JP2012164481A - Nonaqueous electrolyte secondary battery and method for manufacturing the same - Google Patents
Nonaqueous electrolyte secondary battery and method for manufacturing the same Download PDFInfo
- Publication number
- JP2012164481A JP2012164481A JP2011022991A JP2011022991A JP2012164481A JP 2012164481 A JP2012164481 A JP 2012164481A JP 2011022991 A JP2011022991 A JP 2011022991A JP 2011022991 A JP2011022991 A JP 2011022991A JP 2012164481 A JP2012164481 A JP 2012164481A
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- active material
- electrode active
- oxygen
- secondary battery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
本発明は、リチウムを吸蔵・放出可能な物質を負極活物質に用いた非水電解質二次電池に係り、特に低い不可逆容量で高い充放電容量が得られるシリコン系材料を負極活物質に用いた非水電解質二次電池及びその製造方法に関する。 The present invention relates to a non-aqueous electrolyte secondary battery using a material capable of occluding and releasing lithium as a negative electrode active material, and in particular, a silicon-based material capable of obtaining a high charge / discharge capacity with a low irreversible capacity is used as a negative electrode active material. The present invention relates to a non-aqueous electrolyte secondary battery and a manufacturing method thereof.
近年、高出力、高エネルギー密度の二次電池として、非水系溶媒にリチウム塩からなる溶質を溶解させた非水系電解液を用いて、リチウムイオンを正極と負極との間で移動させて充放電するリチウムイオン二次電池が主流を占めるようになってきた。これらリチウムイオン二次電池の負極活物質には、金属リチウムや、リチウムイオンの吸蔵・放出が可能な黒鉛、コークス、有機物焼成体等の炭素材料が用いられてきた。負極活物質として金属リチウムを用いた場合には、電極電位が最も卑であるため、電池の電圧が最も高くなり、エネルギー密度も高く好ましい。しかし、負極活物質として金属リチウムを用いると、充放電によって負極表面にデンドライトや不働体化合物が生成し、充放電による負極の劣化が大きく、充放電サイクル寿命が短いという問題があった。これに対し、負極活物質に炭素材料を用いた場合には、充放電によって負極界面で非水電解液が分解したり、あるいは炭素材料が負極集電箔から脱離して、次第に充放電容量が低下する等の問題があった。また、炭素材料は、結晶層間や格子間隙間にリチウムイオンをインターカレーション又はデインターカレーションするものであるから、原理的に炭素原子６個にリチウムイオンを１個しか吸蔵・放出できないため、エネルギー密度を十分に高めることができない課題もあった。 In recent years, as a secondary battery with high output and high energy density, a non-aqueous electrolyte solution in which a solute composed of a lithium salt is dissolved in a non-aqueous solvent is used to move lithium ions between the positive electrode and the negative electrode to charge and discharge. Lithium ion rechargeable batteries are becoming mainstream. As the negative electrode active material of these lithium ion secondary batteries, carbon materials such as metallic lithium and graphite, coke, and organic fired body capable of occluding and releasing lithium ions have been used. When metallic lithium is used as the negative electrode active material, since the electrode potential is the lowest, the battery voltage is the highest and the energy density is high, which is preferable. However, when metallic lithium is used as the negative electrode active material, there is a problem that dendrites and passive compounds are generated on the negative electrode surface by charge and discharge, the negative electrode is greatly deteriorated by charge and discharge, and the charge / discharge cycle life is short. In contrast, when a carbon material is used as the negative electrode active material, the non-aqueous electrolyte is decomposed at the negative electrode interface due to charge / discharge, or the carbon material is detached from the negative electrode current collector foil, so that the charge / discharge capacity gradually increases. There was a problem such as lowering. In addition, since carbon materials intercalate or deintercalate lithium ions between crystal layers or between lattice gaps, in principle, only one lithium ion can be occluded / released to 6 carbon atoms. There was also a problem that the energy density could not be sufficiently increased.
一方、これらの課題に対して、ゲルマニウムイ（Ｇｅ）、ケイ素（Ｓｉ）、スズ（Ｓｎ）等のリチウム（Ｌｉ）と合金化する材料を負極活物質に使用する試みがなされてきた。とりわけ、Ｓｉは、地球上に豊富に存在する材料であって、電極電位も低く、単位質量当たりの理論容量は炭素材料の１桁以上の向上が見込めるなど、有望な負極材料として注目されている。 On the other hand, in order to deal with these problems, attempts have been made to use, as the negative electrode active material, a material that forms an alloy with lithium (Li) such as germanium (Ge), silicon (Si), and tin (Sn). In particular, Si is an abundant material on the earth, has a low electrode potential, and has attracted attention as a promising negative electrode material, such as a theoretical capacity per unit mass that can be improved by an order of magnitude over that of carbon materials. .
しかし、Ｓｉ等のリチウムと合金化する材料は、リチウムイオンの吸蔵・放出に伴う体積の膨張・収縮（体積変化）が大きく、充放電サイクルによって粒子の微細化が生じて充放電容量の低下（充放電サイクル特性の劣化）を招くことが知られている。これを防ぐため、粒子のナノサイズ化や炭素材料との複合化、更に遷移金属との複合化等が検討されているが、実用化に至っていない。 However, materials that alloy with lithium, such as Si, have a large volume expansion / contraction (volume change) that accompanies the insertion and extraction of lithium ions, resulting in particle miniaturization caused by charge / discharge cycles, resulting in a decrease in charge / discharge capacity ( It is known to cause deterioration of charge / discharge cycle characteristics. In order to prevent this, nano-sized particles, compounding with a carbon material, and compounding with a transition metal have been studied, but have not yet been put into practical use.
一方、Ｓｉとその酸化物とをナノサイズで複合化したＳｉＯｘは充放電サイクル特性が大幅に向上することが報告されて、非水電解質二次電池に適用され始めている（例えば、特許文献１参照）。 On the other hand, it has been reported that SiOx in which Si and its oxide are combined in a nano size greatly improves charge / discharge cycle characteristics, and has begun to be applied to non-aqueous electrolyte secondary batteries (see, for example, Patent Document 1). ).
ケイ素と酸化ケイ素との複合酸化物（ＳｉＯｘ）を負極活物質に用いることにより、リチウムイオンの吸蔵・放出に伴う体積の膨張・収縮が抑制されて充放電サイクル特性は大幅に改善される。しかしながら、上記負極活物質は充電容量に対する放電容量の比（クーロン効率）が低いという問題があった。特に、初回充放電時のクーロン効率がケイ素単独の場合に比べ大幅に低く、即ち不可逆容量が大きく、高効率の二次電池を構成する上での問題となっていた。 By using a composite oxide of silicon and silicon oxide (SiOx) as the negative electrode active material, volume expansion / contraction associated with insertion / extraction of lithium ions is suppressed, and charge / discharge cycle characteristics are greatly improved. However, the negative electrode active material has a problem that the ratio of discharge capacity to charge capacity (Coulomb efficiency) is low. In particular, the Coulomb efficiency at the first charge / discharge is significantly lower than that of silicon alone, that is, the irreversible capacity is large, which is a problem in constructing a highly efficient secondary battery.
本発明は、上記問題を解決するもので、ＳｉＯｘからなる負極活物質の不可逆容量の低減を図り、高効率で、且つ高容量の非水電解質二次電池及びその製造方法を提供することにある。 The present invention solves the above problem, and aims to provide a non-aqueous electrolyte secondary battery having high efficiency and high capacity, and a method for producing the same, by reducing the irreversible capacity of the negative electrode active material made of SiOx. .
