、黒鉛結晶が発達している天然黒鉛は、Ｃ軸方向の結晶の層間の結合力が、結晶の面方向の結合に比べて弱いため、粉砕により黒鉛層間の結合が切れ、アスペクト比が大きいいわゆる鱗片状の黒鉛粒子となる。鱗片状黒鉛は、アスペクト比が大きいために、有機系結着剤と混練して集電体に塗布して電極を作製したときに、鱗片状黒鉛粒子が集電体の面方向に配向し、その結果、充放電特性や急速充放電特性が低下しやすくなる問題がある。 However, natural graphite, which has developed graphite crystals, has weaker bond strength between crystal layers in the C-axis direction than the bond in the crystal plane direction. It becomes what is called scale-like graphite particles. Since the scaly graphite has a large aspect ratio, when the electrode is prepared by kneading with an organic binder and applying to the current collector, the scaly graphite particles are oriented in the surface direction of the current collector, As a result, there is a problem that charging / discharging characteristics and rapid charging / discharging characteristics tend to deteriorate.
また、黒鉛粒子は、理論容量が３７２Ａｈ／ｋｇとされており、現状、黒鉛粒子自身の容量の飛躍的な増加は難しい状況となっている。しかしながら、黒鉛粒子は、非晶質炭素粒子に比べて真密度が高く、電池の高エネルギー密度化に有効とされている。電池の高エネルギー密度化には、負極の電極密度を高くする必要があり、負極の高電極密度化に耐えうる負極材の開発が求められている。 Further, the graphite particles have a theoretical capacity of 372 Ah / kg, and at present, it is difficult to dramatically increase the capacity of the graphite particles themselves. However, the graphite particles have a higher true density than the amorphous carbon particles, and are effective for increasing the energy density of the battery. In order to increase the energy density of a battery, it is necessary to increase the electrode density of the negative electrode, and development of a negative electrode material that can withstand the increase in the electrode density of the negative electrode is required.
本発明は、高電極密度化での特性低下が少なく、放電負荷特性、充放電効率及び高い電池容量を有するリチウム二次電池とそれを得るためのリチウム二次電池用負極及びリチウム二次電池用負極材を提供することを目的とする。 The present invention relates to a lithium secondary battery having a small characteristic deterioration due to higher electrode density, discharge load characteristics, charge / discharge efficiency and high battery capacity, and a lithium secondary battery negative electrode and a lithium secondary battery for obtaining the same. An object is to provide a negative electrode material.
本発明者らは、鋭意検討を行った結果、特定の形状パラメータを有する炭素粒子を負極材とすることで、上記課題を解決できることを見いだした。 As a result of intensive studies, the present inventors have found that the above problem can be solved by using carbon particles having a specific shape parameter as a negative electrode material.
すなわち、本発明は下記（１）〜（６）に記載の事項を特徴とするものである。
（１）真円を１．００として、円相当径から求めた円の周囲長を粒子像の周囲長で割ることで得られる円形度が、０．８５以上０．９０以下であるリチウム二次電池用負極材。
（２）円形度が異なる少なくとも２種類の炭素粒子（炭素Ａ、炭素Ｂ）を含み、炭素Ａの円形度が０．８８以上であり、炭素Ｂの円形度が０．８８未満である（１）のリチウム二次電池用負極材。
（３）平均粒子径が１０μｍ以上５０μｍ以下、真密度が２２００ｋｇ／ｍ３以上、比表面積が６ｍ２／ｇ以下、かさ密度が６００ｋｇ／ｍ３以上１１００ｋｇ／ｍ２以下であり、かさ密度が炭素Ａ＞炭素Ｂとなる（１）又は（２）の炭素粒子を用いたリチウム二次電池用負極材。
（４）炭素Ｂが、複数の扁平状の黒鉛質微粒子を配向面が非平行となるように集合或いは結合させてなる黒鉛であり、炭素Ｂの混合割合が３０％以上７０％以下である（１）〜（３）いずれか一つに記載のリチウム二次電池用負極材。
（５）上記（１）〜（４）のいずれか一つに記載のリチウム二次電池用負極材を用いてなるリチウム二次電池用負極。
（６）上記（５）記載のリチウム二次電池用負極を用いてなるリチウム二次電池。
That is, the present invention is characterized by the following items (1) to (6).
(1) Lithium secondary having a circularity of 0.85 or more and 0.90 or less obtained by dividing the circumference of a circle obtained from the equivalent circle diameter by the circumference of the particle image with a perfect circle of 1.00 Negative electrode material for batteries.
(2) It includes at least two types of carbon particles (carbon A and carbon B) having different circularity, the circularity of carbon A is 0.88 or more, and the circularity of carbon B is less than 0.88 (1 ) Negative electrode material for lithium secondary battery.
(3) The average particle diameter is 10 μm or more and 50 μm or less, the true density is 2200 kg / m 3 or more, the specific surface area is 6 m 2 / g or less, the bulk density is 600 kg / m 3 or more and 1100 kg / m 2 or less, and the bulk density is carbon. A> A negative electrode material for a lithium secondary battery using the carbon particles of (1) or (2) that becomes carbon B.
(4) Carbon B is graphite in which a plurality of flat graphite fine particles are aggregated or bonded so that the orientation planes are non-parallel, and the mixing ratio of carbon B is 30% or more and 70% or less ( 1)-(3) The negative electrode material for lithium secondary batteries as described in any one.
(5) A negative electrode for a lithium secondary battery, comprising the negative electrode material for a lithium secondary battery according to any one of (1) to (4) above.
(6) A lithium secondary battery using the negative electrode for a lithium secondary battery described in (5) above.
本発明によれば、放電負荷特性、充放電効率及び高電池容量化に優れたリチウム二次電池とそれを得るためのリチウム二次電池用負極、リチウム二次電池用負極材を提供することが可能となる。 ADVANTAGE OF THE INVENTION According to this invention, the lithium secondary battery excellent in discharge load characteristic, charging / discharging efficiency, and high battery capacity, the negative electrode for lithium secondary batteries for obtaining it, and the negative electrode material for lithium secondary batteries are provided. It becomes possible.
