JP2005259617A - Lithium ion secondary battery - Google Patents

Lithium ion secondary battery Download PDF

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JP2005259617A
JP2005259617A JP2004071854A JP2004071854A JP2005259617A JP 2005259617 A JP2005259617 A JP 2005259617A JP 2004071854 A JP2004071854 A JP 2004071854A JP 2004071854 A JP2004071854 A JP 2004071854A JP 2005259617 A JP2005259617 A JP 2005259617A
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positive electrode
battery
coating amount
negative electrode
active material
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Yoshin Yagi
陽心 八木
Takahiro Yamaki
孝博 山木
Masahiro Kasai
昌弘 葛西
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Resonac Corp
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Shin Kobe Electric Machinery Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery in which high output performance can be secured even under cryogenic temperature environment. <P>SOLUTION: A positive electrode active material is made to be a complex oxide of layered crystalline structure expressed in a composition formula LiNi<SB>X</SB>Mn<SB>Y</SB>Co<SB>Z</SB>M<SB>α</SB>O<SB>2</SB>(M:Fe, Cr, Cu, Al, Mg, Si, X+Y+Z+α=1, 0.25≤X≤0.55, 0.25≤Y≤0.55, 0.15≤Z≤0.4, and 0≤α≤0.1). The positive electrode mixture is applied to aluminum foil with the amount of 8.0-14.5 mg/cm<SP>2</SP>. A negative electrode active material is made to be an amorphous carbon of the initial charge capacity of 450 mAh/g. By adjusting the amount of application of the negative mixture to a rolled copper foil, the ratio of the negative electrode initial charge capacity to the positive electrode initial charge capacity is made to be 0.80-1.11, and the ratio of coating amount of the negative electrode mixture to coating amount of the positive electrode mixture is made to be 0.27-0.41. Even under the cryogenic temperature environment, diffusion move of the lithium ion in the positive electrode active material and the positive electrode mixture is secured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明はリチウムイオン二次電池に係り、特に、正極活物質を含む正極合剤が塗着された正極及び負極活物質を含む負極合剤が塗着された負極を非水電解液に浸潤させたリチウムイオン二次電池に関する。   The present invention relates to a lithium ion secondary battery, and in particular, a non-aqueous electrolyte solution is infiltrated with a positive electrode coated with a positive electrode mixture containing a positive electrode active material and a negative electrode coated with a negative electrode mixture containing a negative electrode active material. The present invention relates to a lithium ion secondary battery.

リチウムイオン二次電池は、ニッケル水素二次電池や鉛蓄電池に比べ、軽量で高出力特性を有することから、各種携帯型機器や情報機器用の電源として広く使用されており、最近では、電気自動車やハイブリッド型電気自動車等の動力用電源としても期待されている。同時にその使用場所としては屋内のみならず屋外も想定されており、低温環境下での出力特性も要求されつつある。   Lithium ion secondary batteries are widely used as power sources for various portable devices and information devices because they are lighter and have higher output characteristics than nickel metal hydride secondary batteries and lead-acid batteries. It is also expected to be used as a power source for power sources such as hybrid electric vehicles. At the same time, it is assumed that the place of use is not only indoors but also outdoors, and output characteristics in a low temperature environment are being demanded.

動力用電源にリチウムイオン二次電池を使用する方法の１つとして、数秒程度の短時間に高負荷（大電流）で高出力を得る方法が挙げられる。リチウムイオン二次電池では、電池内部の構造部材、正極、負極及び非水電解液でのリチウムイオンの反応や移動に起因する内部抵抗（電池抵抗）が生じるため、高出力を発揮するには、電池抵抗を低減することで高負荷における電圧損失を抑制することが望まれる。このような電池抵抗を低減して出力特性を向上させる試みとして、マンガン酸リチウムを用いた正極合剤の塗着量を所定範囲とする技術が開示されている（例えば、特許文献１参照）。   One method of using a lithium ion secondary battery as a power source for power is to obtain a high output with a high load (large current) in a short time of about several seconds. In a lithium ion secondary battery, since internal resistance (battery resistance) resulting from the reaction and movement of lithium ions in the structural member, positive electrode, negative electrode, and non-aqueous electrolyte in the battery occurs, It is desired to suppress voltage loss at high loads by reducing battery resistance. As an attempt to reduce the battery resistance and improve the output characteristics, a technique for setting the coating amount of the positive electrode mixture using lithium manganate within a predetermined range is disclosed (for example, see Patent Document 1).

一般に、リチウムイオン二次電池の正極では、正極集電体に正極合剤が塗着されている。正極合剤には、スピネル結晶構造や層状結晶構造のリチウム遷移金属複合酸化物等の正極活物質と、正極の電子伝導性を確保するための黒鉛系や非晶質系の炭素粉末等の粒子又は各種形状の導電剤と、これらの正極活物質及び導電剤を正極集電体に塗着するための樹脂等の結着剤とが配合されている。正極合剤中に正極活物質、導電剤、結着剤で形成される空間（隙間）には、非水電解液が保持される。充放電時には、正極活物質と非水電解液との界面でリチウムイオンが正極活物質に脱離、挿入され、正極活物質の結晶構造中をリチウムイオンが拡散移動する。正極活物質に脱離、挿入されたリチウムイオンが非水電解液中を拡散移動して負極活物質に挿入、脱離されることで、リチウムイオン二次電池の充放電が進行する。リチウムイオンが三次元的に拡散移動するスピネル結晶構造のリチウム遷移金属複合酸化物と比較して、リチウムイオンが二次元的に拡散移動する層状結晶構造のリチウム遷移金属複合酸化物では、リチウムイオンの拡散移動の抵抗が小さく高出力を得ることができる。   Generally, in a positive electrode of a lithium ion secondary battery, a positive electrode mixture is applied to a positive electrode current collector. The positive electrode mixture includes a positive electrode active material such as a spinel crystal structure or a layered crystal structure lithium transition metal composite oxide, and particles such as graphite and amorphous carbon powder for ensuring the electron conductivity of the positive electrode. Alternatively, various types of conductive agents and a binder such as a resin for coating these positive electrode active materials and conductive agents on the positive electrode current collector are blended. A nonaqueous electrolytic solution is held in a space (gap) formed by the positive electrode active material, the conductive agent, and the binder in the positive electrode mixture. At the time of charge / discharge, lithium ions are desorbed and inserted into the positive electrode active material at the interface between the positive electrode active material and the non-aqueous electrolyte, and lithium ions diffuse and move in the crystal structure of the positive electrode active material. The lithium ions desorbed and inserted into the positive electrode active material diffuse and move in the non-aqueous electrolyte and are inserted into and desorbed from the negative electrode active material, so that charging / discharging of the lithium ion secondary battery proceeds. Compared with a spinel crystal structure lithium transition metal composite oxide in which lithium ions diffuse and move three-dimensionally, the lithium transition metal composite oxide in a layered crystal structure in which lithium ions diffuse and move in two dimensions The resistance of diffusion movement is small and high output can be obtained.

ところが、低温環境下では、正極活物質の結晶構造が収縮するため、結晶構造中のリチウムイオンの拡散移動が阻害されると共に、非水電解液の電気伝導度が低下するため、非水電解液中でもリチウムイオンの拡散移動が阻害される。このため、電池抵抗が増大して出力の低下を招く。このような低温環境下でのレート特性を改善するため、非水電解液に負極での溶媒の分解が少ない含硫黄化合物を含有させる技術が開示されている（例えば、特許文献２参照）。   However, in a low temperature environment, the crystal structure of the positive electrode active material shrinks, so that the diffusion transfer of lithium ions in the crystal structure is hindered, and the electrical conductivity of the nonaqueous electrolyte decreases. Among them, the diffusion movement of lithium ions is inhibited. For this reason, battery resistance increases and the output falls. In order to improve the rate characteristics under such a low temperature environment, a technique is disclosed in which a non-aqueous electrolyte contains a sulfur-containing compound that causes little decomposition of the solvent at the negative electrode (see, for example, Patent Document 2).

特開２００１−１７６４９９号公報JP 2001-176499 A 特開２００１−１８５２１５号公報JP 2001-185215 A

しかしながら、寒冷地の屋外では極低温環境（−３０°Ｃ前後）となることもあり得る。このような極低温環境下では、リチウムイオン二次電池を構成する正極や負極及び非水電解液におけるリチウムイオンの反応や拡散移動が大きく阻害され、電池抵抗が著しく増大する。特に、層状結晶構造のリチウム遷移金属複合酸化物では極低温環境下で結晶構造が収縮しやすいため、電池抵抗が更に増大する。   However, it may be a very low temperature environment (around −30 ° C.) outdoors in a cold region. Under such an extremely low temperature environment, the reaction and diffusion movement of lithium ions in the positive electrode, the negative electrode and the non-aqueous electrolyte constituting the lithium ion secondary battery are greatly inhibited, and the battery resistance is remarkably increased. In particular, in a lithium transition metal composite oxide having a layered crystal structure, since the crystal structure easily contracts under an extremely low temperature environment, the battery resistance is further increased.

