JP5165258B2 - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary battery Download PDFInfo
- Publication number
- JP5165258B2 JP5165258B2 JP2007045405A JP2007045405A JP5165258B2 JP 5165258 B2 JP5165258 B2 JP 5165258B2 JP 2007045405 A JP2007045405 A JP 2007045405A JP 2007045405 A JP2007045405 A JP 2007045405A JP 5165258 B2 JP5165258 B2 JP 5165258B2
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- secondary battery
- electrolyte secondary
- nonaqueous electrolyte
- active material
- 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.)
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- 239000011255 nonaqueous electrolyte Substances 0.000 title claims description 47
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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
-
- 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
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Description
本発明は、リチウムと合金化が可能な元素の酸化物を負極活物質として含有する非水電解質二次電池に関する。 The present invention relates to a non-aqueous electrolyte secondary battery containing, as a negative electrode active material, an oxide of an element that can be alloyed with lithium.
非水電解質二次電池は高電圧・高容量であることから、その発展に対して大きな期待が寄せられている。従来、非水電解質二次電池の負極活物質には、ＬｉまたはＬｉ合金が用いられてきた。しかし、充電時に、デンドライト状のＬｉが析出するため内部短絡が起こり易いという問題があった。また、析出したデンドライト状のＬｉは高比表面積で活性が高く、安全性に欠けるという問題があった。さらに、デンドライト状のＬｉの表面と電解液中の有機溶媒とが反応してＬｉ表面に電子導電性を欠いた界面皮膜が形成されるため電池の内部抵抗が高くなり、結果としてサイクル特性が劣化するという問題があった。 Since non-aqueous electrolyte secondary batteries have high voltage and high capacity, great expectations are placed on their development. Conventionally, Li or a Li alloy has been used as a negative electrode active material of a nonaqueous electrolyte secondary battery. However, there is a problem that an internal short circuit easily occurs because dendritic Li precipitates during charging. In addition, the deposited dendritic Li has a problem that it has a high specific surface area, high activity, and lacks safety. In addition, the dendritic Li surface reacts with the organic solvent in the electrolyte to form an interfacial film lacking electronic conductivity on the Li surface, which increases the internal resistance of the battery, resulting in degradation of cycle characteristics. There was a problem to do.
現状では、ＬｉやＬｉ合金に代えて、Ｌｉイオンを挿入および脱離可能な、天然または人造の黒鉛系炭素材料を負極材料として用いることにより、非水電解質二次電池のサイクル特性の劣化を抑制している。 Presently, natural or artificial graphite-based carbon materials that can insert and desorb Li ions in place of Li and Li alloys are used as negative electrode materials to suppress deterioration of cycle characteristics of non-aqueous electrolyte secondary batteries. doing.
一方、小型化および多機能化した携帯機器用の電池について、さらなる高容量化が望まれるにつれて、低結晶性炭素、Ｓｉ（シリコン）、Ｓｎ（錫）等のように、より多くのＬｉを収容可能な高容量材料が負極材料（以下「高容量負極材料」ともいう）として注目を集めている。ＬｉｔＳｉ(０≦ｔ≦５)を負極活物質として用いた非水電解質二次電池も開示されている（例えば、特許文献１参照）。 On the other hand, as batteries for portable devices that have become smaller and more multifunctional are desired to have higher capacity, they accommodate more Li, such as low crystalline carbon, Si (silicon), Sn (tin), etc. Possible high capacity materials are attracting attention as negative electrode materials (hereinafter also referred to as “high capacity negative electrode materials”). A nonaqueous electrolyte secondary battery using Li t Si (0 ≦ t ≦ 5) as a negative electrode active material is also disclosed (see, for example, Patent Document 1).
また、携帯機器等の先端機器用の電池については、高容量であることに加えて重負荷放電特性が優れていること（放電電流密度が大きいこと）も求められている。そのため、高容量負極材料について、重負荷放電特性を向上させる最も簡便な方法として、高容量負極材料を微粒子化すること、すなわち、高容量負極材料の反応面積を大きくすることが考えられている（例えば、非特許文献１参照）。
しかし、微粉化された負極材料をそのまま用いて塗料を作製する場合、負極材料の比表面積が大きいために、多量のバインダが必要であり、多量のバインダを用いても、その塗料を用いて作製される合剤層の集電体に対する接着性が悪く、その結果、サイクル特性等の特性に悪影響を及ぼしていた。そこで、Ｓｉの超微粒子がＳｉＯ２中に分散した構造を持つＳｉＯｘが注目されている（例えば、特許文献２および３参照）。この材料を用いると、Ｌｉと反応するＳｉが微粒子であるため、充放電がスムーズに行われ、かつ粒子自体はＳｉＯｘであり表面積は小さく、塗料化した際の塗料性や合剤層の集電体に対する接着性にも問題はない。
一方で、本発明者らの検討により、ＳｉＯｘあるいはＳｎＯｘにおいても、Ｌｉを合金化可能な最大量まで挿入して充放電を行うと、サイクル劣化は著しく低下する結果となることが判明した。これは、充放電による体積膨張収縮によって徐々にＳｉＯｘ粒子あるいはＳｎＯｘ粒子が粉砕され、表面に析出した活性な超微粒子のＳｉやＳｎが電解液などと反応して内部の抵抗を増大させるためだと推察される。また、ＳｉＯｘは導電性の低い酸化物であるため、重負荷放電特性に課題を有することも判明した。 On the other hand, as a result of investigations by the present inventors, it has been found that, even in SiO x or SnO x , when charging and discharging are performed by inserting Li up to the maximum amount that can be alloyed, the cycle deterioration is significantly reduced. . This is because SiO x particles or SnO x particles are gradually pulverized by volume expansion and contraction due to charge and discharge, and active ultrafine particles Si and Sn deposited on the surface react with the electrolyte and increase the internal resistance. It is guessed that. It has also been found that SiO x has a problem in heavy load discharge characteristics because it is an oxide with low conductivity.
本発明は、上記課題を解決するためになされたものであり、ＳｉまたはＳｎとＯとを構成元素に含む化合物を負極活物質とし、高容量でサイクル特性等の特性が優れ、かつ重負荷放電特性にも優れた非水電解質二次電池を提供することを目的とする。 The present invention has been made in order to solve the above-described problems, and uses a compound containing Si or Sn and O as constituent elements as a negative electrode active material, has high capacity, excellent characteristics such as cycle characteristics, and heavy load discharge. It aims at providing the nonaqueous electrolyte secondary battery excellent also in the characteristic.
本発明の非水電解質二次電池は、リチウム含有複合酸化物を正極活物質として含有する正極と、負極と、非水溶媒にリチウム塩を溶解した非水電解質とを備えた非水電解質二次電池であって、上記リチウム含有複合酸化物は、層状構造であり、上記負極は、ＳｉまたはＳｎとＯとを構成元素に含む化合物（ただし、ＳｉとＳｎの総量に対するＯの原子比ｘは、０．５≦ｘ≦１．５である）を含むコアとその表面を被覆する炭素の被覆層とで構成された負極活物質を含有し、上記非水電解質は、ハロゲン置換された環状カーボネートを含有し、上記正極活物質の重量Ｐと上記負極活物質の重量Ｎとの比Ｐ／Ｎが、３．７〜６．８に制限されていることを特徴とする。
A non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery comprising a positive electrode containing a lithium-containing composite oxide as a positive electrode active material, a negative electrode, and a non-aqueous electrolyte in which a lithium salt is dissolved in a non-aqueous solvent. In the battery, the lithium-containing composite oxide has a layered structure, and the negative electrode is a compound containing Si or Sn and O as constituent elements (provided that the atomic ratio x of O to the total amount of Si and Sn is 0.5 ≦ x ≦ 1.5) and a negative electrode active material composed of a carbon coating layer covering the surface of the core, and the non-aqueous electrolyte includes a halogen-substituted cyclic carbonate. And the ratio P / N of the weight P of the positive electrode active material and the weight N of the negative electrode active material is limited to 3.7 to 6.8.
本発明によれば、高容量でサイクル特性等の特性が優れ、かつ重負荷放電特性にも優れた非水電解質二次電池を提供することができる。 According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery having a high capacity, excellent characteristics such as cycle characteristics, and excellent heavy load discharge characteristics.
以下に、本発明の非水電解質二次電池の一例について説明する。 Hereinafter, an example of the nonaqueous electrolyte secondary battery of the present invention will be described.