以下、本発明を詳細に説明する。
＜リチウム二次電池用負極材＞
Hereinafter, the present invention will be described in detail.
<Anode material for lithium secondary battery>
本発明のリチウム二次電池用負極材は、真円を１．００として、円相当径から求めた円の周囲長を粒子像の周囲長で割ることで得られる円形度が、０．８５以上０．９０以下であることを特徴とする。負極材の円形度が前記範囲内であると、高電極密度化においても圧縮性及び電極密着性が低下せず、低電極密度時のような電池特性を維持することができる。ここで、電極密着性とは、スチレンブタジエンゴム等の結着剤を含んだ負極材と集電体である銅箔等で構成する電極が、両者とも剥離せずに密着しているかどうかをはんだんする指標である。一般的に強い力で電極を圧縮した場合、負極材と銅箔は剥離し易く、充放電効率等の電池特性が低下する傾向にある。また、電池の高容量には、電極の圧縮による高密度化が必要不可欠であるため、電極密着性の低下を制御することが重要となる。 The negative electrode material for a lithium secondary battery of the present invention has a circularity obtained by dividing the circumference of the circle obtained from the equivalent circle diameter by the circumference of the particle image with a perfect circle of 1.00, 0.85 or more It is characterized by being 0.90 or less. When the circularity of the negative electrode material is within the above range, even when the electrode density is increased, the compressibility and the electrode adhesion are not lowered, and the battery characteristics as in the case of the low electrode density can be maintained. Here, the electrode adhesion refers to whether or not an electrode composed of a negative electrode material containing a binder such as styrene butadiene rubber and a copper foil as a current collector is in close contact without peeling. It is an indicator to be used. In general, when an electrode is compressed with a strong force, the negative electrode material and the copper foil are easily peeled off, and battery characteristics such as charge / discharge efficiency tend to be lowered. Moreover, since high density by compression of an electrode is indispensable for the high capacity | capacitance of a battery, it is important to control the fall of electrode adhesiveness.
また、本発明のリチウム二次電池用負極材は、円形度が異なる少なくとも２種類の炭素粒子を混合してなることが好ましい。ここで、２種類の炭素粒子を炭素Ａと炭素Ｂとすると、炭素Ａの円形度は０．８８以上、炭素Ｂの円形度は０．８８未満であり、炭素Ｂに比べて炭素Ａが高い円形度であり、真円（円形度１．００）に近づく。炭素Ａの円形度は０．９０以上であることがさらに好ましい。また、炭素Ｂの円形度は０．８０以上０．８５未満であることがさらに好ましい。炭素Ａと炭素Ｂの円形度の差は、０．０５以上が好ましく、０．１０以上０．１５以下がより好ましい。 Moreover, the negative electrode material for a lithium secondary battery of the present invention is preferably formed by mixing at least two types of carbon particles having different circularities. Here, when the two types of carbon particles are carbon A and carbon B, the circularity of carbon A is 0.88 or more, the circularity of carbon B is less than 0.88, and carbon A is higher than carbon B. The circularity is close to a perfect circle (circularity 1.00). More preferably, the circularity of the carbon A is 0.90 or more. Further, the circularity of the carbon B is more preferably 0.80 or more and less than 0.85. The difference in circularity between carbon A and carbon B is preferably 0.05 or more, and more preferably 0.10 or more and 0.15 or less.
なお、本発明における円形度は、真円を１．００として、円相当径から求めた円の周囲長を粒子像の周囲長で割ることで得られる値であるが、例えば、フロー式粒子像分析装置（例えば、シスメックス株式会社 ＦＰＩＡ−３０００）で測定することができる。 The circularity in the present invention is a value obtained by dividing the circumference of a circle obtained from the equivalent circle diameter by the circumference of the particle image, assuming that the perfect circle is 1.00. It can be measured with an analyzer (for example, Sysmex Corporation FPIA-3000).
炭素Ａと炭素Ｂは混合することに本発明のリチウム二次電池用負極とすることができる。炭素Ａと炭素Ｂを混合する方法として特に制限はないが。例えば、室温において公知の混合装置を用いて行うことができる。混合装置としては、例えば、リボン型混合機、Ｖ型混合機、円錐型混合機、プラネタリミキサ、らいかい機等が挙げられる。 Carbon A and carbon B can be mixed to form the negative electrode for a lithium secondary battery of the present invention. Although there is no restriction | limiting in particular as a method of mixing carbon A and carbon B. For example, it can be performed using a known mixing apparatus at room temperature. Examples of the mixing apparatus include a ribbon type mixer, a V type mixer, a conical mixer, a planetary mixer, and a rough machine.
また、上記炭素粒子Ｂは、複数の扁平状の黒鉛質微粒子を配向面が非平行となるように集合或いは結合させてなる黒鉛が好ましい。上記形状を有する炭素粒子Ｂは、円形度は高くないが充放電効率、放電負荷特性等に優れる傾向がある。しかしながら、粒子内部に多くの微細な細孔を有することから、結着剤の粒子が細孔に入りこみ、電極密着性は低下する場合がある。 The carbon particles B are preferably graphite obtained by collecting or bonding a plurality of flat graphite fine particles so that their orientation planes are non-parallel. The carbon particles B having the above shape tend to be excellent in charge / discharge efficiency, discharge load characteristics, etc., although the circularity is not high. However, since there are many fine pores inside the particles, the binder particles may enter the pores and electrode adhesion may be reduced.
