JP2006222073A - Nonaqueous secondary battery and method of manufacturing its anode - Google Patents
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Abstract
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本発明は、非水系二次電池およびその負極の製造方法に関し、特に好適な材料を好適な順序で混練する製造方法に関する。 The present invention relates to a non-aqueous secondary battery and a method for producing the negative electrode thereof, and particularly relates to a production method for kneading suitable materials in a suitable order.
近年、起電力が高く、高エネルギー密度を有しているリチウムイオン二次電池は、移動体通信機器や携帯電子機器の発展にともない、市場ではますますの高容量化が求められている。この種のリチウム二次電池負極材料として、リチウム金属を用いると、エネルギー密度は高いが、充放電を繰り返すと、負極表面に樹枝上のデンドライドが成長するため、充放電効率低下によるサイクル特性の低下や、内部短絡による安全性の低下などの課題があった。そこで現在、リチウム（Ｌｉ）イオンを可逆的に吸蔵および放出でき、サイクル特性や安全性に優れた材料である黒鉛などの炭素材料を用いた非水系二次電池が実用化されている。しかしながら、黒鉛で構成された負極の理論容量は約３７２ｍＡｈ／ｇと金属リチウムに比べて１０分の１程度に過ぎず、また現在既に実用化されている電池は、上記理論容量にほぼ近い容量を有している（３５０ｍＡｈ／ｇ）ことから、炭素材料でのこれ以上の高容量化には限界があった。 In recent years, lithium ion secondary batteries with high electromotive force and high energy density are required to have higher capacities in the market with the development of mobile communication devices and portable electronic devices. When lithium metal is used as the negative electrode material for this type of lithium secondary battery, the energy density is high, but when charging and discharging are repeated, dendrites on the dendrite grow on the negative electrode surface, resulting in a decrease in cycle characteristics due to a decrease in charging and discharging efficiency. In addition, there are problems such as a decrease in safety due to an internal short circuit. Therefore, a non-aqueous secondary battery using a carbon material such as graphite, which is a material that can reversibly store and release lithium (Li) ions and has excellent cycle characteristics and safety, has been put into practical use. However, the theoretical capacity of the negative electrode made of graphite is about 372 mAh / g, which is only about one-tenth of that of metallic lithium, and the battery that is already in practical use has a capacity almost similar to the above theoretical capacity. Since it has (350 mAh / g), there is a limit to the further increase in capacity of the carbon material.
そこで負極用電極材料として、現在注目されているのが、ケイ素（Ｓｉ）やスズ（Ｓｎ）などの元素を含む合金系の電極材料である。ＳｉやＳｎなどのある種の金属元素はＬｉを電気化学的に吸蔵および放出できる。また炭素材料に比べて理論容量が大きく、高容量化が可能である。例えば、Ｓｉの場合、その理論容量は約４１９９ｍＡｈ／ｇと黒鉛の場合の約１１．０倍である。しかし、これらの元素を含む合金材料はＬｉイオンを吸蔵する際、その結晶構造内において、Ｌｉイオンを吸蔵するために大きな膨張をともなう特徴がある。例えば、Ｓｉが最大限Ｌｉイオンを吸蔵すると、Ｌｉイオンを吸蔵していないときに比べて、理論的に約４．０倍、Ｓｎでは約３．８倍の膨張が起きると考えられる。これに対して黒鉛ではＬｉイオンが黒鉛の層間に挿入される（インターカレーション反応）ため、膨張は約１．１倍と小さい。したがって合金材料では、膨張にともなって発生する応力は、黒鉛に比べて非常に大きく、これが炭素材料に比べて寿命特性が大きく低下する原因となっている。これについて以下に説明する。合金材料はそれ自身の導電性は黒鉛に比べ小さいため、炭素材料などの導電材を添加する必要がある。しかしながら、導電材としてカーボンブラックなどの粒子状炭素を用いた場合、充放電を繰り返すと、膨張・収縮時の応力により、導電材の導電ネットワーク構造が切断されてしまい、導電性を確保できなくなる。すなわち、合金材料では合材層の導電性低下が、寿命特性の大幅低下の一因となっている。 Therefore, as an electrode material for a negative electrode, an alloy electrode material containing an element such as silicon (Si) or tin (Sn) is currently attracting attention. Certain metal elements such as Si and Sn can occlude and release Li electrochemically. In addition, the theoretical capacity is larger than that of the carbon material, and the capacity can be increased. For example, in the case of Si, the theoretical capacity is about 4199 mAh / g, which is about 11.0 times that of graphite. However, when an alloy material containing these elements occludes Li ions, the alloy material has a feature of large expansion in order to occlude Li ions in the crystal structure. For example, when Si occludes Li ions as much as possible, it is theoretically expected to expand about 4.0 times and Sn about 3.8 times that when Li ions are not occluded. On the other hand, in Lithium, Li ions are inserted between graphite layers (intercalation reaction), so the expansion is as small as about 1.1 times. Therefore, in the alloy material, the stress generated along with the expansion is much larger than that of graphite, which causes the life characteristics to be greatly deteriorated as compared with the carbon material. This will be described below. Since the alloy material has a lower conductivity than graphite, it is necessary to add a conductive material such as a carbon material. However, when particulate carbon such as carbon black is used as the conductive material, if charging / discharging is repeated, the conductive network structure of the conductive material is cut by stress during expansion and contraction, and the conductivity cannot be ensured. That is, in the alloy material, the decrease in conductivity of the composite layer contributes to a significant decrease in life characteristics.
そこで、このような膨張・収縮の大きな合金材料においても導電ネットワーク構造を確保するために、導電材として繊維状炭素を含有することによって、寿命特性が向上することが報告されている（例えば、特許文献１参照）。 Therefore, in order to ensure a conductive network structure even in such an alloy material having a large expansion / contraction, it has been reported that the life characteristics are improved by containing fibrous carbon as a conductive material (for example, patents). Reference 1).
しかしながら、繊維状炭素、特にアスペクト比の大きなものは凝集性が高く、合材ペースト中に繊維状炭素を粉末で添加し、攪拌を行っても、均一に分散することは困難である。すなわち繊維状炭素の導電ネットワーク構造を充分に活用しているとは言えない。 However, fibrous carbon, particularly those having a large aspect ratio, have high agglomeration properties, and even if fibrous carbon is added as powder to the composite paste and stirred, it is difficult to uniformly disperse. That is, it cannot be said that the conductive network structure of fibrous carbon is fully utilized.