上記事案に鑑み本発明は、極低温環境下でも高出力性能を確保可能なリチウムイオン二次電池を提供することを課題とする。   In view of the above circumstances, an object of the present invention is to provide a lithium ion secondary battery that can ensure high output performance even in a cryogenic environment.

上記課題を解決するために、本発明は、正極活物質を含む正極合剤が塗着された正極及び負極活物質を含む負極合剤が塗着された負極を非水電解液に浸潤させたリチウムイオン二次電池において、前記正極活物質が組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される六方晶系の層状結晶構造の複合酸化物であり、前記正極合剤の塗着量が８．０ｍｇ／ｃｍ２以上１４．５ｍｇ／ｃｍ２以下であることを特徴とする。 In order to solve the above-mentioned problems, the present invention has made a non-aqueous electrolyte infiltrate a positive electrode coated with a positive electrode mixture containing a positive electrode active material and a negative electrode coated with a negative electrode mixture containing a negative electrode active material. in the lithium ion secondary battery, the positive active material composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0 .55, 0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), and a complex oxide having a layered crystal structure of hexagonal system, the coating amount of the positive electrode mixture is characterized in that it is 8.0 mg / cm 2 or more 14.5 mg / cm 2 or less.

本発明では、正極活物質を組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される六方晶系の層状結晶構造の複合酸化物とすることで、複合酸化物の層状結晶構造が安定化するため、−３０°Ｃ前後の極低温環境下でも複合酸化物中のリチウムイオンの拡散移動が確保される。正極合剤の塗着量が８．０ｍｇ／ｃｍ２未満では正極合剤中の非水電解液の保持量が減少し、反対に塗着量が１４．５ｍｇ／ｃｍ２を超えると正極合剤の電子移動に伴う抵抗増大の影響が大きくなる。このため、正極合剤の塗着量を８．０ｍｇ／ｃｍ２以上１４．５ｍｇ／ｃｍ２以下とすることで、正極合剤中のリチウムイオンの拡散移動を阻害することなく電池抵抗を抑制し出力特性に優れるリチウムイオン二次電池を得ることができる。 In the present invention, the composition formula of the positive electrode active material LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55,0 .25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), a composite oxide having a hexagonal layered crystal structure Therefore, the diffusion movement of lithium ions in the composite oxide is ensured even under an extremely low temperature environment of around −30 ° C. When the coating amount of the positive electrode mixture is less than 8.0 mg / cm 2 , the retained amount of the non-aqueous electrolyte in the positive electrode mixture decreases, and conversely, when the coating amount exceeds 14.5 mg / cm 2 , the positive electrode mixture The effect of the increase in resistance due to the electron movement of becomes large. Therefore, the the coating amount of the positive electrode mixture by a 8.0 mg / cm 2 or more 14.5 mg / cm 2 or less, the battery resistance is suppressed without inhibiting the diffusion transfer of lithium ions in the positive electrode mixture A lithium ion secondary battery having excellent output characteristics can be obtained.

本発明において、負極活物質を主として非晶質炭素とすれば、極低温環境下でも負極活物質の構造が安定なため、負極でのリチウムイオンの拡散移動が確保されるので、リチウムイオン二次電池の出力特性を向上させることができる。また、リチウムイオン二次電池の充放電では、正極及び負極に脱離、挿入されるリチウムイオンの量は等しいことから、正極の初充電容量に対する負極の初充電容量の比を０．８０未満とすると充電時に単位量当たりの正極活物質から脱離するリチウムイオンの量が減少して出力の低下を招き、反対に、初充電容量の比が１．１１を超えると充電時に単位量当たりの正極活物質から脱離するリチウムイオンの量が増加して層状結晶構造の安定性を低下させるので、正極の初充電容量に対する負極の初充電容量の比を０．８０以上１．１１以下とすることが好ましい。更に、正極合剤の塗着量に対する負極合剤の塗着量の割合を０．２７未満とすると正極合剤の塗着量が負極合剤より大きくなり正極合剤での抵抗が増大し、反対に、塗着量の割合が０．４１を超えると負極合剤の塗着量が正極合剤より大きくなり負極合剤での抵抗が増大するため、リチウムイオン二次電池の出力低下を招くので、正極合剤の塗着量に対する負極合剤の塗着量の割合を０．２７以上０．４１以下とすることが好ましい。この場合に、リチウムイオン二次電池の非水電解液を構成する溶媒を、環状又は直鎖状のカーボネート類を主成分とすることが好ましい。   In the present invention, if the negative electrode active material is mainly amorphous carbon, the structure of the negative electrode active material is stable even in an extremely low temperature environment, so that the diffusion movement of lithium ions in the negative electrode is ensured. The output characteristics of the battery can be improved. Further, in the charge / discharge of the lithium ion secondary battery, since the amount of lithium ions desorbed and inserted into the positive electrode and the negative electrode is equal, the ratio of the initial charge capacity of the negative electrode to the initial charge capacity of the positive electrode is less than 0.80. Then, the amount of lithium ions desorbed from the positive electrode active material per unit amount at the time of charging decreases, leading to a decrease in output. Conversely, when the ratio of the initial charge capacity exceeds 1.11, the positive electrode per unit amount at the time of charging Since the amount of lithium ions desorbed from the active material is increased and the stability of the layered crystal structure is lowered, the ratio of the initial charge capacity of the negative electrode to the initial charge capacity of the positive electrode is 0.80 or more and 1.11 or less. Is preferred. Furthermore, when the ratio of the coating amount of the negative electrode mixture to the coating amount of the positive electrode mixture is less than 0.27, the coating amount of the positive electrode mixture is larger than that of the negative electrode mixture and the resistance in the positive electrode mixture is increased. On the other hand, if the ratio of the coating amount exceeds 0.41, the coating amount of the negative electrode mixture becomes larger than that of the positive electrode mixture and the resistance in the negative electrode mixture increases, leading to a decrease in the output of the lithium ion secondary battery. Therefore, the ratio of the coating amount of the negative electrode mixture to the coating amount of the positive electrode mixture is preferably 0.27 or more and 0.41 or less. In this case, the solvent constituting the non-aqueous electrolyte of the lithium ion secondary battery is preferably composed mainly of cyclic or linear carbonates.

本発明によれば、正極活物質を組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される六方晶系の層状結晶構造の複合酸化物とすることで、複合酸化物の層状結晶構造が安定化するため、極低温環境下でも複合酸化物中のリチウムイオンの拡散移動が確保されると共に、正極合剤の塗着量を８．０ｍｇ／ｃｍ２以上１４．５ｍｇ／ｃｍ２以下とすることで、正極合剤中の非水電解液の保持量が適正化され正極合剤による抵抗増大が抑制されるので、正極合剤中のリチウムイオンの拡散移動を阻害することなく電池抵抗を抑制し出力特性に優れるリチウムイオン二次電池を得ることができる、という効果を得ることができる。 According to the present invention, the composition formula of the positive electrode active material LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55 0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), a composite oxide having a layered crystal structure of hexagonal system. Since the layered crystal structure of the oxide is stabilized, the diffusion migration of lithium ions in the composite oxide is ensured even in an extremely low temperature environment, and the coating amount of the positive electrode mixture is 8.0 mg / cm 2 or more and 14. By setting the amount to 5 mg / cm 2 or less, the retention amount of the non-aqueous electrolyte in the positive electrode mixture is optimized and the increase in resistance due to the positive electrode mixture is suppressed, so that the diffusion movement of lithium ions in the positive electrode mixture is inhibited. To obtain a lithium ion secondary battery with excellent output characteristics by suppressing battery resistance Can bets can obtain an effect that.

以下、図面を参照して、本発明を円筒型リチウムイオン二次電池に適用した実施の形態について説明する。   Embodiments in which the present invention is applied to a cylindrical lithium ion secondary battery will be described below with reference to the drawings.

（正極活物質の調製）
原料としてリチウム化合物の炭酸リチウム、ニッケル化合物の炭酸ニッケル、マンガン化合物の二酸化マンガン、コバルト化合物の炭酸コバルトを使用した。調製する複合酸化物にＦｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉの元素を含有させる場合には、含有させる元素を含む炭酸塩を使用した。このとき、Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉの２種以上の元素を含有させてもよい。各原料を組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される複合酸化物となるように配合比を調整して混合した。混合した原料を空気中で６００〜９００°Ｃの温度で、５〜２０時間焼成後、室温まで自然冷却させて複合酸化物を合成した。 (Preparation of positive electrode active material)
Lithium compound lithium carbonate, nickel compound nickel carbonate, manganese compound manganese dioxide, and cobalt compound cobalt carbonate were used as raw materials. When the prepared complex oxide contains Fe, Cr, Cu, Al, Mg, and Si elements, a carbonate containing the contained elements was used. At this time, two or more elements of Fe, Cr, Cu, Al, Mg, and Si may be included. Each raw material composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55,0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), and the mixing ratio was adjusted so as to be a composite oxide represented by mixing. The mixed raw material was fired in air at a temperature of 600 to 900 ° C. for 5 to 20 hours, and then naturally cooled to room temperature to synthesize a composite oxide.

