JP5125050B2 - Nonaqueous electrolyte secondary battery - Google Patents

Nonaqueous electrolyte secondary battery Download PDF

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JP5125050B2
JP5125050B2 JP2006275988A JP2006275988A JP5125050B2 JP 5125050 B2 JP5125050 B2 JP 5125050B2 JP 2006275988 A JP2006275988 A JP 2006275988A JP 2006275988 A JP2006275988 A JP 2006275988A JP 5125050 B2 JP5125050 B2 JP 5125050B2
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和田　　隆
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Description

本発明は、負極活物質に難黒鉛化性炭素と易黒鉛化性炭素とを含む非水二次電解質電池に関する。   The present invention relates to a non-aqueous secondary electrolyte battery containing non-graphitizable carbon and graphitizable carbon in a negative electrode active material.

リチウムイオン二次電池をはじめとする非水電解質二次電池は、高エネルギー密度、高出力などの優れた特徴をもっているため、携帯電話、ビデオカメラ、パソコンなどの携帯機器の電源として、広く普及している。また、非水電解質二次電池を電気自動車の電源に利用するため、大型で大容量の非水電解質二次電池の開発も盛んにおこなわれている。   Non-aqueous electrolyte secondary batteries, including lithium ion secondary batteries, have excellent features such as high energy density and high output, so they are widely used as power sources for mobile devices such as mobile phones, video cameras, and personal computers. ing. In addition, in order to use a non-aqueous electrolyte secondary battery as a power source for an electric vehicle, a large-sized and large-capacity non-aqueous electrolyte secondary battery has been actively developed.

特に、電気自動車においては非水二次電解質電池の長寿命化と高出力化とが重要な開発課題となっている。この背景には自動車の装置寿命と同等の寿命性能が電池にも求められること、また、自動車の発進時に急速放電性能が必要であることなどがあげられる。   In particular, in an electric vehicle, it is an important development subject to increase the life and output of a non-aqueous secondary electrolyte battery. This is because the battery is required to have a life performance equivalent to the equipment life of the automobile, and the rapid discharge performance is necessary when the automobile starts.

リチウムイオン二次電池の正極活物質には、リチウム含有層状コバルト酸化物（以下「Ｃｏ系化合物」とする）、リチウム含有層状ニッケル酸化物（以下「Ｎｉ系化合物」とする）又はスピネル型リチウムマンガン複合酸化物（以下「Ｍｎ系化合物」とする）を用い、負極活物質にはリチウムを吸蔵・放出可能な炭素材料などを用いた長寿命な非水電解質二次電池が実用化されている。   Examples of the positive electrode active material of the lithium ion secondary battery include lithium-containing layered cobalt oxide (hereinafter referred to as “Co-based compound”), lithium-containing layered nickel oxide (hereinafter referred to as “Ni-based compound”), or spinel type lithium manganese. A long-life nonaqueous electrolyte secondary battery using a composite oxide (hereinafter referred to as “Mn-based compound”) and using a carbon material capable of occluding and releasing lithium as a negative electrode active material has been put into practical use.

この炭素材料としてフェノールホルムアルデヒド樹脂炭、フルフリールアルコール樹脂炭、カーボンブラック、塩化ビニリデン炭、セルローズ炭のような難黒鉛化性炭素や、ピッチコークス、メソカーボンマイクロビーズ、ニードルコークス、バルクメソフェーズコークス、フリュードコークス、ギルソナイトコークスのような易黒鉛化性炭素などを用いた非水電解質二次電池は、充放電深度の変化にともなって充放電電圧がなだらかに変化し、電池の充放電状態を容易に把握することができる。   As this carbon material, non-graphitizable carbon such as phenol formaldehyde resin charcoal, furfuryl alcohol resin charcoal, carbon black, vinylidene chloride charcoal, cellulose charcoal, pitch coke, mesocarbon micro beads, needle coke, bulk mesophase coke, In non-aqueous electrolyte secondary batteries using graphitizable carbon such as flue coke and gilsonite coke, the charge / discharge voltage changes gradually with the change in charge / discharge depth, and the charge / discharge state of the battery changes. It can be easily grasped.

このため、難黒鉛化性炭素や易黒鉛化性炭素を負極活物質として用いた非水電解質二次電池は電気自動車やハイブリッド電気自動車の高性能電源として使用されていおり、さらなる需要拡大が見込まれている。   For this reason, non-aqueous electrolyte secondary batteries using non-graphitizable carbon or easily graphitizable carbon as a negative electrode active material are used as high-performance power sources for electric vehicles and hybrid electric vehicles, and further demand expansion is expected. ing.

難黒鉛化性炭素は六角網面構造が発達しておらず、充放電に伴う活物質粒子の膨張収縮が小さい。このため、充放電サイクル時に導電パスが切断されにくく、良好な充放電サイクル性能を示す。また、電解液の還元分解を伴う不導体皮膜の成長が起こりにくいため、長期保存性能も良好である。   The non-graphitizable carbon does not have a hexagonal network structure, and the expansion and contraction of the active material particles accompanying charge / discharge is small. For this reason, a conductive path is hard to be cut | disconnected at the time of a charging / discharging cycle, and favorable charging / discharging cycling performance is shown. In addition, since the non-conductive film does not easily grow with reductive decomposition of the electrolyte, long-term storage performance is also good.

しかしながら、難黒鉛化性炭素には結晶構造の歪みや空隙が多いため電子導電性が小さく、良好な出力性能を示す非水電解質二次電池を作製することは困難であった。   However, since non-graphitizable carbon has many crystal structure distortions and voids, it has been difficult to produce a non-aqueous electrolyte secondary battery that has low electronic conductivity and good output performance.

一方、易黒鉛化性炭素は比較的結晶構造が発達しているため、難黒鉛化性炭素に比べて電子導電性が大きく、良好な出力性能を示す非水電解質二次電池を作製することが可能である。また、易黒鉛化性炭素は難黒鉛化性炭素に比べて真密度が大きいため電極密度の向上が容易であり、高容量の電池を得ることができるという利点も有している。   On the other hand, since graphitizable carbon has a relatively developed crystal structure, it is possible to produce a non-aqueous electrolyte secondary battery that has higher electronic conductivity than non-graphitizable carbon and exhibits good output performance. Is possible. Moreover, since graphitizable carbon has a higher true density than non-graphitizable carbon, it is easy to improve the electrode density, and it has an advantage that a high-capacity battery can be obtained.

しかしながら、易黒鉛化性炭素は、充放電に伴うＣ軸方向への膨張収縮が大きいため、導電パスの切断がおこりやすく、良好の充放電サイクル性能を得ることが困難であるという問題があった。   However, graphitizable carbon has a problem that it is difficult to obtain good charge / discharge cycle performance because the expansion and contraction in the C-axis direction accompanying charge / discharge is large, and the conductive path is easily cut. .

このような問題を解決する方法として、特許文献１には難黒鉛化性炭素と易黒鉛化性炭素を含有するする負極において、難黒鉛化性炭素の含有量を１〜３０重量％あるいは０．５から２０重量％とする技術が開示されている。   As a method for solving such a problem, Patent Document 1 discloses that in a negative electrode containing non-graphitizable carbon and graphitizable carbon, the content of non-graphitizable carbon is 1 to 30% by weight or 0. A technique of 5 to 20% by weight is disclosed.