また導電材の分散性を向上させるために、導電材を結着材で先に混練することで導電性カーボンやグラファイトの分散性を向上させることが報告されている（例えば、特許文献２参照）。
しかしながら、上記方法ではカーボンブラックやグラファイトのような粒子状炭素は比較的分散が容易であるが、非常に凝集性の高い繊維状炭素ではポリマーの量が不充分であるために充分な分散状態が得られない。 However, in the above method, particulate carbon such as carbon black and graphite is relatively easy to disperse. However, the amount of polymer is insufficient in the case of fibrous carbon having very high cohesiveness, so that a sufficient dispersion state is obtained. I can't get it.
そこで発明者は鋭意研究の結果、負極合材ペーストの作製方法を改善することにより、アスペクト比の比較的大きな繊維状炭素においても均一に合材ペースト中に分散できることを見出した。すなわち、ポリマーと繊維状炭素をある一定比率であらかじめ分散した繊維状炭素ペーストを作製したのち、合金材料を添加することにより、合材ペースト中の分散性を向上し、繊維状炭素の導電ネットワーク構造の有効活用が可能となる。その結果、合金材料の膨張時においても、導電性の大幅な低下を抑制でき、寿命特性の大幅低下の抑制が可能となる。 As a result of intensive studies, the inventor has found that fibrous carbon having a relatively large aspect ratio can be uniformly dispersed in the composite paste by improving the method for producing the negative electrode composite paste. That is, after preparing a fibrous carbon paste in which polymer and fibrous carbon are previously dispersed in a certain ratio, the dispersibility in the composite paste is improved by adding an alloy material, and the conductive network structure of fibrous carbon Can be effectively utilized. As a result, even when the alloy material is expanded, a significant decrease in conductivity can be suppressed, and a significant decrease in life characteristics can be suppressed.
本発明は、上記課題に鑑みて、成し遂げられたものであり、その目的は負極合材ペーストの作製方法を改善することにより、繊維状炭素の分散性を向上し、合金材料のようなＬｉイオンを吸蔵する際に大きな膨張をともなう電極板においても、導電性の大幅な低下を抑制する負極を提供するものである。 The present invention has been accomplished in view of the above problems, and its purpose is to improve the dispersibility of fibrous carbon by improving the method for producing a negative electrode composite paste, and Li ions such as alloy materials. The present invention also provides a negative electrode that suppresses a significant decrease in conductivity even in an electrode plate having a large expansion when occluded.
また、本発明は、さらに、上記負極を用いて電池を構成することにより、高容量化と良好な寿命特性の両立が可能な非水系二次電池を提供するものである。 The present invention further provides a non-aqueous secondary battery capable of achieving both high capacity and good life characteristics by constituting a battery using the negative electrode.
本発明の請求項１に記載の非水系二次電池用負極の製造方法は、導電材と、ポリマーと、分散媒にて湿潤せしめ、一次混練したのち、活物質および分散媒を添加し、混練するという手順において、活物質の構成元素として、少なくともＳｉを含んでおり、導電材は少なくともアスペクト比が１０以上１００００以下の繊維状炭素を含むことを特徴とするものである。 In the method for producing a negative electrode for a non-aqueous secondary battery according to claim 1 of the present invention, the conductive material, the polymer and the dispersion medium are wetted with a dispersion medium, and after the primary kneading, the active material and the dispersion medium are added and kneaded. In this procedure, at least Si is included as a constituent element of the active material, and the conductive material includes fibrous carbon having an aspect ratio of 10 or more and 10,000 or less.
本発明の請求項２に記載の非水系二次電池用負極の製造方法は、一次混練におけるポリマーの添加重量が、繊維状炭素の添加重量の２．０倍以上６．０倍以下であることを特徴とするものである。 In the method for producing a negative electrode for a non-aqueous secondary battery according to claim 2 of the present invention, the weight of the polymer added in the primary kneading is 2.0 times or more and 6.0 times or less of the weight of the fibrous carbon. It is characterized by.
本発明の請求項３に記載の非水系二次電池用負極の製造方法は、繊維状炭素の添加量が、活物質１００重量部当たり３．０重量部以上１２．０重量部以下であることを特徴とするものである。 In the method for producing a negative electrode for a non-aqueous secondary battery according to claim 3 of the present invention, the amount of fibrous carbon added is 3.0 to 12.0 parts by weight per 100 parts by weight of the active material. It is characterized by.
本発明の請求項４に記載の非水系二次電池は、負極が請求項１から３のいずれか一項に記載の非水系二次電池用負極の製造方法によって製造された負極を用いることを特徴とするものである。 The non-aqueous secondary battery according to claim 4 of the present invention uses a negative electrode manufactured by the method for manufacturing a negative electrode for a non-aqueous secondary battery according to any one of claims 1 to 3. It is a feature.
本発明によれば、繊維状炭素の分散性を向上させることが可能となるため、合金材料のようなＬｉイオンを吸蔵する際に大きな膨張をともなう電極板においても、導電性の大幅な低下を抑制する負極を提供することができる。さらに本発明によれば、高容量化と良好な寿命特性の両立が可能な非水系二次電池を提供することができる。 According to the present invention, it becomes possible to improve the dispersibility of fibrous carbon, and therefore, even in an electrode plate with large expansion when occlusion of Li ions such as an alloy material, the conductivity is greatly reduced. A negative electrode to be suppressed can be provided. Furthermore, according to the present invention, it is possible to provide a non-aqueous secondary battery capable of achieving both high capacity and good life characteristics.
本発明の好ましい形態を以下に示す。 Preferred embodiments of the present invention are shown below.
本発明の骨子は、複合リチウム酸化物を活物質とする正極と、リチウムを保持しうる材料を活物質とする負極と、セパレータと、非水溶媒からなる電解液により構成される非水系二次電池において、負極合材ペーストの作製方法として、繊維状炭素とポリマーと溶媒にて一次混練を行うことにより、繊維状炭素の分散性を向上させ、合金材料のようなＬｉイオンを吸蔵する際に大きな膨張をともなう電極板においても、安定に導電性を確保できる負極を提供することにある。 The gist of the present invention is a non-aqueous secondary composed of a positive electrode using a composite lithium oxide as an active material, a negative electrode using a material capable of holding lithium as an active material, a separator, and a non-aqueous solvent. In a battery, as a method for producing a negative electrode composite paste, when primary carbon is kneaded with fibrous carbon, a polymer, and a solvent, the dispersibility of the fibrous carbon is improved and Li ions such as alloy materials are occluded. An object of the present invention is to provide a negative electrode capable of stably ensuring conductivity even in an electrode plate with large expansion.