本発明の非水電解質二次電池は、正極と、負極と、非水電解質とを含む非水電解質二次電池であって、前記負極は、負極集電体と、前記負極集電体の上に形成された負極活物質含有層とを含み、前記負極活物質含有層は、ケイ素と、酸素と、水素とを構成元素として含む負極活物質を含み、前記酸素の前記負極活物質中での含有量は、前記ケイ素に対して原子比で０．５以上１．５以下であり、前記負極活物質を構成する水素は、前記負極活物質を構成する酸素と結合していることを特徴とする。 The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the negative electrode is formed on the negative electrode current collector and the negative electrode current collector. A negative electrode active material-containing layer formed on the negative electrode active material-containing layer, wherein the negative electrode active material-containing layer includes a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements. Content is 0.5 or more and 1.5 or less by atomic ratio with respect to the silicon, and hydrogen constituting the negative electrode active material is combined with oxygen constituting the negative electrode active material, To do.
また、本発明の非水電解質二次電池の第１の製造方法は、ケイ素と、酸素と、水素とを構成元素として含む負極活物質を用いた非水電解質二次電池の製造方法であって、ケイ素と、酸素とを含み、前記酸素を、前記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、前記負極活物質前駆体を、３００℃以上１０００℃以下の水素ガス中で熱処理する工程とを含み、前記熱処理により、前記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする。 The first method for producing a nonaqueous electrolyte secondary battery of the present invention is a method for producing a nonaqueous electrolyte secondary battery using a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements. A step of producing a negative electrode active material precursor comprising silicon and oxygen, wherein the oxygen is contained in an atomic ratio of 0.5 to 1.5 with respect to the silicon, and the negative electrode active material precursor And a step of heat-treating in a hydrogen gas at 300 ° C. or higher and 1000 ° C. or lower, wherein oxygen constituting the negative electrode active material precursor is combined with hydrogen by the heat treatment.
また、本発明の非水電解質二次電池の第２の製造方法は、ケイ素と、酸素と、水素とを構成元素として含む負極活物質を用いた非水電解質二次電池の製造方法であって、ケイ素と、酸素とを含み、前記酸素を、前記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、前記負極活物質前駆体を、１５０℃以上６００℃以下で、２気圧以上３００気圧以下の水蒸気中で高圧水蒸気処理する工程とを含み、前記高圧水蒸気処理により、前記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする。 A second method for producing a nonaqueous electrolyte secondary battery according to the present invention is a method for producing a nonaqueous electrolyte secondary battery using a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements. A step of producing a negative electrode active material precursor comprising silicon and oxygen, wherein the oxygen is contained in an atomic ratio of 0.5 to 1.5 with respect to the silicon, and the negative electrode active material precursor A high-pressure steam treatment in steam at 150 ° C. to 600 ° C. in a steam of 2 to 300 atm, and oxygen and hydrogen constituting the negative electrode active material precursor are formed by the high-pressure steam treatment. It is characterized by combining.
本発明により、高効率で、且つ高容量の非水電解質二次電池を提供できる。 According to the present invention, a highly efficient and high capacity non-aqueous electrolyte secondary battery can be provided.
従来のケイ素と酸化ケイ素との複合酸化物（ＳｉＯｘ）は、図２に示すようにＳｉＯ2のマトリックス中にＳｉの微結晶が点在する構造となっている。 A conventional composite oxide of silicon and silicon oxide (SiOx) has a structure in which Si microcrystals are scattered in a SiO 2 matrix as shown in FIG.
また、ＳｉＯｘのＬｉの吸蔵・放出メカニズムは、図３に示すように概略次のように説明できる。先ず、充電（Ｌｉ吸蔵）時には、ＳｉＯ2マトリックスとＬｉとが反応してリチウムシリケートが生成すると共に、Ｓｉ微結晶とＬｉとが反応してＳｉＬｉ合金が生成する〔図３（ａ）〕。また、放電（Ｌｉ放出）時は、ＳｉＬｉ合金からＬｉがイオンとなって溶出すると共にＳｉが析出て再結晶化する〔図３（ｂ）〕。即ち、ＳｉとＬｉとの反応は可逆的に生ずる。一方、充電時に生成したリチウムシリケートは、電気化学的に安定な物質であって放電時にもその構造を維持する。即ち、ＳｉＯ2とＬｉとは不可逆な反応となり、これが不可逆容量となってしまう。従って、不可逆容量の低減はリチウムシリケートの生成を抑制すればよいことが分かる。 Further, the mechanism of insertion / extraction of Li in SiOx can be roughly explained as follows as shown in FIG. First, at the time of charging (Li occlusion), the SiO 2 matrix and Li react to generate lithium silicate, and the Si microcrystal and Li react to generate a SiLi alloy [FIG. 3 (a)]. At the time of discharge (Li release), Li is eluted from the SiLi alloy as ions and Si is precipitated and recrystallized [FIG. 3 (b)]. That is, the reaction between Si and Li occurs reversibly. On the other hand, lithium silicate produced during charging is an electrochemically stable substance and maintains its structure during discharging. That is, SiO 2 and Li become an irreversible reaction, which becomes an irreversible capacity. Therefore, it can be seen that the reduction of the irreversible capacity may be achieved by suppressing the generation of lithium silicate.
本発明者等は、充電時の上記リチウムシリケートの生成過程を分析及びシミュレーション技術を用いて詳細に調べた結果、充電後のマトリックス（ＳｉＯ2）部は、Ｌｉ4ＳｉＯ4及びＬｉ2ＳｉＯ3を主組成とするリチウムシリケートと未反応のＳｉＯ2との複合酸化物からなることが判明した。その反応過程については、ＳｉＯ2中のＯ−Ｓｉ−Ｏネットワークにおける結合欠陥（Ｏの未結合手）にＬｉが結合することで、上記リチウムシリケートの生成反応が進行することが分かった。即ち、図４に示すように、Ｌｉ吸蔵前のマトリックス（ＳｉＯ2）部には、ＳｉＯ2中のＯ−Ｓｉ−Ｏネットワークにおける結合欠陥（Ｏの未結合手）が存在している。また、図５に示すように、Ｌｉ吸蔵後のマトリックス（ＳｉＯ2）部では、上記結合欠陥（Ｏの未結合手）にＬｉが結合して吸蔵されている。このため、ＳｉＯ2中のＯの未結合手を減らすか、あるいは予め別イオンでＯの未結合手を終端させておくことで、ＳｉＯ2とＬｉとの反応を抑制できると考えられる。本発明者等は鋭意検討の結果、ＳｉＯｘの負極材料に水素（Ｈ）原子を添加することで、ＳｉＯ2中のＯの未結合手をＨで終端できることを見出し、本発明を完成するに至った。 As a result of detailed examination of the generation process of the lithium silicate at the time of charging using analysis and simulation techniques, the present inventors have found that the matrix (SiO 2 ) portion after charging contains Li 4 SiO 4 and Li 2 SiO 3 . It was found to be composed of a composite oxide of lithium silicate as the main composition and unreacted SiO 2 . For its reaction process, that Li is bound to the binding defects in O-SiO network in SiO 2 (dangling bonds of O), formation reaction of the lithium silicate was found to proceed. That is, as shown in FIG. 4, bond defects (O dangling bonds) in the O—Si—O network in SiO 2 exist in the matrix (SiO 2 ) portion before Li storage. Further, as shown in FIG. 5, in the matrix (SiO 2 ) portion after the occlusion of Li, Li is bonded to and occluded by the bond defects (O dangling bonds). For this reason, it is considered that the reaction between SiO 2 and Li can be suppressed by reducing the number of O dangling bonds in SiO 2 or by terminating the dangling bonds of O with another ion in advance. As a result of intensive studies, the present inventors have found that the dangling bonds of O in SiO 2 can be terminated with H by adding hydrogen (H) atoms to the negative electrode material of SiOx, and the present invention has been completed. It was.