炭素粒子Ｂの製造方法としては、例えば、フルードコークス、ニードルコークス等の各種コークス類と石炭系、石油系、人造等の各種ピッチと、タールバインダと、に鉄、ニッケル、チタン、ホウ素等、これらの炭化物、酸化物、窒化物などの黒鉛化触媒を添加して混合し、焼成、黒鉛化することが挙げられる。
一方、上記炭素粒子Ａは円形度が高く、真円に近い形状となる。円形度が高い粒子は、一般的にかさ密度も高く、ペースト状の負極材を集電体に塗工する際、より高密度にすることが可能となる。さらに、かさ密度が高く、円形度が高い粒子は、単位面積当たりの結着剤の量も多く、電極密着性が向上する傾向がある。
炭素粒子Ａの製造方法としては、例えば、鱗状の天然黒鉛に機械的衝撃を与えることにより作製することができる。このような機械的衝撃を与える装置としては、例えば、ホソカワミクロン社製ファカルティ等が用いられる。
炭素粒子Ａと炭素粒子Ｂとの混合割合は、炭素粒子Ｂの割合が３０％以上７０％以下であることが好ましい。例えば、複数の扁平状の黒鉛質微粒子を配向面が非平行となるように集合或いは結合させてなる黒鉛を炭素粒子Ｂとした場合、その割合が多いほど、充放電効率や放電負荷特性が向上するが、電極密着性は低下する傾向がある。一方、それに対して、炭素粒子の混合割合が少ない場合、電極密着性は向上する傾向がある。炭素粒子Ｂの割合が上記範囲内であれば、充放電効率や放電負荷特性の向上と電極密着性の向上とのバランスがとれやすい点で好ましい。
Examples of the method for producing the carbon particles B include various cokes such as fluid coke and needle coke, various pitches such as coal-based, petroleum-based and artificial, and tar binders, iron, nickel, titanium, boron, etc. And adding a graphitization catalyst such as carbide, oxide, nitride, etc., mixing, firing, and graphitizing.
On the other hand, the carbon particles A have a high degree of circularity and have a shape close to a perfect circle. Particles with a high degree of circularity generally have a high bulk density, and can be made to have a higher density when a paste-like negative electrode material is applied to a current collector. Furthermore, particles having a high bulk density and a high degree of circularity have a large amount of binder per unit area and tend to improve electrode adhesion.
As a manufacturing method of carbon particle A, it can produce by giving a mechanical impact to scale-like natural graphite, for example. As a device for applying such a mechanical impact, for example, a Faculty manufactured by Hosokawa Micron Corporation or the like is used.
The mixing ratio of the carbon particles A and the carbon particles B is preferably such that the ratio of the carbon particles B is 30% or more and 70% or less. For example, when carbon particles B are formed by assembling or bonding a plurality of flat graphite fine particles so that their orientation planes are non-parallel, the higher the ratio, the better the charge / discharge efficiency and discharge load characteristics. However, the electrode adhesion tends to decrease. On the other hand, when the mixing ratio of the carbon particles is small, the electrode adhesion tends to be improved. If the ratio of the carbon particles B is within the above range, it is preferable in terms of easy balance between improvement of charge / discharge efficiency and discharge load characteristics and improvement of electrode adhesion.
本発明のリチウム二次電池用負極材は、平均粒子径が１０μｍ以上５０μｍ以下であることが好ましく、１５μｍ以上３０μｍ以下であることがより好ましく、１８μｍ以上２５μｍ以下がさらに好ましい。平均粒子径が１０μｍ以上であれば、比表面積が大きくなりすぎず、充放電効率が低下するのを抑制することができ好ましい。一方、平均粒子径が５０μｍ以下であれば、電極塗工時の筋引きの発生を抑制することができ、放電負荷特性向上の点で好ましい。ここで、平均粒子径は、レーザー光散乱法を利用した粒子径分布測定装置（例えば、株式会社島津製作所製 ＳＡＬＤ−３０００）を用いて測定することができる。 The negative electrode material for a lithium secondary battery of the present invention preferably has an average particle size of 10 μm to 50 μm, more preferably 15 μm to 30 μm, and still more preferably 18 μm to 25 μm. If the average particle diameter is 10 μm or more, the specific surface area does not become too large, and it is possible to suppress a decrease in charge / discharge efficiency. On the other hand, if the average particle diameter is 50 μm or less, the occurrence of streaks during electrode coating can be suppressed, which is preferable in terms of improving discharge load characteristics. Here, the average particle size can be measured using a particle size distribution measuring device (for example, SALD-3000 manufactured by Shimadzu Corporation) using a laser light scattering method.
また、炭素粒子Ａ及び炭素粒子Ｂを混合して本発明のリチウム二次電池用負極材とする場合、それぞれの炭素粒子において、上記平均粒子径に範囲であることが好ましい。 Moreover, when mixing the carbon particle A and the carbon particle B to make the negative electrode material for a lithium secondary battery of the present invention, it is preferable that the average particle diameter is in the range for each carbon particle.
また、本発明のリチウム二次電池用負極材は、真密度が２２００ｋｇ／ｍ３以上であることが好ましい。炭素の分類の観点では、結晶性が低い炭素（非晶質炭素）に比べると結晶性が高い炭素、いわゆる黒鉛が好ましい。炭素の結晶性は、充放電効率に大きく影響を与え、結晶性が高い程、充放電効率に優れる点で好ましい。 Moreover, it is preferable that the true density of the negative electrode material for a lithium secondary battery of the present invention is 2200 kg / m 3 or more. From the viewpoint of classification of carbon, carbon having higher crystallinity than carbon having low crystallinity (amorphous carbon), so-called graphite, is preferable. The crystallinity of carbon greatly affects the charge / discharge efficiency, and the higher the crystallinity, the better the charge / discharge efficiency.
結晶性を表す指標としては、例えば、炭素粒子の黒鉛結晶の層間距離ｄ（００２）、炭素粒子のＣ軸方向の結晶子サイズＬｃ等が挙げられる。 Examples of the index representing crystallinity include an interlayer distance d (002) of graphite crystals of carbon particles, a crystallite size Lc in the C-axis direction of carbon particles, and the like.