その作製方法を以下に示す。まず、導電材と、ポリマーを分散媒にて湿潤させ、粘性の高い状態で一次混練を行うことで、繊維状炭素をポリマー中に均一分散させた繊維状炭素ペーストの作製を行う。粘性を上げ、せん断力を向上させるためには、一次混練におけるポリマーの添加重量を繊維状炭素の添加重量の２．０倍以上６．０倍以下とすることが好ましい。このときの分散方法としては、二軸混練機、三本ロール、ニーダーなど、各種分散機を用いることができる。次に、その混練物に活物質と分散媒を分割添加することにより、集電体への塗着に最適な粘度に調整して負極合材ペーストを作製した。 The manufacturing method is shown below. First, a fibrous carbon paste in which fibrous carbon is uniformly dispersed in a polymer is prepared by wetting a conductive material and a polymer with a dispersion medium and performing primary kneading in a highly viscous state. In order to increase the viscosity and improve the shearing force, it is preferable that the addition weight of the polymer in the primary kneading is 2.0 times or more and 6.0 times or less the addition weight of the fibrous carbon. As a dispersing method at this time, various dispersing machines such as a twin-screw kneader, a three-roller, and a kneader can be used. Next, an active material and a dispersion medium were dividedly added to the kneaded product to adjust the viscosity to be optimal for application to the current collector, thereby preparing a negative electrode mixture paste.
負極用活物質としてはリチウムと合金可能な金属が挙げられる。その中でもＳｉやＳｎなどの元素が好ましく、特にＳｉが好ましい。またＳｉやＳｎはそれ自身の導電性が低いため、これらの元素とこれらの元素の合金を複合粒子化したものを活物質として用いてもよい。Ｓｉ合金としては具体的には、ＭｘＳｉ（ＭはＳｉを除く１つ以上の金属元素）で表される化合物で、ＳｉＢ４、ＳｉＢ６、Ｍｇ２Ｓｉ、Ｎｉ２Ｓｉ、ＴｉＳｉ２、ＭｏＳｉ２、ＣｏＳｉ２、ＮｉＳｉ２、ＣａＳｉ２、ＣｒＳｉ２、Ｃｕ５Ｓｉ、ＦｅＳｉ２、ＭｎＳｉ２、ＮｂＳｉ２、ＴａＳｉ２、ＶＳｉ２、ＷＳｉ２、ＺｎＳｉ２などが挙げられる。 Examples of the active material for the negative electrode include metals that can be alloyed with lithium. Among these, elements such as Si and Sn are preferable, and Si is particularly preferable. Further, since Si and Sn themselves have low conductivity, a composite particle of these elements and an alloy of these elements may be used as the active material. Specifically, the Si alloy is a compound represented by M x Si (M is one or more metal elements excluding Si), and is SiB 4 , SiB 6 , Mg 2 Si, Ni 2 Si, TiSi 2 , MoSi. 2, CoSi 2, NiSi 2, CaSi 2, CrSi 2, Cu 5 Si, FeSi 2, MnSi 2, NbSi 2, TaSi 2, VSi 2, WSi 2, ZnSi 2 , and the like.
さらに本発明では１つ以上の非金属元素を含む、炭素以外の４Ｂ族元素も負極活物質として利用できる。本材料中には１種以上の４Ｂ族炭素が含まれていてもよい。例示するならば、ＳｉＣ、Ｓｉ３Ｎ４、Ｓｉ２Ｎ２Ｏ、ＳｉＯｘ（式中、０＜ｘ≦２）、ＬｉＳｉＯなどが挙げられる。 Furthermore, in this invention, 4B group elements other than carbon containing one or more nonmetallic elements can also be utilized as a negative electrode active material. The material may contain one or more 4B group carbons. Illustrative examples include SiC, Si 3 N 4 , Si 2 N 2 O, SiO x (where 0 <x ≦ 2), LiSiO, and the like.
導電材としては、カーボンナノチューブ、カーボンナノファイバ、ＶＧＣＦなど、各種繊維状炭素材料を用いることができる。またアセチレンブラック（ＡＢ）、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカーボンブラックや各種グラファイトを組み合わせて用いてもよい。 As the conductive material, various fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and VGCF can be used. Further, carbon black such as acetylene black (AB), ketjen black, channel black, furnace black, lamp black, thermal black, and various graphites may be used in combination.
繊維状炭素のアスペクト比は１０以上１００００以下のものを用いることができる。さらに望ましくは１０以上１０００以下である。アスペクト比が５以下の場合、合金材料のようなＬｉイオンを吸蔵する際に大きな膨張をともなう場合、充放電時の応力により、導電ネットワーク構造を維持できない。またアスペクト比が１００００を超える場合、炭素繊維の凝集性が大きくなるため、本発明における負極合材ペースト作製方法においても、繊維状炭素を均一に分散できない。そのため、いずれの場合もサイクル特性が低下するため好ましくない。 The aspect ratio of fibrous carbon can be 10 or more and 10,000 or less. More desirably, it is 10 or more and 1000 or less. When the aspect ratio is 5 or less, the conductive network structure cannot be maintained due to stress during charging / discharging in the case where large expansion occurs when occlusion of Li ions such as an alloy material. In addition, when the aspect ratio exceeds 10,000, the cohesiveness of the carbon fibers increases, so that the fibrous carbon cannot be uniformly dispersed even in the negative electrode composite paste preparation method of the present invention. Therefore, in any case, the cycle characteristics deteriorate, which is not preferable.
また繊維状炭素の添加量は活物質１００重量部当たり３．０重量部以上１２．０重量部以下が好ましい。さらに望ましくは４．０重量部以上８．０重量部以下である。３．０重量部よりも少量である場合は、膨張時の応力により導電ネットワーク構造を維持できないことにより、また１２．０重量部を超える場合、導電材と電解液との反応によるガスが発生し、正極と負極との間の反応距離が大きくなることにより、いずれもサイクル特性が低下するため好ましくない。 The amount of fibrous carbon added is preferably 3.0 to 12.0 parts by weight per 100 parts by weight of the active material. More desirably, it is 4.0 parts by weight or more and 8.0 parts by weight or less. If the amount is less than 3.0 parts by weight, the conductive network structure cannot be maintained due to stress during expansion, and if it exceeds 12.0 parts by weight, gas is generated due to the reaction between the conductive material and the electrolyte. Any increase in the reaction distance between the positive electrode and the negative electrode is undesirable because the cycle characteristics deteriorate.