得られた複合酸化物についてＸ線回折測定を行い、六方晶系の層状結晶構造を有することを確認し、原子吸光分析で各元素の組成を確認した。また、得られた複合酸化物の初充電容量を、対極及び参照極に金属リチウムを用いた電気化学セルで以下のようにして測定した。   The obtained composite oxide was subjected to X-ray diffraction measurement to confirm that it had a hexagonal layered crystal structure, and the composition of each element was confirmed by atomic absorption analysis. Further, the initial charge capacity of the obtained composite oxide was measured by an electrochemical cell using metallic lithium as a counter electrode and a reference electrode as follows.

得られた複合酸化物８６重量％に、導電剤として９重量％の鱗片状黒鉛と１．５重量％のアセチレンブラックを加えてよく混合し、結着剤のポリフッ化ビニリデン（以下、ＰＶＤＦと略記する。）３．５重量％を溶媒のＮ−メチルピロリドン（以下、ＮＭＰと略記する。）に溶解させた溶液を加えて更に混合し正極合剤スラリを作製した。作製した正極合剤スラリを厚さ２０μｍのアルミニウム箔（正極集電体）に実質的に均一かつ均等に塗布した後、８０°Ｃの温度で乾燥させた。乾燥後、打ち抜き治具を用いて直径１５ｍｍに打ち抜いた後プレスして試験正極を作製した。試験正極の作製では、別の方法として、後述するリチウムイオン二次電池用の正極を適当な大きさに裁断又は打ち抜きするようにしてもよい。   To 86% by weight of the obtained composite oxide, 9% by weight of flaky graphite and 1.5% by weight of acetylene black are added and mixed well as a conductive agent, and the binder is polyvinylidene fluoride (hereinafter abbreviated as PVDF). A solution prepared by dissolving 3.5% by weight in N-methylpyrrolidone (hereinafter abbreviated as NMP) as a solvent was added and further mixed to prepare a positive electrode mixture slurry. The prepared positive electrode mixture slurry was applied to a 20 μm thick aluminum foil (positive electrode current collector) substantially uniformly and uniformly, and then dried at a temperature of 80 ° C. After drying, it was punched to a diameter of 15 mm using a punching jig and then pressed to prepare a test positive electrode. In the production of the test positive electrode, as another method, a positive electrode for a lithium ion secondary battery, which will be described later, may be cut or punched into an appropriate size.

作製した試験正極を秤量し、アルミニウム箔と正極合剤スラリ中の複合酸化物との重量を基に、試験正極中の複合酸化物の重量を算出した。この試験正極と金属リチウム対極と金属リチウム参照極とを用い、電気化学セルを作製した。   The prepared test positive electrode was weighed, and the weight of the composite oxide in the test positive electrode was calculated based on the weight of the aluminum foil and the composite oxide in the positive electrode mixture slurry. An electrochemical cell was produced using this test positive electrode, a metal lithium counter electrode, and a metal lithium reference electrode.

図１に示すように、電気化学セル１０は、容器となる略円筒状のセル容器７を有している。セル容器７には、試験正極１を含む積層体が挿入されている。積層体は、厚さ４０μｍのポリプロピレン製のセパレータ３、金属リチウムの対極２、セパレータ３、試験正極１、セパレータ３の順に試験正極１と対極２とが直接接触しないように積層されている。積層体は、上下２枚のステンレス製板６の間に加圧状態で挟持されている。セル容器７には、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）の体積比１：１：１の混合溶媒に１モル／リットルの６フッ化リン酸リチウム（ＬｉＰＦ６）を溶解させた非水電解液５が注入されている。積層体の上方には、矩形状の金属リチウムの参照極４が非水電解液５に参照極４の下部の略半分を浸漬させて吊下されている。試験正極１、対極２には、それぞれリード線が接続されており、図示を省略した電流計を介して図示しない充電装置に接続されている。参照極４には、リード線が接続されており、電圧計を介して試験正極１及び対極２に接続されている。なお、電気化学セルの作製は、アルゴンガス等の不活性ガスを封入したグローブボックス中で行う。 As shown in FIG. 1, the electrochemical cell 10 has a substantially cylindrical cell container 7 that serves as a container. A laminated body including the test positive electrode 1 is inserted into the cell container 7. The laminated body is laminated so that the test cathode 1 and the counter electrode 2 are not in direct contact with each other in the order of a polypropylene separator 3 having a thickness of 40 μm, a metal lithium counter electrode 2, a separator 3, a test cathode 1, and a separator 3. The laminate is sandwiched between the upper and lower stainless steel plates 6 in a pressurized state. The cell container 7 includes 1 mol / liter lithium hexafluorophosphate (LiPF 6 ) in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a volume ratio of 1: 1: 1. A nonaqueous electrolytic solution 5 in which is dissolved is injected. Above the laminate, a rectangular metallic lithium reference electrode 4 is suspended by immersing substantially half of the lower part of the reference electrode 4 in a non-aqueous electrolyte 5. A lead wire is connected to each of the test positive electrode 1 and the counter electrode 2 and is connected to a charging device (not shown) via an ammeter (not shown). A lead wire is connected to the reference electrode 4, and is connected to the test positive electrode 1 and the counter electrode 2 through a voltmeter. The electrochemical cell is produced in a glove box in which an inert gas such as argon gas is enclosed.

電気化学セル１０を作製後、時間率０．３３Ｃ相当の電流値で、金属リチウム基準で４．３Ｖまでの定電流定電圧充電を４時間行い、その際の初充電電気量を測定した。測定した初充電電気量と上述した試験正極の複合酸化物重量とから複合酸化物の単位重量当たりの初充電容量を算出した。リチウムイオン二次電池の正極初充電容量は、算出した単位重量当たりの初充電容量と電池作製に用いる複合酸化物重量とから算出した。   After producing the electrochemical cell 10, constant current and constant voltage charging up to 4.3 V on the basis of metallic lithium was performed for 4 hours at a current value corresponding to a time rate of 0.33 C, and the initial charge amount at that time was measured. The initial charge capacity per unit weight of the composite oxide was calculated from the measured initial charge electricity amount and the composite oxide weight of the test positive electrode described above. The positive electrode initial charge capacity of the lithium ion secondary battery was calculated from the calculated initial charge capacity per unit weight and the weight of the composite oxide used for battery production.

（正極の作製）
正極活物質として上述した組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２で表される六方晶系の層状複合酸化物を用いた。複合酸化物粉末８６重量％と導電剤として９重量％の鱗片状黒鉛と１．５重量％のアセチレンブラックとをよく混合した。更に、結着剤として３．５重量％のＰＶＤＦをＮＭＰに溶解させた溶液を加えて混合し正極合剤スラリを作製した。作製した正極合剤スラリを所定厚さのアルミニウム箔の両面に実質的に均一かつ均等に塗布して８０〜１００°Ｃの温度で乾燥させた。アルミニウム箔は厚さ１０〜３０μｍとすることが好ましい。このとき、乾燥後の正極合剤の塗着量が８．０〜１４．５ｍｇ／ｃｍ２の範囲となるように塗着量を調製した。その後ロールプレス機により圧縮成形し、後述する所定の大きさに裁断後、アルミニウム箔製の正極リード片を溶接し正極を作製した。 (Preparation of positive electrode)
Using hexagonal layered composite oxide represented by the composition formula described above as the positive electrode active material LiNi X Mn Y Co Z M α O 2. 86% by weight of the composite oxide powder, 9% by weight of flaky graphite and 1.5% by weight of acetylene black were mixed well as a conductive agent. Further, a positive electrode mixture slurry was prepared by adding and mixing a solution obtained by dissolving 3.5% by weight of PVDF in NMP as a binder. The produced positive electrode mixture slurry was applied substantially uniformly and evenly on both surfaces of an aluminum foil having a predetermined thickness, and dried at a temperature of 80 to 100 ° C. The aluminum foil is preferably 10 to 30 μm thick. At this time, the coating amount was adjusted so that the coating amount of the positive electrode mixture after drying was in the range of 8.0 to 14.5 mg / cm 2 . Thereafter, it was compression-molded by a roll press and cut into a predetermined size, which will be described later, and then a positive electrode lead piece made of aluminum foil was welded to produce a positive electrode.