また、特許文献２には負極に難黒鉛化性炭素と易黒鉛化性炭素との混合物の焼成物を用いる技術が開示されている。さらに、特許文献３には易黒鉛化性炭素を難黒鉛化性炭素で被覆する、あるいは難黒鉛化性炭素を易黒鉛化性炭素で被覆する技術、および、核となる黒鉛化炭素と殻となる黒鉛化炭素との重量比の範囲は１：１から１：０．１であることが開示されている。
特開平０６−３３３５６４号公報 特開平１１−２６５７１８号公報 特開平０８−０６９８１９号公報 Patent Document 2 discloses a technique using a fired product of a mixture of non-graphitizable carbon and graphitizable carbon for the negative electrode. Further, Patent Document 3 discloses a technique for coating graphitizable carbon with non-graphitizable carbon, or a technique for coating non-graphitizable carbon with graphitizable carbon, and graphitized carbon and shell as cores. It is disclosed that the range of the weight ratio with graphitized carbon is 1: 1 to 1: 0.1.
Japanese Patent Laid-Open No. 06-333564 Japanese Patent Laid-Open No. 11-265718 Japanese Patent Laid-Open No. 08-069819

非水電解質二次電池の充放電サイクル性能を向上するためには、上記の特許文献に記されるように、負極活物質として難黒鉛化性炭素および易黒鉛化性炭素をある所定量で含有する負極を用いる方法が提案されている。しかし、特許文献１に記載される難黒鉛化性炭素と易黒鉛化性炭素の含有率では、易黒鉛化性炭素の充放電にともな膨張収縮を抑制することができず、充放電サイクル性能の向上において十分な効果を得ることができない。また、特許文献２および３に記載の方法は、製造工程が複雑になる、コストがかかりすぎるなどの問題が避けられず、より簡便で効果の高い方法の開発が必要とされていた。   In order to improve the charge / discharge cycle performance of the non-aqueous electrolyte secondary battery, as described in the above patent document, the negative electrode active material contains non-graphitizable carbon and graphitizable carbon in a predetermined amount. A method using a negative electrode has been proposed. However, the content of the non-graphitizable carbon and the graphitizable carbon described in Patent Document 1 cannot suppress expansion and contraction associated with charge / discharge of the graphitizable carbon, and charge / discharge cycle performance. It is not possible to obtain a sufficient effect in improving the quality. In addition, the methods described in Patent Documents 2 and 3 inevitably suffer from problems such as complicated manufacturing processes and excessive costs, and development of a simpler and more effective method is required.

本発明の目的は、リチウムを吸蔵放出可能なリチウム複合酸化物を活物質とする正極と、リチウムを吸蔵放出可能な炭素材料を活物質とする負極と、非水電解質を含む電池において、優れた出力性能および充放電サイクル性能を示す非水電解質二次電池を提供することにある。   An object of the present invention is excellent in a battery including a positive electrode using a lithium composite oxide capable of occluding and releasing lithium as an active material, a negative electrode using a carbon material capable of occluding and releasing lithium as an active material, and a non-aqueous electrolyte. It is providing the nonaqueous electrolyte secondary battery which shows output performance and charging / discharging cycling performance.

請求項１の発明は、リチウムを含む遷移金属複合酸化物を正極活物質とする正極と、炭素材料を負極活物質とする負極と、非水電解液とを備えた非水電解質二次電池において、前記炭素材料が難黒鉛化性炭素の粒子と易黒鉛化性炭素の粒子とを含み、前記難黒鉛化性炭素の粒子と前記易黒鉛化性炭素の粒子に占める前記易黒鉛化性炭素の粒子の割合が４〜４０重量％であり、前記易黒鉛化性炭素の粒子の平均粒径が前記難黒鉛化性炭素の粒子の平均粒径の０．３〜１倍であることを特徴とする。 The invention of claim 1 is a non-aqueous electrolyte secondary battery comprising a positive electrode using a transition metal composite oxide containing lithium as a positive electrode active material, a negative electrode using a carbon material as a negative electrode active material, and a non-aqueous electrolyte. , wherein the carbon material comprises particles of particle and graphitizable carbon of non-graphitizable carbon, the graphitizable carbon and the hardly graphitizable carbon particles occupied in the graphitizable carbon particles and wherein the ratio of particles is 4 to 40 wt%, average particle diameter of the easily graphitizable carbon particles is 0.3 to 1 times the average particle diameter of the flame-graphitizable carbon particles To do.

本発明によれば、負極活物質である難黒鉛化性炭素と易黒鉛化性炭素に占める易黒鉛化性炭素の割合を４〜４０重量％とし、易黒鉛化性炭素の平均粒径を難黒鉛化性炭素の平均粒径の０．３〜１倍とすることによって、難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率から計算される平均値よりも良好な出力性能が得られ、かつ良好な充放電サイクル性能を有する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, the ratio of the non-graphitizable carbon as the negative electrode active material and the graphitizable carbon in the graphitizable carbon is 4 to 40% by weight, and the average particle size of the graphitizable carbon is difficult. By setting the average particle size of graphitizable carbon to 0.3 to 1 times, better output performance than the average value calculated from the mixing ratio of the output performance of non-graphitizable carbon and graphitizable carbon can be obtained. It is possible to provide a nonaqueous electrolyte secondary battery that is obtained and has good charge / discharge cycle performance.

すなわち、難黒鉛化性炭素および易黒鉛化性炭素を含有する負極において、充放電サイクル性能および出力性能を向上するためには、それぞれの平均粒径の比が非常に重要なパラメータとなる。充放電に伴う易黒鉛化性炭素の膨張収縮率は難黒鉛化性炭素の膨張収縮率よりも大きい。このため、難黒鉛化性炭素よりも平均粒径の小さい易黒鉛化性炭素を選択することによって易黒鉛化性炭素の膨張収縮による導電パスの切断が緩和され、かつ良好な電子導電性を確保することができ、良好な充放電サイクル性能および出力性能を得ることができるのである。   That is, in the negative electrode containing non-graphitizable carbon and graphitizable carbon, in order to improve charge / discharge cycle performance and output performance, the ratio of the respective average particle diameters is a very important parameter. The expansion / contraction rate of graphitizable carbon accompanying charge / discharge is larger than the expansion / contraction rate of non-graphitizable carbon. Therefore, by selecting graphitizable carbon having an average particle size smaller than that of non-graphitizable carbon, the cutting of the conductive path due to expansion and contraction of graphitizable carbon is mitigated, and good electronic conductivity is ensured. Therefore, good charge / discharge cycle performance and output performance can be obtained.

以下、本発明を詳細に説明するが、本発明が以下の実施の形態に限定されないことはいうまでもない。   Hereinafter, the present invention will be described in detail, but it goes without saying that the present invention is not limited to the following embodiments.

本発明の非水電解質二次電池は、リチウムを吸蔵放出可能なリチウム複合酸化物を活物質とする正極と、リチウムを吸蔵・放出可能な難黒鉛化性炭素および易黒鉛化性炭素を活物質とする負極と、非水電解液、およびセパレータからなる発電要素が電池ケースに収納された非水電解質二次電池において、難黒鉛化性炭素と易黒鉛化性炭素に占める易黒鉛化性炭素の割合が４〜４０重量％であり、易黒鉛化性炭素の平均粒径が難黒鉛化性炭素の平均粒径の０．３〜１倍であることを特徴とする。   The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode having a lithium composite oxide capable of occluding and releasing lithium as an active material, a non-graphitizable carbon and an easily graphitizable carbon capable of occluding and releasing lithium as an active material. In a non-aqueous electrolyte secondary battery in which a power generation element comprising a negative electrode, a non-aqueous electrolyte, and a separator is housed in a battery case, the graphitizable carbon occupies the non-graphitizable carbon and the graphitizable carbon. The ratio is 4 to 40% by weight, and the average particle size of graphitizable carbon is 0.3 to 1 times the average particle size of non-graphitizable carbon.