本発明の非水電解質二次電池に用いる負極活物質は、ＳｉまたはＳｎとＯとを構成元素に含む化合物（ただし、ＳｉとＳｎの総量に対するＯの原子比ｘは、０．５≦ｘ≦１．５である）を含むコアと、その表面を被覆する炭素の被覆層とで構成された複合材料である。上記ＳｉまたはＳｎとＯとを構成元素に含む化合物は、ＳｉＯ２のようなＳｉの酸化物、ＳｎＯ２のようなＳｎの酸化物、Ｓｉ１−ｔＳｎｔＯ２のようなＳｉとＳｎの複合酸化物のほかに、Ｓｉ、ＳｎあるいはＳｉ−Ｓｎ合金の微結晶または非晶質相を含んでいてもよく、この場合、ＳｉとＳｎの総量に対するＯの原子比は、上記微結晶または非晶質相のＳｉおよびＳｎを含めた比率で考えればよい。さらに、上記酸化物、複合酸化物、微結晶および非晶質相には、Ｃｏ、Ｎｉ、Ｍｎ、ＴｉなどＳｉおよびＳｎ以外の元素が含まれていてもよい。 The negative electrode active material used in the nonaqueous electrolyte secondary battery of the present invention is a compound containing Si or Sn and O as constituent elements (provided that the atomic ratio x of O with respect to the total amount of Si and Sn is 0.5 ≦ x ≦ 1.5) and a carbon coating layer covering the surface of the core. The compound containing Si or Sn and O as constituent elements includes Si oxide such as SiO 2 , Sn oxide such as SnO 2 , and Si and Sn such as Si 1-t Sn t O 2 . In addition to the complex oxide, it may contain a microcrystalline or amorphous phase of Si, Sn, or Si—Sn alloy. In this case, the atomic ratio of O to the total amount of Si and Sn is the above-mentioned microcrystalline or non-crystalline. What is necessary is just to consider by the ratio containing Si and Sn of a crystalline phase. Furthermore, the oxide, composite oxide, microcrystal, and amorphous phase may contain elements other than Si and Sn, such as Co, Ni, Mn, and Ti.
すなわち、上記の化合物には、単純なＳｉあるいはＳｎの酸化物や複合酸化物だけでなく、例えば一般式ＳｉＯｘとして表され、非晶質のＳｉＯ２マトリックス中に、Ｓｉ（例えば、微結晶Ｓｉ）が分散した構造のものなども含まれる。この場合は、非晶質のＳｉＯ２と、その中に分散しているＳｉを合わせて、上記の原子比ｘが０．５≦ｘ≦１．５を満足していればよい。例えば、非晶質のＳｉＯ２マトリックス中に、Ｓｉが分散した構造で、ＳｉＯ２とＳｉのモル比が１：１の化合物の場合、ｘ＝１であるので、組成式としてはＳｉＯで表記される。このような構造の化合物の場合、例えば、Ｘ線回折分析では、Ｓｉ（微結晶Ｓｉ）の存在に起因するピークが観察されない場合もあるが、透過型電子顕微鏡で観察すると、微細なＳｉの存在が確認できる。 That is, the above compound includes not only a simple Si or Sn oxide or complex oxide, but also, for example, represented by the general formula SiO x , and Si (for example, microcrystalline Si) in an amorphous SiO 2 matrix. ) Are dispersed. In this case, amorphous SiO 2 and Si dispersed therein may be combined so that the atomic ratio x satisfies 0.5 ≦ x ≦ 1.5. For example, in the case of a compound in which Si is dispersed in an amorphous SiO 2 matrix and the molar ratio of SiO 2 and Si is 1: 1, x = 1, so the composition formula is expressed as SiO. The In the case of a compound having such a structure, for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.
さらに、上記ＳｉまたはＳｎとＯとを構成元素に含む化合物は、その表面が炭素で被覆されて複合材料とされる。前述の通りＳｉＯｘは導電性が乏しく、またＳｎの酸化物も重負荷放電特性に対応できるほどの導電性を有していないため、これを負極活物質として用いる際には、良好な電池特性確保の観点から、導電助剤を使用し、負極内におけるＳｉＯｘと導電助剤との混合・分散を良好にして、優れた導電ネットワークを形成する必要がある。そこで、本発明では、ＳｉまたはＳｎとＯとを構成元素に含む化合物の表面の炭素による被覆を行う。これにより、単にＳｉやＳｎの酸化物と炭素材料からなる導電助剤とを混合して用いる場合よりも、負極における導電ネットワークを良好に形成させ、負荷特性を向上させることができる。また、コアの部分が微粉化するのを防ぐ効果も期待でき、サイクル特性を向上させることもできる。 Further, the compound containing Si or Sn and O as constituent elements is coated with carbon to form a composite material. As described above, since SiO x has poor conductivity, and Sn oxide does not have sufficient conductivity to cope with heavy load discharge characteristics, good battery characteristics are obtained when this is used as a negative electrode active material. From the viewpoint of securing, it is necessary to use a conductive auxiliary agent to improve the mixing and dispersion of SiO x and the conductive auxiliary agent in the negative electrode to form an excellent conductive network. Therefore, in the present invention, the surface of a compound containing Si or Sn and O as constituent elements is coated with carbon. As a result, the conductive network in the negative electrode can be formed better and the load characteristics can be improved than in the case of simply using a mixture of a Si or Sn oxide and a conductive additive made of a carbon material. Moreover, the effect which prevents that a core part pulverizes can also be anticipated, and it can also improve cycling characteristics.
また、上記表面に炭素の被覆層を有する複合材料と、導電助剤として機能する炭素材料とをさらに複合化してもよく、これにより負極の導電性をより一層向上させることができるので、充放電サイクル特性や重負荷放電特性などの電池特性をさらに向上させることも可能となる。例えば、炭素で被覆されたＳｉＯｘと炭素材料との複合体として、炭素で被覆されたＳｉＯｘと炭素材料との混合物を更に造粒した造粒体などを用いることができる。 Further, the composite material having the carbon coating layer on the surface and the carbon material functioning as a conductive auxiliary agent may be further combined, thereby further improving the conductivity of the negative electrode. Battery characteristics such as cycle characteristics and heavy load discharge characteristics can be further improved. For example, it can be used as a complex with SiO x and the carbon material coated with carbon, such as granulated material mixture is further granulated with SiO x and the carbon material coated with carbon.
また、上記負極活物質のコアとなる材料は、ＳｉまたはＳｎとＯとを構成元素に含む化合物とそれよりも比抵抗値が小さい導電性材料との複合体、例えば、ＳｉＯｘと炭素粉末との造粒体であってもよく、ＳｉＯｘと炭素粉末が分散した状態で複合化された複合体をさらに炭素で被覆して形成される負極活物質であれば、材料内部のコアの部分にも良好な導電性を付与することができるため、重負荷放電特性などの電池特性をさらに向上させることができる。 In addition, the material serving as the core of the negative electrode active material is a composite of a compound containing Si or Sn and O as a constituent element and a conductive material having a smaller specific resistance value, such as SiO x and carbon powder. In the case of a negative electrode active material formed by coating a composite obtained by dispersing SiO x and carbon powder in a dispersed state with carbon, the core part inside the material may be used. Therefore, it is possible to further improve battery characteristics such as heavy load discharge characteristics.
上記複合体の形成に用い得る上記導電性材料としては、例えば、黒鉛、低結晶性炭素、カーボンナノチューブ、気相成長炭素繊維、カーボンブラック（アセチレンブラック、ケッチェンブラックを含む）などの炭素材料、ニッケル、銅、チタンなどの金属材料が好ましいものとして挙げられる。 Examples of the conductive material that can be used to form the composite include carbon materials such as graphite, low crystalline carbon, carbon nanotubes, vapor grown carbon fiber, and carbon black (including acetylene black and ketjen black), Metal materials such as nickel, copper, and titanium are preferable.
上記導電性材料の形状としては、繊維状またはコイル状のものが好ましく用いられる。繊維状またコイル状の導電性材料は、導電ネットワークを形成し易く、かつ表面積の大きい点において好ましい。 As the shape of the conductive material, a fibrous or coiled shape is preferably used. A fibrous or coiled conductive material is preferable in that it easily forms a conductive network and has a large surface area.
上記例示の導電性材料の中でも、繊維状の炭素材料が特に好ましく用いられる。繊維状の炭素材料は、その形状が細い糸状であり柔軟性が高いために、電池の充放電に伴うＳｉまたはＳｎの酸化物の膨張収縮に追従でき、また、嵩密度が大きいために、酸化物粒子（ＳｉＯｘなど）と多くの接合点を持つことができるからである。繊維状の炭素としては、例えば、ポリアクリロニトリル（ＰＡＮ）系炭素繊維、ピッチ系炭素繊維、気相成長炭素繊維、カーボンナノチューブなどが挙げられ、これらの何れを用いてもよい。 Among the conductive materials exemplified above, a fibrous carbon material is particularly preferably used. The fibrous carbon material has a thin thread shape and high flexibility, so that it can follow the expansion and contraction of the oxide of Si or Sn accompanying the charging / discharging of the battery, and the bulk density is high, so it is oxidized. This is because it can have many junctions with physical particles (such as SiO x ). Examples of the fibrous carbon include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube, and any of these may be used.
なお、繊維状の炭素材料や繊維状の金属は、例えば、気相法にて酸化物粒子の表面に形成することもできる。 The fibrous carbon material or fibrous metal can also be formed on the surface of the oxide particles by, for example, a vapor phase method.
ＳｉＯｘなどの酸化物の比抵抗値が、通常、１０３〜１０７ｋΩｃｍであるのに対して、上記例示の導電性材料の比抵抗値は、通常、１０−５〜１０ｋΩｃｍである。 The specific resistance value of an oxide such as SiO x is usually 10 3 to 10 7 kΩcm, whereas the specific resistance value of the above-described conductive material is usually 10 −5 to 10 kΩcm.