図１（ａ）は、Ｏの未結合手をＨで終端したＳｉＯｘ粒子の模式部分断面図であり、図１（ｂ）は、Ｈ終端したマトリックス（ＳｉＯ2）部の分子構造を示す図である。Ｈ終端されてＳｉ−Ｏ−Ｈ結合を有するＳｉＯ2は、電気化学的に安定であって、Ｌｉとの反応を生じることもなく、Ｓｉ微結晶のＬｉの吸蔵・放出にも何ら影響を及ぼさないことも確認した。従って、上記Ｈ終端ＳｉＯｘを負極活物質に用いると、高容量を維持したまま、不可逆容量を激減できることが分かる。 FIG. 1A is a schematic partial cross-sectional view of a SiOx particle in which a dangling bond of O is terminated with H, and FIG. 1B is a diagram showing a molecular structure of a matrix (SiO 2 ) portion terminated with H. is there. SiO 2 having an H-terminated Si—O—H bond is electrochemically stable, does not cause a reaction with Li, and has no influence on the absorption and release of Li in Si microcrystals. It was also confirmed that there is no. Therefore, it can be seen that when the H-terminated SiOx is used as the negative electrode active material, the irreversible capacity can be drastically reduced while maintaining a high capacity.
以下、本発明の非水電解質二次電池について説明する。本発明の非水電解質二次電池は、正極と、負極と、非水電解質とを備えている。 Hereinafter, the nonaqueous electrolyte secondary battery of the present invention will be described. The nonaqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, and a nonaqueous electrolyte.
先ず、本発明に係る負極について説明する。本発明に係る負極は、負極集電体と、上記負極集電体の上に形成された負極活物質含有層とを備えている。 First, the negative electrode according to the present invention will be described. The negative electrode according to the present invention includes a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector.
上記負極活物質含有層は、ケイ素と、酸素と、水素とを構成元素として含む負極活物質を含み、上記酸素の上記負極活物質中での含有量は、上記ケイ素に対して原子比で０．５以上１．５以下であり、上記負極活物質を構成する水素は、上記負極活物質を構成する酸素と結合している。 The negative electrode active material-containing layer includes a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements, and the content of oxygen in the negative electrode active material is 0 in atomic ratio with respect to silicon. 5 or more and 1.5 or less, and hydrogen constituting the negative electrode active material is bonded to oxygen constituting the negative electrode active material.
上記負極活物質を構成する酸素は水素と結合しているため、負極活物質のマトリックス（ＳｉＯ2）部には、ＳｉＯ2中のＯ−Ｓｉ−Ｏネットワークにおける結合欠陥（Ｏの未結合手）がほとんど存在しないと考えられる。このため、充電時においてＳｉＯ2とＬｉとの反応によるリチウムシリケートの生成を抑制でき、負極活物質の不可逆容量を低減できる。これにより、本発明の非水電解質二次電池の初回のクーロン効率を８５％以上にすることができる。 For oxygen constituting the negative electrode active material is bonded to hydrogen, the anode active material matrix is (SiO 2) portions, bonding defects in the O-SiO network in SiO 2 (dangling bonds O) Is considered to be almost nonexistent. Therefore, it is possible to suppress the generation of lithium silicate by the reaction of SiO 2 and Li during charging can be reduced irreversible capacity of the negative electrode active material. Thereby, the initial coulomb efficiency of the nonaqueous electrolyte secondary battery of the present invention can be 85% or more.
また、上記負極活物質は、ＳｉＯｘ：Ｈ（０．５≦ｘ≦１．５）と表現でき、少なくとも充電前の初期状態（リチウム吸蔵前）においては、非晶質のＳｉＯ2マトリックス中にＳｉ微結晶が点在し、Ｈ原子がＳｉＯ2中に存在する結合欠陥（Ｏの未結合手）と結合して、ＳｉＯ2はＳｉ−Ｏ−Ｈ結合を有する形態を成している。上記負極活物質におけるＳｉとＯとの典型的な原子比は、１：１であり、ＳｉＯｘ：Ｈ（ｘ＝１）と表現できる。 The negative electrode active material can be expressed as SiOx: H (0.5 ≦ x ≦ 1.5), and at least in an initial state before charging (before lithium storage), Si in the amorphous SiO 2 matrix. The crystallites are interspersed, and H atoms are combined with bond defects (O dangling bonds) existing in SiO 2 , so that SiO 2 has a form having a Si—O—H bond. A typical atomic ratio of Si and O in the negative electrode active material is 1: 1, and can be expressed as SiOx: H (x = 1).
上記負極活物質含有層は、上記負極集電体の上に、成分元素をスパッタリング法、真空蒸着法等の物理的気相成長（ＰＶＤ）法、又は化学的気相成長（ＣＶＤ）法等の方法により、上記負極活物質の単一結晶層を積層させて薄膜状の形態で形成できる。 The negative electrode active material-containing layer is formed on the negative electrode current collector by a physical vapor deposition (PVD) method such as a sputtering method or a vacuum deposition method, or a chemical vapor deposition (CVD) method. By the method, a single crystal layer of the negative electrode active material can be laminated to form a thin film.
また、上記負極活物質含有層は、微粉化された上記負極活物質と、更にバインダとを含む形態であってもよい。この形態では、充放電時のＳｉの体積変化に伴う応力緩和の効果があり、充放電サイクル特性の更なる向上が図れる。また、本形態では、前述のＰＶＤ法又はＣＶＤ法により負極活物質含有層を形成する場合に比べて、簡易な設備で実施可能なため、大量生産に適しており、製造コストの低減化も可能である。上記微粉化された負極活物質の間の電子伝導性を補助するために、上記負極活物質含有層は、更に電子伝導助剤を含んでいてもよい。本形態の負極活物質含有層は、上記負極活物質と上記バインダと上記電子伝導助剤と溶剤とを混合した負極活物質含有スラリーを上記負極集電体の上に塗布する塗布法により形成できる。 Further, the negative electrode active material-containing layer may include the finely divided negative electrode active material and a binder. In this form, there is an effect of stress relaxation accompanying the volume change of Si at the time of charge / discharge, and the charge / discharge cycle characteristics can be further improved. Also, in this embodiment, compared to the case where the negative electrode active material-containing layer is formed by the PVD method or the CVD method described above, it can be carried out with simple equipment, so it is suitable for mass production and the manufacturing cost can be reduced. It is. In order to assist electronic conductivity between the finely divided negative electrode active materials, the negative electrode active material-containing layer may further contain an electron conduction aid. The negative electrode active material-containing layer of this embodiment can be formed by a coating method in which a negative electrode active material-containing slurry obtained by mixing the negative electrode active material, the binder, the electron conduction assistant, and a solvent is applied onto the negative electrode current collector. .
上記バインダとしては、例えば、でんぷん、ポリビニルアルコール、ポリアクリル酸、カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシプロピルセルロース、再生セルロース、ジアセチルセルロース等の多糖類及びそれらの変成体；ポリビニルクロリド、ポリビニルピロリドン、ポリテトラフルオロエチレン、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリエチレン、ポリプロピレン、ポリアミドイミド、ポリアミド等の熱可塑性樹脂及びそれらの変成体；ポリイミド；エチレン−プロピレン−ジエンターポリマー（ＥＰＤＭ）、スルホン化ＥＰＤＭ、スチレンブタジエンゴム（ＳＢＲ）、ブタジエンゴム、ポリブタジエン、フッ素ゴム、ポリエチレンオキシド等のゴム状弾性を有するポリマー及びそれらの変成体；等が挙げられ、これらの１種又は２種以上を用いることができる。 Examples of the binder include starch, polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose (CMC), hydroxypropylcellulose, regenerated cellulose, diacetylcellulose, and other polysaccharides and modified products thereof; polyvinylchloride, polyvinylpyrrolidone, polytetrafluoro Thermoplastic resins such as ethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polyamideimide, polyamide, and their modified products; polyimide; ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR) ), Polymers having rubber-like elasticity such as butadiene rubber, polybutadiene, fluorine rubber, polyethylene oxide, and their modified products; Or more can be used species or two or.