本発明において「難黒鉛化性炭素と易黒鉛化性炭素に占める易黒鉛化性炭素の割合」とは、黒鉛化性炭素と易黒鉛化性炭素の合計重量に対する易黒鉛化性炭素の重量の割合（重量％）を意味するものとする。   In the present invention, the “ratio of graphitizable carbon and non-graphitizable carbon to non-graphitizable carbon” means the weight of graphitizable carbon relative to the total weight of graphitizable carbon and graphitizable carbon. It means the percentage (% by weight).

また、「平均粒径」とは、島津社製のレーザー回折式粒度分布測定装置ＳＡＬＤ−２０００Ｊ（０．０３〜７００μレンジ）を使用し、カスケード使用の条件で乾式分散させ測定した粒子径のうち、累積値が５０％のときの粒子径を意味するものとする。   In addition, the “average particle size” is a particle size measured by dry dispersion under the conditions of cascade use using a laser diffraction particle size distribution analyzer SALD-2000J (0.03 to 700 μ range) manufactured by Shimadzu Corporation. The particle diameter when the cumulative value is 50% is meant.

本発明において「難黒鉛化性炭素」とは、常圧下あるいは減圧下で３３００Ｋ付近の超高温まで加熱しても黒鉛に変換し得ない非晶質炭素を意味する。   In the present invention, “non-graphitizable carbon” means amorphous carbon that cannot be converted to graphite even when heated to an ultrahigh temperature of about 3300 K under normal pressure or reduced pressure.

なお、難黒鉛化性炭素においては、充放電に伴う格子体積の変化が小さいことが望ましく、Ｘ線広角回折法から測定される（００２）面の面間隔が３．７０オングストローム以上であり、結晶子の大きさがｃ軸方向（Ｌｃ）で１．５ｎｍ以下であることが好ましい。   In addition, in non-graphitizable carbon, it is desirable that the change in the lattice volume accompanying charging / discharging is small, and the (002) plane spacing measured by the X-ray wide angle diffraction method is 3.70 angstroms or more. The size of the child is preferably 1.5 nm or less in the c-axis direction (Lc).

また、本発明において「易黒鉛化性炭素」とは、３３００Ｋ前後の高温処理により黒鉛に変換しうる非晶質炭素を意味する。   In the present invention, “easily graphitizable carbon” means amorphous carbon that can be converted to graphite by high-temperature treatment at around 3300K.

なお、易黒鉛化性炭素は、ある程度の結晶構造が成長させることで電子導電性を大きくする効果が期待できるが、結晶構造が発達しすぎると充放電に伴う格子体積の変化が大きくなりすぎ、良好な充放電サイクル性能を得ることができない。このため、易黒鉛化性炭素のＸ線広角回折法から測定される（００２）面の面間隔は、３．４５〜３．５５オングストロームであることが好ましい。   In addition, graphitizable carbon can be expected to increase the electronic conductivity by growing a certain degree of crystal structure, but if the crystal structure develops too much, the change in lattice volume accompanying charge / discharge becomes too large, Good charge / discharge cycle performance cannot be obtained. For this reason, it is preferable that the (002) plane spacing measured from the X-ray wide angle diffraction method of graphitizable carbon is 3.45 to 3.55 angstroms.

易黒鉛化性炭素と難黒鉛化性炭素に占める易黒鉛化性炭素の割合が４重量％より少ない場合、難黒鉛化性炭素と易黒鉛化性炭素の混合物の電子導電性が難黒鉛化性炭素とほぼ同じになるため、良好な出力性能を得ることはできない。一方、難黒鉛化性炭素と易黒鉛化性炭素に占める易黒鉛化性炭素の割合が４０重量％を越える場合、充放電に伴う易黒鉛化性炭素の膨張収縮に起因した導電パスの切断を抑制することができないため、充放電サイクル性能が低下する。   When the ratio of graphitizable carbon to non-graphitizable carbon is less than 4% by weight, the electronic conductivity of the mixture of non-graphitizable carbon and graphitizable carbon is non-graphitizable. Since it is almost the same as carbon, good output performance cannot be obtained. On the other hand, when the ratio of the graphitizable carbon to the non-graphitizable carbon and the graphitizable carbon exceeds 40% by weight, the conductive path is cut off due to the expansion / contraction of the graphitizable carbon accompanying charge / discharge. Since it cannot suppress, charging / discharging cycle performance falls.

また、難黒鉛化性炭素または易黒鉛化性炭素の平均粒径が小さいほど活物質内におけるリチウムイオンの拡散経路が短くなるため良好な出力性能を得ることができるが、平均粒径が小さすぎると電解液との反応に伴う不導体皮膜の成長が促進されるため、難黒鉛化性炭素の平均粒径は５〜２５μｍであることが好ましく、易黒鉛化性炭素の平均粒径は難黒鉛化性炭素の０．３〜１倍とする必要がある。   Also, the smaller the average particle size of non-graphitizable carbon or graphitizable carbon is, the shorter the lithium ion diffusion path in the active material, the better the output performance can be obtained, but the average particle size is too small The growth of the non-conductive film accompanying the reaction between the electrolyte and the electrolyte is promoted, so that the average particle size of the non-graphitizable carbon is preferably 5 to 25 μm, and the average particle size of the graphitizable carbon is non-graphite It is necessary to make it 0.3 to 1 times that of carbon.

また、易黒鉛化性炭素の平均粒径が難黒鉛化性炭素の平均粒径の０．３倍より小さい場合、平均粒径の大きな難黒鉛化性炭素で構成される空隙に易黒鉛化性炭素が詰まりすぎてしまうため、リチウムイオンの拡散経路が狭くなり、出力性能の低下を引き起こす。一方、易黒鉛化性炭素の平均粒径が難黒鉛化性炭素の平均粒径の１倍より大きい場合、上述したような易黒鉛化性炭素の膨張収縮の緩和効果が十分に得られず、充放電サイクル性能が低下する。   In addition, when the average particle size of the graphitizable carbon is smaller than 0.3 times the average particle size of the non-graphitizable carbon, it is easy to graphitize the voids composed of the non-graphitizable carbon having a large average particle size. Since carbon is clogged too much, the diffusion path of lithium ions becomes narrow, resulting in a decrease in output performance. On the other hand, when the average particle size of the graphitizable carbon is larger than one time the average particle size of the non-graphitizable carbon, the above-described relaxation effect of expansion and contraction of the graphitizable carbon cannot be sufficiently obtained. Charge / discharge cycle performance decreases.

なお、本発明の非水電解質二次電池の負極活物質としては、難黒鉛化性炭素と易黒鉛化性炭素以外に、黒鉛、カーボンブラック、気相成長炭素繊維などの炭素を含んでもよい。   In addition, as a negative electrode active material of the nonaqueous electrolyte secondary battery of the present invention, carbon such as graphite, carbon black, and vapor growth carbon fiber may be included in addition to non-graphitizable carbon and graphitizable carbon.