（負極の作製）
負極活物質として非晶質炭素を用いた。非晶質炭素の単位重量当たりの初充電容量を、上述した正極活物質の複合酸化物の初充電容量を求める方法と同様にして求めた。すなわち、試験負極を作製して電気化学セルを組み立てた後、時間率０．３３Ｃ相当の電流値で、金属リチウム基準で５ｍＶまでの定電流定電圧充電を４時間行い、その際の初充電電気量を測定した。測定した初充電電気量と試験負極の非晶質炭素重量とから非晶質炭素の単位重量当たりの初充電容量を算出した。この結果、非晶質炭素の単位重量当たりの初充電容量４５０ｍＡｈ／ｇとなった。リチウムイオン二次電池の負極初充電容量は、算出した単位重量当たりの初充電容量と電池作製に用いる非晶質炭素重量とから算出した。 (Preparation of negative electrode)
Amorphous carbon was used as the negative electrode active material. The initial charge capacity per unit weight of amorphous carbon was determined in the same manner as the method for determining the initial charge capacity of the composite oxide of the positive electrode active material described above. That is, after preparing a test negative electrode and assembling an electrochemical cell, constant current and constant voltage charging up to 5 mV with respect to metallic lithium was performed for 4 hours at a current value equivalent to a time rate of 0.33 C, and the initial charge electric power at that time The amount was measured. The initial charge capacity per unit weight of amorphous carbon was calculated from the measured initial charge electricity amount and the amorphous carbon weight of the test negative electrode. As a result, the initial charge capacity per unit weight of amorphous carbon was 450 mAh / g. The negative electrode initial charge capacity of the lithium ion secondary battery was calculated from the calculated initial charge capacity per unit weight and the amorphous carbon weight used for battery production.

非晶質炭素９１重量％に２重量％のアセチレンブラックを加えて混合し、更に、結着剤として７重量％のＰＶＤＦをＮＭＰに溶解させた溶液を加えて混合し負極合剤スラリを作製した。作製した負極合剤スラリを所定厚さの圧延銅箔（負極集電体）の両面に実質的に均一かつ均等に塗布して８０〜１００°Ｃの温度で乾燥させた。圧延銅箔は厚さ７〜２０μｍとすることが好ましい。このとき、上述した正極初充電容量に対する負極初充電容量の比（以下、容量比と略記する。）が０．８０〜１．１１の範囲、かつ、上述した正極合剤の塗着量に対する負極合剤の塗着量の割合（以下、塗着量比と略記する。）が０．２７〜０．４１の範囲となるように負極合剤の塗着量を調整した。その後ロールプレス機により圧縮成形し、後述する所定の大きさに裁断後、銅箔製の負極リード片を溶接し負極を作製した。   A negative electrode mixture slurry was prepared by adding 2% by weight of acetylene black to 91% by weight of amorphous carbon and mixing, and further adding and mixing a solution prepared by dissolving 7% by weight of PVDF in NMP as a binder. . The prepared negative electrode mixture slurry was applied substantially uniformly and evenly on both sides of a rolled copper foil (negative electrode current collector) having a predetermined thickness, and dried at a temperature of 80 to 100 ° C. The rolled copper foil is preferably 7 to 20 μm in thickness. At this time, the ratio of the negative electrode initial charge capacity to the positive electrode initial charge capacity (hereinafter abbreviated as capacity ratio) is in the range of 0.80 to 1.11, and the negative electrode with respect to the coating amount of the positive electrode mixture described above. The coating amount of the negative electrode mixture was adjusted so that the ratio of the coating amount of the mixture (hereinafter abbreviated as the coating amount ratio) was in the range of 0.27 to 0.41. Thereafter, it was compression-molded by a roll press machine, cut into a predetermined size, which will be described later, and then a negative electrode lead piece made of copper foil was welded to produce a negative electrode.

（電池組立）
図２に示すように、作製した正極１１と負極１２とをこれらが直接接触しないように所定厚さ、気孔率４０％の微多孔性ポリプロピレンフィルムのセパレータ１３を介して捲回し電極群を作製した。セパレータ１３は厚さ１５〜５０μｍの範囲とすることが好ましい。このとき、正極合剤及び負極合剤の塗着量に応じて正極及び負極の長さを調整することで、電極群の体積が電池によらず一定となるように捲回した。作製した電極群をＳＵＳ製で長さ９０ｍｍ、直径３２ｍｍの円筒状の電池缶１４に挿入し、負極リード片１５を電池缶１４の内底部に溶接し、正極端子を兼ねる密閉蓋部１６に正極リード片１７を溶接した。乾燥空気中又は不活性ガス雰囲気下で、電池缶１４内に非水電解液を３０ｇ注液した後に、パッキン１８を介して電池缶１４に密閉蓋部１６をかしめて密閉して円筒型リチウムイオン二次電池２０の組立を完成させた。非水電解液には、ＥＣ、ＤＭＣ、ＤＥＣの体積比１：１：１の混合溶媒に電解質として１モル／リットルのＬｉＰＦ６を溶解させたものを用いた。 (Battery assembly)
As shown in FIG. 2, the produced positive electrode 11 and negative electrode 12 were wound through a separator 13 of a microporous polypropylene film having a predetermined thickness and a porosity of 40% so that they were not in direct contact with each other, and an electrode group was produced. . The separator 13 preferably has a thickness in the range of 15 to 50 μm. At this time, by adjusting the lengths of the positive electrode and the negative electrode in accordance with the amount of the positive electrode mixture and the negative electrode mixture applied, the volume of the electrode group was wound so as to be constant regardless of the battery. The produced electrode group is inserted into a cylindrical battery can 14 made of SUS and having a length of 90 mm and a diameter of 32 mm. A negative electrode lead piece 15 is welded to the inner bottom of the battery can 14, and a positive electrode is formed on the sealing lid portion 16 that also serves as a positive electrode terminal. The lead piece 17 was welded. After injecting 30 g of non-aqueous electrolyte into the battery can 14 in dry air or under an inert gas atmosphere, the battery lid 14 is caulked with a sealing lid 16 via a packing 18 to seal the cylindrical lithium ion. The assembly of the secondary battery 20 was completed. As the non-aqueous electrolyte, a solution obtained by dissolving 1 mol / liter of LiPF 6 as an electrolyte in a mixed solvent of EC, DMC, and DEC in a volume ratio of 1: 1: 1 was used.

リチウムイオン二次電池の充放電では、正極活物質と、正極合剤中に正極活物質等で形成される空間（隙間）に保持される非水電解液との界面でリチウムイオンが脱離、挿入し、同時に正極活物質の結晶構造中をリチウムイオンが拡散移動する。脱離、挿入したリチウムイオンが正極及び負極間の非水電解液中を拡散移動することで充放電が進行する。−３０°Ｃ前後の極低温環境下では、正極活物質及び非水電解液中のリチウムイオンの移動速度が低下するため、電池抵抗の増大を引き起こし出力低下を招くと考えられる。また、正極活物質には、従来からスピネル結晶構造や層状結晶構造のリチウム遷移金属複合酸化物が使用されている。層状結晶構造ではリチウムイオンが二次元的に拡散移動するため、リチウムイオンが三次元的に拡散移動するスピネル結晶構造と比較して、リチウムイオンの拡散移動の抵抗が小さく、高出力のリチウムイオン二次電池を得ることができる。ところが、層状結晶構造では、極低温環境下となると、層状結晶構造の収縮が起こり、リチウムイオンの拡散移動を阻害するため、出力低下を招く。   In the charge / discharge of the lithium ion secondary battery, lithium ions are desorbed at the interface between the positive electrode active material and the non-aqueous electrolyte held in the space (gap) formed by the positive electrode active material in the positive electrode mixture, At the same time, lithium ions diffuse and move in the crystal structure of the positive electrode active material. Charge / discharge progresses by the lithium ions that have been desorbed and inserted diffusely move in the non-aqueous electrolyte between the positive electrode and the negative electrode. In an extremely low temperature environment of around −30 ° C., the movement speed of lithium ions in the positive electrode active material and the non-aqueous electrolyte solution is decreased, which causes an increase in battery resistance and a decrease in output. As the positive electrode active material, a lithium transition metal composite oxide having a spinel crystal structure or a layered crystal structure has been conventionally used. In a layered crystal structure, lithium ions diffuse and move two-dimensionally. Therefore, compared to a spinel crystal structure in which lithium ions diffuse and move three-dimensionally, the resistance to diffusion and movement of lithium ions is small, and high-power lithium ion A secondary battery can be obtained. However, in a layered crystal structure, under an extremely low temperature environment, the layered crystal structure contracts and inhibits lithium ion diffusion and migration, leading to a decrease in output.