さらに負極用ポリマーとしてはＰＶＤＦおよびその変性体をはじめ各種バインダーを用いることができる。また共重合体ゴム粒子（ＳＢＲ）およびその変性体と、カルボキシメチルセルロース（ＣＭＣ）をはじめとするセルロース系樹脂や、ポリアクリル酸（ＰＡＡ）、ポリビニルアルコール（ＰＶＡ）、ポリエチレンオキサイド（ＰＥＯ）など併用して少量添加することも可能である。ポリマー複数のポリマーを用いる場合、せん断力向上の観点から、増粘効果の高いポリマーを一次混練で投入することが好ましい。この場合、一次混練で投入したポリマー以外は、二次混練で投入することが可能である。 Furthermore, as the polymer for the negative electrode, various binders such as PVDF and modified products thereof can be used. Copolymer rubber particles (SBR) and their modified products are used in combination with cellulose resins such as carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyethylene oxide (PEO), etc. It is also possible to add a small amount. When using a plurality of polymers, it is preferable to add a polymer having a high thickening effect by primary kneading from the viewpoint of improving the shearing force. In this case, the polymer other than the polymer charged in the primary kneading can be charged in the secondary kneading.
さらに、正極については、活物質として種々のコバルト酸リチウム（アルミニウム、マグネシウムなどの共晶体を含む）、ニッケル酸リチウム（コバルトなどの置換体を含む）、マンガン酸リチウムなどの複合酸化物を挙げることができる。 Furthermore, for the positive electrode, various active materials such as lithium cobaltate (including eutectics such as aluminum and magnesium), lithium nickelate (including substitutes such as cobalt), and complex oxides such as lithium manganate Can do.
このときの導電材種としてはアセチレンブラック（ＡＢ）、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカーボンブラックや各種グラファイト、および繊維状炭素を単独、あるいは組み合わせて用いてもよい。 In this case, carbon black such as acetylene black (AB), ketjen black, channel black, furnace black, lamp black, thermal black, various graphites, and fibrous carbon may be used alone or in combination. Good.
ポリマーとしては正極用ポリマーとして公知のものであればよく、ＰＶＤＦおよびその変性体をはじめ各種バインダーを用いることができる。 The polymer may be any known polymer for positive electrodes, and various binders such as PVDF and modified products thereof can be used.
電解液については、塩としてＬｉＰＦ６およびＬｉＢＦ４などの各種リチウム化合物を用いることができる。また溶媒としてエチレンカーボネート（ＥＣ）、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）を単独および組み合わせて用いることができる。また正負極上に良好な皮膜を形成させたり、過充電時の安定性を保証するために、ビニレンカーボネート（ＶＣ）やシクロヘキシルベンゼン（ＣＨＢ）およびその変性体を用いたりすることも可能である。 About electrolyte solution, various lithium compounds, such as LiPF6 and LiBF4, can be used as a salt. Further, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC) can be used alone or in combination as a solvent. It is also possible to use vinylene carbonate (VC), cyclohexylbenzene (CHB), or a modified product thereof in order to form a good film on the positive and negative electrodes and to ensure stability during overcharge.
セパレータについては、非水系二次電池の使用範囲に耐えうる組成であれば特に限定されないが、ポリエチレン・ポリプロピレンなどのオレフィン系樹脂の微多孔フィルムを、単一あるいは複合して用いるのが一般的でありまた態様として好ましい。このセパレータの厚みは特に限定されないが、１０μｍ〜２５μｍであることが好ましい。 The separator is not particularly limited as long as it has a composition that can withstand the range of use of the non-aqueous secondary battery. However, it is common to use a microporous film of an olefin resin such as polyethylene / polypropylene as a single or a composite. Also preferred as an embodiment. The thickness of the separator is not particularly limited, but is preferably 10 μm to 25 μm.
本実施例では非水系二次電池の一例としてリチウムイオン電池を用いて、混練方法の検討に付いて説明する。 In this embodiment, a lithium ion battery is used as an example of a non-aqueous secondary battery, and a study on a kneading method will be described.
（実施例１）
最初に、負極活物質として、Ｔｉ−Ｓｉ合金材料を作製した。Ｓｉ粒子（純度９９．９％、平均粒子径２０μｍ）と、Ｔｉ粒子（純度９９．９％）とを重量比Ｓｉ：Ｔｉ＝６０：４０の比率で混合したのち、ガスアトマイズ法により約１７μｍ〜２３μｍの平均粒子径を有する合金材料を得た。得られた合金粒子のＸＲＤプロファイルは結晶質な相を示す複数のピークを有しており、次に得られた合金材料を、ステンレス製ボール（合金：ボール比＝１：１０（重量比））とともに、アトライタボールミルによって機械的に粉砕し（Ａｒ雰囲気中、回転数６０００ｒｐｍに固定、３時間）、電極材料として粉末を得た。なお上記粉末は、空気に接触させず、Ａｒ雰囲気下で置かれた状態で取り出した。このようにして作製したＴｉ−Ｓｉ電極材料粉末に対して、ＸＲＤによる結晶構造分析および透過電子顕微鏡（ＴＥＭ）観察を行ったところ、少なくともＳｉ相と、ＴｉＳｉ２の金属化合物からなる相とを有する非晶質の合金であることが分かった。
Example 1
First, a Ti—Si alloy material was produced as a negative electrode active material. Si particles (purity 99.9%, average particle diameter 20 μm) and Ti particles (purity 99.9%) are mixed at a weight ratio of Si: Ti = 60: 40, and then about 17 μm to 23 μm by gas atomization. An alloy material having an average particle size of The XRD profile of the obtained alloy particles has a plurality of peaks indicating a crystalline phase. Next, the obtained alloy material is made of stainless steel balls (alloy: ball ratio = 1: 10 (weight ratio)). At the same time, it was mechanically pulverized by an attritor ball mill (fixed at 6000 rpm for 3 hours in an Ar atmosphere) to obtain a powder as an electrode material. The powder was taken out in a state of being placed in an Ar atmosphere without being brought into contact with air. When the Ti-Si electrode material powder thus produced was subjected to XRD crystal structure analysis and transmission electron microscope (TEM) observation, it had at least a Si phase and a phase composed of a metal compound of TiSi 2. It was found to be an amorphous alloy.
次に、上記のようにして作製した負極活物質を用いて負極を作製した。活物質１０ｇと、導電材として繊維状炭素粉末（昭和電工製ＶＧＣＦ、アスペクト比１００）０．６ｇと、ポリマーとしてＰＶＤＦ＃１３２０（呉羽化学製）のＮＭＰ（Ｎ−２−メチルピロリドン）溶液（固形分重量：１２．０重量％）２０．０ｇと、ＮＭＰとを用い、図１に示すフローチャートのように、負極合材ペーストを作製した。すなわちまずＶＧＣＦと、ＰＶＤＦと、ＮＭＰとを双腕型混練機にて一次混練を行い、充分に繊維状炭素の分散性を向上した。この一次混練物に電極材料およびＮＭＰを添加したのち、二次混練を行い、負極合材ペーストを得た。 Next, a negative electrode was produced using the negative electrode active material produced as described above. 10 g of active material, 0.6 g of fibrous carbon powder (VGCF manufactured by Showa Denko, aspect ratio 100) as a conductive material, and an NMP (N-2-methylpyrrolidone) solution (solid) of PVDF # 1320 (manufactured by Kureha Chemical) as a polymer (Min weight: 12.0% by weight) 20.0 g and NMP were used to produce a negative electrode mixture paste as shown in the flowchart of FIG. That is, first, VGCF, PVDF, and NMP were first kneaded in a double-arm kneader to sufficiently improve the dispersibility of fibrous carbon. After adding an electrode material and NMP to this primary kneaded material, secondary kneading was performed to obtain a negative electrode mixture paste.