本発明の非水電解質二次電池の外観を図１に、電池の電極群を図２に示す。図１および図２において、１は非水電解質二次電池、２は電極群、２ａは正極、２ｂは負極、２ｃはセパレータ、３は電池ケース、３ａは電池ケースのケース部、３ｂは電池ケースの蓋部、４は正極端子、５は負極端子、６は安全弁、７は電解液注液口である。   The external appearance of the nonaqueous electrolyte secondary battery of the present invention is shown in FIG. 1, and the electrode group of the battery is shown in FIG. 1 and 2, 1 is a non-aqueous electrolyte secondary battery, 2 is an electrode group, 2a is a positive electrode, 2b is a negative electrode, 2c is a separator, 3 is a battery case, 3a is a case part of the battery case, and 3b is a battery case. , 4 is a positive terminal, 5 is a negative terminal, 6 is a safety valve, and 7 is an electrolyte injection port.

本発明の非水電解質二次電池は、正極２ａと負極２ｂとがセパレータ２ｃを介して長円形状に巻回されてなる電極群２を電池ケースのケース部３ａに収納し、電池ケースのケース部３ａと電池ケースの蓋部３ｂとをレーザー溶接で封口し、非水電解液（図示せず）を注液口７から注液し、その後、注液口７を封口して構成されている。   In the nonaqueous electrolyte secondary battery of the present invention, an electrode group 2 in which a positive electrode 2a and a negative electrode 2b are wound in an oval shape via a separator 2c is housed in a case portion 3a of the battery case, The portion 3a and the battery case lid portion 3b are sealed by laser welding, a non-aqueous electrolyte (not shown) is injected from the injection port 7, and then the injection port 7 is sealed. .

本発明の非水電解質二次電池に用いられる正極、セパレータおよび電解液などは、特に従来用いられてきたものと異なるところはなく、通常用いられているものが使用できる。なお、図２では、電極群の形状としては長円形状を示したが、円形状でもよい。また、電極群の形状は巻回型に限らず、平板状極板を積層した形状でもよい。   The positive electrode, separator, electrolyte, and the like used for the nonaqueous electrolyte secondary battery of the present invention are not particularly different from those conventionally used, and commonly used ones can be used. In FIG. 2, an ellipse is shown as the shape of the electrode group, but it may be a circle. Further, the shape of the electrode group is not limited to the winding type, and may be a shape in which flat plate plates are laminated.

本発明の非水電解質二次電池に用いる正極活物質としては、リチウムを吸蔵・放出可能なマンガン酸リチウム（ＬｉＭｎ２Ｏ４）、コバルト酸リチウム（ＬｉＣｏＯ２）、ニッケル酸リチウム（ＬｉＮｉＯ２）などのリチウムを吸蔵放出可能なリチウム複合酸化物、性能改善のために各複合酸化物の遷移金属部分が他の遷移金属や軽金属、後遷移金属で置換されたリチウム複合酸化物、などが挙げられる。 Examples of the positive electrode active material used in the non-aqueous electrolyte secondary battery of the present invention include lithium manganate (LiMn 2 O 4 ), lithium cobaltate (LiCoO 2 ), and lithium nickelate (LiNiO 2 ) capable of inserting and extracting lithium. Lithium composite oxides capable of inserting and extracting lithium, lithium composite oxides in which the transition metal portion of each composite oxide is replaced with another transition metal or light metal, or a post-transition metal for performance improvement.

また、本発明の非水電解質二次電池に用いるセパレータとしては、ポリエチレン等のポリオレフィン樹脂からなる微多孔膜が用いられ、材料、重量平均分子量や空孔率の異なる複数の微多孔膜が積層してなるものや、これらの微多孔膜に各種の可塑剤、酸化防止剤、難燃剤などの添加剤を適量含有しているものであってもよい。   In addition, as the separator used in the nonaqueous electrolyte secondary battery of the present invention, a microporous membrane made of polyolefin resin such as polyethylene is used, and a plurality of microporous membranes having different materials, weight average molecular weights and porosity are laminated. Or those containing a suitable amount of various plasticizers, antioxidants, flame retardants and the like in these microporous membranes.

本発明の非水電解質二次電池で用いられる非水電解質としては、非水電解液であっても、ポリマー電解質、室温溶融塩またはイオン液体、固体電解質であっても構わない。   The non-aqueous electrolyte used in the non-aqueous electrolyte secondary battery of the present invention may be a non-aqueous electrolyte, a polymer electrolyte, a room temperature molten salt or ionic liquid, or a solid electrolyte.

本発明の非水電解質二次電池に用いる電解液の有機溶媒には、特に制限はなく、例えば、ジメチルカーボネート、メチルエチルカーボネート、ジエチルカーボネートなどの低粘度の鎖状炭酸エステルと、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などの高誘電率の環状炭酸エステル、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、１−３ジオキソラン、メチルアセテート、メチルプロピオネート、ビニレンカーボネート、ジメチルホルムアミド、スルホランおよびこれらの混合溶媒等を挙げることができる。   There are no particular limitations on the organic solvent of the electrolytic solution used in the non-aqueous electrolyte secondary battery of the present invention. For example, low-viscosity chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate, ethylene carbonate, propylene High dielectric constant cyclic carbonates such as carbonate and butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1-3 dioxolane, methyl acetate, methyl propionate, vinylene carbonate, dimethylformamide , Sulfolane, and mixed solvents thereof.

また、本発明の非水電解質二次電池に用いることのできるポリマー電解質にも、特に制限はなく、例えば、ビニリデンフルオライド・ヘキサフルオロプロピレンコポリマー（Ｐ（ＶＤＦ／ＨＦＰ））、ポリビニリデンフルオライド（ＰＶＤＦ）、ポリ塩化ビニル（ＰＶＣ）、ポリアクリロニトリル（ＰＡＮ）、ポリエチレンオキシド、ポリプロピレンオキシド、ポリ塩化ビニリデン、ポリメチルメタクリレート、ポリメチルアクリレート、ポリ４０ビニルアルコール、ポリメタクリロニトリル、ポリビニルアセテート、ポリビニルピロリドン、ポリエチレンイミン、ポリブタジエン、ポリスチレン、ポリイソプレン、もしくはこれらの誘導体を、単独で、あるいは混合したものからなるリチウムイオン伝導性ポリマーを用いることができる。   The polymer electrolyte that can be used in the non-aqueous electrolyte secondary battery of the present invention is not particularly limited. For example, vinylidene fluoride / hexafluoropropylene copolymer (P (VDF / HFP)), polyvinylidene fluoride ( PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polyethylene oxide, polypropylene oxide, polyvinylidene chloride, polymethyl methacrylate, polymethyl acrylate, poly 40 vinyl alcohol, polymethacrylonitrile, polyvinyl acetate, polyvinyl pyrrolidone, A lithium ion conductive polymer composed of polyethyleneimine, polybutadiene, polystyrene, polyisoprene, or derivatives thereof alone or in combination can be used.

また、本発明の非水電解質二次電池に用いる電解質塩としては、特に制限はなく、ＬｉＣｌＯ４、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＰＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２、ＬｉＩ、ＬｉＡｌＣｌ４等およびそれらの混合物が挙げられる。好ましくは、ＬｉＢＦ４、ＬｉＰＦ６のうちの１種または２種以上を混合したリチウム塩がよい。 As the electrolyte salt used for the nonaqueous electrolyte secondary battery of the present invention is not particularly limited, LiClO 4, LiBF 4, LiAsF 6, LiPF 6, LiCF 3 SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2 ) 2 , LiI, LiAlCl 4 and the like and mixtures thereof. Preferably, a lithium salt obtained by mixing one or more of LiBF 4 and LiPF 6 is preferable.