本実施形態では、正極活物質に組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される六方晶系の層状結晶構造の複合酸化物を用いる。このため、層状結晶構造中にＮｉ、Ｃｏ及び選択的にＭが存在することで複合酸化物の層状結晶構造が安定化して層状結晶構造の収縮が抑制され、極低温環境下でも複合酸化物中のリチウムイオンの拡散移動が確保される。これにより、電池抵抗の増大が抑制されるので、出力特性に優れるリチウムイオン二次電池を得ることができる。 In this embodiment, the composition formula in the positive electrode active material LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55, 0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1). A composite oxide having a layered crystal structure of a hexagonal system is used. For this reason, the presence of Ni, Co, and selectively M in the layered crystal structure stabilizes the layered crystal structure of the composite oxide and suppresses the shrinkage of the layered crystal structure. The diffusion movement of lithium ions is ensured. Thereby, since increase in battery resistance is suppressed, a lithium ion secondary battery excellent in output characteristics can be obtained.

また、正極合剤の塗着量が８．０ｍｇ／ｃｍ２未満では正極合剤に保持される非水電解液の量が減少するため、正極活物質に対するリチウムイオンの脱離、挿入を阻害し、反対に塗着量が１４．５ｍｇ／ｃｍ２を超えると、正極合剤に保持される非水電解液の効果が十分に得られず、正極合剤の電子移動に伴う抵抗増大の影響（電子移動の阻害）が大きくなるため、電池抵抗を増大させる。本実施形態では、正極合剤の塗着量を８．０ｍｇ／ｃｍ２以上１４．５ｍｇ／ｃｍ２以下とする。このため、正極合剤に保持される非水電解液の量が適正化され正極合剤による電子移動の阻害が抑制されるので、リチウムイオンの脱離、挿入を阻害することなく電池抵抗の増大を抑制し出力特性に優れるリチウムイオン二次電池を得ることができる。 In addition, if the coating amount of the positive electrode mixture is less than 8.0 mg / cm 2 , the amount of the non-aqueous electrolyte retained in the positive electrode mixture is reduced, which inhibits lithium ion desorption and insertion into the positive electrode active material. On the contrary, if the coating amount exceeds 14.5 mg / cm 2 , the effect of the non-aqueous electrolyte retained in the positive electrode mixture cannot be sufficiently obtained, and the influence of the increase in resistance accompanying the electron transfer of the positive electrode mixture ( (Inhibition of electron transfer) increases, so that battery resistance is increased. In the present embodiment, the coating deposition amount of the positive electrode mixture and 8.0 mg / cm 2 or more 14.5 mg / cm 2 or less. For this reason, the amount of non-aqueous electrolyte retained in the positive electrode mixture is optimized and inhibition of electron transfer by the positive electrode mixture is suppressed, so that the battery resistance is increased without hindering lithium ion desorption and insertion. It is possible to obtain a lithium ion secondary battery that is excellent in output characteristics.

更に、正極の充放電により複合酸化物からリチウムイオンが脱離、挿入するため、複合酸化物のリチウム組成が変化し、これに伴い正極の電位が変化する。極低温環境下では、複合酸化物のリチウム組成変化が、複合酸化物の結晶構造中のリチウムイオンの拡散移動速度に影響を与えるため、正極抵抗、すなわち電池抵抗に与える影響が大きくなる。このことは、結晶を構成する元素間の静電的な相互作用によるものと考えられる。一方、主として非晶質炭素の負極活物質を含む負極では、充放電に伴い負極の電位が連続的に変化する。通常、リチウムイオン二次電池の充放電では、正極及び負極に挿入、脱離するリチウムイオンの量は等しい。正極活物質量を減らす（容量比を増やす）と、充電時の正極活物質量からのリチウムイオン脱離量が増加する。一方、正極活物質量を増やす（容量比を減らす）と、充電時の正極活物質量からのリチウムイオン脱離量が減少する。従って、リチウムイオン二次電池の容量比を調整することで充電状態における複合酸化物のリチウム組成を制御することが可能となる。容量比を０．８０未満とすると充電時に単位量当たりの正極活物質から脱離するリチウムイオン量が減少するため、出力の低下を招き、反対に、容量比が１．１１を超えると充電時に単位量当たりの正極活物質から脱離するリチウムイオン量が増加するため、層状結晶構造の安定性を低下させる。本実施形態では、容量比を０．８０以上１．１１以下とするため、充電時の複合酸化物のリチウム組成が適正化される。このため、極低温環境下でもリチウムイオン二次電池の出力特性を向上させることができる。   Further, since lithium ions are desorbed and inserted from the composite oxide by charging and discharging the positive electrode, the lithium composition of the composite oxide changes, and the potential of the positive electrode changes accordingly. Under an extremely low temperature environment, a change in the lithium composition of the composite oxide affects the diffusion transfer rate of lithium ions in the crystal structure of the composite oxide, so that the influence on the positive electrode resistance, that is, the battery resistance, becomes large. This is considered to be due to electrostatic interaction between elements constituting the crystal. On the other hand, in a negative electrode mainly including an amorphous carbon negative electrode active material, the potential of the negative electrode changes continuously with charge and discharge. Usually, in charging / discharging of a lithium ion secondary battery, the amount of lithium ions inserted and removed from the positive electrode and the negative electrode is equal. When the amount of the positive electrode active material is reduced (the capacity ratio is increased), the amount of lithium ion desorption from the amount of the positive electrode active material during charging is increased. On the other hand, when the amount of the positive electrode active material is increased (the capacity ratio is decreased), the amount of lithium ion desorption from the amount of the positive electrode active material during charging is decreased. Therefore, it is possible to control the lithium composition of the composite oxide in the charged state by adjusting the capacity ratio of the lithium ion secondary battery. If the capacity ratio is less than 0.80, the amount of lithium ions desorbed from the positive electrode active material per unit amount during charging will decrease, leading to a decrease in output. Conversely, if the capacity ratio exceeds 1.11, charging will occur. Since the amount of lithium ions desorbed from the positive electrode active material per unit amount increases, the stability of the layered crystal structure is lowered. In this embodiment, since the capacity ratio is 0.80 or more and 1.11 or less, the lithium composition of the composite oxide at the time of charging is optimized. For this reason, the output characteristics of the lithium ion secondary battery can be improved even in a cryogenic environment.

また更に、上述した容量比を適切に調整するためには、塗着量比を適正に調整することが重要である。塗着量比が０．２７未満では正極合剤の塗着量が負極合剤より大きくなるため、正極合剤での抵抗が増大し、反対に、塗着量の割合が０．４１を超えると負極合剤の塗着量が正極合剤より大きくなるため、負極合剤での抵抗が増大するので、リチウムイオン二次電池の出力低下を招く。本実施形態では、塗着量比を０．２７〜０．４１の範囲とするため、容量比の調整が確実となり、極低温環境下でのリチウムイオン二次電池の出力特性を更に向上させることができる。   Furthermore, in order to appropriately adjust the above-described capacity ratio, it is important to appropriately adjust the coating amount ratio. When the coating amount ratio is less than 0.27, the coating amount of the positive electrode mixture becomes larger than that of the negative electrode mixture, so that the resistance in the positive electrode mixture increases, and conversely, the ratio of the coating amount exceeds 0.41. Since the coating amount of the negative electrode mixture becomes larger than that of the positive electrode mixture, the resistance of the negative electrode mixture increases, which causes a decrease in the output of the lithium ion secondary battery. In the present embodiment, since the coating amount ratio is in the range of 0.27 to 0.41, adjustment of the capacity ratio is ensured, and the output characteristics of the lithium ion secondary battery in a cryogenic environment are further improved. Can do.

次に、本実施形態に従い、正極活物質の組成、正極合剤の塗着量、容量比、塗着量比を変えて作製した円筒型リチウムイオン二次電池２０の実施例について説明する。なお、比較のために作製した比較例の電池についても併記する。   Next, an example of the cylindrical lithium ion secondary battery 20 produced by changing the composition of the positive electrode active material, the coating amount of the positive electrode mixture, the capacity ratio, and the coating amount ratio according to the present embodiment will be described. In addition, it describes together about the battery of the comparative example produced for the comparison.