上記電子伝導助剤としては、非水電解質二次電池内において化学変化を起こさないものであれば特に限定されず、例えば、カーボンブラック（サーマルブラック、ファーネスブラック、チャンネルブラック、ケッチェンブラック、アセチレンブラック等）、炭素繊維、金属粉（銅粉、ニッケル粉、アルミニウム粉、銀粉等）、金属繊維、ポリフェニレン誘導体（特開昭５９−２０９７１号公報に記載のもの）等の材料を、１種又は２種以上用いることができる。これらの中でも、カーボンブラックを用いることが好ましく、ケッチェンブラックやアセチレンブラックがより好ましい。 The electron conduction aid is not particularly limited as long as it does not cause a chemical change in the nonaqueous electrolyte secondary battery. For example, carbon black (thermal black, furnace black, channel black, ketjen black, acetylene black) Etc.), carbon fiber, metal powder (copper powder, nickel powder, aluminum powder, silver powder, etc.), metal fiber, polyphenylene derivative (described in JP-A-59-20971), etc. More than one species can be used. Among these, carbon black is preferably used, and ketjen black and acetylene black are more preferable.
また、上記電子伝導助剤を使用する代わりに、上記負極活物質を導電性材料で被覆してもよい。上記導電性材料としては、例えば、カーボンブラック等の炭素材料、又は銅等の金属材料が使用できる。 Further, instead of using the electron conduction aid, the negative electrode active material may be coated with a conductive material. As the conductive material, for example, a carbon material such as carbon black or a metal material such as copper can be used.
上記負極活物質含有スラリーに用いる溶剤については特に限定されず、例えば、Ｎ−メチル−２−ピロリドン（ＮＭＰ）等の有機溶剤が使用できる。 It does not specifically limit about the solvent used for the said negative electrode active material containing slurry, For example, organic solvents, such as N-methyl- 2-pyrrolidone (NMP), can be used.
上記微粉化された負極活物質の粒子径は特に限定されず、例えば０．１〜１０μｍの粒子径の微粒子を用いればよい。上記微粒子の粒子径は、レーザー散乱粒度分布計を用いて測定できる。 The particle size of the finely divided negative electrode active material is not particularly limited, and for example, fine particles having a particle size of 0.1 to 10 μm may be used. The particle diameter of the fine particles can be measured using a laser scattering particle size distribution meter.
上記負極集電体としては、銅又は銅合金からなる箔等を用いることができる。上記負極集電体の厚さは特に限定されないが、強度と体積効率を考慮して５〜３０μｍの範囲で設定される。また、上記負極集電体の表面には、深さが１μｍ以下程度の凹凸があってもよく、その材質には、Ｃｕ／Ｎｉ／Ｃｕ等のクラッド材を使用してもよい。 As the negative electrode current collector, a foil made of copper or a copper alloy can be used. The thickness of the negative electrode current collector is not particularly limited, but is set in the range of 5 to 30 μm in consideration of strength and volume efficiency. The surface of the negative electrode current collector may have irregularities with a depth of about 1 μm or less, and a clad material such as Cu / Ni / Cu may be used as the material thereof.
上記負極活物質含有層の厚さは、負極活物質含有層の組成や形成方法により異なり、特に限定されないが、例えば、スパッタリング法では０．１〜１０μｍ、塗布法では１〜１００μｍとすればよい。 The thickness of the negative electrode active material-containing layer varies depending on the composition and formation method of the negative electrode active material-containing layer, and is not particularly limited. For example, the thickness may be 0.1 to 10 μm in the sputtering method and 1 to 100 μm in the coating method. .
次に、本発明に係る正極について説明する。本発明に係る正極は、正極集電体と、上記正極集電体の上に形成された正極活物質含有層とを備えている。 Next, the positive electrode according to the present invention will be described. The positive electrode according to the present invention includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector.
上記正極は、正極活物質と電子伝導助剤とバインダと溶剤とを混合した正極活物質含有スラリーを上記正極集電体の上に塗布する塗布法により形成できるが、他の方法で形成してもよい。 The positive electrode can be formed by a coating method in which a positive electrode active material-containing slurry in which a positive electrode active material, an electron conduction assistant, a binder, and a solvent are mixed is applied on the positive electrode current collector. Also good.
上記正極活物質としては、例えば、リチウム含有マンガン酸化物、リチウム含有コバルト酸化物、リチウム含有バナジウム酸化物、リチウム含有ニッケル酸化物、リチウム含有鉄酸化物、リチウム含有クロム酸化物、リチウム含有チタン酸化物等のリチウム含有遷移金属酸化物、あるいはこれらの混合物を用いることができる。 Examples of the positive electrode active material include lithium-containing manganese oxide, lithium-containing cobalt oxide, lithium-containing vanadium oxide, lithium-containing nickel oxide, lithium-containing iron oxide, lithium-containing chromium oxide, and lithium-containing titanium oxide. Lithium-containing transition metal oxides such as these, or a mixture thereof can be used.
上記電子伝導助剤、上記バインダ及び上記溶剤は、負極で用いる電子伝導助剤、バインダ及び溶剤と同様のものを使用できる。また、正極で用いる電子伝導助剤としては、更に天然黒鉛（鱗状黒鉛、鱗片状黒鉛、土状黒鉛等）、人造黒鉛等も用いることができる。 As the electron conduction assistant, the binder and the solvent, those similar to the electron conduction assistant, binder and solvent used in the negative electrode can be used. Further, as the electron conduction aid used in the positive electrode, natural graphite (such as scale-like graphite, scale-like graphite, earth-like graphite), artificial graphite and the like can also be used.
上記正極集電体としては、アルミニウム又はアルミニウム合金からなる箔等を用いることができる。上記正極集電体の厚さは特に限定されないが、強度と体積効率を考慮して５〜３０μｍの範囲で設定される。 As the positive electrode current collector, a foil made of aluminum or an aluminum alloy can be used. The thickness of the positive electrode current collector is not particularly limited, but is set in the range of 5 to 30 μm in consideration of strength and volume efficiency.
上記正極活物質含有層の厚さは、正極活物質含有層の組成や形成方法により異なり、特に限定されないが、例えば、塗布法では１〜１００μｍとすればよい。 The thickness of the positive electrode active material-containing layer varies depending on the composition and formation method of the positive electrode active material-containing layer and is not particularly limited. For example, the coating method may be 1 to 100 μm.
次に、本発明に係る非水電解質について説明する。本発明に係る非水電解質としては、下記の溶媒中に下記の無機イオン塩を溶解させることにより調製した電解液が使用できる。 Next, the nonaqueous electrolyte according to the present invention will be described. As the non-aqueous electrolyte according to the present invention, an electrolytic solution prepared by dissolving the following inorganic ion salt in the following solvent can be used.
溶媒としては、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、メチルエチルカーボネート（ＭＥＣ）、γ−ブチロラクトン、１，２−ジメトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン、ジメチルスルフォキシド、１，３−ジオキソラン、ホルムアミド、ジメチルホルムアミド、ジオキソラン、アセトニトリル、ニトロメタン、蟻酸メチル、酢酸メチル、燐酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、３−メチル−２−オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、ジエチルエーテル、１，３−プロパンサルトン等の非プロトン性有機溶媒を、１種又は２種以上用いることができる。 Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), γ-butyrolactone, 1, 2 -Dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivatives, Sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, diethyl ether, 1,3-propane sultone, etc. Protic organic solvents may be used singly or in combination.