本発明の非水電解質二次電池においては、これらの有機溶媒と電解質とを組み合わせて、電解液として使用する。なお、これらの電解液の中では、エチレンカーボネート、ジメチルカーボネート、メチルエチルカーボネートを混合して使用すると、リチウムイオンの伝導度が極大となるために好ましい。   In the nonaqueous electrolyte secondary battery of the present invention, these organic solvents and an electrolyte are combined and used as an electrolytic solution. In these electrolytic solutions, it is preferable to use a mixture of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate because the lithium ion conductivity is maximized.

その他の電池の構成要素として、集電体、端子、絶縁板、電池ケース等があるが、これらの部品についても従来用いられてきたものをそのまま用いることができる。   Other battery components include a current collector, a terminal, an insulating plate, a battery case, and the like. Conventionally, these components can be used as they are.

以下に、本発明の実施例を、比較例とあわせて説明する。   Examples of the present invention will be described below together with comparative examples.

［実施例１〜４および比較例１〜４］
［実施例１］
負極活物質としては、難黒鉛化性炭素（以下では「ＨＣ」とする）と易黒鉛化性炭素との重量比９６：４の混合物を用いた。ＨＣとしては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．８０オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で１．１ｎｍ、平均粒径が１０μｍのものを用いた。易黒鉛化性炭素としては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．４８オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で２.０ｎｍ、平均粒径が６μｍのコークス（以下では「Ｃｓ」とする）を用いた。したがって、Ｃｓの平均粒径はＨＣの平均粒径の０．６倍である。 [Examples 1 to 4 and Comparative Examples 1 to 4]
[Example 1]
As the negative electrode active material, a 96: 4 weight ratio mixture of non-graphitizable carbon (hereinafter referred to as “HC”) and graphitizable carbon was used. As HC, the (002) plane spacing measured by X-ray wide angle diffraction method is 3.80 angstroms, the crystallite size is 1.1 nm in the c-axis direction (Lc), and the average grain size is 10 μm Was used. As graphitizable carbon, the (002) plane spacing measured by X-ray wide angle diffraction method is 3.48 Å, the crystallite size is 2.0 nm in the c-axis direction (Lc), and the average particle size Was 6 μm coke (hereinafter referred to as “Cs”). Therefore, the average particle size of Cs is 0.6 times the average particle size of HC.

負極は、上記負極活物質９４重量％と結着剤であるポリフッ化ビニリデン（以下「ＰＶｄＦ」とする）６重量％とを混合し、これに含水量５０ｐｐｍ以下のＮ−メチル−２−ピロリドン（以下「ＮＭＰ」とする）を加えてペースト状としたスラリーを、銅箔上に塗布、乾燥して作製した。負極の乾燥は、０．０１ｔｏｒｒ以下の真空下１５０℃で１２時間以上おこなった。   In the negative electrode, 94% by weight of the negative electrode active material and 6% by weight of polyvinylidene fluoride (hereinafter referred to as “PVdF”) as a binder are mixed, and this is mixed with N-methyl-2-pyrrolidone having a water content of 50 ppm or less ( (Hereinafter referred to as “NMP”) was added to a paste to form a paste, which was applied onto a copper foil and dried. The negative electrode was dried at 150 ° C. for 12 hours or more under a vacuum of 0.01 torr or less.

正極は、正極活物質としてのＬｉＭｎ２Ｏ４（以下「Ｍｎ系」とする）の粉体８７重量％と導電助剤であるアセチレンブラック５重量％と結着剤であるＰＶｄＦ８重量％とを混合し、これにＮＭＰを加えてペースト状としたスラリーを、アルミニウム箔上に塗布、乾燥して作製した。正極の乾燥条件は、負極に場合と同じとした。 The positive electrode is a mixture of 87% by weight of LiMn 2 O 4 (hereinafter referred to as “Mn-based”) powder as a positive electrode active material, 5% by weight of acetylene black as a conductive additive and 8% by weight of PVdF as a binder. Then, NMP was added to the slurry to form a paste, which was applied onto an aluminum foil and dried. The drying conditions for the positive electrode were the same as those for the negative electrode.

ロールプレスをおこなった正極および負極を、図２に示すようにセパレーターを介して長円形状に捲回して電極群を構成した後、この電極群を長円筒形の有底アルミニウム容器に挿入し、さらに、電極群の巻芯部に充填物をつめた後に電解液を注入し、レーザー溶接にて容器と蓋とを封口溶接し、実施例１の非水電解質二次電池Ａを作製した。なお、スラリー作製から電極加工、電池組立に至る全ての工程は、露点−５０℃以下のドライルーム中でおこなった。作製した電池の設計容量は５５０ｍＡｈとした。   As shown in FIG. 2, the positive electrode and the negative electrode subjected to roll press are wound into an oval shape via a separator to form an electrode group, and then the electrode group is inserted into a long cylindrical bottomed aluminum container, Furthermore, after filling the core part of the electrode group with the filler, the electrolyte solution was injected, and the container and the lid were sealed and welded by laser welding to produce the nonaqueous electrolyte secondary battery A of Example 1. All processes from slurry preparation to electrode processing and battery assembly were performed in a dry room with a dew point of -50 ° C or lower. The design capacity of the manufactured battery was 550 mAh.

［実施例２］
負極活物質としてＨＣとＣｓの重量比８０：２０の混合物を用いたこと以外は実施例１と同様にして、実施例２の非水電解質二次電池Ｂを作製した。 [Example 2]
A nonaqueous electrolyte secondary battery B of Example 2 was produced in the same manner as in Example 1 except that a mixture of HC and Cs at a weight ratio of 80:20 was used as the negative electrode active material.

［実施例３］
負極活物質としてＨＣとＣｓの重量比７０：３０の混合物を用いたこと以外は実施例１と同様にして、実施例３の非水電解質二次電池Ｃを作製した。 [Example 3]
A nonaqueous electrolyte secondary battery C of Example 3 was produced in the same manner as in Example 1 except that a mixture of HC and Cs having a weight ratio of 70:30 was used as the negative electrode active material.

［実施例４］
負極活物質としてＨＣとＣｓの重量比６０：４０の混合物を用いたこと以外は実施例１と同様にして、実施例４の非水電解質二次電池Ｄを作製した。 [Example 4]
A nonaqueous electrolyte secondary battery D of Example 4 was produced in the same manner as in Example 1 except that a mixture of HC and Cs having a weight ratio of 60:40 was used as the negative electrode active material.

［比較例１］
負極活物質としてＨＣのみを用いたこと以外は実施例１と同様にして、比較例１の非水電解質二次電池Ｅを作製した。 [Comparative Example 1]
A nonaqueous electrolyte secondary battery E of Comparative Example 1 was produced in the same manner as Example 1 except that only HC was used as the negative electrode active material.

［比較例２］
負極活物質としてＨＣとＣｓの重量比９８：２の混合物を用いたこと以外は実施例１と同様にして、比較例２の非水電解質二次電池Ｆを作製した。 [Comparative Example 2]
A nonaqueous electrolyte secondary battery F of Comparative Example 2 was produced in the same manner as in Example 1 except that a mixture of HC and Cs having a weight ratio of 98: 2 was used as the negative electrode active material.