なお、上記例示の導電性材料のうち、各種炭素材料は、炭素被覆層を表面に有する前述の複合材料と炭素材料との複合体を構成するための材料としても使用することができる。 Among the conductive materials exemplified above, various carbon materials can also be used as materials for forming a composite of the above-described composite material having a carbon coating layer on the surface and the carbon material.
本発明に係る上記負極活物質の作製方法について、以下に、ＳｉＯｘを例に挙げて説明する。 The method for producing the negative electrode active material according to the present invention will be described below by taking SiO x as an example.
まず、ＳｉＯｘを含む複合材料のコアを作製する方法について説明する。ＳｉＯｘが分散媒に分散した分散液を用意し、それを噴霧し乾燥して、複数の粒子を含む複合粒子を作製する。分散媒としては、例えば、エタノールなどを用いることができる。分散液の噴霧は、通常、５０〜３００℃の雰囲気内で行うことが適当である。上記の方法以外にも、振動型や遊星型のボールミルやロッドミルなどを用いた機械的な方法による造粒方法においても、同様の複合粒子を作製することができる。 First, a method for producing a composite material core containing SiO x will be described. A dispersion liquid in which SiO x is dispersed in a dispersion medium is prepared, and sprayed and dried to produce composite particles including a plurality of particles. For example, ethanol or the like can be used as the dispersion medium. It is appropriate to spray the dispersion in an atmosphere of 50 to 300 ° C. In addition to the above method, similar composite particles can be produced also by a granulation method by a mechanical method using a vibration type or planetary type ball mill or rod mill.
なお、ＳｉとＯを構成元素に含む化合物（ただし、Ｓｉに対するＯの原子比ｘは、０．５≦ｘ≦１．５である）としては、一般式ＳｉＯｘ（０．５≦ｘ≦１．５）で表わされるケイ素酸化物粉末や、これを有機物ガス中や不活性ガス中で１０００℃程度の温度で熱処理したものを用いればよい。また、ＳｉＯｘと、ＳｉＯｘよりも比抵抗値の小さい導電性材料との造粒体を作製する場合には、ＳｉＯｘが分散媒に分散した分散液中に上記導電性材料を添加し、この分散液を用いて、ＳｉＯｘを複合化する場合と同様の手法によって複合粒子（造粒体）とすればよい。さらに、上記と同様の機械的な方法による造粒方法によっても、ＳｉＯｘと導電性材料との造粒体を作製することができる。 As a compound containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5), the general formula SiO x (0.5 ≦ x ≦ 1) is used. .5) or a heat-treated silicon oxide powder in an organic gas or an inert gas at a temperature of about 1000 ° C. may be used. Further, a SiO x, in the case of manufacturing a granulated body with small conductive material resistivity value than SiO x is, SiO x is adding the conductive material dispersion obtained by dispersing in a dispersion medium, Using this dispersion, composite particles (granulated body) may be formed by the same technique as that for combining SiO x . Furthermore, a granulated body of SiO x and a conductive material can also be produced by a granulation method using the same mechanical method as described above.
次に、コアとなるＳｉＯｘ粒子単体またはＳｉＯｘと導電性材料との造粒体と、炭化水素系ガスとを気相中にて加熱して、炭化水素系ガスの熱分解により生じた炭素を、粒子の表面上に堆積させる。このように、気相成長（ＣＶＤ）法によれば、炭化水素系ガスが複合粒子の隅々にまで行き渡り、粒子の表面や表面の空孔内に、導電性を有する炭素を含む薄くて均一な皮膜（炭素被覆層）を形成できることから、少量の炭素によってＳｉＯｘ粒子に均一性よく導電性を付与できる。 Next, carbon produced by thermal decomposition of the hydrocarbon gas by heating the SiO x particles as a core alone or a granulated body of SiO x and a conductive material and a hydrocarbon gas in a gas phase Is deposited on the surface of the particles. As described above, according to the vapor deposition (CVD) method, the hydrocarbon-based gas spreads to every corner of the composite particle, and the surface of the particle and the pores on the surface are thin and uniform containing conductive carbon. Since a thin film (carbon coating layer) can be formed, the SiO x particles can be imparted with good conductivity with a small amount of carbon.
炭素で被覆されたＳｉＯｘの製造において、気相成長（ＣＶＤ）法の処理温度（雰囲気温度）については、炭化水素系ガスの種類によっても異なるが、通常、６００〜１２００℃が適当であり、中でも、７００℃以上であることが好ましく、８００℃以上であることが更に好ましい。処理温度が高い方が不純物の残存が少なく、かつ導電性の高い炭素を含む被覆層を形成できるからである。 In the production of carbon-coated SiO x , the processing temperature (atmospheric temperature) of the vapor deposition (CVD) method varies depending on the type of hydrocarbon gas, but usually 600 to 1200 ° C. is appropriate, Especially, it is preferable that it is 700 degreeC or more, and it is still more preferable that it is 800 degreeC or more. This is because the higher the treatment temperature, the less the remaining impurities, and the formation of a coating layer containing carbon having high conductivity.
炭化水素系ガスの液体ソースとしては、トルエン、ベンゼン、キシレン、メシチレンなどを用いることができるが、取り扱い易いトルエンが特に好ましい。これらを気化させる（例えば、窒素ガスでバブリングする）ことにより炭化水素系ガスを得ることができる。また、メタンガスやアセチレンガスなどを用いることもできる。 As the liquid source of the hydrocarbon-based gas, toluene, benzene, xylene, mesitylene and the like can be used, but toluene that is easy to handle is particularly preferable. A hydrocarbon-based gas can be obtained by vaporizing them (for example, bubbling with nitrogen gas). Moreover, methane gas, acetylene gas, etc. can also be used.
また、気相成長（ＣＶＤ）法にてＳｉＯｘ粒子（ＳｉＯｘ複合粒子、またはＳｉＯｘと導電性材料との造粒体）の表面を炭素で覆った後に、石油系ピッチ、石炭系のピッチ、熱硬化製樹脂、およびナフタレンスルホン酸塩とアルデヒド類との縮合物よりなる群から選択される少なくとも１種の有機化合物を、炭素を含む被覆層に付着させた後、上記有機化合物が付着した粒子を焼成してもよい。 In addition, after the surface of SiO x particles (SiO x composite particles, or a granulated body of SiO x and a conductive material) is covered with carbon by a vapor deposition (CVD) method, petroleum-based pitch or coal-based pitch is used. At least one organic compound selected from the group consisting of a thermosetting resin and a condensate of naphthalene sulfonate and aldehyde is attached to a coating layer containing carbon, and then the organic compound is attached. The particles may be fired.
具体的には、炭素で被覆されたＳｉＯｘ粒子（ＳｉＯｘ複合粒子、またはＳｉＯｘと導電性材料との造粒体）と、上記有機化合物とが分散媒に分散した分散液を用意し、この分散液を噴霧し乾燥して、有機化合物によって被覆された粒子を形成し、その有機化合物によって被覆された粒子を焼成する。 Specifically, a dispersion liquid in which carbon-coated SiO x particles (SiO x composite particles or a granulated body of SiO x and a conductive material) and the organic compound are dispersed in a dispersion medium is prepared, The dispersion is sprayed and dried to form particles coated with the organic compound, and the particles coated with the organic compound are fired.
上記ピッチとしては等方性ピッチを、熱硬化製樹脂としてはフェノール樹脂、フラン樹脂、フルフラール樹脂などを用いることができる。ナフタレンスルホン酸塩とアルデヒド類との縮合物としては、ナフタレンスルホン酸ホルムアルデヒド縮合物を用いることができる。 An isotropic pitch can be used as the pitch, and a phenol resin, a furan resin, a furfural resin, or the like can be used as the thermosetting resin. As the condensate of naphthalene sulfonate and aldehydes, naphthalene sulfonic acid formaldehyde condensate can be used.
炭素で被覆されたＳｉＯｘ粒子と上記有機化合物を分散させるための分散媒としては、例えば、水、アルコール類（エタノールなど）を用いることができる。分散液の噴霧は、通常、５０〜３００℃の雰囲気内で行うことが適当である。焼成温度は、通常、６００〜１２００℃が適当であるが、中でも７００℃以上が好ましく、８００℃以上であることが更に好ましい。処理温度が高い方が不純物の残存が少なく、かつ導電性の高い良質な炭素材料を含む被覆層を形成できるからである。ただし、処理温度はＳｉＯｘの融点以下であることを要する。 As the dispersion medium for dispersing the carbon-coated SiO x particles and the organic compound, for example, water or alcohols (ethanol or the like) can be used. It is appropriate to spray the dispersion in an atmosphere of 50 to 300 ° C. The firing temperature is usually 600 to 1200 ° C., preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the processing temperature, the less the remaining impurities, and the formation of a coating layer containing a high-quality carbon material with high conductivity. However, the processing temperature needs to be lower than the melting point of SiO x .