（実施例１）
下表１に示すように、実施例１では、正極活物質に組成比の異なる複合酸化物を用い、正極合剤の塗着量を８．０ｍｇ／ｃｍ２、容量比を１．１１とし、塗着量比を変えて、電池１〜電池５の５種類のリチウムイオン電池２０を作製した。電池作製では、正極集電体のアルミニウム箔の厚さ２０μｍ、負極集電体の圧延銅箔の厚さ１５μｍ、セパレータ１３の厚さ４０μｍとした。正極活物質として、電池１では初充電容量１７４ｍＡｈ／ｇ、組成式ＬｉＮｉ０．３９Ｍｎ０．４Ｃｏ０．２Ａｌ０．０１Ｏ２の複合酸化物粉末を、電池２では初充電容量１７４ｍＡｈ／ｇ、組成式ＬｉＮｉ０．３４Ｍｎ０．３６Ｃｏ０．３Ｏ２の複合酸化物を、電池３では初充電容量１８５ｍＡｈ／ｇ、組成式ＬｉＮｉ０．５５Ｍｎ０．２５Ｃｏ０．２１Ｏ２の複合酸化物を、電池４では初充電容量１７４ｍＡｈ／ｇ、組成式ＬｉＮｉ０．２５Ｍｎ０．５５Ｃｏ０．１５Ｃｒ０．０５Ｏ２の複合酸化物を、電池５では初充電容量１６５ｍＡｈ／ｇ、組成式ＬｉＮｉ０．２９Ｍｎ０．３Ｃｏ０．４Ｍｇ０．０１Ｏ２の複合酸化物をそれぞれ用いた。また、電池１では負極の塗着量を３．０５ｍｇ／ｃｍ２、塗着量比０．３８、電池２では負極の塗着量を３．０５ｍｇ／ｃｍ２、塗着量比０．３８、電池３では負極の塗着量を３．２５ｍｇ／ｃｍ２、塗着量比０．４１、電池４では負極の塗着量を３．０５ｍｇ／ｃｍ２、塗着量比０．３８、電池５では負極の塗着量を２．９０ｍｇ／ｃｍ２、塗着量比０．３６とした。 (Example 1)
As shown in Table 1 below, in Example 1, composite oxides having different composition ratios were used as the positive electrode active material, the coating amount of the positive electrode mixture was 8.0 mg / cm 2 , and the capacity ratio was 1.11. Five types of lithium ion batteries 20, batteries 1 to 5, were produced by changing the coating amount ratio. In battery preparation, the thickness of the aluminum foil of the positive electrode current collector was 20 μm, the rolled copper foil of the negative electrode current collector was 15 μm thick, and the thickness of the separator 13 was 40 μm. As the positive electrode active material, in the battery 1, an initial charge capacity of 174 mAh / g, a composite oxide powder having a composition formula of LiNi 0.39 Mn 0.4 Co 0.2 Al 0.01 O 2 was used, and in the battery 2, an initial charge capacity of 174 mAh / g g, composite oxide of composition formula LiNi 0.34 Mn 0.36 Co 0.3 O 2 , the initial charge capacity 185 mAh / g in battery 3, composition formula LiNi 0.55 Mn 0.25 Co 0.21 O 2 In the battery 4, an initial charge capacity of 174 mAh / g, a composite oxide of the composition formula LiNi 0.25 Mn 0.55 Co 0.15 Cr 0.05 O 2 , and in the battery 5, an initial charge capacity of 165 mAh / g g, composite oxides of composition formula LiNi 0.29 Mn 0.3 Co 0.4 Mg 0.01 O 2 were used. Battery 1 has a negative electrode coating amount of 3.05 mg / cm 2 and a coating amount ratio of 0.38. Battery 2 has a negative electrode coating amount of 3.05 mg / cm 2 and a coating amount ratio of 0.38. Battery 3 has a negative electrode coating amount of 3.25 mg / cm 2 and a coating amount ratio of 0.41, and Battery 4 has a negative electrode coating amount of 3.05 mg / cm 2 and a coating amount ratio of 0.38. Then, the coating amount of the negative electrode was 2.90 mg / cm 2 and the coating amount ratio was 0.36.

（比較例１）
表１に示すように、比較例１では、正極活物質に組成比の異なる複合酸化物を用い、塗着量比を変える以外は実施例１と同様にして、比較電池１〜比較電池４の４種類のリチウムイオン電池を作製した。正極活物質として、比較電池１では初充電容量１９８ｍＡｈ／ｇ、組成式ＬｉＮｉ０．８Ｃｏ０．１５Ａｌ０．０５Ｏ２の複合酸化物、比較電池２では初充電容量１７３ｍＡｈ／ｇ、の組成式ＬｉＭｎＯ２の複合酸化物、比較電池３では初充電容量１６０ｍＡｈ／ｇ、組成式ＬｉＣｏＯ２の複合酸化物をそれぞれ用いた。また、比較電池１では負極の塗着量を３．６０ｍｇ／ｃｍ２、塗着量比０．４５、比較電池２では負極の塗着量を３．０５ｍｇ／ｃｍ２、塗着量比０．３８、比較電池３では負極の塗着量を２．８０ｍｇ／ｃｍ２、塗着量比０．３５とした。比較電池４では、正極活物質に初充電容量１１０ｍＡｈ／ｇ、組成式ＬｉＭｎ１．９５Ａｌ０．０５Ｏ４の複合酸化物を用い、負極の塗着量を２．２５ｍｇ／ｃｍ２、塗着量比０．３９とした。 (Comparative Example 1)
As shown in Table 1, in Comparative Example 1, the comparative batteries 1 to 4 were compared in the same manner as in Example 1 except that composite oxides having different composition ratios were used for the positive electrode active material and the coating amount ratio was changed. Four types of lithium ion batteries were produced. As the positive electrode active material, the comparative battery 1 had an initial charge capacity of 198 mAh / g, a composite oxide of composition formula LiNi 0.8 Co 0.15 Al 0.05 O 2 , and the comparative battery 2 had an initial charge capacity of 173 mAh / g. In the composite oxide of the formula LiMnO 2 and the comparative battery 3, an initial charge capacity of 160 mAh / g and a composite oxide of the composition formula LiCoO 2 were used. In Comparative Battery 1, the negative electrode coating amount was 3.60 mg / cm 2 and the coating amount ratio was 0.45. In Comparative Battery 2, the negative electrode coating amount was 3.05 mg / cm 2 and the coating amount ratio was 0.00. In Comparative Battery 3, the coating amount of the negative electrode was 2.80 mg / cm 2 and the coating amount ratio was 0.35. In Comparative Battery 4, a composite oxide having an initial charge capacity of 110 mAh / g and a composition formula of LiMn 1.95 Al 0.05 O 4 was used as the positive electrode active material, and the negative electrode coating amount was 2.25 mg / cm 2 . The quantity ratio was 0.39.

（実施例２）
下表２に示すように、実施例２では、正極合剤の塗着量を変える以外は実施例１の電池１と同様にして電池６〜電池７を作製した。正極合剤の塗着量は、電池６では１１．０ｍｇ／ｃｍ２、電池７では１４．５ｍｇ／ｃｍ２とした。また、負極合剤の塗着量は、塗着量比０．３８となるように、電池６では４．２ｍｇ／ｃｍ２、電池７では５．３５ｍｇ／ｃｍ２とした。なお、下表２には、実施例１の電池１についても併記した。 (Example 2)
As shown in Table 2 below, in Example 2, batteries 6 to 7 were produced in the same manner as the battery 1 of Example 1 except that the amount of the positive electrode mixture applied was changed. The coating amount of positive electrode mixture, 11.0 mg / cm 2 in the battery 6, and the the battery 7 14.5mg / cm 2. Further, the coating amount of the negative electrode mixture, so that the the coating amount ratio 0.38, 4.2 mg / cm 2 in the battery 6, and the the battery 7 5.35mg / cm 2. In Table 2, the battery 1 of Example 1 is also shown.

（比較例２）
表２に示すように、比較例２では、正極合剤の塗着量を変える以外は実施例１の電池１と同様にして比較電池５〜比較電池６を作製した。正極合剤の塗着量は、比較電池５では６．５ｍｇ／ｃｍ２、比較電池６では１８．０ｍｇ／ｃｍ２とした。また、負極合剤の塗着量は、塗着量比０．３８となるように、比較電池５では２．５ｍｇ／ｃｍ２、比較電池６では６．９ｍｇ／ｃｍ２とした。 (Comparative Example 2)
As shown in Table 2, in Comparative Example 2, Comparative Battery 5 to Comparative Battery 6 were produced in the same manner as Battery 1 of Example 1 except that the amount of positive electrode mixture applied was changed. The coating amount of positive electrode mixture, comparative battery 5, 6.5 mg / cm 2, was 18.0 mg / cm 2 in Comparative cell 6. Further, the coating amount of the negative electrode mixture, so that the the coating amount ratio 0.38, comparative battery 5, 2.5 mg / cm 2, was 6.9 mg / cm 2 in Comparative cell 6.

（実施例３）
下表３に示すように、実施例３では、容量比及び塗着量比を変える以外は実施例２の電池７と同様にして電池８〜電池９を作製した。電池８では容量比０．９６、塗着量比０．３３とし、電池９では容量比０．８０、塗着量比０．２７とした。負極合剤の塗着量は、電池８では４．６５ｍｇ／ｃｍ２、電池９では３．３５ｍｇ／ｃｍ２とした。なお、下表３には、実施例２の電池７についても併記した。 (Example 3)
As shown in Table 3 below, in Example 3, batteries 8 to 9 were produced in the same manner as the battery 7 of Example 2, except that the capacity ratio and the coating amount ratio were changed. Battery 8 had a capacity ratio of 0.96 and a coating amount ratio of 0.33, and Battery 9 had a capacity ratio of 0.80 and a coating amount ratio of 0.27. The coating amount of the negative electrode mixture, 4.65mg / cm 2 in the battery 8, and the 3.35 mg / cm 2 in the battery 9. In Table 3, the battery 7 of Example 2 is also shown.