［比較例３］
負極活物質としてＨＣとＣｓの重量比４０：６０の混合物を用いたこと以外は実施例１と同様にして、比較例３の非水電解質二次電池Ｇを作製した。 [Comparative Example 3]
A nonaqueous electrolyte secondary battery G of Comparative Example 3 was produced in the same manner as in Example 1, except that a mixture of HC and Cs having a weight ratio of 40:60 was used as the negative electrode active material.

［比較例４］
負極活物質としてＣｓのみを用いたこと以外は実施例１と同様にして、比較例４の非水電解質二次電池Ｈを作製した。 [Comparative Example 4]
A nonaqueous electrolyte secondary battery H of Comparative Example 4 was produced in the same manner as in Example 1 except that only Cs was used as the negative electrode active material.

［特性測定］
実施例１〜４および比較例１〜４の非水電解質二次電池Ａ〜Ｈについて、次の条件で初期放電容量測定、出力測定および充放電サイクル試験をおこなった。
１．初期放電容量測定
試験電池を２５℃環境下で、５５０ｍＡ定電流で４．２Ｖまで充電した後、さらに４．２Ｖ定電圧で、充電時間の合計が３時間となるように定電圧充電をおこなった。その後、５５０ｍＡ定電流で２．５Ｖまで放電した。この充放電を３回繰り返し、３回目の放電容量を初期放電容量と定めた。
２．出力測定
この初期放電容量に対する放電深度（ＤＯＤ）５０％において、５５ｍＡ、１１０ｍＡ、５５０ｍＡでの放電を１０秒間おこなった。各電流値で放電した際の１０秒目の電圧と電流との関係から、下限電圧を２．５Ｖとした際の電流値を外挿し、得られた電流値および下限電圧から出力を算出した。
３．充放電サイクル試験
試験電池を、初期放電容量測定と同じ条件で５００回充放電し、５００サイクル目の放電容量を求めた。そして、初期放電容量に対する５００サイクル目の放電容量の比を「容量保持率（％）」とした。 [Characteristic measurement]
For the nonaqueous electrolyte secondary batteries A to H of Examples 1 to 4 and Comparative Examples 1 to 4, initial discharge capacity measurement, output measurement, and charge / discharge cycle test were performed under the following conditions.
1. Initial discharge capacity measurement The test battery was charged to 4.2 V at a constant current of 550 mA in a 25 ° C. environment, and then charged at a constant voltage of 4.2 V so that the total charging time was 3 hours. . Thereafter, the battery was discharged to 2.5 V at a constant current of 550 mA. This charge / discharge was repeated three times, and the third discharge capacity was determined as the initial discharge capacity.
2. Output measurement Discharge at 55 mA, 110 mA, and 550 mA was performed for 10 seconds at a discharge depth (DOD) of 50% with respect to the initial discharge capacity. From the relationship between the voltage and current at 10 seconds when discharging at each current value, the current value when the lower limit voltage was 2.5 V was extrapolated, and the output was calculated from the obtained current value and lower limit voltage.
3. Charge / Discharge Cycle Test The test battery was charged and discharged 500 times under the same conditions as the initial discharge capacity measurement, and the discharge capacity at the 500th cycle was determined. The ratio of the discharge capacity at the 500th cycle to the initial discharge capacity was defined as “capacity holding ratio (%)”.

実施例１〜４および比較例１〜４の非水電解質二次電池Ａ〜Ｈの、負極活物質であるＨＣとＣｓに対するＣｓの割合（Ｃｓ／（ＨＣ＋Ｃｓ）、重量％）および特性測定結果を表１にまとめた。また、負極中のＨＣとＣｓに対するＣｓの割合と出力との関係を図３に示した。   In the nonaqueous electrolyte secondary batteries A to H of Examples 1 to 4 and Comparative Examples 1 to 4, the ratio of Cs to HC and Cs (Cs / (HC + Cs), weight%) and characteristic measurement results of the negative electrode active materials are shown. The results are summarized in Table 1. Further, the relationship between the ratio of Cs to HC and Cs in the negative electrode and the output is shown in FIG.

Figure 0005125050
Figure 0005125050

表１から、容量保持率はＣｓの割合が大きくなるにしたがって減少し、Ｃｓの割合が６０％以上の比較例３の電池Ｇおよび比較例４の電池Ｈでは、容量保持率が著しく低下した。また、図３に示したＣｓの割合と出力の関係から、出力はＣｓの割合が小さくなるにしたがって減少することがわかった。   From Table 1, the capacity retention decreased as the ratio of Cs increased, and the capacity retention decreased significantly in the battery G of Comparative Example 3 and the battery H of Comparative Example 4 in which the Cs ratio was 60% or more. Further, it was found from the relationship between the Cs ratio and the output shown in FIG. 3 that the output decreases as the Cs ratio decreases.

なお、図３より、易黒鉛化性炭素の含有量が４〜４０重量％であった場合、難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率から計算される平均値よりも良好な出力性能が得られることがわかった。   In addition, from FIG. 3, when content of graphitizable carbon is 4 to 40 weight%, it is more than the average value calculated from the mixing ratio of the output performance of non-graphitizable carbon and graphitizable carbon. It was found that good output performance can be obtained.

例えば、難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率を４０：６０とした場合、比較例１および比較例４の出力から算出される平均値は３７．６Ｗであり、比較例３の出力が難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率から計算される平均値とほぼ同等であることがわかった。   For example, when the mixing ratio of the output performance of non-graphitizable carbon and graphitizable carbon is 40:60, the average value calculated from the outputs of Comparative Example 1 and Comparative Example 4 is 37.6 W. It was found that the output of Example 3 was almost equal to the average value calculated from the mixing ratio of the non-graphitizable carbon and graphitizable carbon output performance.

一方、難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率を８０：２０とした場合、比較例１および比較例４の出力から算出される平均値は３３．２Ｗであり、実施例２の出力が難黒鉛化性炭素および易黒鉛化性炭素の出力性能の混合比率から計算される平均値よりも良好であることがわかった。   On the other hand, when the mixing ratio of the non-graphitizable carbon and the easily graphitizable carbon is set to 80:20, the average value calculated from the outputs of Comparative Example 1 and Comparative Example 4 is 33.2 W. It was found that the output of Example 2 was better than the average value calculated from the mixing ratio of the non-graphitizable carbon and graphitizable carbon output performance.

また、実施例１〜４の電池Ａ〜Ｄでは、容量維持率は８０％以上で、出力も３３Ｗ以上で、良好な充放電サイクル性能と高出力特性を示すことがわかった。   In addition, in the batteries A to D of Examples 1 to 4, it was found that the capacity retention rate was 80% or more, the output was 33 W or more, and good charge / discharge cycle performance and high output characteristics were exhibited.

［実施例５〜７および比較例５、６］
［実施例５］
負極活物質として、ＨＣとＣｓとの重量比７５：２５の混合物を用い、平均粒径が３μｍのＣｓを用いたこと以外は実施例１と同様にして、実施例５の非水電解質二次電池Ｉを作製した。電池Ｉでは、Ｃｓの平均粒径はＨＣの平均粒径の０．３倍である。 [Examples 5 to 7 and Comparative Examples 5 and 6]
[Example 5]
The nonaqueous electrolyte secondary of Example 5 was used in the same manner as in Example 1 except that a mixture of HC and Cs in a weight ratio of 75:25 was used as the negative electrode active material, and Cs having an average particle diameter of 3 μm was used. Battery I was produced. In battery I, the average particle size of Cs is 0.3 times the average particle size of HC.