このようなペーストを集電体上に、乾燥後の合材厚さが約７０μｍになるようにナイフコータによって塗布した。塗布後、６０℃の大気中にて送風乾燥を行い、負極粗製物を作製した。この負極粗製物を直径５５ｍｍφに打ち抜き、負極を作製した。これを実施例１の負極電極板とする。 Such a paste was applied onto a current collector by a knife coater so that the thickness of the mixed material after drying was about 70 μm. After application, blown drying was performed in the atmosphere at 60 ° C. to produce a negative electrode crude product. This crude negative electrode was punched out to a diameter of 55 mmφ to produce a negative electrode. This is the negative electrode plate of Example 1.
正極は以下のようにして作製した。正極材料であるＬｉＣｏＯ２はＬｉ２ＣＯ３とＣｏＣＯ３とを所定のモル比で混合し、９５０℃で加熱することによって合成した。さらに、これを１００メッシュ以下の大きさに分級した。次に正極材料１００ｇに対して、導電材としてアセチレンブラック３ｇ、結着材としてＰＶＤＦ＃１３２０のＮＭＰ水溶液３３．３とを用い、充分に混合して負極合材ペーストを得た。このスペーストをアルミニウム芯材上に塗布して乾燥し、さらにプレスして５０ｍｍφに打ち抜くことによって正極を得た。 The positive electrode was produced as follows. LiCoO 2 which is a positive electrode material was synthesized by mixing Li 2 CO 3 and CoCO 3 at a predetermined molar ratio and heating at 950 ° C. Furthermore, this was classified into a size of 100 mesh or less. Next, with respect to 100 g of the positive electrode material, 3 g of acetylene black as a conductive material and 33.3 NMP aqueous solution of PVDF # 1320 as a binder were mixed well to obtain a negative electrode mixture paste. This space was coated on an aluminum core, dried, pressed, and punched to 50 mmφ to obtain a positive electrode.
上記のように作製した正極および負極とポリエチレン製セパレータ（厚さ２７μｍ）とを電解液（ＬｉＰＦ６のエチレンカーボネート＋ジエチルカーボネート（体積比１：３）溶液（濃度１ｍｏｌ／Ｌ））に充分に含浸させ、セパレータを正極および負極によって挟持し、電池を作製した。これを実施例１のリチウムイオン電池とする。 The positive electrode and negative electrode prepared as described above and a polyethylene separator (thickness 27 μm) are sufficiently impregnated in an electrolytic solution (LiPF 6 ethylene carbonate + diethyl carbonate (volume ratio 1: 3) solution (concentration 1 mol / L)). The separator was sandwiched between the positive electrode and the negative electrode to produce a battery. This is the lithium ion battery of Example 1.
（実施例２）
まず、図２に示すフローチャートのように、負極を作製した。すなわち実施例１では二次混練において、活物質と、ＮＭＰとを一括で添加したところを、等量となるよう２分割して添加した以外は実施例１と全く同様の作製手順で負極電極板を得た。これを実施例２の負極電極板とする。
(Example 2)
First, as in the flowchart shown in FIG. 2, a negative electrode was produced. That is, in Example 1, in the secondary kneading, the negative electrode plate was prepared in exactly the same production procedure as in Example 1 except that the active material and NMP were added together in two portions so as to be equal. Got. This is the negative electrode plate of Example 2.
正極電極板は実施例１と同様に作製したものを用い、また実施例１と同様に作製した電池を実施例２のリチウムイオン電池とする。 A positive electrode plate produced in the same manner as in Example 1 was used, and a battery produced in the same manner as in Example 1 was used as the lithium ion battery in Example 2.
（比較例１）
まず、図３に示すフローチャートのように、負極を作製した。すなわち一次混練において、活物質と、ＶＧＣＦと、ＰＶＤＦと、ＮＭＰとを一括で添加し、混練を行った以外は実施例１と全く同様の作製手順で負極電極板を得た。これを比較例１の負極電極板とする。
(Comparative Example 1)
First, as shown in the flowchart of FIG. 3, a negative electrode was produced. That is, in the primary kneading, a negative electrode plate was obtained in the same production procedure as in Example 1 except that the active material, VGCF, PVDF, and NMP were added all at once and kneading was performed. This is the negative electrode plate of Comparative Example 1.
正極電極板は実施例１と同様に作製したものを用い、また実施例１と同様に作製した電池を比較例１のリチウムイオン電池とする。 A positive electrode plate produced in the same manner as in Example 1 was used, and a battery produced in the same manner as in Example 1 was used as the lithium ion battery in Comparative Example 1.
（比較例２）
まず、図４に示すフローチャートのように、負極を作製した。すなわち一次混練において活物質と、ＰＶＤＦと、ＮＭＰを添加し、一次混練を行ったのち、ＶＧＣＦと、ＮＭＰとを添加し、二次混練を行った以外は実施例１と全く同様の作製手順で負極電極板を得た。これを比較例２の負極電極板とする。
(Comparative Example 2)
First, a negative electrode was produced as shown in the flowchart of FIG. That is, in the primary kneading, the active material, PVDF, and NMP were added, and after the primary kneading, VGCF and NMP were added and the secondary kneading was performed. A negative electrode plate was obtained. This is the negative electrode plate of Comparative Example 2.
正極電極板は実施例１と同様に作製したものを用い、また実施例１と同様に作製した電池を比較例２のリチウムイオン電池とする。 A positive electrode plate produced in the same manner as in Example 1 was used, and a battery produced in the same manner as in Example 1 was used as the lithium ion battery in Comparative Example 2.