以上、ＳｉＯｘを例に挙げて説明したが、Ｓｎの酸化物やＳｉとＳｎの複合酸化物を用いる場合にも、上記と同様にして負極活物質を形成することができる。 As described above, SiO x has been described as an example. However, in the case of using an Sn oxide or a complex oxide of Si and Sn, the negative electrode active material can be formed in the same manner as described above.
本発明においては、上記負極活物質を用いて負極を構成し、ＬｉＣｏＯ２、ＬｉＮｉＯ２などに代表される層状構造のリチウム含有複合酸化物や、ＬｉＭｎ２Ｏ４、Ｌｉ４／３Ｔｉ５／３Ｏ４などに代表されるスピネル構造のリチウム含有複合酸化物などを正極活物質として正極を構成するが、正極活物質の重量Ｐと上記負極活物質の重量Ｎとの比（Ｐ／Ｎ）が３．７〜６．８となるようそれぞれの電極の構成を調整する。上記比率を３．７以上とすることにより、負極活物質の高容量という特徴を生かして電池を高容量化することができ、一方、上記比率を６．８以下とすることにより、負極の充電電気量を一定以下に制限して、充放電における負極活物質の体積膨張・収縮量を制限することができる。電池内での充放電において、負極活物質中のＳｉ１モル当たりの放電電気量がおよそ３５〜７０Ａｈとなる範囲で上記活物質が利用されることが望ましいが、Ｐ／Ｎ比を上記範囲とすることにより、負極活物質の放電電気量を好適な範囲に調整することができる。また、ＳｉＯｘの充電時の状態をＬｉ（ａ＋ｂ）ＳｉＯｘと表わした場合には、充放電に利用されるＬｉのモル比：ａが、１．３５≦ａ≦２．６５となることが望ましい。ここで、ｂは充放電に利用されない不可逆容量分のＬｉのモル比を表わす。また、Ｓｎについても同様であり、ＳｉとＳｎのどちらも含有する場合は、両者を合わせて考えればよい。 In the present invention, a negative electrode is formed using the negative electrode active material, and a lithium-containing composite oxide having a layered structure typified by LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , Li 4/3 Ti 5/3. A positive electrode is formed using a lithium-containing composite oxide having a spinel structure typified by O 4 as a positive electrode active material, and the ratio (P / N) of the weight P of the positive electrode active material to the weight N of the negative electrode active material is The configuration of each electrode is adjusted to be 3.7 to 6.8. By setting the ratio to 3.7 or more, the capacity of the battery can be increased by taking advantage of the high capacity of the negative electrode active material. On the other hand, by setting the ratio to 6.8 or less, charging of the negative electrode is possible. By limiting the amount of electricity to a certain value or less, the volume expansion / contraction amount of the negative electrode active material in charge / discharge can be limited. In charging and discharging in the battery, it is desirable that the active material is used in a range where the amount of discharge electricity per mole of Si in the negative electrode active material is about 35 to 70 Ah, but the P / N ratio is in the above range. Thereby, the discharge electricity quantity of a negative electrode active material can be adjusted to a suitable range. Further, when a state during charging of the SiO x expressed as Li (a + b) SiO x, the molar ratio of Li to be used for charging and discharging: a is to be a 1.35 ≦ a ≦ 2.65 desirable. Here, b represents the molar ratio of Li for the irreversible capacity not used for charging and discharging. The same applies to Sn. When both Si and Sn are contained, both may be considered together.
本発明では、上記のように、負極活物質の充放電における利用率を一定範囲とすることにより、体積膨張・収縮量が制限され、粒子の粉砕などが起こりにくくなるが、完全に粒子の微粉化を抑制できるわけではない。しかし、非水電解質にハロゲン置換された環状カーボネートを含有させることにより、ＳｉＯｘなど複合材料のコアを形成する材料の粉砕によって生じる新生面に上記添加剤が被膜を形成し、電解液との反応を抑制することができるため、高容量を維持したままサイクル特性を向上させることが可能となる。ここで、負極活物質の放電電気量を上記好適な範囲より多くし、負極活物質の利用率を高めた場合、ハロゲン置換された環状カーボネートによる被膜形成量が多くなりすぎ、被膜形成に伴うガス発生や負極の反応性低下など上記化合物を含有させる弊害が顕著になるため、負極活物質の放電電気量が上記範囲となるよう電池を構成することが望ましい。 In the present invention, as described above, by making the utilization rate in charge / discharge of the negative electrode active material within a certain range, the volume expansion / contraction amount is limited and particle crushing is less likely to occur. It cannot be suppressed. However, by adding a halogen-substituted cyclic carbonate to the non-aqueous electrolyte, the above additive forms a film on the new surface generated by crushing the material forming the core of the composite material such as SiO x , and reacts with the electrolyte. Therefore, cycle characteristics can be improved while maintaining a high capacity. Here, when the discharge electricity amount of the negative electrode active material is increased from the above preferred range and the utilization factor of the negative electrode active material is increased, the film formation amount by the halogen-substituted cyclic carbonate becomes too large, and the gas accompanying the film formation It is desirable to configure the battery so that the amount of discharge electricity of the negative electrode active material falls within the above range, since adverse effects of containing the above compounds such as generation and reduced reactivity of the negative electrode become significant.
次に、本発明の負極活物質を用いた非水電解質二次電池の一例について説明する。本発明では、上記負極活物質を用い、非水電解質にハロゲン置換された環状カーボネートを含有させたこと以外は、従来から知られた一般的な非水電解質二次電池と同様の構成をしており、形状等についても制限はない。例えば、コイン型、ボタン型、シート型、積層型、円筒型、偏平型、角型、電気自動車等に用いる大型のもの等いずれであってもよい。 Next, an example of a non-aqueous electrolyte secondary battery using the negative electrode active material of the present invention will be described. In the present invention, the negative electrode active material is used, and the non-aqueous electrolyte has a structure similar to a conventional non-aqueous electrolyte secondary battery except that a halogen-substituted cyclic carbonate is contained. There is no limitation on the shape and the like. For example, any of a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square type, a large type used for an electric vehicle, etc. may be used.
負極は、上記負極活物質と、バインダ（結着剤）等とを含む混合物に、適当な溶剤を加えて十分に混練して得た負極合剤ペーストを、集電体に塗布し、その負極合剤ペーストを所定の厚さおよび所定の密度に制御することにより形成できる。上記混合物には、さらに導電助剤を添加してもよい。また、上記以外の活物質を混合してもよい。 The negative electrode is obtained by applying a negative electrode mixture paste obtained by sufficiently kneading an appropriate solvent to a mixture containing the above negative electrode active material and a binder (binder), and applying the mixture to a current collector. It can be formed by controlling the mixture paste to a predetermined thickness and a predetermined density. You may add a conductive support agent to the said mixture further. Moreover, you may mix active materials other than the above.
導電助剤としては、非水電解質二次電池において化学変化を起こさない電子伝導性材料であれば特に限定されない。通常、天然黒鉛（鱗状黒鉛、鱗片状黒鉛、土状黒鉛等）、人工黒鉛、カーボンブラック、アセチレンブラック、ケッチェンブラック、炭素繊維や金属粉（銅、ニッケル、チタン等）、金属繊維およびポリフェニレン誘導体（特開昭５９−２０９７１号公報に記載）等の材料を１種、または２種以上用いることができる。 The conductive auxiliary agent is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in the nonaqueous electrolyte secondary battery. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, titanium, etc.), metal fiber and polyphenylene derivatives One kind or two or more kinds of materials (described in JP-A-59-20971) can be used.
バインダとしては、通常、でんぷん、ポリビニルアルコール、カルボキシメチルセルロース、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、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、ポリ弗化ビニリデン、ポリエチレン、ポリプロピレン、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、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多糖類、熱可塑性樹脂、その他のゴム状弾性を有するポリマー等や、これらの変成体のうち少なくとも1種または２種以上を用いることができる。 As the binder, starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-dienter Polymer (EPDM), sulfonated EPDM, styrene butadiene rubber, butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide and other polysaccharides, thermoplastic resins, other polymers having rubbery elasticity, etc., and at least of these modified products 1 type (s) or 2 or more types can be used.
正極は、正極活物質と導電助剤とバインダとを含む混合物に、適当な溶剤を加えて十分に混練して得た正極合剤ペーストを、集電体に塗布し、所定の厚さおよび所定の電極密度に制御することにより形成できる。バインダおよび導電助剤については、負極で例示したものと同様のものを用いることができる。 For the positive electrode, a positive electrode mixture paste obtained by adding a suitable solvent to a mixture containing a positive electrode active material, a conductive additive and a binder and kneading the mixture sufficiently is applied to a current collector, and has a predetermined thickness and a predetermined thickness. It can be formed by controlling the electrode density. About a binder and a conductive support agent, the thing similar to what was illustrated with the negative electrode can be used.