［実施例６］
平均粒径が７．５μｍのＣｓを用いたこと以外は実施例５と同様にして、実施例６の非水電解質二次電池Ｊを作製した。電池Ｊでは、Ｃｓの平均粒径はＨＣの平均粒径の０．７５倍である。 [Example 6]
A nonaqueous electrolyte secondary battery J of Example 6 was produced in the same manner as Example 5 except that Cs having an average particle size of 7.5 μm was used. In the battery J, the average particle size of Cs is 0.75 times the average particle size of HC.

［実施例７］
平均粒径が１０μｍのＣｓを用いたこと以外は実施例５と同様にして、実施例７の非水電解質二次電池Ｋを作製した。電池Ｋでは、Ｃｓの平均粒径はＨＣの平均粒径の１.０倍である。 [Example 7]
A nonaqueous electrolyte secondary battery K of Example 7 was produced in the same manner as Example 5 except that Cs having an average particle diameter of 10 μm was used. In the battery K, the average particle size of Cs is 1.0 times the average particle size of HC.

［比較例５］
平均粒径が１μｍのＣｓを用いたこと以外は実施例５と同様にして、比較例５の非水電解質二次電池Ｌを作製した。電池Ｌでは、Ｃｓの平均粒径はＨＣの平均粒径の０．１倍である。 [Comparative Example 5]
A nonaqueous electrolyte secondary battery L of Comparative Example 5 was produced in the same manner as Example 5 except that Cs having an average particle diameter of 1 μm was used. In the battery L, the average particle size of Cs is 0.1 times the average particle size of HC.

［比較例６］
平均粒径が１５μｍのＣｓを用いたこと以外は実施例５と同様にして、比較例６の非水電解質二次電池Ｍを作製した。電池Ｍでは、Ｃｓの平均粒径はＨＣの平均粒径の１．５倍である。 [Comparative Example 6]
A nonaqueous electrolyte secondary battery M of Comparative Example 6 was produced in the same manner as in Example 5 except that Cs having an average particle diameter of 15 μm was used. In the battery M, the average particle size of Cs is 1.5 times the average particle size of HC.

実施例５〜７および比較例５、６の非水電解質二次電池Ｉ〜Ｍについても、実施例１の場合と同じ条件で、初期放電容量測定、出力測定および充放電サイクル試験をおこなった。測定結果を表２にまとめた。   For the nonaqueous electrolyte secondary batteries I to M of Examples 5 to 7 and Comparative Examples 5 and 6, initial discharge capacity measurement, output measurement, and charge / discharge cycle test were performed under the same conditions as in Example 1. The measurement results are summarized in Table 2.

Figure 0005125050
Figure 0005125050

表２に示すように、ＨＣの平均粒径に対するＣｓの平均粒径の比を０．４〜１の範囲とすることによって、良好な充放電サイクル性能および出力性能を得られることがわかった。   As shown in Table 2, it was found that good charge / discharge cycle performance and output performance can be obtained by setting the ratio of the average particle size of Cs to the average particle size of HC in the range of 0.4 to 1.

［実施例８〜１０］
［実施例８］
負極活物質として、ＨＣとＣｓとの重量比７５：２５の混合物を用い、ＨＣとしては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．８０オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で１．１ｎｍ、平均粒径が２０μｍのものを用い、易黒鉛化性炭素としては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．４８オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で２.０ｎｍ、平均粒径が１５μｍのＣｓを用いたこと以外は実施例１と同様にして、実施例８の非水電解質二次電池Ｎを作製した。電池Ｎでは、負極中のＨＣとＣｓに対するＣｓの割合は２５重量％であり、Ｃｓの平均粒径はＨＣの平均粒径の０．７５倍である。 [Examples 8 to 10]
[Example 8]
As the negative electrode active material, a mixture of HC and Cs in a weight ratio of 75:25 was used. As HC, the (002) plane spacing measured by X-ray wide angle diffraction method was 3.80 angstroms, and the crystallite size was large. As the graphitizable carbon, the distance between the (002) planes measured by the X-ray wide angle diffraction method is 3. The nonaqueous electrolyte secondary of Example 8 was the same as Example 1 except that Cs having a thickness of 48 Å, a crystallite size of 2.0 nm in the c-axis direction (Lc), and an average particle size of 15 μm was used. Battery N was produced. In the battery N, the ratio of Cs to HC and Cs in the negative electrode is 25% by weight, and the average particle size of Cs is 0.75 times the average particle size of HC.

［実施例９］
ＨＣとしては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．７０オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で１．５ｎｍ、平均粒径が１０μｍのものを用い、易黒鉛化性炭素としては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．４６オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で1．７ｎｍ、平均粒径が７．５μｍのＣｓを用いたこと以外は実施例８と同様にして、実施例９の非水電解質二次電池Ｏを作製した。 [Example 9]
As HC, (002) plane spacing measured by X-ray wide angle diffraction method is 3.70 angstroms, crystallite size is 1.5 nm in c-axis direction (Lc), and average grain size is 10 μm As the graphitizable carbon, the (002) plane spacing measured by X-ray wide angle diffraction method is 3.46 angstroms, and the crystallite size is 1.7 nm in the c-axis direction (Lc). A nonaqueous electrolyte secondary battery O of Example 9 was produced in the same manner as in Example 8, except that Cs having an average particle diameter of 7.5 μm was used.

［実施例１０］
ＨＣとしては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．７７オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で１．３ｎｍ、平均粒径が１５μｍのものを用い、易黒鉛化性炭素としては、Ｘ線広角回折法から測定される（００２）面の面間隔が３．４４オングストローム、結晶子の大きさがｃ軸方向（Ｌｃ）で２．１ｎｍ、平均粒径が１１．２５μｍのＣｓを用いたこと以外は実施例８と同様にして、実施例１０の非水電解質二次電池Ｐを作製した。 [Example 10]
As HC, (002) plane spacing measured by X-ray wide angle diffraction method is 3.77 angstrom, crystallite size is 1.3 nm in c-axis direction (Lc), and average grain size is 15 μm As the graphitizable carbon, the (002) plane spacing measured by X-ray wide angle diffraction method is 3.44 angstroms, and the crystallite size is 2.1 nm in the c-axis direction (Lc). A nonaqueous electrolyte secondary battery P of Example 10 was produced in the same manner as in Example 8, except that Cs having an average particle diameter of 11.25 μm was used.

実施例８〜１０の非水電解質二次電池Ｎ〜Ｐについても、実施例１の場合と同じ条件で、初期放電容量測定、出力測定および充放電サイクル試験をおこなった。測定結果を表３にまとめた。   For the non-aqueous electrolyte secondary batteries N to P of Examples 8 to 10, initial discharge capacity measurement, output measurement, and charge / discharge cycle test were performed under the same conditions as in Example 1. The measurement results are summarized in Table 3.

Figure 0005125050
Figure 0005125050

表３に示すように、ＨＣやＣｓの種類を変えた場合でも、良好な充放電サイクル性能および出力性能を得られることがわかった。   As shown in Table 3, it was found that good charge / discharge cycle performance and output performance can be obtained even when the types of HC and Cs are changed.