無機イオン塩としては、Ｌｉ塩、例えば、ＬｉＣｌＯ4、ＬｉＢＦ4、ＬｉＰＦ6、ＬｉＣＦ3ＳＯ3、ＬｉＣＦ3ＣＯ2、ＬｉＡｓＦ6、ＬｉＳｂＦ6、ＬｉＢ10Ｃｌ10、低級脂肪族カルボン酸Ｌｉ、ＬｉＡｌＣｌ4、ＬｉＣｌ、ＬｉＢｒ、ＬｉＩ、クロロボランＬｉ、四フェニルホウ酸Ｌｉ等を、１種又は２種以上用いることができる。 As the inorganic ion salt, Li salt, for example, LiClO 4, LiBF 4, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower aliphatic carboxylic acids Li, LiAlCl 4 , LiCl, LiBr, LiI, chloroborane Li, Li tetraphenylborate, or the like can be used alone or in combination.
本発明の非水電解質二次電池は、上記負極、上記正極及び上記非水電解質等を備えていればよく、その他の構成要素や構造等については制限されない。例えば、セパレータとしては、強度が十分で、且つ電解液を多く保持できるものがよく、そのような観点から、厚さが１０〜５０μｍで開口率が３０〜７０％の、ポリエチレン、ポリプロピレン、又はエチレン−プロピレン共重合体を含む微多孔フィルムや不織布等が好ましい。 The nonaqueous electrolyte secondary battery of the present invention is not limited as long as it includes the negative electrode, the positive electrode, the nonaqueous electrolyte, and the like. For example, as the separator, a separator having sufficient strength and capable of holding a large amount of electrolyte is preferable. From such a viewpoint, polyethylene, polypropylene, or ethylene having a thickness of 10 to 50 μm and an aperture ratio of 30 to 70% is preferable. -A microporous film or a nonwoven fabric containing a propylene copolymer is preferred.
また、本発明の非水電解質二次電池では、その形状等についても特に制限はない。例えば、コイン形、ボタン形、シート形、積層形、円筒形、偏平形、角形、電気自動車等に用いる大型のものなど、何れであってもよい。 Moreover, in the nonaqueous electrolyte secondary battery of this invention, there is no restriction | limiting in particular also about the shape. For example, any of a coin shape, a button shape, a sheet shape, a laminated shape, a cylindrical shape, a flat shape, a square shape, a large size used for an electric vehicle, etc. may be used.
次に、本発明の非水電解質二次電池の製造方法について説明する。 Next, the manufacturing method of the nonaqueous electrolyte secondary battery of this invention is demonstrated.
本発明の非水電解質二次電池の第１の製造方法は、ケイ素と、酸素とを含み、上記酸素を、上記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、上記負極活物質前駆体を、３００℃以上１０００℃以下の水素ガス中で熱処理する工程とを含み、上記熱処理により、上記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする。 A first method for producing a nonaqueous electrolyte secondary battery according to the present invention includes silicon and oxygen, and the negative electrode includes the oxygen in an atomic ratio of 0.5 to 1.5 with respect to the silicon. An oxygen that constitutes the negative electrode active material precursor by the heat treatment, including a step of producing an active material precursor and a step of heat-treating the negative electrode active material precursor in a hydrogen gas of 300 ° C. to 1000 ° C. And hydrogen are bonded to each other.
上記熱処理により、上記負極活物質前駆体を構成する酸素と、水素とが結合し、ＳｉＯ2中のＯの未結合手をＨで終端でき、不可逆容量の低い負極活物質を得ることができる。 By the heat treatment, oxygen constituting the negative electrode active material precursor and hydrogen are bonded, and the dangling bonds of O in SiO 2 can be terminated with H, so that a negative electrode active material having a low irreversible capacity can be obtained.
上記熱処理温度は、３００℃以上１０００℃以下の範囲である必要があり、Ｏの未結合手へのＨの終端反応効率の点からは４００℃以上７００℃以下がより好ましい。熱処理温度が３００℃未満では、水素のＨ−Ｈ結合を切断するエネルギーが不足する傾向があり、熱処理温度が１０００℃を超えると、Ｓｉ−ＯとＨとの結合よりも、Ｓｉ−Ｏ−Ｈ結合からのＨの離脱反応が支配的になると考えられるからである。 The heat treatment temperature needs to be in the range of 300 ° C. or higher and 1000 ° C. or lower, and is more preferably 400 ° C. or higher and 700 ° C. or lower from the viewpoint of the efficiency of termination reaction of H to the unbonded O. When the heat treatment temperature is less than 300 ° C., energy for breaking the H—H bond of hydrogen tends to be insufficient, and when the heat treatment temperature exceeds 1000 ° C., Si—O—H is more than the bond between Si—O and H. This is because it is considered that the elimination reaction of H from the bond becomes dominant.
上記熱処理の時間は、１時間以上１２時間以下が好ましい。上記負極活物質前駆体を構成する酸素と、水素とが結合反応をより確実に行なうためである。 The heat treatment time is preferably 1 hour or more and 12 hours or less. This is because oxygen and hydrogen constituting the negative electrode active material precursor perform a bonding reaction more reliably.
また、本発明の非水電解質二次電池の第２の製造方法は、ケイ素と、酸素とを含み、上記酸素を、上記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、上記負極活物質前駆体を、１５０℃以上６００℃以下で、２気圧以上３００気圧以下の水蒸気中で高圧水蒸気処理する工程とを含み、上記高圧水蒸気処理により、上記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする。 The second method for producing a non-aqueous electrolyte secondary battery of the present invention includes silicon and oxygen, and the oxygen is included in an atomic ratio of 0.5 to 1.5 with respect to the silicon. A process for producing a negative electrode active material precursor, and a process for subjecting the negative electrode active material precursor to a high-pressure steam treatment at a temperature of 150 ° C. to 600 ° C. in a steam of 2 to 300 atm. By the treatment, oxygen constituting the negative electrode active material precursor is combined with hydrogen.
上記高圧水蒸気処理により、高圧水蒸気により発生するＨ原子による還元作用よってＳｉＯ2中のＯの未結合手をＨで終端できる。更に、高圧水蒸気によりＯ原子も生じ、このＯ原子による酸化作用によってＳｉＯ2中のＯの未結合手を削減できる。このため、不可逆容量の低い負極活物質を得ることができる。 By the high-pressure steam treatment, the dangling bonds of O in SiO 2 can be terminated with H by the reducing action of H atoms generated by the high-pressure steam. Further, O atoms are also generated by the high-pressure steam, and the dangling bonds of O in SiO 2 can be reduced by the oxidizing action of the O atoms. For this reason, a negative electrode active material with a low irreversible capacity can be obtained.
上記高圧水蒸気処理において、温度は１５０℃以上６００℃以下の範囲である必要があり、１５０℃以上４００℃以下が好ましく、圧力は２気圧以上３００気圧以下の範囲であることが必要であり、５気圧以上２６０気圧以下が好ましい。温度１５０℃未満、圧力２気圧未満では、Ｈ原子による還元作用及びＯ原子による酸化作用が低くなる傾向があり、温度６００℃、圧力３００気圧を超えると、酸化作用が支配的になり、可逆容量部のＳｉ微粒子の酸化が進行するため放電容量が低下すると考えられるからである。 In the high-pressure steam treatment, the temperature needs to be in the range of 150 ° C. or more and 600 ° C. or less, preferably 150 ° C. or more and 400 ° C. or less, and the pressure needs to be in the range of 2 to 300 atm. The pressure is preferably from atmospheric pressure to 260 atmospheric pressure. When the temperature is less than 150 ° C. and the pressure is less than 2 atm, the reducing action by H atoms and the oxidizing action by O atoms tend to be low, and when the temperature exceeds 600 ° C. and the pressure is 300 atm, the oxidizing action becomes dominant and the reversible capacity. This is because the discharge capacity is considered to decrease because the oxidation of the Si fine particles in the portion proceeds.