正極活物質としては、特に制限はなく各種のものを使用できるが、特に、ＬｉｘＣｏＯ２、ＬｉｘＮｉＯ２、ＬｉｘＭｎＯ２、ＬｉｘＣｏｙＮｉ１−ｙＯ２、ＬｉｘＣｏｙＭ１−ｙＯ２、ＬｉｘＮｉ１−ｙＭｙＯ２、ＬｉｘＭｎｙＮｉｚＣｏ１−ｙ−ｚＯ２、ＬｉｘＭｎ２Ｏ４、ＬｉｘＭｎ２−ｙＭｙＯ４（Ｍは、Ｍｇ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、ＡｌおよびＣｒからなる群から選ばれる少なくとも一種。０≦ｘ≦１．１、０＜ｙ＜１．０、２．０≦ｚ≦２．２）等のＬｉ含有複合酸化物が好適である。 There are no particular limitations on the positive electrode active material, and various materials can be used. In particular, Li x CoO 2 , Li x NiO 2 , Li x MnO 2 , Li x Co y Ni 1-y O 2 , Li x Co y M 1-y O 2, Li x Ni 1-y M y O 2, Li x Mn y Ni z Co 1-y-z O 2, Li x Mn 2 O 4, Li x Mn 2-y M y O 4 (M is at least one selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cu, Zn, Al and Cr. 0 ≦ x ≦ 1.1, 0 <y <1.0, 2.0 ≦ Li-containing composite oxides such as z ≦ 2.2) are preferred.
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良く、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、またはエチレン−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。 As the separator, a separator having sufficient strength and capable of holding a large amount of electrolytic solution is good. From such a viewpoint, polyethylene, polypropylene, or ethylene-propylene copolymer having a thickness of 10 to 50 μm and an aperture ratio of 30 to 70% is used. A microporous film or a non-woven fabric containing a coalescence is preferable.
非水電解質は、環状カーボネートおよび鎖状カーボネートより選ばれる少なくとも１種の非水溶媒にリチウム塩を溶解したものを使用するのが望ましい。 As the nonaqueous electrolyte, it is desirable to use a lithium salt dissolved in at least one nonaqueous solvent selected from cyclic carbonate and chain carbonate.
環状カーボネートとしては、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などを用いることができ、鎖状カーボネートとしては、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネートなどを用いることができる。また、上記以外の溶媒として、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、スルホラン、３−メチル−２−オキサゾリジノン、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溶媒を１種、または２種以上用いてもよい。 As the cyclic carbonate, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate and the like can be used, and as the chain carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like can be used. In addition to the above solvents, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate , One or more of aprotic solvents such as methyl acetate, phosphoric acid triester, trimethoxymethane, sulfolane, 3-methyl-2-oxazolidinone, diethyl ether, 1,3-propane sultone may be used. .
また、本発明において、非水電解質に含有させるハロゲン置換された環状カーボネートとしては、下記の一般式で表される化合物を用いることができる。 In the present invention, as the halogen-substituted cyclic carbonate to be contained in the nonaqueous electrolyte, a compound represented by the following general formula can be used.
上記式中、Ｒ１、Ｒ２、Ｒ３、Ｒ４はそれぞれ、水素、ハロゲン元素または炭素数１〜１０のアルキル基を表しており、アルキル基の水素の一部または全部がハロゲン元素で置換されていてもよく、Ｒ１〜Ｒ４の少なくとも１つはハロゲン元素を含むものである。また、アルキル基を有する場合、その炭素数は少ないほどよく、上記ハロゲン元素としては、フッ素が最も好ましい。非水電解質中でのハロゲン置換された環状カーボネートの含有量は、０．５〜２０重量％とするのがよい。 In the above formula, R 1 , R 2 , R 3 , and R 4 each represent hydrogen, a halogen element, or an alkyl group having 1 to 10 carbon atoms, and part or all of the hydrogen in the alkyl group is substituted with a halogen element. And at least one of R 1 to R 4 contains a halogen element. Moreover, when it has an alkyl group, the carbon number is so small that it is good, and as said halogen element, a fluorine is the most preferable. The content of the halogen-substituted cyclic carbonate in the non-aqueous electrolyte is preferably 0.5 to 20% by weight.
上記非水電解質に含まれる環状カーボネートは、全てが上記ハロゲン置換された環状カーボネートであってもよく、また、ハロゲン置換されていない前述の環状カーボネートとハロゲン置換された上記環状カーボネートとの混合体であってもよい。なお、ハロゲン置換されていない環状カーボネートとして、ビニレンカーボネートを含有させれば、ハロゲン置換された環状カーボネートと共にサイクル特性向上の作用がより発揮されやすくなる。 The cyclic carbonate contained in the non-aqueous electrolyte may be all the halogen-substituted cyclic carbonate, or a mixture of the above-mentioned cyclic carbonate that is not halogen-substituted and the halogen-substituted cyclic carbonate. There may be. In addition, if vinylene carbonate is contained as a cyclic carbonate that is not halogen-substituted, the effect of improving the cycle characteristics is more likely to be exhibited together with the halogen-substituted cyclic carbonate.
電解質であるリチウム塩としては、例えば、ＬｉＣｌＯ４、ＬｉＢＦ４、ＬｉＰＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＮ（ＣＦ３ＳＯ２）２、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等を用いることができ、それらの１種、または２種以上を混合して用いることができる。特に、サイクル特性の点からは、少なくともＬｉＢＦ４を含有させることが望ましく、その含有量を０．５〜１０重量％とすることが望ましい。ＬｉＢＦ４を含有させる場合、ＬｉＢＦ４以外のリチウム塩、例えばＬｉＰＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２などを共存させることにより、電池の特性を向上させることができるので好ましい。非水電解質中でのリチウム塩全体の濃度は、０．２〜３．０ｍｏｌ／ｄｍ３とするのが適当である。 Examples of the lithium salt as the electrolyte, for example, LiClO 4, LiBF 4, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiN (CF 3 SO 2) 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower Aliphatic carboxylic acid Li, LiAlCl 4 , LiCl, LiBr, LiI, chloroborane Li, tetraphenylborate Li, and the like can be used, and one or a mixture of two or more thereof can be used. In particular, from the viewpoint of cycle characteristics, at least LiBF 4 is desirably contained, and the content is desirably 0.5 to 10% by weight. When LiBF 4 is contained, it is preferable to coexist a lithium salt other than LiBF 4 , for example, LiPF 6 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2, etc., because the characteristics of the battery can be improved. The concentration of the entire lithium salt in the nonaqueous electrolyte is suitably 0.2 to 3.0 mol / dm 3 .
以下、実施例により本発明をさらに詳しく説明する。ただし、本発明はこれらの実施例に限定されるものではない。尚、以下の実施例において、複合粒子の平均粒径は、マイクロトラック社製ＭＩＣＲＯＴＲＡＣ ＨＲＡ（Ｍｏｄｅｌ：９３２０−Ｘ１００）を用いてレーザー回折式粒度分布測定法により測定した。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the following examples, the average particle size of the composite particles was measured by a laser diffraction particle size distribution measurement method using MICROTRAC HRA (Model: 9320-X100) manufactured by Microtrack.
（実施例１）
ＳｉＯ粉末（平均粒径：１μｍ）２００ｇと黒鉛（平均粒径：３μｍ）６０ｇおよびバインダのポリエチレン樹脂粒子３０ｇを４Ｌのステンレス製容器に入れ、さらにステンレス製のボールを入れて振動ミルにて３時間混合、粉砕、造粒を行い、平均粒径が１９μｍの複合体粒子を形成した。続いて、複合体粒子１０ｇを沸騰床反応器中で約９５０℃に加熱し、加熱された複合体粒子に、トルエンと窒素ガスとからなる２５℃の混合ガスを接触させ、９５０℃で６０分間ＣＶＤ処理を行った。このようにして、上記混合ガスが熱分解して生じた炭素材料を複合体粒子の表面に堆積させることにより、ＳｉＯと黒鉛との複合体をコアとし、その表面に炭素の被覆層が形成された平均粒径が２０μｍの負極活物質を得た。被覆層形成前後の重量変化から、負極活物質の組成を算出したところ、ＳｉＯ：黒鉛：ＣＶＤ炭素＝６０：２５：１５（重量比）であった。
Example 1
200 g of SiO powder (average particle size: 1 μm), 60 g of graphite (average particle size: 3 μm) and 30 g of polyethylene resin particles of binder are put in a 4 L stainless steel container, and further a stainless steel ball is put in a vibration mill for 3 hours. Mixing, pulverization, and granulation were performed to form composite particles having an average particle diameter of 19 μm. Subsequently, 10 g of the composite particles were heated to about 950 ° C. in a boiling bed reactor, and a mixed gas of 25 ° C. composed of toluene and nitrogen gas was brought into contact with the heated composite particles, and the mixture particles were heated at 950 ° C. for 60 minutes. A CVD process was performed. In this way, by depositing the carbon material generated by thermal decomposition of the mixed gas on the surface of the composite particle, a composite of SiO and graphite is used as a core, and a carbon coating layer is formed on the surface. A negative electrode active material having an average particle size of 20 μm was obtained. The composition of the negative electrode active material was calculated from the change in weight before and after the coating layer was formed, and was SiO: graphite: CVD carbon = 60: 25: 15 (weight ratio).