［実施例１１、１２および比較例７〜１０］
［実施例１１］
正極活物質としてＬｉＮｉＯ２を用いたこと以外は実施例６と同様にして、実施例１１の非水電解液電池Ｑを作製した。電池Ｑでは、負極中のＨＣとＣｓに対するＣｓの割合は２５重量％であり、Ｃｓの平均粒径はＨＣの平均粒径の０．７５倍である。 [Examples 11 and 12 and Comparative Examples 7 to 10]
[Example 11]
A nonaqueous electrolyte battery Q of Example 11 was produced in the same manner as Example 6 except that LiNiO 2 was used as the positive electrode active material. In the battery Q, the ratio of Cs to HC and Cs in the negative electrode is 25% by weight, and the average particle size of Cs is 0.75 times the average particle size of HC.

［実施例１２］
正極活物質としてＬｉＣｏＯ２を用いたこと以外は実施例６と同様にして、実施例１２の非水電解液電池Ｒを作製した。電池Ｒでは、負極中のＨＣとＣｓに対するＣｓの割合は２５重量％であり、Ｃｓの平均粒径はＨＣの平均粒径の０．７５倍である。 [Example 12]
A nonaqueous electrolyte battery R of Example 12 was produced in the same manner as in Example 6 except that LiCoO 2 was used as the positive electrode active material. In the battery R, the ratio of Cs to HC and Cs in the negative electrode is 25% by weight, and the average particle size of Cs is 0.75 times the average particle size of HC.

［比較例７］
正極活物質としてＬｉＮｉＯ２を用いたこと以外は比較例１と同様にして、比較例７の非水電解液電池Ｓを作製した。電池Ｓでは、負極活物質はＨＣのみである。 [Comparative Example 7]
A nonaqueous electrolyte battery S of Comparative Example 7 was produced in the same manner as Comparative Example 1 except that LiNiO 2 was used as the positive electrode active material. In the battery S, the negative electrode active material is only HC.

［比較例８］
正極活物質としてＬｉＮｉＯ２を用いたこと以外は比較例４と同様にして、比較例８の非水電解液電池Ｔを作製した。電池Ｔでは、負極活物質はＣｓのみである。 [Comparative Example 8]
A nonaqueous electrolyte battery T of Comparative Example 8 was produced in the same manner as Comparative Example 4 except that LiNiO 2 was used as the positive electrode active material. In the battery T, the negative electrode active material is only Cs.

［比較例９］
正極活物質としてＬｉＣｏＯ２を用いたこと以外は比較例１と同様にして、比較例９の非水電解液電池Ｕを作製した。電池Ｕでは、負極活物質はＨＣのみである。 [Comparative Example 9]
A nonaqueous electrolyte battery U of Comparative Example 9 was produced in the same manner as Comparative Example 1 except that LiCoO 2 was used as the positive electrode active material. In the battery U, the negative electrode active material is only HC.

［比較例１０］
正極活物質としてＬｉＣｏＯ２を用いたこと以外は比較例４と同様にして、比較例１０の非水電解液電池Ｖを作製した。電池Ｖでは、負極活物質はＣｓのみである。 [Comparative Example 10]
A nonaqueous electrolyte battery V of Comparative Example 10 was produced in the same manner as Comparative Example 4 except that LiCoO 2 was used as the positive electrode active material. In the battery V, the negative electrode active material is only Cs.

実施例１１、１２および比較例７〜１０の非水電解質二次電池Ｑ〜Ｖの内容を表４にまとめた。なお、表４には、比較のため、実施例６、比較例１および比較例４の結果も示した。   The contents of the nonaqueous electrolyte secondary batteries Q to V of Examples 11 and 12 and Comparative Examples 7 to 10 are summarized in Table 4. Table 4 also shows the results of Example 6, Comparative Example 1, and Comparative Example 4 for comparison.

Figure 0005125050
Figure 0005125050

実施例１１、１２および比較例７〜１０の非水電解質二次電池Ｑ〜Ｖについても、実施例１の場合と同じ条件で、初期放電容量測定、出力測定および充放電サイクル試験をおこなった。測定結果を表５にまとめた。なお、表５には、比較のため、実施例６、比較例１および比較例４の結果も示した。   For the nonaqueous electrolyte secondary batteries Q to V of Examples 11 and 12 and Comparative Examples 7 to 10, initial discharge capacity measurement, output measurement, and charge / discharge cycle test were performed under the same conditions as in Example 1. The measurement results are summarized in Table 5. Table 5 also shows the results of Example 6, Comparative Example 1, and Comparative Example 4 for comparison.

Figure 0005125050
Figure 0005125050

表５に示す結果より、正極に各種リチウム複合酸化物を用いた非水電解質二次電池においても、負極中のＣｓの割合と、ＨＣとＣｓの平均粒径の比を制御することにより、ＨＣおよびＣｓの出力性能の混合比率から計算される平均値よりも良好な出力性能が得られ、かつ良好な充放電サイクル性能を有する非水電解質二次電池を提供することができることがわかった。   From the results shown in Table 5, even in a non-aqueous electrolyte secondary battery using various lithium composite oxides for the positive electrode, by controlling the ratio of Cs in the negative electrode and the ratio of the average particle size of HC and Cs, It was found that an output performance better than the average value calculated from the mixing ratio of the output performance of Cs and Cs can be obtained, and a nonaqueous electrolyte secondary battery having good charge / discharge cycle performance can be provided.

本発明の非水電解質二次電池の外観を示す図。The figure which shows the external appearance of the nonaqueous electrolyte secondary battery of this invention. 電池の電極群を示す図。The figure which shows the electrode group of a battery. 負極中のＨＣとＣｓに対するＣｓの割合と出力との関係を示す図。The figure which shows the relationship between the ratio of Cs with respect to HC and Cs in a negative electrode, and an output.

符号の説明Explanation of symbols

１ 非水電解質二次電池
２ 電極群
２ａ 正極
２ｂ 負極
２ｃ セパレータ
３ 電池ケース DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 2 Electrode group 2a Positive electrode 2b Negative electrode 2c Separator 3 Battery case

Claims (1)

リチウムを含む遷移金属複合酸化物を正極活物質とする正極と、炭素材料を負極活物質とする負極と、非水電解質とを備えた非水電解質二次電池において、前記炭素材料が難黒鉛化性炭素の粒子と易黒鉛化性炭素の粒子とを含み、前記難黒鉛化性炭素の粒子と前記易黒鉛化性炭素の粒子に占める前記易黒鉛化性炭素の粒子の割合が４〜４０重量％であり、前記易黒鉛化性炭素の粒子の平均粒径が前記難黒鉛化性炭素の粒子の平均粒径の０．３〜１倍であることを特徴とする非水電解質二次電池。
In a non-aqueous electrolyte secondary battery comprising a positive electrode having a transition metal composite oxide containing lithium as a positive electrode active material, a negative electrode having a carbon material as a negative electrode active material, and a non-aqueous electrolyte, the carbon material is hardly graphitized. and a sexual carbon in the particles and graphitizable carbon particles, the proportion of the easily graphitizable carbon particles and the flame-graphitizable carbon particles occupied in the graphitizable carbon particles 4 to 40 weight % a and a non-aqueous electrolyte secondary battery wherein an average particle diameter of the easily graphitizable carbon particles is 0.3 to 1 times the average particle diameter of the flame-graphitizable carbon particles.
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