本発明のリチウム二次電池用負極材は、炭素粒子の黒鉛結晶の層間距離ｄ（００２）が３．３８Å以下であることが好ましく、３．３５〜３．３７Åの範囲であることがより好ましい。ｄ（００２）が３．３８Å以下であれば、充放電効率に優れる傾向がある。ｄ（００２）の下限値に特に制限はないが、純粋な黒鉛結晶のｄ（００２）の理論値で通常３．３５Å以上とされる。 In the negative electrode material for a lithium secondary battery of the present invention, the interlayer distance d (002) of graphite crystals of carbon particles is preferably 3.38 mm or less, and more preferably in the range of 3.35 to 3.37 mm. . If d (002) is 3.38 mm or less, the charge / discharge efficiency tends to be excellent. There is no particular limitation on the lower limit of d (002), but the theoretical value of d (002) of pure graphite crystal is usually 3.35 mm or more.
本発明の炭素粒子のｄ（００２）の測定は、詳しくは、Ｘ線（ＣｕＫα線）を炭素粒子に照射し、回折線をゴニオメーターにより測定して得られた回折プロファイルにより、回折角２θ＝２４〜２６°付近に現れる炭素ｄ（００２）面に対応した回折ピークより、ブラッグの式を用い算出する In detail, the d (002) of the carbon particles of the present invention is measured by irradiating the carbon particles with X-rays (CuKα rays) and measuring the diffraction lines with a goniometer. It is calculated from the diffraction peak corresponding to the carbon d (002) plane appearing in the vicinity of 24 to 26 ° using the Bragg equation.
本発明において、炭素粒子のｄ（００２）を３．３８Å以下とするには、結晶性の高い天然黒鉛を用いるか、結晶性を高くした人造黒鉛を用いればよい。結晶性を高くするには、例えば、２０００℃以上の温度で熱処理を施せばよい。 In the present invention, natural graphite having high crystallinity or artificial graphite having high crystallinity may be used in order to make d (002) of the carbon particles 3.38 mm or less. In order to increase the crystallinity, for example, heat treatment may be performed at a temperature of 2000 ° C. or higher.
また、炭素粒子のＣ軸方向の結晶子サイズＬｃも広角Ｘ線回折による測定から算出される炭素の結晶性を表す値で、この値が５００Å以上であると放電容量に優れ、充放電効率にに優れる傾向があり好ましい。Ｌｃの上限値に特に制限はないが、通常１００００Å以下とされる。 In addition, the crystallite size Lc in the C-axis direction of the carbon particles is a value representing the crystallinity of carbon calculated from the measurement by wide-angle X-ray diffraction. It is preferable that it tends to be excellent. Although there is no restriction | limiting in particular in the upper limit of Lc, Usually, it shall be 10,000 or less.
本発明の炭素粒子のＬｃの測定は、通常の方法が用いられるが、具体的には以下のようにして行う。広角Ｘ線回折測定装置を用い、学振法に基づき、結晶子の大きさＬｃを算出する。 An ordinary method is used to measure Lc of the carbon particles of the present invention. Specifically, the measurement is performed as follows. The crystallite size Lc is calculated based on the Gakushin method using a wide-angle X-ray diffractometer.
また、本発明の炭素粒子のＬｃを５００Å以上とするには、結晶性の高い天然黒鉛を用いるか、結晶性を高くした人造黒鉛を用いればよい。結晶性を高くするには、例えば、２０００℃以上の温度で熱処理を施せばよい。 In order to make the Lc of the carbon particles of the present invention 500 or more, natural graphite with high crystallinity or artificial graphite with high crystallinity may be used. In order to increase the crystallinity, for example, heat treatment may be performed at a temperature of 2000 ° C. or higher.
本発明のリチウム二次電池用負極材は、比表面積が６ｍ２／ｇ以下であることが好ましく、５ｍ２／ｇ以下であることががより好ましく、２．５ｍ２／ｇ以上４．５ｍ２／ｇ以下であることがさらに好ましい。比表面積が６ｍ２／ｇ以上であれば、電解液との反応面積が大きくなりすぎず、充放電効率に優れる点で好ましい。なお、比表面積は、例えば、ＢＥＴ法等の既知の方法により測定することができるができる。
本発明のリチウム二次電池用負極材は、かさ密度が６００ｋｇ／ｍ３以上１１００ｋｇ／ｍ３以下であることが好ましい。かさ密度が６００ｋｇ／ｍ３以上であれば、結着剤、増粘剤及び水を含んだペースト状の負極材を集電体に塗工する際、粘度の増加が抑制され、塗工しやすく好ましい。
＜リチウム二次電池用負極＞
本発明のリチウム二次電池用負極は、本発明のリチウム二次電池用負極材を用いてなり、例えば、本発明のリチウム二次電池用負極材、有機系結着剤（バインダー）および必要に応じて添加される各種添加剤等を溶剤などとともに撹拌機、ボールミル、スーパーサンドミル、加圧ニーダー等により混練し、粘度を調整してペースト状の負極材スラリーとした後、これを例えば、メタルマスク印刷法、静電塗装法、ディップコート法、スプレーコート法、ロールコート法、ドクターブレード法、グラビアコート法、スクリーン印刷法など公知の方法により集電体に塗布、乾燥し、必要に応じて、ロールプレス等の成形法により圧縮成形することで形成することができる。また、ペースト状の負極材スラリーをシート状、ペレット状等に成形し、これをロールプレス等の成形法により集電体と一体化することで形成することもできる。
The negative electrode material for a lithium secondary battery of the present invention preferably has a specific surface area of 6 m 2 / g or less, more preferably 5 m 2 / g or less, and 2.5 m 2 / g or more and 4.5 m 2. / G or less is more preferable. If the specific surface area is 6 m 2 / g or more, the reaction area with the electrolytic solution does not become too large, which is preferable in terms of excellent charge / discharge efficiency. The specific surface area can be measured by a known method such as the BET method.
The negative electrode material for a lithium secondary battery of the present invention preferably has a bulk density of 600 kg / m 3 or more and 1100 kg / m 3 or less. When the bulk density is 600 kg / m 3 or more, an increase in viscosity is suppressed when a paste-like negative electrode material containing a binder, a thickener, and water is applied to a current collector, and the coating is easy to apply. preferable.