次に、上記負極活物質８０重量％と、黒鉛１０重量％と、導電助剤としてケッチェンブラック（平均粒径：０．０５μｍ）２重量％と、バインダとしてポリフッ化ビニリデン８重量％と、脱水Ｎ−メチルピロリドンとを混合して得たスラリーを、銅箔からなる集電体に塗布し、乾燥後プレスして、集電体の一方の面に厚み３７μｍの負極合剤層を形成した。その後、直径１６ｍｍに打ち抜き、真空で２４時間乾燥させて、円盤状の負極を得た。
一方、対極としての正極は以下のようにして作製した。まず、正極活物質ＬｉＣｏＯ２を９６重量％と、導電助剤としてケッチェンブラック（平均粒径：０．０５μｍ）２重量％と、バインダとしてポリフッ化ビニリデン２重量％と、脱水Ｎ−メチルピロリドンとを混合して得たスラリーを、アルミ箔からなる集電体に塗布し、乾燥後プレスして、集電体の一方の面に厚み８５μｍの正極合剤層を形成した。その後、直径１５ｍｍに打ち抜き、真空で２４時間乾燥させて、円盤状の正極を得た。バインダとケッチェンブラックの重量を差し引いた活物質重量は、それぞれ正極５６．８ｍｇ、負極９．２０ｍｇであり、活物質の重量比（Ｐ／Ｎ）は６．１７であった。
Next, 80% by weight of the negative electrode active material, 10% by weight of graphite, 2% by weight of ketjen black (average particle size: 0.05 μm) as a conductive additive, 8% by weight of polyvinylidene fluoride as a binder, dehydration A slurry obtained by mixing N-methylpyrrolidone was applied to a current collector made of copper foil, dried and pressed to form a negative electrode mixture layer having a thickness of 37 μm on one surface of the current collector. Thereafter, it was punched out to a diameter of 16 mm and dried in a vacuum for 24 hours to obtain a disc-shaped negative electrode.
On the other hand, the positive electrode as a counter electrode was produced as follows. First, 96% by weight of the positive electrode active material LiCoO 2 , 2 % by weight of ketjen black (average particle size: 0.05 μm) as a conductive additive, 2% by weight of polyvinylidene fluoride as a binder, dehydrated N-methylpyrrolidone, The slurry obtained by mixing was applied to a current collector made of aluminum foil, dried and pressed to form a positive electrode mixture layer having a thickness of 85 μm on one surface of the current collector. Thereafter, it was punched out to a diameter of 15 mm and dried in a vacuum for 24 hours to obtain a disc-shaped positive electrode. The active material weights obtained by subtracting the weights of the binder and ketjen black were 56.8 mg for the positive electrode and 9.20 mg for the negative electrode, respectively, and the weight ratio (P / N) of the active material was 6.17.
次に、エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）の体積比１：２の混合溶媒に１ｍｏｌ／ｄｍ３のＬｉＰＦ６を溶解させた溶液に、４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）を８重量％溶解させた電解液を調製し、ステンレス製の収納容器に導電性接着剤を用いて上記負極を接着し、負極の上にセパレータと上記正極とをこの順で配置した後、上記電解液０．３ｍｌを収納容器内に注入し、ガスケット付きの封口体にて収納容器内を密閉して、コイン型電池を得た。尚、セパレータには微孔性ポリエチレンフィルムを用いた。 Next, 4-fluoro-1,3-dioxolane-2-2 was dissolved in a solution of 1 mol / dm 3 of LiPF 6 in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1: 2. An electrolyte solution in which 8% by weight of ON (FEC) is dissolved is prepared, the negative electrode is adhered to a stainless steel container using a conductive adhesive, and the separator and the positive electrode are arranged in this order on the negative electrode. After that, 0.3 ml of the electrolytic solution was poured into the storage container, and the storage container was sealed with a sealing body with a gasket to obtain a coin-type battery. A microporous polyethylene film was used as the separator.
上記コイン型電池について、０．５ｍＡ／ｃｍ２の電流密度で充電電圧が４．２Ｖに達するまで行う定電流充電と、４．２Ｖの定電圧で電流密度が１／１０に低下するまで行う定電圧充電とからなる定電流−定電圧充電による充電、および、電流密度を０．５ｍＡ／ｃｍ２とし放電終止電圧を２．５Ｖとする放電との組み合わせによる充放電サイクルを１００サイクル繰り返し、１サイクル目の充電容量に対する放電容量の割合を初回充放電効率とし、２サイクル目の放電容量を負極容量（ただし、負極活物質１ｇ当たりに換算）とし、２サイクル目の放電容量に対する１００サイクル目の放電容量の割合を容量維持率として求めた。また、上記試験を行った電池とは別に、２サイクル目の放電を５ｍＡ／ｃｍ２の電流密度で行ったときの放電容量を測定し、上記負極容量に対する割合を重負荷特性として評価した。 For the coin-type battery, constant current charging is performed until the charging voltage reaches 4.2 V at a current density of 0.5 mA / cm 2 , and constant current charging is performed until the current density decreases to 1/10 at a constant voltage of 4.2 V. 100 cycles of charging / discharging cycle by combination of charging with constant current-constant voltage charging consisting of voltage charging and discharging with current density of 0.5 mA / cm 2 and discharge end voltage of 2.5 V, 1 cycle The ratio of the discharge capacity to the charge capacity of the eye is the initial charge / discharge efficiency, and the discharge capacity of the second cycle is the negative electrode capacity (however, converted per 1 g of the negative electrode active material). The ratio of the capacity was determined as the capacity maintenance rate. Separately from the battery subjected to the test, the discharge capacity when the second cycle discharge was performed at a current density of 5 mA / cm 2 was measured, and the ratio to the negative electrode capacity was evaluated as the heavy load characteristic.
（実施例２）
エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）の体積比１：２の混合溶媒に１ｍｏｌ／ｄｍ３のＬｉＰＦ６を溶解させた溶液に、４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）を８重量％、ＬｉＢＦ４を５重量％溶解した電解液を調製し、これを用いた以外は実施例１と同様にしてコイン型電池を作製した。
(Example 2)
To a solution of 1 mol / dm 3 LiPF 6 dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1: 2, 4-fluoro-1,3-dioxolan-2-one (FEC) ) And 5% by weight of LiBF 4 were prepared, and a coin type battery was fabricated in the same manner as in Example 1 except that this was used.
（実施例３）
エチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）の体積比１：２の混合溶媒に１ｍｏｌ／ｄｍ３のＬｉＰＦ６を溶解させた溶液に、４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）を８重量％、ＬｉＢＦ４を５重量％、ビニレンカーボネート（ＶＣ）を２重量％溶解した電解液を調製し、これを用いた以外は実施例１と同様にしてコイン型電池を作製した。
(Example 3)
To a solution of 1 mol / dm 3 LiPF 6 dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1: 2, 4-fluoro-1,3-dioxolan-2-one (FEC) ), 8 wt% LiBF 4 , 5 wt% LiBF 4 and 2 wt% vinylene carbonate (VC) were prepared, and a coin type battery was fabricated in the same manner as in Example 1 except that this was used.
（実施例４）
ＳｉＯを沸騰床反応器中で約９５０℃に加熱し、加熱されたＳｉＯ粒子にトルエンと窒素ガスとからなる２５℃の混合ガスを接触させ、９５０℃で６０分間ＣＶＤ処理を行って炭素被覆層を有するＳｉＯ粒子（平均粒径：８μｍ）を形成した。この粒子１５０ｇと黒鉛（平均粒径３μｍ）１５０ｇを４Ｌのアルミナ製容器に入れ、さらにアルミナ製のボールを入れて振動ミルにて１時間混合を行い、炭素被覆層を有するＳｉＯ粒子と黒鉛との複合体よりなる負極活物質を形成した。その結果、平均粒径は１０μｍとなった。この負極活物質の組成は、ＳｉＯ：黒鉛：ＣＶＤ炭素＝５５：４５：１０（重量比）であった。
Example 4
The SiO 2 is heated to about 950 ° C. in a boiling bed reactor, a mixed gas of 25 ° C. composed of toluene and nitrogen gas is brought into contact with the heated SiO particles, and a CVD treatment is performed at 950 ° C. for 60 minutes to form a carbon coating layer. SiO particles having an average particle diameter (average particle diameter: 8 μm) were formed. 150 g of these particles and 150 g of graphite (average particle size 3 μm) are put in a 4 L alumina container, and further, an alumina ball is added and mixed in a vibration mill for 1 hour, and the SiO particles having a carbon coating layer and graphite are mixed. A negative electrode active material made of a composite was formed. As a result, the average particle size was 10 μm. The composition of this negative electrode active material was SiO: graphite: CVD carbon = 55: 45: 10 (weight ratio).