（比較例３）
表３に示すように、比較例３では、容量比及び塗着量比を変える以外は実施例２の電池７と同様にして比較電池７〜比較電池８を作製した。比較電池７では容量比０．７０、塗着量比０．２４とし、比較電池８では容量比１．２５、塗着量比０．４３とした。負極合剤の塗着量は、比較電池７では３．９ｍｇ／ｃｍ２、比較電池８では６．０５ｍｇ／ｃｍ２とした。 (Comparative Example 3)
As shown in Table 3, in Comparative Example 3, Comparative Battery 7 to Comparative Battery 8 were produced in the same manner as Battery 7 of Example 2 except that the capacity ratio and the coating amount ratio were changed. Comparative battery 7 had a capacity ratio of 0.70 and a coating amount ratio of 0.24, and comparative battery 8 had a capacity ratio of 1.25 and a coating amount ratio of 0.43. The coating amount of the negative electrode mixture, 3.9 mg / cm 2 in Comparative cell 7, was 6.05mg / cm 2 in Comparative cell 8.

（電池抵抗の測定）
作製した各実施例の各電池及び各比較例の各電池を室温にて充電と放電とを３回繰り返した。充電条件は、０．３３Ｃ相当の充電電流値、上限電圧４．１Ｖで４時間の定電流定電圧充電とし、放電条件は、０．３３Ｃ相当の放電電流値、下限電圧２．７Ｖの定電流放電とした。次いで、室温にて０．３３Ｃ相当の電流値、上限電圧４．１Ｖで４時間の定電流定電圧充電を行った。充電した電池を電流線、電圧線が挿入されている低温槽内に移して結線した後、低温槽内を−３０°Ｃとして６時間経過後に電池抵抗の測定を開始した。まず、放電前の開回路電圧Ｖ０を測定した後、放電電流Ｉ＝３．５Ａで５秒間放電を行い、放電５秒目の電圧Ｖ５を測定した。両者の差（Ｖ０−Ｖ５）を求めて電圧降下ΔＶとし、電圧降下ΔＶと放電電流Ｉとの商（ΔＶ／Ｉ）を算出して−３０°Ｃでの電池抵抗とした。下表４に各電池の−３０°Ｃでの電池抵抗の測定結果を示す。 (Measurement of battery resistance)
Charging and discharging were repeated three times at room temperature for each battery of each of the produced examples and each of the comparative examples. The charging condition is a constant current constant voltage charge for 4 hours at a charge current value equivalent to 0.33 C and an upper limit voltage of 4.1 V, and the discharge condition is a constant current of a discharge current value equivalent to 0.33 C and a lower limit voltage of 2.7 V Discharged. Subsequently, constant current constant voltage charging was performed at room temperature for 4 hours at a current value corresponding to 0.33 C and an upper limit voltage of 4.1 V. After the charged battery was transferred into a low-temperature bath in which current lines and voltage lines were inserted and connected, the temperature of the low-temperature bath was set to −30 ° C. and measurement of battery resistance was started after 6 hours. First, after measuring the open circuit voltage V0 before discharge, discharge was performed at a discharge current I = 3.5A for 5 seconds, and the voltage V5 at the discharge 5 seconds was measured. The difference (V0−V5) between the two was obtained and used as the voltage drop ΔV, and the quotient (ΔV / I) between the voltage drop ΔV and the discharge current I was calculated to obtain the battery resistance at −30 ° C. Table 4 below shows the measurement results of the battery resistance of each battery at −30 ° C.

表４に示すように、−３０°Ｃでの電池抵抗は、正極活物質を上述した組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される複合酸化物以外とした比較例１の比較電池１では２０６ｍΩ、比較電池２では２４８ｍΩ、比較電池３では２０３ｍΩ、比較電池４では２２５ｍΩとなった。これに対して、上述した組成式で表される複合酸化物を用いた実施例１の電池１では１６７ｍΩ、電池２では１５７ｍΩ、電池３では１７１ｍΩ、電池４では１７７ｍΩ、電池５では１７６ｍΩとなり電池抵抗が低下した。比較電池１では塗着量比を０．４５としたことから、正極合剤の塗着量を８．０〜１４．５ｍｇ／ｃｍ２の範囲、容量比を０．８０〜１．１１の範囲としても、正極活物質が上述した組成式で表される以外の複合酸化物、塗着量比が０．２７〜０．４１の範囲以外では、−３０°Ｃでの電池抵抗が増大することが判明した。 As shown in Table 4, the battery resistance at −30 ° C. is the composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1, 0.25 ≦ X ≦ 0.55, 0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1) The comparative battery 1 of Comparative Example 1 was 206 mΩ, the comparative battery 2 was 248 mΩ, the comparative battery 3 was 203 mΩ, and the comparative battery 4 was 225 mΩ. In contrast, in the battery 1 of Example 1 using the composite oxide represented by the above-described composition formula, the battery resistance is 167 mΩ, the battery 2 is 157 mΩ, the battery 3 is 171 mΩ, the battery 4 is 177 mΩ, and the battery 5 is 176 mΩ. Decreased. In Comparative Battery 1, since the coating amount ratio was 0.45, the coating amount of the positive electrode mixture was in the range of 8.0 to 14.5 mg / cm 2 and the capacity ratio was in the range of 0.80 to 1.11. However, when the positive electrode active material is a composite oxide other than that represented by the composition formula described above and the coating amount ratio is outside the range of 0.27 to 0.41, the battery resistance at −30 ° C. increases. There was found.

また、正極合剤の塗着量を６．５ｍｇ／ｃｍ２とした比較例２の比較電池５では、電池抵抗が２０８ｍΩとなり、塗着量を１８．０ｍｇ／ｃｍ２とした比較電池６では、電池抵抗が２１４ｍΩとなった。これに対して、正極合剤の塗着量をそれぞれ１１．０、１４．５ｍｇ／ｃｍ２とした実施例２の電池６及び電池７では、電池抵抗がそれぞれ１７２ｍΩ、１８８ｍΩと低下した。このことから、上述した実施例１の電池１の結果を合わせると、正極活物質に上述した組成式で表される複合酸化物を用い、塗着量比及び容量比を上述した範囲としても、正極合剤の塗着量が上述した範囲以外では、−３０°Ｃでの電池抵抗が増大することが判明した。 Further, in Comparative Battery 5 of Comparative Example 2 in which the coating amount of the positive electrode mixture was 6.5 mg / cm 2 , the battery resistance was 208 mΩ, and in Comparative Battery 6 in which the coating amount was 18.0 mg / cm 2 , The battery resistance was 214 mΩ. On the other hand, in the battery 6 and the battery 7 of Example 2 in which the coating amount of the positive electrode mixture was 11.0 and 14.5 mg / cm 2 , the battery resistances decreased to 172 mΩ and 188 mΩ, respectively. From this, when the results of the battery 1 of Example 1 described above are combined, the composite oxide represented by the composition formula described above is used as the positive electrode active material, and the coating amount ratio and the capacity ratio are within the above-described ranges. It was found that the battery resistance at −30 ° C. increased when the coating amount of the positive electrode mixture was outside the range described above.

更に、容量比０．７０、塗着量比０．２４とした比較例３の比較電池７では、電池抵抗が１９６ｍΩとなり、容量比１．２５、塗着量比０．４３とした比較電池８では、電池抵抗が１９４ｍΩとなった。これに対して、容量比をそれぞれ０．９６、０．８０とし、塗着量比をそれぞれ０．３３、０．２７とした実施例３の電池８及び電池９では、電池抵抗がそれぞれ１８２ｍΩ、１８８ｍΩと低下した。このことから、上述した実施例１の電池３及び実施例２の電池７の結果を合わせると、正極活物質に上述した組成式で表される複合酸化物を用い、正極合剤の塗着量を上述した範囲としても、容量比及び塗着量比が上述した範囲以外では、−３０°Ｃでの電池抵抗が増大することが判明した。   Further, in the comparative battery 7 of Comparative Example 3 having a capacity ratio of 0.70 and a coating amount ratio of 0.24, the battery resistance was 196 mΩ, and the comparative battery 8 having a capacity ratio of 1.25 and a coating amount ratio of 0.43. Then, the battery resistance was 194 mΩ. On the other hand, in the battery 8 and the battery 9 of Example 3 in which the capacity ratio was 0.96 and 0.80 and the coating amount ratio was 0.33 and 0.27, respectively, the battery resistance was 182 mΩ, It decreased to 188 mΩ. Therefore, when the results of the battery 3 of Example 1 and the battery 7 of Example 2 are combined, the composite oxide represented by the composition formula described above is used for the positive electrode active material, and the coating amount of the positive electrode mixture Even in the above-described range, it was found that the battery resistance at −30 ° C. increased when the capacity ratio and the coating amount ratio were outside the ranges described above.