<Anode for lithium secondary battery>
The negative electrode for a lithium secondary battery according to the present invention uses the negative electrode material for a lithium secondary battery according to the present invention. For example, the negative electrode material for a lithium secondary battery according to the present invention, an organic binder (binder) and the necessity The various additives to be added in accordance with the solvent are kneaded with a stirrer, ball mill, super sand mill, pressure kneader, etc., and the viscosity is adjusted to obtain a paste-like negative electrode material slurry. Apply to the current collector by a known method such as printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method, screen printing method, etc., if necessary, It can be formed by compression molding by a molding method such as a roll press. Alternatively, the paste-like negative electrode material slurry can be formed into a sheet shape, a pellet shape, or the like, and then integrated with the current collector by a forming method such as a roll press.
上記有機系結着剤としては、例えば、ポリエチレン、ポリプロピレン、エチレンプロピレンターポリマー、ブタジエンゴム、スチレンブタジエンゴム、ブチルゴム；メチルアクリレート、メチルメタクリレート、エチルアクリレート、エチルメタクリレート、ブチルアクリレート、ブチルメタクリレート、ヒドロキシエチルアクリレート、ヒドロキシエチルメタクリレート等のエチレン性不飽和カルボン酸エステル；アクリル酸、メタクリル酸、イタコン酸、フマル酸、マレイン酸等のエチレン性不飽和カルボン酸；アクリロニトリル、メタクリロニトリル等の不飽和ニトリル；ポリ弗化ビニリデン、ポリエチレンオキサイド、ポリエピクロルヒドリン、ポリフォスファゼン、ポリアクリロニトリル等のイオン導電率の大きな高分子化合物などが使用できる。上記有機系結着剤は、本発明のリチウム二次電池用負極材と有機系結着剤との混合物１００重量部に対して１〜２０重量部含まれることが好ましい。 Examples of the organic binder include polyethylene, polypropylene, ethylene propylene terpolymer, butadiene rubber, styrene butadiene rubber, and butyl rubber; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and hydroxyethyl acrylate. Ethylenically unsaturated carboxylic acid esters such as hydroxyethyl methacrylate; ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; unsaturated nitriles such as acrylonitrile and methacrylonitrile; Polymer compounds with high ionic conductivity such as vinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, etc. There can be used. The organic binder is preferably contained in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the mixture of the negative electrode material for a lithium secondary battery of the present invention and the organic binder.
また、上記溶剤としては、通常、結着剤を溶解又は分散可能な溶媒が使用され、例えば、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルホルムアミド等の有機溶媒を例示することができる。溶剤の使用量は、ペースト状となる限り特に制限されず、例えば、本発明のリチウム二次電池用負極材１００重量部に対して、通常、６０〜１５０重量部程度、好ましくは６０〜１００重量部程度である。 Moreover, as said solvent, the solvent which can melt | dissolve or disperse | distribute a binder normally is used, For example, organic solvents, such as N-methyl-2-pyrrolidone and N, N- dimethylformamide, can be illustrated. The amount of the solvent used is not particularly limited as long as it is in a paste form. For example, it is usually about 60 to 150 parts by weight, preferably 60 to 100 parts by weight with respect to 100 parts by weight of the negative electrode material for a lithium secondary battery of the present invention. About a part.
また、上記添加剤として、負極材スラリーの増粘剤を用いることもできる。この増粘剤としては、例えば、カルボキシメチルセルロース、カルボキシメチルセルロースナトリウム、メチルセルロース、ヒドロキシメチルセルロース、エチルセルロース、ポリビニルアルコール、ポリアクリル酸（塩）、酸化スターチ、リン酸化スターチ、カゼインなどが挙げられる。また、上記添加剤として、電極としての導電性を向上させるために導電補助剤を混合してもよい。導電補助剤としては、例えば、天然黒鉛、人造黒鉛、カーボンブラック（例えば、アセチレンブラック、サーマルブラック、ファーネスブラック）、グラファイトあるいは導電性を示す酸化物や窒化物等が挙げられ、これらは単独で又は２種以上組み合わせて使用できる。このような添加剤の使用量は、二次電池の特性を低下させない範囲であれば特に限定されないが、本発明のリチウム二次電池用負極材と添加剤の総量に対して１〜１０重量％程度が好ましく、１〜５重量％程度がより好ましい。 Moreover, the thickener of a negative electrode material slurry can also be used as said additive. Examples of the thickener include carboxymethyl cellulose, sodium carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein. Moreover, you may mix a conductive support agent in order to improve the electroconductivity as an electrode as said additive. Examples of the conductive auxiliary agent include natural graphite, artificial graphite, carbon black (for example, acetylene black, thermal black, furnace black), graphite, conductive oxide, nitride, and the like. Two or more types can be used in combination. The amount of the additive used is not particularly limited as long as it does not deteriorate the characteristics of the secondary battery, but is 1 to 10% by weight based on the total amount of the negative electrode material for lithium secondary battery and the additive of the present invention. About 1 to 5 weight% is more preferable.
また、上記集電体としては、例えば、アルミニウム、ニッケル、銅等の箔、メッシュなど、公知のものを使用することができる。また、上記負極材ペーストの集電体への塗布量は、特に制限はないが、５〜１５ｍｇ／ｃｍ２程度が好ましく、７〜１３ｍｇ／ｃｍ２程度がより好ましい。 Moreover, as said collector, well-known things, such as foil, meshes, such as aluminum, nickel, copper, can be used, for example. The coating amount of the current collector of the negative electrode material paste is not particularly limited, preferably about 5 to 15 mg / cm 2, about 7~13mg / cm 2 is more preferable.
＜リチウム二次電池＞
本発明のリチウム二次電池は、本発明のリチウム二次電池用負極を用いてなり、例えば、本発明のリチウム二次電池用負極と正極とをセパレータを介して対向して配置し、電解液を注入することにより得ることができる。リチウム二次電池の代表例としては、リチウムイオン二次電池が挙げられる。また、この他にも、通常当該分野において使用されるガスケット、封口板、ケースなどをさらに備えていてもよい。
<Lithium secondary battery>
The lithium secondary battery of the present invention uses the negative electrode for a lithium secondary battery of the present invention. For example, the negative electrode for a lithium secondary battery of the present invention and a positive electrode are arranged to face each other with a separator interposed therebetween, and an electrolyte solution Can be obtained by injecting. A typical example of the lithium secondary battery is a lithium ion secondary battery. In addition, a gasket, a sealing plate, a case, and the like that are usually used in the field may be further provided.