上記高圧水蒸気処理の時間は、１時間以上１２時間以下が好ましい。上記負極活物質前駆体を構成する酸素と、水素とが結合反応をより確実に行なうためである。 The time for the high-pressure steam treatment is preferably 1 hour or more and 12 hours or less. This is because oxygen and hydrogen constituting the negative electrode active material precursor perform a bonding reaction more reliably.
以下、本発明の実施例を詳細に説明するが、本発明は以下の実施例に限定されるものではない。 Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.
（実施例１）
負極は次のように作製した。先ず、Ｓｉ結晶基板とＳｉＯ2基板とを用意した。これらの基板をターゲット材として用いて、２源同時スパッタリング法より、ＳｉとＯとの原子比が約１：１のＳｉＯ膜を作製した。これを一旦薄膜片として回収し、ＳｉＯ2のマトリックス中に数〜１０ｎｍ程度の粒子径のＳｉ微結晶が点在した態様のＳｉＯ片とした。このＳｉＯ片をボールミルで粉砕し、フィルターで濾過することで、粒子径５μｍ以下のＳｉＯ微粉体を作製した。その後、このＳｉＯ微粉体を６００℃の水素ガス中で３時間の熱処理を行なった。
Example 1
The negative electrode was produced as follows. First, a Si crystal substrate and a SiO 2 substrate were prepared. Using these substrates as target materials, SiO films having an atomic ratio of Si and O of about 1: 1 were prepared by the two-source simultaneous sputtering method. This was once recovered as a thin film piece to obtain a SiO piece having an aspect in which Si microcrystals having a particle diameter of about several to 10 nm were scattered in a SiO 2 matrix. This SiO piece was pulverized with a ball mill and filtered with a filter to prepare a SiO fine powder having a particle diameter of 5 μm or less. Then, this SiO fine powder was heat-treated in hydrogen gas at 600 ° C. for 3 hours.
次に、このＳｉＯ微粉体を７２質量％（固形分全量中の含有量。以下同じ。）と、バインダとしてポリアミドイミド８質量％と、電子伝導助剤としてケッチェンブラック（平均粒子径０．０５μｍ）２０質量％と、溶媒としての脱水ＮＭＰとを混合して負極活物質含有スラリーを調製した。続いて、ブレードコーターを用いて、この負極活物質含有スラリーを厚みが１０μｍの銅箔からなる集電体の両面に塗布し、１００℃で乾燥した後ローラープレス機により圧縮成形して、片面当たりの厚みが１５μｍの負極活物質含有層を形成した。その後、この負極活物質含有層付き集電体を真空中、１００℃で１５時間乾燥させた。その後、この負極活物質含有層付き集電体を幅３７ｍｍに裁断して短冊状の負極を得た。 Next, 72% by mass of this SiO fine powder (content in the total solid content; the same shall apply hereinafter), 8% by mass of polyamideimide as a binder, and ketjen black (average particle diameter of 0.05 μm as an electron conduction aid) ) 20% by mass and dehydrated NMP as a solvent were mixed to prepare a negative electrode active material-containing slurry. Subsequently, using a blade coater, this negative electrode active material-containing slurry was applied to both sides of a current collector made of a copper foil having a thickness of 10 μm, dried at 100 ° C., and then compression-molded with a roller press machine. A negative electrode active material-containing layer having a thickness of 15 μm was formed. Then, this collector with a negative electrode active material content layer was dried in vacuum at 100 ° C for 15 hours. Thereafter, the current collector with the negative electrode active material-containing layer was cut into a width of 37 mm to obtain a strip-shaped negative electrode.
一方、正極は次のようにして作製した。先ず、正極活物質としてＬｉ1.0Ｎｉ0.94Ｍｎ0.03Ｍｇ0.03Ｏ2を９６質量％（固形分全量中の含有量。以下同じ。）と、電子伝導助剤としてケッチェンブラック（平均粒子径０．０５μｍ）２質量％と、バインダとしてＰＶＤＦ２質量％と、溶媒としての脱水ＮＭＰとを混合して得た正極活物質含有スラリーを、厚みが１５μｍのアルミニウム箔からなる集電体の両面に塗布し、乾燥後プレスして、片面当たりの厚みが７０μｍの正極活物質含有層を形成した。その後、この正極活物質含有層付き集電体を幅３６ｍｍに裁断して短冊状の正極を得た。 On the other hand, the positive electrode was produced as follows. First, 96% by mass of Li 1.0 Ni 0.94 Mn 0.03 Mg 0.03 O 2 as a positive electrode active material (content in the total amount of solids, the same applies hereinafter), and Ketjen black (average particle diameter of 0.05 μm as an electron conduction aid) ) A positive electrode active material-containing slurry obtained by mixing 2% by mass, 2% by mass of PVDF as a binder, and dehydrated NMP as a solvent was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm and dried. Post pressing was performed to form a positive electrode active material-containing layer having a thickness of 70 μm per side. Thereafter, the current collector with the positive electrode active material-containing layer was cut into a width of 36 mm to obtain a strip-shaped positive electrode.
次に、上記負極と上記正極とを、微孔性ポリエチレンフィルム製のセパレータ（厚み１８μｍ、開口率５０％）を介して重ね合わせてロール状に巻回した後、正極及び負極にそれぞれ端子を溶接し、厚み４ｍｍ、幅３４ｍｍ、高さ４３ｍｍのアルミニウム製電池缶に挿入し、蓋を溶接して取り付けた。その後、蓋の注液口よりＥＣ：ＤＥＣ＝３：７（体積比）の溶媒にＬｉＰＦ6を１ｍｏｌ／Ｌの濃度で溶解させて調製した電解液（非水電解質）２．５ｇを上記電池缶内に注入し、上記注液口を封口して、本実施例の角形非水電解質二次電池を得た。 Next, the negative electrode and the positive electrode are overlapped via a microporous polyethylene film separator (thickness 18 μm, opening ratio 50%) and wound in a roll shape, and then terminals are welded to the positive electrode and the negative electrode, respectively. And it inserted in the aluminum battery can of thickness 4mm, width 34mm, and height 43mm, and the lid was welded and attached. Thereafter, 2.5 g of an electrolytic solution (nonaqueous electrolyte) prepared by dissolving LiPF 6 at a concentration of 1 mol / L in a solvent of EC: DEC = 3: 7 (volume ratio) from the liquid inlet of the lid The liquid injection port was sealed, and the rectangular non-aqueous electrolyte secondary battery of this example was obtained.
（実施例２）
ＳｉＯ微粉体に対する水素ガス中での熱処理に替えて、ステンレス鋼製の内容量２４０ｃｍ3の高圧容器中にＳｉＯ微粉体３０ｇと、水（Ｈ2Ｏ）２．８６ｇとを入れて密閉し、温度２５０℃、圧力約２７気圧で３時間、高圧水蒸気処理を行なった以外は、実施例１と同様にして負極を作製し、その負極を用いた以外は実施例１と同様にして本実施例の角形非水電解質二次電池を作製した。
(Example 2)
Instead of heat treatment in hydrogen gas for SiO fine powder, 30 g of SiO fine powder and 2.86 g of water (H 2 O) were placed in a high pressure vessel made of stainless steel with an internal volume of 240 cm 3 and sealed. A negative electrode was produced in the same manner as in Example 1 except that the high-pressure steam treatment was performed at 250 ° C. and a pressure of about 27 atm for 3 hours. The negative electrode was used in the same manner as in Example 1 except that the negative electrode was used. A square nonaqueous electrolyte secondary battery was produced.
（比較例１）
ＳｉＯ微粉体に対する水素ガス中での熱処理を行なわなかった以外は、実施例１と同様にして負極を作製し、その負極を用いた以外は実施例１と同様にして本比較例の角形非水電解質二次電池を作製した。
(Comparative Example 1)
A negative electrode was prepared in the same manner as in Example 1 except that the heat treatment in hydrogen gas was not performed on the SiO fine powder. An electrolyte secondary battery was produced.