次に、上記負極活物質９０重量％と、導電助剤としてケッチェンブラック（平均粒径：０．０５μｍ）２重量％と、バインダとしてポリフッ化ビニリデン８重量％と、脱水Ｎ−メチルピロリドンとを混合して得たスラリーを、銅箔からなる集電体に塗布し、乾燥後プレスして、集電体の一方の面に厚み３７μｍの負極合剤層を形成した。その後、直径１６ｍｍに打ち抜き、真空で２４時間乾燥させて、円盤状の負極を得た。一方、正極および電解液は実施例１と同様のものを用い、実施例１と同様にしてコイン型電池を作製した。この電池における活物質重量は、正極：５６．８ｍｇ、負極：９．１ｍｇであり、活物質の重量比（Ｐ／Ｎ）は６．２４であった。 Next, 90% by weight of the negative electrode active material, 2% by weight of ketjen black (average particle size: 0.05 μm) as a conductive auxiliary agent, 8% by weight of polyvinylidene fluoride as a binder, and dehydrated N-methylpyrrolidone The slurry obtained by mixing was applied to a current collector made of copper foil, dried and pressed to form a negative electrode mixture layer having a thickness of 37 μm on one surface of the current collector. Thereafter, it was punched out to a diameter of 16 mm and dried in a vacuum for 24 hours to obtain a disc-shaped negative electrode. On the other hand, the same positive electrode and electrolytic solution as in Example 1 were used, and a coin-type battery was produced in the same manner as in Example 1. The weight of the active material in this battery was 56.8 mg for the positive electrode and 9.1 mg for the negative electrode, and the weight ratio (P / N) of the active material was 6.24.
（実施例５）
ＳｉＯ粉末（平均粒径：１μｍ）を原料とし、撹拌式の転動造粒機（ホソカワミクロン社製、アグロマスタ）を用いて造粒し、平均粒径が１９μｍの粒子とした。続いて、前記造粒体１０ｇを沸騰床床反応器中で約１０００℃に加熱し、加熱された造粒体にベンゼンと窒素ガスとからなる２５℃の混合ガスを接触させ、１０００℃で６０分間ＣＶＤ処理を行った。このようにして、上記混合ガスが熱分解して生じたＣＶＤ炭素を表面に堆積させ、ＳｉＯをコアとし、その表面に炭素の被覆層が形成された平均粒径が２０μｍの負極活物質を得た。被覆層形成前後の重量変化から負極活物質の組成を算出したところ、ＳｉＯ：ＣＶＤ炭素＝８５：１５（重量比）であった。
(Example 5)
SiO powder (average particle size: 1 μm) was used as a raw material, and granulated using a stirring-type rolling granulator (Agromaster, manufactured by Hosokawa Micron Corporation) to obtain particles having an average particle size of 19 μm. Subsequently, 10 g of the granulated body was heated to about 1000 ° C. in a boiling bed reactor, and the heated granulated body was brought into contact with a mixed gas of 25 ° C. composed of benzene and nitrogen gas, and 60 ° C. at 60 ° C. CVD treatment was performed for a minute. In this way, a negative electrode active material having an average particle size of 20 μm is obtained, in which CVD carbon generated by thermal decomposition of the mixed gas is deposited on the surface, SiO is used as a core, and a carbon coating layer is formed on the surface. It was. When the composition of the negative electrode active material was calculated from the change in weight before and after the formation of the coating layer, it was SiO: CVD carbon = 85: 15 (weight ratio).
次に、上記負極活物質を用いて負極を作製した。上記負極活物質６０重量％と、黒鉛３０重量％と、導電助剤としてケッチェンブラック（平均粒径：０．０５μｍ）２重量％と、バインダとしてポリフッ化ビニリデン８重量％と、脱水Ｎ−メチルピロリドンとを混合して得たスラリーを、銅箔からなる集電体に塗布し、乾燥後プレスして、集電体の一方の面に厚み３５μｍの負極合剤層を形成した。その後、直径１６ｍｍに打ち抜き、真空で２４時間乾燥させて、円盤状の負極を得た。一方、正極および電解液は実施例１と同様のものを用い、実施例１と同様にしてコイン型電池を作製した。この電池における活物質重量は、正極：５６．８ｍｇ、負極：８．７５ｍｇであり、活物質の重量比（Ｐ／Ｎ）は６．４９であった。 Next, a negative electrode was produced using the negative electrode active material. 60% by weight of the negative electrode active material, 30% by weight of graphite, 2% by weight of ketjen black (average particle size: 0.05 μm) as a conductive additive, 8% by weight of polyvinylidene fluoride as a binder, and dehydrated N-methyl The slurry obtained by mixing pyrrolidone was applied to a current collector made of copper foil, dried and pressed to form a negative electrode mixture layer having a thickness of 35 μm on one surface of the current collector. Thereafter, it was punched out to a diameter of 16 mm and dried in a vacuum for 24 hours to obtain a disc-shaped negative electrode. On the other hand, the same positive electrode and electrolytic solution as in Example 1 were used, and a coin-type battery was produced in the same manner as in Example 1. The weight of the active material in this battery was 56.8 mg for the positive electrode and 8.75 mg for the negative electrode, and the weight ratio (P / N) of the active material was 6.49.
（実施例６）
ＳｉＯ粉末（平均粒径：１μｍ）と、繊維状炭素（平均長さ：２μｍ、平均直径：０．０８μｍ）と、ポリビニルピロリドン１０ｇとを、エタノール１Ｌ中にて混合し、これらをさらに湿式のジェットミルにて混合してスラリーを得た。スラリーの作製に用いたＳｉＯと繊維状炭素（ＣＦ）との総重量は１００ｇとし、重量比は、ＳｉＯ：ＣＦ＝８０：２０とした。次に、上記スラリーを用いてスプレードライ法（雰囲気温度：２００℃）にて、ＳｉＯと繊維状炭素との複合体粒子を作製した。複合体粒子の平均粒径は１０μｍであった。続いて、複合体粒子１０ｇを沸騰床反応器中で約１０００℃に加熱し、加熱された複合体粒子にベンゼンと窒素ガスとからなる２５℃の混合ガスを接触させ、１０００℃で６０分間ＣＶＤ処理を行った。このようにして、上記混合ガスが熱分解して生じた炭素材料を複合体粒子の表面に堆積させて被覆層を形成し、負極活物質を得た。
(Example 6)
SiO powder (average particle size: 1 μm), fibrous carbon (average length: 2 μm, average diameter: 0.08 μm), and 10 g of polyvinylpyrrolidone are mixed in 1 L of ethanol, and these are further mixed with a wet jet. The slurry was mixed by a mill. The total weight of SiO and fibrous carbon (CF) used for the preparation of the slurry was 100 g, and the weight ratio was SiO: CF = 80: 20. Next, composite particles of SiO and fibrous carbon were produced using the slurry by a spray drying method (atmosphere temperature: 200 ° C.). The average particle size of the composite particles was 10 μm. Subsequently, 10 g of the composite particles are heated to about 1000 ° C. in a boiling bed reactor, a mixed gas of 25 ° C. composed of benzene and nitrogen gas is brought into contact with the heated composite particles, and CVD is performed at 1000 ° C. for 60 minutes. Processed. In this way, a carbon material generated by thermal decomposition of the mixed gas was deposited on the surface of the composite particles to form a coating layer, and a negative electrode active material was obtained.
この負極活物質の平均粒径は、炭素被覆層形成前の複合体粒子の平均粒径とほぼ同じであり、また、被覆層形成前後の重量変化から負極活物質の組成を算出したところ、ＳｉＯ：ＣＦ：ＣＶＤ炭素＝６８：１７：１５（重量比）であった。 The average particle size of the negative electrode active material is substantially the same as the average particle size of the composite particles before the carbon coating layer is formed, and the composition of the negative electrode active material is calculated from the change in weight before and after the formation of the coating layer. : CF: CVD carbon = 68: 17: 15 (weight ratio).
次に、上記負極活物質を用いて負極を作製した。上記負極材料７５重量％と、黒鉛１５重量％と、導電助剤としてケッチェンブラック（平均粒径：０．０５μｍ）２重量％と、バインダとしてポリフッ化ビニリデン８重量％と、脱水Ｎ−メチルピロリドンとを混合して得たスラリーを、銅箔からなる集電体に塗布し、乾燥後プレスして、集電体の一方の面に厚み３６μｍの負極合剤層を形成した。その後、直径１６ｍｍに打ち抜き、真空で２４時間乾燥させて、円盤状の負極を得た。一方、正極および電解液は実施例１と同様のものを用い、実施例１と同様にしてコイン型電池を作製した。この電池における活物質重量は、正極：５６．８ｍｇ、負極：８．６８ｍｇであり、活物質の重量比（Ｐ／Ｎ）は６．５４であった。 Next, a negative electrode was produced using the negative electrode active material. 75% by weight of the negative electrode material, 15% by weight of graphite, 2% by weight of ketjen black (average particle size: 0.05 μm) as a conductive additive, 8% by weight of polyvinylidene fluoride as a binder, and dehydrated N-methylpyrrolidone Was applied to a current collector made of copper foil, dried and pressed to form a negative electrode mixture layer having a thickness of 36 μm on one surface of the current collector. Thereafter, it was punched out to a diameter of 16 mm and dried in a vacuum for 24 hours to obtain a disc-shaped negative electrode. On the other hand, the same positive electrode and electrolytic solution as in Example 1 were used, and a coin-type battery was produced in the same manner as in Example 1. The active material weight in this battery was positive electrode: 56.8 mg, negative electrode: 8.68 mg, and the weight ratio (P / N) of the active material was 6.54.