上記正極は、負極と同様にして、集電体表面上に正極活物質や導電剤等を含む正極材層を形成することで得ることができる。 The positive electrode can be obtained by forming a positive electrode material layer containing a positive electrode active material, a conductive agent and the like on the current collector surface in the same manner as the negative electrode.
上記正極活物質としては、特に制限はなく、例えば、ＬｉＮｉＯ２、ＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、ＬｉＭｎＯ２、ＬｉＣｏ０．３３Ｎｉ０．３３Ｍｎ０．３３Ｏ２等のリチウム複合酸化物やＣｒ３Ｏ８、Ｃｒ２Ｏ５、Ｖ２Ｏ５、Ｖ６Ｏ１３、ＶＯ２、ＭｎＯ２、ＴｉＯ２、ＭｏＶ２Ｏ８、ＴｉＳ２、Ｖ２Ｓ５、ＶＳ２、ＭｏＳ２、ＭｏＳ３，ポリアニリン、ポリピロール等の導電性ポリマー、多孔質炭素等などを単独或いは混合して使用することができる。また、上記導電剤としては、例えば、天然黒鉛、人造黒鉛、カーボンブラック、アセチレンブラックなどを例示できる。 As the positive electrode active material is not particularly limited, for example, LiNiO 2, LiCoO 2, LiMn 2 O 4, LiMnO 2, LiCo 0.33 Ni 0.33 Mn 0.33 O 2 and lithium composite oxides and Cr 3 O 8 , Cr 2 O 5 , V 2 O 5 , V 6 O 13 , VO 2 , MnO 2 , TiO 2 , MoV 2 O 8 , TiS 2 , V 2 S 5 , VS 2 , MoS 2 , MoS 3 , Conductive polymers such as polyaniline and polypyrrole, porous carbon and the like can be used alone or in combination. Examples of the conductive agent include natural graphite, artificial graphite, carbon black, and acetylene black.
上記電解液としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＣｌＦ４、ＬｉＳｂＦ６、ＬｉＡｌＯ４、ＬｉＡｌＣｌ４、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣｌ、ＬｉＩ、ＬｉＳＯ３ＣＦ３等の溶媒和しにくいアニオンを生成するリチウム塩（電解質）を、例えば、カーボネート類、ラクトン類、鎖状エーテル類、環状エーテル類、スルホラン類、スルホキシド類、ニトリル類、アミド類、ポリオキシアルキレングリコール類等の非水系溶媒に溶解した、いわゆる有機電解液を使用する。 Examples of the electrolytic solution include LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiClF 4 , LiSbF 6 , LiAlO 4 , LiAlCl 4 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ). 2 , LiC (CF 3 SO 2 ) 3 , LiCl, LiI, LiSO 3 CF 3 and other lithium salts (electrolytes) that produce anions that are difficult to solvate, such as carbonates, lactones, chain ethers, cyclic A so-called organic electrolytic solution dissolved in a non-aqueous solvent such as ethers, sulfolanes, sulfoxides, nitriles, amides, polyoxyalkylene glycols or the like is used.
上記非水系溶媒としては、具体的には、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネート、シクロペンタノン、スルホラン、３−メチルスルホラン、２，４−ジメチルスルホラン、ジメチルスルホキシド、３−メチル−１，３−オキサゾリジン−２―オン、γ−ブチロラクトン、ジメチルカーボネート、ジエチルカーボネート、ジプロピルカーボネート、メチルエチルカーボネート、メチルプロピルカーボネート、メチルブチルカーボネート、エチルプロピルカーボネート、エチルブチルカーボネート、１，２−ジメトキシエタン、ジメチルエーテル、ジエチルエーテル、テトラヒドロフラン、２−メチルテトラヒドロフラン、４−メチルジオキソラン、１，３−ジオキソラン、アセトニトリル、プロピオニトリル、ベンゾニトリル、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、ジエチレングリコール、酢酸メチル、酢酸エチル等を用いることができ、これら溶媒は、単独でも２種以上を混合したものであってもよい。 Specific examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, dimethyl sulfoxide, and 3-methyl. -1,3-oxazolidine-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, 1,2-dimethoxy Ethane, dimethyl ether, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 4-methyldioxolane, 1,3-dioxolane, aceto Nitrile, propionitrile, benzonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, diethylene glycol, methyl acetate, ethyl acetate, etc. can be used, and these solvents can be used alone or as a mixture of two or more. It may be.
また、上記電解質の濃度は、特に限定されないが、電解液１リットルに対して電解質０．３〜５モルであることが好ましく、０．５〜３モルであることがより好ましく、０．８〜１．５モルであることが特に好ましい。 The concentration of the electrolyte is not particularly limited, but is preferably 0.3 to 5 mol, more preferably 0.5 to 3 mol, and more preferably 0.8 to 1 mol per liter of the electrolyte. It is especially preferable that it is 1.5 mol.
上記セパレータとしては、例えば、ポリエチレン、ポリプロピレン等のポリオレフィンを主成分とした不織布、クロス、多孔質フィルム又はそれらを組み合わせたものを使用することができる。なお、作製する二次電池の正極と負極が使用中も直接接触しない構造にした場合は、セパレータを使用しなくとも良い。 As said separator, the nonwoven fabric, cloth, porous film which combined polyolefin, such as polyethylene and a polypropylene, a porous film, or those combined can be used, for example. In addition, when it is set as the structure where the positive electrode and negative electrode of the secondary battery which are produced do not contact directly during use, it is not necessary to use a separator.