次に、実施例１、実施例２及び比較例１の電池を用いて充放電特性の評価を行った。充放電条件は次のとおりとした。即ち、充電は、電流を０．５Ｃとして定電流で行い、充電電圧が４．２Ｖに達した後、電流が１／１０となるまで定電圧で行った。また、放電は、電流を０．５Ｃとして定電流で行い、放電終止電圧は２．５Ｖとした。 Next, the charge / discharge characteristics were evaluated using the batteries of Example 1, Example 2, and Comparative Example 1. The charge / discharge conditions were as follows. That is, charging was performed at a constant current with a current of 0.5 C, and after the charging voltage reached 4.2 V, the charging was performed at a constant voltage until the current became 1/10. The discharge was performed at a constant current with a current of 0.5 C, and the discharge end voltage was 2.5V.
表１に初回充電容量、初回放電容量、及びクーロン効率を示した。充電容量及び放電容量は、いずれも負極活物質の単位質量当たりの電気容量である。クーロン効率は、下記計算式から算出した。 Table 1 shows the initial charge capacity, initial discharge capacity, and coulomb efficiency. The charge capacity and the discharge capacity are both electric capacities per unit mass of the negative electrode active material. Coulomb efficiency was calculated from the following formula.
クーロン効率（％）＝（初回放電容量／初回充電容量）×１００ Coulomb efficiency (%) = (initial discharge capacity / initial charge capacity) × 100
表１から実施例１及び実施例２の電池では、いずれも初回のクーロン効率が８５％以上と高率であることが分かる。また、上記と同様の充放電条件により２サイクル目のクーロン効率も測定したが、いずれも９９％以上の高率であった。一方、比較例１の電池では、初回のクーロン効率が約６２％と低く、２サイクル目のクーロン効率も低かった。これは、実施例１及び実施例２の電池では、負極活物質のＳｉＯ2マトリックス中のＯの未結合手をＨで終端できたため、充電時にリチウムシリケートの生成を抑制できたためと考えられる。一方、比較例１の電池では、負極活物質のＳｉＯ2マトリックス中のＯの未結合手が終端できていないため、充電時にリチウムシリケートの生成を抑制できなかったものと考えられる。 It can be seen from Table 1 that in the batteries of Example 1 and Example 2, the initial coulombic efficiency is as high as 85% or more. Further, the Coulomb efficiency at the second cycle was also measured under the same charge / discharge conditions as described above, but all were high rates of 99% or more. On the other hand, in the battery of Comparative Example 1, the initial Coulomb efficiency was as low as about 62%, and the Coulomb efficiency in the second cycle was also low. This is presumably because in the batteries of Example 1 and Example 2, since the dangling bonds of O in the SiO 2 matrix of the negative electrode active material could be terminated with H, the generation of lithium silicate during charging could be suppressed. On the other hand, in the battery of Comparative Example 1, since the O dangling bonds in the SiO 2 matrix of the negative electrode active material were not terminated, it is considered that the formation of lithium silicate could not be suppressed during charging.
また、実施例２は実施例１よりも高い初回のクーロン効率を示したが、これは高圧水蒸気処理では、水蒸気の分解で生成したＯ原子（又はＯイオン）とＨ原子（又はＨイオン）によって酸化と還元とが同時に起こると考えられ、このため、ＳｉＯ2の結合欠陥（Ｏの未結合手）を酸化によって低減しつつ、残された未結合手が効率よく還元されてＨにより終端されたためであると考えられる。 In addition, Example 2 showed higher initial Coulomb efficiency than Example 1, but this was caused by O atoms (or O ions) and H atoms (or H ions) generated by decomposition of water vapor in the high-pressure steam treatment. Oxidation and reduction are considered to occur at the same time. For this reason, the bonding defects (O dangling bonds) of SiO 2 are reduced by oxidation, and the remaining dangling bonds are efficiently reduced and terminated by H. It is thought that.
以上のように、本発明の実施例１及び実施例２の電池では、不可逆容量を大幅に低減できたことが分かる。また、これにより、正極容量の利用率を高めることができるので、二次電池としても高効率且つ高容量化が図れた。 As described above, it can be seen that the irreversible capacity can be greatly reduced in the batteries of Example 1 and Example 2 of the present invention. In addition, this makes it possible to increase the utilization rate of the positive electrode capacity, so that it is possible to achieve high efficiency and high capacity as a secondary battery.
以上のように本発明は、高効率で、且つ高容量の非水電解質二次電池を提供でき、かかる非水電解質二次電池は、さまざまな電源として利用できる。 As described above, the present invention can provide a high-efficiency and high-capacity non-aqueous electrolyte secondary battery, and the non-aqueous electrolyte secondary battery can be used as various power sources.
Claims (6)
前記負極は、負極集電体と、前記負極集電体の上に形成された負極活物質含有層とを含み、
前記負極活物質含有層は、ケイ素と、酸素と、水素とを構成元素として含む負極活物質を含み、
前記酸素の前記負極活物質中での含有量は、前記ケイ素に対して原子比で０．５以上１．５以下であり、
前記負極活物質を構成する水素は、前記負極活物質を構成する酸素と結合していることを特徴とする非水電解質二次電池。 A non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte,
The negative electrode includes a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector,
The negative electrode active material-containing layer includes a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements,
The content of the oxygen in the negative electrode active material is 0.5 or more and 1.5 or less in atomic ratio with respect to the silicon,
The non-aqueous electrolyte secondary battery, wherein hydrogen constituting the negative electrode active material is bonded to oxygen constituting the negative electrode active material.
ケイ素と、酸素とを含み、前記酸素を、前記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、
前記負極活物質前駆体を、３００℃以上１０００℃以下の水素ガス中で熱処理する工程とを含み、
前記熱処理により、前記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする非水電解質二次電池の製造方法。 A method for producing a non-aqueous electrolyte secondary battery using a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements,
A step of producing a negative electrode active material precursor comprising silicon and oxygen, wherein the oxygen is contained in an atomic ratio of 0.5 to 1.5 with respect to the silicon;
Heat-treating the negative electrode active material precursor in a hydrogen gas at 300 ° C. or higher and 1000 ° C. or lower,
The method for producing a non-aqueous electrolyte secondary battery, wherein oxygen and hydrogen constituting the negative electrode active material precursor are combined by the heat treatment.