（比較例３）
まず、図５に示すフローチャートのように、負極を作製した。すなわち一次混練において活物質と、ＮＭＰを添加し、一次混練を行ったのち、ＶＧＣＦと、ＰＶＤＦと、ＮＭＰとを添加し、二次混練を行った以外は実施例１と全く同様の作製手順で負極電極板を得た。これを比較例３の負極電極板とする。
(Comparative Example 3)
First, as shown in the flowchart of FIG. 5, a negative electrode was produced. That is, in the primary kneading, the active material and NMP were added, and after the primary kneading, VGCF, PVDF, and NMP were added and the secondary kneading was performed. A negative electrode plate was obtained. This is the negative electrode plate of Comparative Example 3.
正極電極板は実施例１と同様に作製したものを用い、また実施例１と同様に作製した電池を比較例３のリチウムイオン電池とする。 A positive electrode plate produced in the same manner as in Example 1 was used, and a battery produced in the same manner as in Example 1 was used as the lithium ion battery in Comparative Example 3.
（比較例４）
まず、図６に示すフローチャートのように、負極を作製した。すなわち一次混練においてＶＧＣＦと、ＮＭＰを添加し、一次混練を行ったのち、活物質と、ＰＶＤＦと、溶媒とを添加し、二次混練を行った以外は実施例１と全く同様の作製手順で負極電極板を得た。これを比較例４の負極電極板とする。
(Comparative Example 4)
First, a negative electrode was produced as shown in the flowchart of FIG. That is, in the primary kneading, VGCF and NMP were added, the primary kneading was performed, the active material, PVDF, and the solvent were added, and the secondary kneading was performed. A negative electrode plate was obtained. This is referred to as a negative electrode plate of Comparative Example 4.
正極電極板は実施例１と同様に作製したものを用い、また実施例１と同様に作製した電池を比較例４のリチウムイオン電池とする。 A positive electrode plate produced in the same manner as in Example 1 was used, and a battery produced in the same manner as in Example 1 was used as the lithium ion battery in Comparative Example 4.
まず、これらの負極電極板を以下に示す方法にて評価した。その結果を（表１）に記す。 First, these negative electrode plates were evaluated by the following methods. The results are shown in (Table 1).
（１００サイクル容量維持率）
最初に、電池を電池電圧が４．０５Ｖになるまで、定電流（充電電流０．２Ｃ（１Ｃは１時間率電流））で充電した。次に、充電電流が０．０１Ｃになるまで定電圧（充電圧４．０５Ｖ）で充電した。その後、電池電圧が２．５Ｖになるまで定電流（０．２Ｃ）で放電した。
(100 cycle capacity maintenance rate)
First, the battery was charged with a constant current (charging current 0.2 C (1 C is 1 hour rate current)) until the battery voltage reached 4.05 V. Next, the battery was charged at a constant voltage (charging pressure 4.05V) until the charging current reached 0.01C. Thereafter, the battery was discharged at a constant current (0.2 C) until the battery voltage reached 2.5V.
２回目からは、電池電圧が４．０５Ｖになるまで充電電流１Ｃの定電流で充電したのちに、充電電流が０．０５Ｃになるまで定電圧（充電圧４．０５Ｖ）で充電し、続けて、電池電圧が２．５Ｖになるまで放電電流１Ｃの定電流で放電するサイクルを繰り返した。これら充放電サイクルは、すべて２０℃に設定した恒温槽の中で行った。このようにして、２サイクル目の電池容量に対する１００サイクル目の電池容量の比を求め、その値に１００をかけて容量維持率（％）とした。容量維持率が１００に近いほど充放電サイクル特性が高いことを示している。 From the second time, after charging with a constant current of charging current 1C until the battery voltage reaches 4.05V, charging with constant voltage (charging pressure 4.05V) until the charging current reaches 0.05C, The cycle of discharging at a constant current of 1 C was repeated until the battery voltage reached 2.5V. These charge / discharge cycles were all performed in a thermostat set at 20 ° C. In this way, the ratio of the battery capacity at the 100th cycle to the battery capacity at the second cycle was determined, and the value was multiplied by 100 to obtain the capacity retention rate (%). The closer the capacity retention rate is to 100, the higher the charge / discharge cycle characteristics.
以下、順を追って評価結果を記す。 The evaluation results are described below in order.
表１より繊維状炭素（ＶＧＣＦ）をポリマー（ＰＶＤＦ）で一次混練し、分散性を向上させたものは１００サイクル容量維持率が良好であることが分かる（実施例１、２）。 It can be seen from Table 1 that those obtained by first kneading fibrous carbon (VGCF) with polymer (PVDF) to improve dispersibility have good 100 cycle capacity retention (Examples 1 and 2).
一方、一次混練にて全材料を一括で混練したものや、繊維状炭素を二次混練以降で添加したものは１００サイクルの容量維持率が低下していることが分かる。これは負極合材ペースト中で繊維状炭素が充分に分散されていないため、充放電時の膨張・収縮による応力により、導電ネットワーク構造を維持できずに、導電性が大幅に低下したためである（比較例１〜３）。 On the other hand, it can be seen that the capacity retention rate of 100 cycles is reduced in the case where all the materials are kneaded in a lump by primary kneading and the case where fibrous carbon is added after the secondary kneading. This is because fibrous carbon is not sufficiently dispersed in the negative electrode mixture paste, and the conductive network structure cannot be maintained due to the stress caused by expansion / contraction during charge / discharge, and the conductivity is greatly reduced ( Comparative Examples 1-3).
また繊維状炭素を一次混練にて分散を行っても、ポリマーを添加しない場合、１００サイクル容量維持率が低下していることが分かる。これは一次混練の際にペーストが充分な粘性を有せず、繊維状炭素を分散するだけのせん断力が得られないためである（比較例４）。 Moreover, even if it disperses | distributes fibrous carbon by primary kneading | mixing, when a polymer is not added, it turns out that 100 cycle capacity | capacitance maintenance factor is falling. This is because the paste does not have a sufficient viscosity during the primary kneading, and a shear force sufficient to disperse the fibrous carbon cannot be obtained (Comparative Example 4).
以上の結果から、本発明の製造方法を用いることにより、サイクル特性に優れた非水系二次電池が実現可能であることが分かった。 From the above results, it was found that a non-aqueous secondary battery having excellent cycle characteristics can be realized by using the manufacturing method of the present invention.
本実施例では、導電材種の検討について説明する。 In this embodiment, the examination of the conductive material type will be described.