また、本発明のリチウム二次電池の構造は、特に限定されないが、通常、正極及び負極と、必要に応じて設けられるセパレータとを、扁平渦巻状に巻回して巻回式極板群としたり、これらを平板状として積層して積層式極板群とし、これら極板群を外装体中に封入した構造とするのが一般的である。また、本発明のリチウム二次電池は、ペーパー型、ボタン型、コイン型、積層型、角型、円筒型など任意の形態とすることができる。なお、図１にリチウム二次電池の一例として、円筒型リチウムイオン二次電池の一例の一部断面正面図を示す。図１に示す円筒型リチウムイオン二次電池は、薄板状に加工された正極１と、同様に加工された負極２がポリエチレン製微孔膜のセパレータ３を介して重ね合わせたものを捲回し、これを金属製の電池缶７に挿入し、密閉化されている。正極１は正極タブ４を介して正極蓋６に接合され、負極２は負極タブ５を介して電池底部に接合されている。正極蓋６はガスケット８にて電池缶（負極缶）７へ固定されている。
In addition, the structure of the lithium secondary battery of the present invention is not particularly limited. Usually, a positive electrode and a negative electrode, and a separator provided as necessary, are wound in a flat spiral shape to form a wound electrode group. These are generally laminated to form a laminated electrode plate group, and the electrode plate group is sealed in an exterior body. Moreover, the lithium secondary battery of the present invention can be in any form such as a paper type, a button type, a coin type, a stacked type, a square type, and a cylindrical type. FIG. 1 shows a partial cross-sectional front view of an example of a cylindrical lithium ion secondary battery as an example of a lithium secondary battery. The cylindrical lithium ion secondary battery shown in FIG. 1 is obtained by winding a positive electrode 1 processed into a thin plate shape and a negative electrode 2 processed in the same manner through a
本発明のリチウム二次電池は、従来の炭素材料を負極に用いたリチウム二次電池と比較して、放電負荷特性、充放電効率、高電池容量化及び安全性に優れるため、各種電子・電機機器、自動車、電力貯蔵などの電源や補助電源として好適である。 The lithium secondary battery of the present invention is superior in discharge load characteristics, charge / discharge efficiency, higher battery capacity and safety compared to conventional lithium secondary batteries using a carbon material as a negative electrode. It is suitable as a power source or auxiliary power source for equipment, automobiles, power storage, etc.
以下、本発明を実施例により具体的に説明するが、本発明は、当該実施例の記載により限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by description of the said Example.
＜リチウム二次電池用負極材の作製＞
（実施例１〜５、比較例１〜４）
表１に示すように、円形度が異なる炭素粒子Ａおよび炭素粒子Ｂを、Ｖ型混合機を用いて１０分間混合し、リチウム二次電池用負極材を作製した。炭素粒子Ａおよび炭素粒子Ｂの円形度、平均粒子径、真密度、比表面積、かさ密度も併せて記載する。
<Preparation of negative electrode material for lithium secondary battery>
(Examples 1-5, Comparative Examples 1-4)
As shown in Table 1, carbon particles A and carbon particles B having different circularities were mixed for 10 minutes using a V-type mixer to prepare a negative electrode material for a lithium secondary battery. The circularity, average particle diameter, true density, specific surface area, and bulk density of the carbon particles A and B are also described.
なお、炭素Ａ、炭素Ｂとして各実施例および比較例で使用した炭素粒子の製造方法については以下のとおりである。また、表１における物質Ａと物質Ｂの混合比率の単位は、重量部である。 In addition, about the manufacturing method of the carbon particle used by each Example and the comparative example as carbon A and carbon B, it is as follows. The unit of the mixing ratio of substance A and substance B in Table 1 is parts by weight.
（Ｉ）物性測定
円形度：試料（炭素粒子Ａ、炭素粒子Ｂ又はリチウム二次電池用負極材）を界面活性剤と共に精製水中に超音波で分散させた溶液を、フロー式粒子像分析装置（シスメックス株式会社 ＦＰＩＡ−３０００）で測定した。真円を１．００として、円相当径から求めた円の周囲長を粒子像の周囲長で割ることで得られる。
(I) Physical property measurement Circularity: A flow particle image analyzer (sample) (carbon particle A, carbon particle B, or negative electrode material for a lithium secondary battery) dispersed in purified water together with a surfactant with purified water. Sysmex Corporation FPIA-3000). It can be obtained by setting the perfect circle to 1.00 and dividing the circumference of the circle obtained from the equivalent circle diameter by the circumference of the particle image.
平均粒子径：試料（炭素粒子Ａ、炭素粒子Ｂ又はリチウム二次電池用負極材）を界面活性剤と共に精製水中に分散させた溶液を、レーザー回折式粒度分布測定装置（株式会社島津製作所製、ＳＡＬＤ−３０００Ｊ）の試料水槽に入れ、超音波をかけながらポンプで循環させながら、レーザー回折式で測定した。得られた測定値のメディアン径を平均粒子径とした。 Average particle diameter: A solution obtained by dispersing a sample (carbon particles A, carbon particles B, or a negative electrode material for a lithium secondary battery) in purified water together with a surfactant is a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, The sample was placed in a sample water tank of SALD-3000J) and measured by laser diffraction while circulating with a pump while applying ultrasonic waves. The median diameter of the measured values obtained was taken as the average particle diameter.
真密度：ＪＩＳ Ｒ７２１２に基づくブタノール法によって測定した。 True density: Measured by a butanol method based on JIS R7212.
比表面積：ｍａｉｃｒｏｍｅｒｉｔｉｃｓ社製 ＡＳＡＰ ２０１０を用い、液体窒素温度での窒素吸着を多点法で測定、ＢＥＴ法に従って算出した。 Specific surface area: Nitrogen adsorption at a liquid nitrogen temperature was measured by a multipoint method using ASAP 2010 manufactured by micromeritics, and calculated according to the BET method.