（比較例１）
電解液に４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）を含有させなかった以外は実施例１と同様にして、コイン型電池を作製した。
(Comparative Example 1)
A coin-type battery was produced in the same manner as in Example 1 except that 4-fluoro-1,3-dioxolan-2-one (FEC) was not contained in the electrolytic solution.
（比較例２）
負極合剤層の厚みを２９μｍとすることにより、負極活物質重量を７．０７ｍｇとし、活物質の重量比（Ｐ／Ｎ）を８．０３とした以外は実施例１と同様にして、コイン型電池を作製した。
(Comparative Example 2)
In the same manner as in Example 1, except that the negative electrode mixture layer thickness was 29 μm, the negative electrode active material weight was 7.07 mg, and the active material weight ratio (P / N) was 8.03. A type battery was produced.
（比較例３）
ＳｉＯ粉末に代えて平均粒径が１μｍのＳｉ粉末（ＳｉＯｘにおけるｘ＝０に相当）を用い、Ｓｉ粉末と黒鉛とポリエチレン樹脂粒子の重量比を１１０ｇ：１５０ｇ：３０ｇとした以外は実施例１と同様にして、平均粒径が２５μｍの負極活物質を形成した。被覆層形成前後の重量変化から、負極活物質の組成を算出したところ、Ｓｉ：黒鉛：ＣＶＤ炭素＝３０：５５：１５（重量比）であった。
(Comparative Example 3)
Example 1 except that Si powder having an average particle diameter of 1 μm (corresponding to x = 0 in SiO x ) was used instead of SiO powder, and the weight ratio of Si powder, graphite, and polyethylene resin particles was changed to 110 g: 150 g: 30 g. In the same manner as described above, a negative electrode active material having an average particle diameter of 25 μm was formed. The composition of the negative electrode active material was calculated from the change in weight before and after the coating layer was formed, and was Si: graphite: CVD carbon = 30: 55: 15 (weight ratio).
以下、実施例１と同様にして、合剤層の厚みを３６μｍとした負極を作製し、コイン型電池を作製した。この電池における活物質重量は、正極：５６．８ｍｇ、負極：９．２０ｍｇであり、活物質の重量比（Ｐ／Ｎ）は６．１７であった。 Thereafter, in the same manner as in Example 1, a negative electrode having a mixture layer thickness of 36 μm was produced to produce a coin-type battery. The active material weight in this battery was positive electrode: 56.8 mg, negative electrode: 9.20 mg, and the weight ratio (P / N) of the active material was 6.17.
（比較例４）
ＳｉＯ粉末と黒鉛とポリエチレン樹脂粒子の重量比を２００ｇ：１１０ｇ：３０ｇとして複合体粒子を形成し、この複合体粒子の表面に炭素の被覆層を形成するＣＶＤ処理に代えて、９５０℃で窒素ガスのみを接触させる焼成処理を行った以外は実施例１と同様にして、平均粒径が２５μｍの負極活物質を形成した。この負極活物質は、表面に炭素の被覆層が形成されておらず、その組成を算出したところ、ＳｉＯ：黒鉛＝６０：４０（重量比）であった。以下、実施例１と同様にして、コイン型電池を作製した。
(Comparative Example 4)
Nitrogen gas is used at 950 ° C. instead of the CVD process in which composite particles are formed with a weight ratio of SiO powder, graphite and polyethylene resin particles of 200 g: 110 g: 30 g, and a carbon coating layer is formed on the surface of the composite particles. A negative electrode active material having an average particle diameter of 25 μm was formed in the same manner as in Example 1 except that the baking treatment in which only the contact was made was performed. This negative electrode active material had no carbon coating layer formed on the surface, and its composition was calculated to be SiO: graphite = 60: 40 (weight ratio). Thereafter, a coin-type battery was produced in the same manner as in Example 1.
上記実施例２〜６および比較例１〜４のコイン型電池についても、実施例１と同様にして、初回充放電効率、負極容量、容量維持率および重負荷特性を測定した。上記それぞれの電池の構成を表１に、特性の測定結果を表２に示す。 For the coin-type batteries of Examples 2-6 and Comparative Examples 1-4, the initial charge / discharge efficiency, negative electrode capacity, capacity retention rate, and heavy load characteristics were measured in the same manner as in Example 1. Table 1 shows the configuration of each battery, and Table 2 shows the measurement results of the characteristics.
上記結果より明らかなように、ＳｉＯｘ（ただし、０．５≦ｘ≦１．５）を含むコアとその表面を被覆する炭素の被覆層とで構成された複合材料を負極活物質とし、非水電解質に、ハロゲン置換された環状カーボネートを含有させ、正極活物質の重量Ｐと負極活物質の重量Ｎとの比（Ｐ／Ｎ）を、３．７〜６．８の範囲に制限した本発明の実施例１〜６の電池では、大きな容量が得られ、サイクル特性を示す容量維持率、重負荷特性共に好ましい結果が得られた。一方、電解質にハロゲン置換された環状カーボネートを含まない比較例１、活物質の重量比が上記範囲を逸脱した比較例２、ＳｉＯｘのｘが上記範囲を逸脱した比較例３、負極活物質の表面に炭素の被覆層が形成されていない比較例４の電池では、サイクル特性および重負荷特性が本発明の電池より劣っていたことから、負極活物質の構成、および正極活物質と負極活物質との重量比を上記範囲とすることにより、非水電解質に含有させた添加剤の効果が発現しやすくなることがわかった。 As is clear from the above results, a composite material composed of a core containing SiO x (where 0.5 ≦ x ≦ 1.5) and a carbon coating layer covering the surface thereof is used as the negative electrode active material, The water electrolyte contains a halogen-substituted cyclic carbonate, and the ratio (P / N) of the weight P of the positive electrode active material to the weight N of the negative electrode active material is limited to a range of 3.7 to 6.8. In the batteries of Examples 1 to 6 of the invention, a large capacity was obtained, and favorable results were obtained for both the capacity maintenance ratio indicating the cycle characteristics and the heavy load characteristics. On the other hand, Comparative Example 1 in which the electrolyte does not contain a halogen-substituted cyclic carbonate, Comparative Example 2 in which the weight ratio of the active material deviates from the above range, Comparative Example 3 in which x of SiO x deviates from the above range, In the battery of Comparative Example 4 in which the carbon coating layer was not formed on the surface, the cycle characteristics and the heavy load characteristics were inferior to the battery of the present invention. Therefore, the configuration of the negative electrode active material, and the positive electrode active material and the negative electrode active material It was found that the effect of the additive contained in the non-aqueous electrolyte is easily manifested by adjusting the weight ratio to the above range.
Claims (15)
上記リチウム含有複合酸化物は、層状構造であり、
上記負極は、ＳｉまたはＳｎとＯとを構成元素に含む化合物（ただし、ＳｉとＳｎの総量に対するＯの原子比ｘは、０．５≦ｘ≦１．５である）を含むコアとその表面を被覆する炭素の被覆層とで構成された負極活物質を含有し、
上記非水電解質は、ハロゲン置換された環状カーボネートを含有し、
上記正極活物質の重量Ｐと上記負極活物質の重量Ｎとの比Ｐ／Ｎが、３．７〜６．８であることを特徴とする非水電解質二次電池。 A non-aqueous electrolyte secondary battery comprising a positive electrode using a lithium-containing composite oxide as a positive electrode active material , a negative electrode, and a non-aqueous electrolyte in which a lithium salt is dissolved in a non-aqueous solvent,
The lithium-containing composite oxide has a layered structure,
The negative electrode includes a core containing Si or a compound containing Sn and O as constituent elements (however, the atomic ratio x of O to the total amount of Si and Sn is 0.5 ≦ x ≦ 1.5) and the surface thereof Containing a negative electrode active material composed of a carbon coating layer covering
The non-aqueous electrolyte contains a halogen-substituted cyclic carbonate,
A nonaqueous electrolyte secondary battery, wherein the ratio P / N of the weight P of the positive electrode active material and the weight N of the negative electrode active material is 3.7 to 6.8.
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| US10340521B2 (en) | 2014-02-28 | 2019-07-02 | Sanyo Electric Co., Ltd. | Non-aqueous electrolyte secondary battery |
| US10276871B2 (en) | 2014-12-09 | 2019-04-30 | Samsung Sdi Co., Ltd. | Rechargeable lithium battery |
| CN110998926A (en) * | 2017-07-21 | 2020-04-10 | 英默里斯石墨及活性炭瑞士有限公司 | Carbon-coated silicon oxide/graphite composite particles, and preparation method and application thereof |
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| JP4910228B2 (en) * | 2000-07-11 | 2012-04-04 | ソニー株式会社 | Nonaqueous electrolyte secondary battery |
| JP4965790B2 (en) * | 2002-10-28 | 2012-07-04 | 株式会社Ｇｓユアサ | Nonaqueous electrolyte secondary battery |
| JP4215718B2 (en) * | 2002-08-22 | 2009-01-28 | 帝人株式会社 | Non-aqueous secondary battery and separator used therefor |
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