図１に示すフローチャートに従い、導電材をそれぞれ、ＶＧＣＦ（アスペクト比：５、１０、１００）、カーボンナノファイバ（アスペクト比：１０００、１００００、５００００）、アセチレンブラック（電気化学製）、ケッチェンブラック（ライオン製）、ＫＳ−４（ティムカル製）を添加した以外は、検討１の実施例１と全く同様の作製手順で負極電極板を得た。これを本検討における比較例５、実施例３、１、４、５および比較例６〜９の負極電極板とする。 According to the flowchart shown in FIG. 1, the conductive materials are VGCF (aspect ratio: 5, 10, 100), carbon nanofiber (aspect ratio: 1000, 10000, 50000), acetylene black (manufactured by Electrochemical), Ketjen black ( A negative electrode plate was obtained by the same production procedure as in Example 1 of Study 1, except that Lion (made by Lion) and KS-4 (made by Timcal) were added. This is the negative electrode plate of Comparative Example 5, Examples 3, 1, 4, 5 and Comparative Examples 6-9 in this study.
正極電極板は検討１の実施例１と同様に作製したものを用い、また検討１の実施例１と同様に作製した電池を本検討における比較例５、実施例３、１、４、５および比較例６〜９のリチウムイオン電池とする。 The positive electrode plate was prepared in the same manner as in Example 1 of Study 1, and the battery fabricated in the same manner as in Example 1 of Study 1 was used as Comparative Example 5, Examples 3, 1, 4, 5, and Lithium ion batteries of Comparative Examples 6 to 9 are used.
次に、これらの電池の１００サイクル容量維持率を検討１と同様の方法で評価を行った。その結果を表２に記す。 Next, the 100 cycle capacity maintenance rate of these batteries was evaluated in the same manner as in Study 1. The results are shown in Table 2.
以下、順を追って評価結果を記す。 The evaluation results are described below in order.
導電材としてＶＧＣＦやカーボンナノファイバのようにアスペクト比が１０〜１００００の繊維状炭素を用いたものは１００サイクルの容量維持率が良好な結果であることが分かる（実施例１、３、４、５）。 It can be seen that a conductive material using fibrous carbon having an aspect ratio of 10 to 10000, such as VGCF and carbon nanofiber, has a good capacity retention rate of 100 cycles (Examples 1, 3, 4, 5).
しかしながら、アスペクト比が１０より小さい繊維状炭素、ＡＢやＫＢなどの粒子状炭素、およびグラファイトを用いた場合、１００サイクル容量維持率が低下していることが分かる（比較例５、比較例７〜９）。これは膨張・収縮時の応力により、導電材の導電ネットワーク構造を維持できず、導電性が大幅に低下するためである。 However, it can be seen that when the fibrous carbon having an aspect ratio of less than 10 is used, particulate carbon such as AB or KB, and graphite are used, the 100 cycle capacity retention rate is reduced (Comparative Example 5 and Comparative Examples 7 to 7). 9). This is because the conductive network structure of the conductive material cannot be maintained due to the stress at the time of expansion / contraction, and the conductivity is greatly lowered.
一方、アスペクト比が１００００を超える繊維状炭素についても１００サイクル容量維持率が低下していることが分かる。これはアスペクト比が１００００を超えるような繊維状炭素の場合（比較例６）、凝集性が非常に高く、本発明における負極合材ペースト作製方法においても、繊維状炭素を均一に分散できないため、同じく膨張・収縮時に、導電ネットワーク構造を維持できないためである。 On the other hand, it can be seen that the 100 cycle capacity retention rate is also reduced for fibrous carbon having an aspect ratio of more than 10,000. In the case of fibrous carbon whose aspect ratio exceeds 10,000 (Comparative Example 6), the cohesiveness is very high, and even in the negative electrode mixture paste preparation method in the present invention, fibrous carbon cannot be uniformly dispersed. Similarly, the conductive network structure cannot be maintained during expansion / contraction.
以上の結果から、本発明の製造方法を充分に活用するためには、用いる導電材はアスペクト比が１０以上１００００以下の繊維状炭素を用いる必要があり、好ましくはアスペクト比が１０以上１０００以下の繊維状炭素を用いることが好ましいことが分かる。 From the above results, in order to fully utilize the production method of the present invention, the conductive material to be used needs to use fibrous carbon having an aspect ratio of 10 or more and 10,000 or less, preferably an aspect ratio of 10 or more and 1,000 or less. It can be seen that it is preferable to use fibrous carbon.
本実施例では、一次混練における導電材とポリマーの添加量比の検討について説明する。 In this example, the study of the ratio of the conductive material and polymer added in the primary kneading will be described.
図１に示すフローチャートに従い、一次混練におけるＰＶＤＦの添加重量を、０．９ｇ、１．２ｇ、２．４ｇ、３．６ｇ、４．８ｇとした以外は検討１の実施例１と全く同様の作製手順で負極電極板を得た。これを本検討における実施例１、６〜９の負極電極板とする。 According to the flow chart shown in FIG. 1, the same production as in Example 1 of Study 1 except that the added weight of PVDF in primary kneading was 0.9 g, 1.2 g, 2.4 g, 3.6 g, and 4.8 g. A negative electrode plate was obtained by the procedure. This is the negative electrode plate of Examples 1 and 6 to 9 in this study.
正極電極板は検討１の実施例１と同様に作製したものを用い、また検討１の実施例１と同様に作製した電池を本検討における実施例１、６〜９のリチウムイオン電池とする。 The positive electrode plate was prepared in the same manner as in Example 1 of Study 1, and the battery produced in the same manner as Example 1 of Study 1 was used as the lithium ion battery of Examples 1 and 6-9 in this study.
次に、これらの電池の１００サイクル容量維持率を検討１と同様の方法で評価を行った。その結果を表３に記す。 Next, the 100 cycle capacity maintenance rate of these batteries was evaluated in the same manner as in Study 1. The results are shown in Table 3.
以下、順を追って評価結果を記す。 The evaluation results are described below in order.
表３より一次混練におけるポリマーの添加重量が繊維状炭素の添加重量の２．０倍以上６．０倍以下である場合、一次混練において高粘性を有し、高せん断力が得られるため、繊維状炭素の分散性を向上させることができる１００サイクル容量維持率が良好であることが分かる（実施例１、７、８）。 From Table 3, when the added weight of the polymer in the primary kneading is 2.0 times or more and 6.0 times or less of the added weight of the fibrous carbon, the fiber has a high viscosity and a high shearing force is obtained in the primary kneading. It can be seen that the 100-cycle capacity retention rate that can improve the dispersibility of the carbon-like carbon is good (Examples 1, 7, and 8).
一方、一次混練におけるポリマーの添加重量が繊維状炭素の添加重量の１．５倍より小さい場合、１００サイクル容量維持率が低下していることが分かる。これはＰＶＤＦ重量が導電材重量に対して少ない場合、ペーストの粘性が低いため、一次混練において、繊維状炭素を分散するだけの充分なせん断力が得られないからである（実施例６）。 On the other hand, when the added weight of the polymer in the primary kneading is smaller than 1.5 times the added weight of the fibrous carbon, it can be seen that the 100 cycle capacity retention rate is lowered. This is because when the PVDF weight is small with respect to the conductive material weight, the viscosity of the paste is low, so that sufficient shearing force to disperse the fibrous carbon cannot be obtained in the primary kneading (Example 6).