かさ密度：かさ密度：２００ｍｌのガラス製メスシリンダーに試料を入れてタッピングし、試料容積が変化しなくなったところでの試料容積を測定し、試料重量を試料容積で除して算出した。
（ＩＩ）炭素粒子Ａ又は炭素粒子Ｂとして使用した材料
（ａ）炭素粒子Ａ
中国産の天然黒鉛を平均粒子径が所望の値となるように粉砕条件を適宜選択して粉砕を行った後、ホソカワミクロン社製ファカルティーＦ−Ｌａｂを用いて、球形化処理を行った。次いで、粉砕した天然黒鉛を２５０メッシュの標準篩を通過させた
（ｂ）炭素粒子Ｂ（粒子写真：図３）
平均粒子径が５μｍのコークス粉末１００重量部、タールピッチ３０重量部、平均粒子径が４８μｍの炭化珪素３０重量部、及びコールタール２０重量部を混合し、２７０℃で１時間混合した。得られた混合物を粉砕し、ペレット状に加圧成形、窒素中で１０００℃で予備焼成した後、アチソン炉を用いて３０００℃で黒鉛化した。上記によって得られた黒鉛ブロックをハンマーミルもしくはジェットミルを用いて、得られる人造黒鉛の平均粒子径が所望の値となるように粉砕条件を適宜選択して粉砕を行った。次いで、粉砕した人造黒鉛を２５０ｍｅｓｈ標準篩を通過させた。得られた人造黒鉛の走査型電子顕微鏡（ＳＥＭ）写真によれば、この黒鉛質粒子は、複数の扁平状の粒子が配向面が非平行となるように集合又は結合した構造をしていた。
Bulk density: Bulk density: A sample was put into a 200 ml glass graduated cylinder and tapped, and the sample volume when the sample volume stopped changing was measured, and the sample weight was divided by the sample volume.
(II) Material used as carbon particle A or carbon particle B (a) Carbon particle A
The natural graphite produced in China was pulverized by appropriately selecting the pulverization conditions so that the average particle diameter would be a desired value, and then spheroidized using a Faculty F-Lab manufactured by Hosokawa Micron. Next, the pulverized natural graphite was passed through a 250 mesh standard sieve. (B) Carbon particle B (particle photograph: FIG. 3)
100 parts by weight of coke powder having an average particle diameter of 5 μm, 30 parts by weight of tar pitch, 30 parts by weight of silicon carbide having an average particle diameter of 48 μm, and 20 parts by weight of coal tar were mixed and mixed at 270 ° C. for 1 hour. The obtained mixture was pulverized, pressed into pellets, pre-fired at 1000 ° C. in nitrogen, and then graphitized at 3000 ° C. using an Atchison furnace. The graphite block obtained as described above was pulverized by using a hammer mill or a jet mill and appropriately selecting the pulverization conditions so that the average particle diameter of the resulting artificial graphite would be a desired value. The pulverized artificial graphite was then passed through a 250 mesh standard sieve. According to the scanning electron microscope (SEM) photograph of the obtained artificial graphite, the graphite particles had a structure in which a plurality of flat particles were aggregated or bonded so that their orientation planes were non-parallel.
（ＩＩＩ）密着性評価方法
表１で作製した評価材が塗布された電極を使用し、ロールプレスを用いて、電極密度１７５０ｋｇ／ｍ３となるようにプレスした。これを長さ１００ｍｍ×幅１０ｍｍの短冊状に切り出し、密着性評価の試験片とした。評価装置には、ＳＨＩＭＰＯ製 ＦＧＣ−０．２Ｂを使用した。電極作製条件は表２に示した。
(III) using an electrode evaluation material produced is applied in the adhesion evaluation method in Table 1, using a roll press, and pressed such that the electrode density 1750 kg / m 3. This was cut into a strip shape having a length of 100 mm and a width of 10 mm to obtain a test piece for adhesion evaluation. As the evaluation device, FGC-0.2B manufactured by SHIMPO was used. The electrode production conditions are shown in Table 2.
（ＩＶ）表３に電池評価方法を示す。 (IV) Table 3 shows battery evaluation methods.
（Ｖ）測定結果
測定結果を表４に示す。
(V) Measurement results Table 4 shows the measurement results.
表４に示されるように、本発明は、充放電効率及び充電負荷特性に優れることが明らかである。 As shown in Table 4, it is apparent that the present invention is excellent in charge / discharge efficiency and charge load characteristics.
また、本発明のリチウム二次電池用負極材又は本発明のリチウムイオン二次電池用負極を用いることにより、高容量で、充放電効率及び充電負荷特性に優れたリチウム二次電池とすることができる。 Moreover, by using the negative electrode material for lithium secondary batteries of the present invention or the negative electrode for lithium ion secondary batteries of the present invention, a lithium secondary battery having high capacity and excellent charge / discharge efficiency and charge load characteristics can be obtained. it can.
１：正極
２：負極
３：セパレータ
４：正極タブ
５：負極タブ
６：正極蓋
７：電池缶（負極缶）
８：ガスケット
1: Positive electrode 2: Negative electrode 3: Separator 4: Positive electrode tab 5: Negative electrode tab 6: Positive electrode lid 7: Battery can (negative electrode can)
8: Gasket
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| WO2018128179A1 (en) * | 2017-01-06 | 2018-07-12 | 日立化成株式会社 | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
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| JP2019175852A (en) * | 2017-01-06 | 2019-10-10 | 日立化成株式会社 | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
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| CN110168787B (en) * | 2017-01-06 | 2022-05-03 | 昭和电工材料株式会社 | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
| WO2020012586A1 (en) * | 2018-07-11 | 2020-01-16 | 日立化成株式会社 | Lithium-ion secondary battery and lithium-ion secondary battery production method |
| WO2020012587A1 (en) * | 2018-07-11 | 2020-01-16 | 日立化成株式会社 | Lithium-ion secondary battery negative electrode material, lithium-ion secondary battery negative electrode, lithium-ion secondary battery, and method for producing lithium-ion secondary battery negative electrode |
| JPWO2020012586A1 (en) * | 2018-07-11 | 2021-07-08 | 昭和電工マテリアルズ株式会社 | Method for manufacturing lithium ion secondary battery and lithium ion secondary battery |
| JP7147844B2 (en) | 2018-07-11 | 2022-10-05 | 昭和電工マテリアルズ株式会社 | Lithium ion secondary battery and method for manufacturing lithium ion secondary battery |
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