ケイ素と、酸素とを含み、前記酸素を、前記ケイ素に対して原子比で０．５以上１．５以下の割合で含む負極活物質前駆体を製造する工程と、
前記負極活物質前駆体を、１５０℃以上６００℃以下で、２気圧以上３００気圧以下の水蒸気中で高圧水蒸気処理する工程とを含み、
前記高圧水蒸気処理により、前記負極活物質前駆体を構成する酸素と、水素とが結合することを特徴とする非水電解質二次電池の製造方法。 A method for producing a non-aqueous electrolyte secondary battery using a negative electrode active material containing silicon, oxygen, and hydrogen as constituent elements,
A step of producing a negative electrode active material precursor comprising silicon and oxygen, wherein the oxygen is contained in an atomic ratio of 0.5 to 1.5 with respect to the silicon;
A step of subjecting the negative electrode active material precursor to a high-pressure steam treatment at a temperature of 150 ° C. or more and 600 ° C. or less in a steam of 2 to 300 atm,
A method for producing a non-aqueous electrolyte secondary battery, wherein oxygen and hydrogen constituting the negative electrode active material precursor are combined by the high-pressure steam treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011022991A JP2012164481A (en) | 2011-02-04 | 2011-02-04 | Nonaqueous electrolyte secondary battery and method for manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011022991A JP2012164481A (en) | 2011-02-04 | 2011-02-04 | Nonaqueous electrolyte secondary battery and method for manufacturing the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2012164481A true JP2012164481A (en) | 2012-08-30 |
Family
ID=46843696
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2011022991A Withdrawn JP2012164481A (en) | 2011-02-04 | 2011-02-04 | Nonaqueous electrolyte secondary battery and method for manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2012164481A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014073155A1 (en) * | 2012-11-08 | 2014-05-15 | 信越化学工業株式会社 | Method for producing silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery, anode member for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery |
| WO2015029100A1 (en) * | 2013-08-26 | 2015-03-05 | 日立オートモティブシステムズ株式会社 | Negative-electrode active material for lithium-ion secondary batteries, lithium-ion secondary battery, and method for manufacturing negative-electrode active material for lithium-ion secondary batteries |
| WO2015046393A1 (en) * | 2013-09-30 | 2015-04-02 | Tdk株式会社 | Negative-electrode active material, negative electrode using same, and lithium-ion secondary battery |
| JP2018006190A (en) * | 2016-07-04 | 2018-01-11 | 信越化学工業株式会社 | Negative electrode active material, negative electrode, lithium ion secondary battery, use method of lithium ion secondary battery, negative electrode active material manufacturing method, and lithium ion secondary battery manufacturing method |
| JP2019121488A (en) * | 2017-12-28 | 2019-07-22 | Jnc株式会社 | Composition for secondary battery negative electrode, secondary battery negative electrode arranged by use thereof, and secondary battery |
| JP2020136075A (en) * | 2019-02-20 | 2020-08-31 | トヨタ自動車株式会社 | Production method of negative electrode active material |
-
2011
- 2011-02-04 JP JP2011022991A patent/JP2012164481A/en not_active Withdrawn
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014096248A (en) * | 2012-11-08 | 2014-05-22 | Shin Etsu Chem Co Ltd | Method for manufacturing silicon-containing particle for nonaqueous electrolytic secondary battery negative electrode active material, nonaqueous electrolytic secondary battery negative electrode material, nonaqueous electrolytic secondary battery, and silicon-containing particle for nonaqueous electrolytic secondary battery negative electrode active material |
| WO2014073155A1 (en) * | 2012-11-08 | 2014-05-15 | 信越化学工業株式会社 | Method for producing silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery, anode member for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery |
| CN104798229A (en) * | 2012-11-08 | 2015-07-22 | 信越化学工业株式会社 | Method for producing silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery, anode member for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and silicon-containing particles for anode active material for non-aqueous electrolyte secondary battery |
| CN104798229B (en) * | 2012-11-08 | 2017-08-25 | 信越化学工业株式会社 | The manufacture method of the silicon-containing particle of anode for nonaqueous electrolyte secondary battery active material, negative electrode material for nonaqueous electrode secondary battery, the silicon-containing particle of rechargeable nonaqueous electrolytic battery and anode for nonaqueous electrolyte secondary battery active material |
| JPWO2015029100A1 (en) * | 2013-08-26 | 2017-03-02 | 日立オートモティブシステムズ株式会社 | Negative electrode active material for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode active material for lithium ion secondary battery |
| WO2015029100A1 (en) * | 2013-08-26 | 2015-03-05 | 日立オートモティブシステムズ株式会社 | Negative-electrode active material for lithium-ion secondary batteries, lithium-ion secondary battery, and method for manufacturing negative-electrode active material for lithium-ion secondary batteries |
| WO2015046393A1 (en) * | 2013-09-30 | 2015-04-02 | Tdk株式会社 | Negative-electrode active material, negative electrode using same, and lithium-ion secondary battery |
| JPWO2015046393A1 (en) * | 2013-09-30 | 2017-03-09 | Tdk株式会社 | Negative electrode active material, negative electrode using the same, and lithium ion secondary battery |
| CN105518910A (en) * | 2013-09-30 | 2016-04-20 | Tdk株式会社 | Negative-electrode active material, negative electrode using same, and lithium-ion secondary battery |
| JP2018006190A (en) * | 2016-07-04 | 2018-01-11 | 信越化学工業株式会社 | Negative electrode active material, negative electrode, lithium ion secondary battery, use method of lithium ion secondary battery, negative electrode active material manufacturing method, and lithium ion secondary battery manufacturing method |
| WO2018008260A1 (en) * | 2016-07-04 | 2018-01-11 | 信越化学工業株式会社 | Negative electrode active material, negative electrode, lithium-ion secondary battery, method for using lithium-ion secondary battery, method for producing negative electrode active material, and method for producing lithium-ion secondary battery |
| US10873082B2 (en) | 2016-07-04 | 2020-12-22 | Shin-Etsu Chemical Co., Ltd. | Negative electrode active material, negative electrode, lithium ion secondary battery, method of using lithium ion secondary battery, method of producing negative electrode active material, and method of producing lithium ion secondary battery |
| JP2019121488A (en) * | 2017-12-28 | 2019-07-22 | Jnc株式会社 | Composition for secondary battery negative electrode, secondary battery negative electrode arranged by use thereof, and secondary battery |
| JP2020136075A (en) * | 2019-02-20 | 2020-08-31 | トヨタ自動車株式会社 | Production method of negative electrode active material |
| JP7147619B2 (en) | 2019-02-20 | 2022-10-05 | トヨタ自動車株式会社 | Method for producing negative electrode active material |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110800142B (en) | Negative active material for lithium secondary battery and method for preparing same | |
| JP5101692B2 (en) | Anode material with excellent conductivity and high-power secondary battery using the same | |
| JP4701579B2 (en) | Negative electrode for secondary battery | |
| JP5046302B2 (en) | Non-aqueous secondary battery | |
| CN111082129B (en) | Electrochemical device and electronic device | |
| JP6258641B2 (en) | Non-aqueous electrolyte secondary battery | |
| TWI431841B (en) | Electrode active material with high capacity | |
| US20130266868A1 (en) | Method of preparing positive active material for rechargeable lithium battery, positive active material for rechargeable lithium battery prepared by using the method, and rechargeable lithium battery including the same | |
| JP2002358954A (en) | Negative electrode for secondary battery and secondary battery using the same | |
| KR20190041420A (en) | Positive electrode active material for lithium secondary battery, preparing method of the same, positive electrode and lithium secondary battery including the same | |
| WO2005064714A1 (en) | Negative electrode material for secondary battery, negative electrode for secondary battery and secondary battery using same | |
| JP6448462B2 (en) | Anode active material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and method for producing anode active material for nonaqueous electrolyte secondary battery | |
| JP7456671B2 (en) | Positive electrode material for lithium secondary batteries, positive electrodes containing the same, and lithium secondary batteries | |
| WO2012077781A1 (en) | Nonaqueous-electrolytic-solution secondary battery, and positive electrode and negative electrode used therefor | |
| JPH08148185A (en) | Nonaqueous electrolyte secondary battery and negative electrode therefor | |
| JP2012164481A (en) | Nonaqueous electrolyte secondary battery and method for manufacturing the same | |
| JPWO2016194733A1 (en) | Lithium ion secondary battery | |
| WO2015015883A1 (en) | Lithium secondary battery and electrolyte solution for lithium secondary batteries | |
| KR20190044544A (en) | Methode for preparing positive electrode active material and secondary battery using the same | |
| JP5365668B2 (en) | Lithium secondary battery and method for producing negative electrode thereof | |
| JP3340337B2 (en) | Non-aqueous secondary battery and method for producing negative electrode active material | |
| JP2010033830A (en) | Negative electrode for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery using the same | |
| WO2016021443A1 (en) | Method for manufacturing negative electrode of lithium-ion cell, and method for manufacturing lithium-ion cell | |
| JP5933252B2 (en) | Non-aqueous secondary battery | |
| JP2011187287A (en) | Nonaqueous electrolyte secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20130123 |
|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20140513 |