また一次混練におけるポリマーの添加重量が繊維状炭素の添加重量の８．０倍以上である場合、充分なせん断力が得られないだけでなく、絶縁体であるポリマーが増量するため、導電性が低下し、同様に１００サイクル容量維持率が低下する（実施例９）。 In addition, when the added weight of the polymer in the primary kneading is 8.0 times or more of the added weight of the fibrous carbon, not only a sufficient shearing force cannot be obtained, but also the amount of the polymer as an insulator is increased, so that the conductivity is increased. In the same manner, the 100 cycle capacity retention rate decreases (Example 9).
以上の結果から、本発明の製造方法を充分に活用するためには、一次混練におけるポリマーの添加重量が繊維状炭素の添加重量の２．０倍以上６．０倍以下が好ましいことが分かる。 From the above results, it can be seen that the addition weight of the polymer in the primary kneading is preferably 2.0 times or more and 6.0 times or less of the addition weight of the fibrous carbon in order to fully utilize the production method of the present invention.
本実施例では、繊維状炭素添加量の検討について説明する。 In this example, the study of the amount of fibrous carbon added will be described.
図１に示すフローチャートに従い、繊維状炭素の添加量を、０．２ｇ、０．３ｇ、０．４ｇ、０．６ｇ、０．８ｇ、１．０ｇ、１．２ｇ、１．５ｇとした以外は検討１の実施例１と全く同様の作製手順で負極電極板を得た。これを本検討における実施例１、１０〜１６の負極電極板とする。 According to the flowchart shown in FIG. 1, the addition amount of fibrous carbon was changed to 0.2 g, 0.3 g, 0.4 g, 0.6 g, 0.8 g, 1.0 g, 1.2 g, and 1.5 g. A negative electrode plate was obtained in the same production procedure as in Example 1 of Study 1. This is the negative electrode plate of Examples 1 and 10 to 16 in this study.
正極電極板は検討１の実施例１と同様に作製したものを用い、また検討１の実施例１と同様に作製した電池を本検討における実施例１、１０〜１６のリチウムイオン電池とする。 The positive electrode plate was prepared in the same manner as in Example 1 of Study 1, and the battery prepared in the same manner as in Example 1 of Study 1 was used as the lithium ion battery of Examples 1 and 10-16 in this study.
次に、これらの電池の１００サイクル容量維持率を検討１と同様の方法で評価を行った。その結果を表４に記す。 Next, the 100 cycle capacity maintenance rate of these batteries was evaluated in the same manner as in Study 1. The results are shown in Table 4.
以下、順を追って評価結果を記す。 The evaluation results are described below in order.
表４より導電材の添加量が活物質１００重量部に対して、３．０重量部以上１２．０重量部以下である場合、１００サイクル容量維持率が良好であることが分かる（実施例１、１１、１５）。 Table 4 shows that when the amount of the conductive material added is 3.0 parts by weight or more and 12.0 parts by weight or less with respect to 100 parts by weight of the active material, the 100 cycle capacity retention rate is good (Example 1). 11, 15).
一方、導電材の添加量が活物質１００重量部に対して、２．０重量部以下の場合、本発明の負極合材ペースト作製方法を用いても、導電性を確保できないため、１００サイクル容量維持率が低下している（実施例１０）。 On the other hand, when the addition amount of the conductive material is 2.0 parts by weight or less with respect to 100 parts by weight of the active material, the conductivity cannot be ensured even if the negative electrode mixture paste preparation method of the present invention is used. The maintenance rate is decreasing (Example 10).
また導電材の添加量が活物質１００重量部に対して、１５．０重量部以上の場合、電解液と導電材との反応によるガスが発生し、正極と負極との間の反応距離が大きくなるため、１００サイクル容量維持率が低下している（実施例１６）。 Further, when the addition amount of the conductive material is 15.0 parts by weight or more with respect to 100 parts by weight of the active material, gas is generated due to the reaction between the electrolytic solution and the conductive material, and the reaction distance between the positive electrode and the negative electrode is large. Therefore, the capacity maintenance rate of 100 cycles is reduced (Example 16).
以上の結果から、本発明の製造方法を充分に活用するためには、導電材の添加量が活物質１００重量部に対して、３．０重量部以上１２．０重量部以下であることが好ましいことが分かる。 From the above results, in order to fully utilize the production method of the present invention, the amount of conductive material added is 3.0 parts by weight or more and 12.0 parts by weight or less with respect to 100 parts by weight of the active material. It turns out that it is preferable.
本発明の非水系二次電池は、サイクル特性の良好なポータブル用高容量電源などとして有用である。 The non-aqueous secondary battery of the present invention is useful as a portable high-capacity power source having good cycle characteristics.
Claims (4)
前記製造方法は、前記導電材Ｂと、前記ポリマーＣと、前記分散媒Ｄとにて湿潤せしめ、一次混練したのち、前記活物質Ａおよび前記分散媒Ｄを添加し、混練するという手順を少なくとも含むものであって、
前記活物質Ａの構成元素として、少なくともＳｉを含んでおり、
前記導電材Ｂは少なくともアスペクト比が１０以上１００００以下の繊維状炭素を含むことを特徴とする非水系二次電池用負極の製造方法。 In the method for producing a negative electrode for a non-aqueous secondary battery configured by kneading and dispersing an active material A, a conductive material B, and a polymer C made of materials capable of holding lithium in a dispersion medium D
The manufacturing method includes at least a procedure in which the conductive material B, the polymer C, and the dispersion medium D are wetted, and after primary kneading, the active material A and the dispersion medium D are added and kneaded. Including
As a constituent element of the active material A, it contains at least Si,
The method for producing a negative electrode for a non-aqueous secondary battery, wherein the conductive material B includes fibrous carbon having an aspect ratio of 10 or more and 10,000 or less.
前記負極が請求項１から３のいずれか一項に記載の非水系二次電池用負極の製造方法によって製造された負極を用いることを特徴とする非水系二次電池。 In a non-aqueous secondary battery composed of an electrolyte comprising a positive electrode having a composite lithium oxide as an active material, a negative electrode having a material capable of holding lithium as an active material, a separator, and a non-aqueous solvent,
The said negative electrode uses the negative electrode manufactured by the manufacturing method of the negative electrode for non-aqueous secondary batteries as described in any one of Claim 1 to 3. The non-aqueous secondary battery characterized by the above-mentioned.
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