以上のことから、正極活物質に組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される複合酸化物を用い、正極合剤の塗着量を８．０〜１４．５ｍｇ／ｃｍ２の範囲、容量比を０．８０〜１．１１の範囲、塗着量比を０．２７〜０．４１の範囲とすることで、−３０°Ｃの極低温環境下でも電池抵抗が低減することが明らかとなった。 From the above, the positive electrode active material in the composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55, 0.25 ≦ Y ≦ 0.55, 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), and the coating amount of the positive electrode mixture is 8.0 to 8.0 By setting the range of 14.5 mg / cm 2 , the volume ratio in the range of 0.80 to 1.11, and the coating amount ratio in the range of 0.27 to 0.41, But it became clear that battery resistance was reduced.

なお、本実施形態では、正極活物質の複合酸化物の原料として、リチウム化合物の炭酸リチウム、ニッケル化合物の炭酸ニッケル、マンガン化合物の二酸化マンガン、コバルト化合物の炭酸コバルト、及び、Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉの元素を含む炭酸塩を例示したが、本発明はこれらに制限されるものではない。例えば、水酸化リチウムや酸化リチウム等のリチウム化合物、炭酸マンガンや硝酸マンガン等のマンガン化合物、及び、ニッケル、コバルトの酸化物、弗化物、炭酸塩、硝酸塩、水酸化物等を用いてもよく、組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される複合酸化物を調製可能な原料であればよい。また、本実施形態では、複合酸化物が層状結晶構造を有する例を示したが、本発明は層状岩塩型結晶構造の複合酸化物にも適用可能である。 In the present embodiment, as a raw material of the composite oxide of the positive electrode active material, lithium compound lithium carbonate, nickel compound nickel carbonate, manganese compound manganese dioxide, cobalt compound cobalt carbonate, and Fe, Cr, Cu, Although carbonates containing Al, Mg, and Si elements are exemplified, the present invention is not limited to these. For example, lithium compounds such as lithium hydroxide and lithium oxide, manganese compounds such as manganese carbonate and manganese nitrate, and nickel, cobalt oxides, fluorides, carbonates, nitrates, hydroxides, etc. may be used. composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55,0.25 ≦ Y ≦ 0.55 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1) as long as it is a raw material capable of preparing a composite oxide. In this embodiment, an example in which the composite oxide has a layered crystal structure has been shown. However, the present invention can also be applied to a composite oxide having a layered rock salt crystal structure.

また、本実施形態では、負極活物質として非晶質炭素を例示したが、本発明はこれに限定されるものではなく、非晶質炭素以外に、例えば、黒鉛系の炭素材を用いてもよい。非晶質炭素及び黒鉛系の炭素材を混合して用いることもできるが、主として非晶質炭素を使用すれば、黒鉛系の炭素材が層状の結晶構造のため、極低温環境下で結晶構造の収縮を引き起こすのに対して、非晶質炭素の構造が極低温環境下でも安定であり好ましい。   In this embodiment, amorphous carbon is exemplified as the negative electrode active material. However, the present invention is not limited to this, and for example, a graphite-based carbon material may be used in addition to amorphous carbon. Good. Amorphous carbon and graphite-based carbon materials can be used as a mixture, but if amorphous carbon is mainly used, the graphite-based carbon material has a layered crystal structure, so that the crystal structure can be obtained in a cryogenic environment. In contrast, the amorphous carbon structure is preferable because it is stable even in a cryogenic environment.

更に、本実施形態では、非水電解液として、ＥＣ、ＤＭＣ、ＤＥＣの体積比１：１：１の混合溶媒にリチウム塩として１モル／リットルのＬｉＰＦ６を溶解させて使用する例を示したが、本発明はこれに限定されるものではない。有機溶媒としては、通常リチウムイオン二次電池に使用可能な有機溶媒を使用することができる。特に、直鎖状又は環状のカーボネート類を主成分とすれば、カーボネート類が高誘電率を有するため、リチウムイオンの解離性を向上させることができる。本実施形態以外のカーボネート類としては、例えば、プロピレンカーボネート、ブチレンカーボネート、メチルエチルカーボネート等が挙げられる。これらを単独又は混合して用いてもよく、更にエステル類、エーテル類等を混合することもできる。本実施形態以外のリチウム塩としては、ＬｉＣｌＯ４、ＬｉＣＦ３ＳＯ３、ＬｉＢＦ４、ＬｉＡｓＦ６等を挙げることができ、これらを単独又は混合して用いることができる。 Furthermore, in the present embodiment, an example in which 1 mol / liter LiPF 6 as a lithium salt is dissolved in a mixed solvent having a volume ratio of 1: 1: 1 of EC, DMC, and DEC as the non-aqueous electrolyte is shown. However, the present invention is not limited to this. As an organic solvent, the organic solvent which can be normally used for a lithium ion secondary battery can be used. In particular, when a linear or cyclic carbonate is used as a main component, since the carbonate has a high dielectric constant, the dissociation property of lithium ions can be improved. Examples of carbonates other than the present embodiment include propylene carbonate, butylene carbonate, methyl ethyl carbonate, and the like. These may be used alone or in combination, and esters, ethers and the like may be further mixed. The lithium salt other than the present embodiment, LiClO 4, LiCF 3 SO 3 , LiBF 4, can be cited LiAsF 6 or the like, can be used alone or in combination.

また更に、本実施形態では、正極及び負極を捲回した電極群を用いた円筒型リチウムイオン二次電池２０を例示したが、本発明は、電池の形状、大きさ等に制限されるものではなく、角形等の形状としてもよい。角形電池を作製するには、正極及び負極を、角形のセンターピンを中心として捲回して捲回群を作製した後、円筒状の電池缶１４に代えて、ＳＵＳ製やアルミニウム製の角形の電池容器に作製した捲回群を収容し非水電解液を注液後、電池缶を密封すればよい。また、捲回群の代わりに、正極及び負極をセパレータを介して順に積層した積層体を用いることもできる。   Furthermore, in the present embodiment, the cylindrical lithium ion secondary battery 20 using the electrode group in which the positive electrode and the negative electrode are wound is illustrated, but the present invention is not limited to the shape, size, etc. of the battery. Alternatively, the shape may be a square or the like. In order to manufacture a prismatic battery, a positive electrode and a negative electrode are wound around a square center pin to form a wound group, and then a SUS or aluminum prismatic battery is used instead of the cylindrical battery can 14. What is necessary is just to seal the battery can after accommodating the wound group produced in the container and injecting a non-aqueous electrolyte. Moreover, the laminated body which laminated | stacked the positive electrode and the negative electrode in order through the separator instead of a winding group can also be used.

更にまた、本実施形態では、導電剤として鱗片状黒鉛及びアセチレンブラックを例示したが、本発明はこれに限定されるものではなく、黒鉛系又は非晶質系の炭素粉末を用いてもよい。更に、正極合剤への導電剤の混合割合は、重量比にして正極活物質の８〜２５％とすることが好ましい。   Furthermore, in this embodiment, scaly graphite and acetylene black are exemplified as the conductive agent, but the present invention is not limited to this, and graphite-based or amorphous carbon powder may be used. Furthermore, the mixing ratio of the conductive agent to the positive electrode mixture is preferably 8 to 25% of the positive electrode active material in weight ratio.

また、本実施形態では、ポリプロピレン製のセパレータを例示したが、本発明はこれに限定されるものではなく、例えば、ポリエチレン等のポリオレフィン樹脂製の多孔質フィルムを用いてもよく、複数の多孔質フィルムを積層した積層体を用いてもよい。   In the present embodiment, a polypropylene separator is exemplified, but the present invention is not limited to this, and for example, a porous film made of polyolefin resin such as polyethylene may be used, and a plurality of porous films may be used. You may use the laminated body which laminated | stacked the film.

本発明に係るリチウムイオン二次電池によれば、極低温環境下でも電池抵抗を抑制して高出力性能を確保可能なため、製造、販売に寄与し、産業上利用することができる。   According to the lithium ion secondary battery according to the present invention, since the battery resistance can be suppressed and high output performance can be ensured even in a cryogenic environment, it contributes to manufacturing and sales and can be used industrially.

本発明が適用可能な実施形態のリチウムイオン二次電池に使用する正極活物質及び負極活物質の初充電容量の測定に用いる電気化学セルの断面図である。It is sectional drawing of the electrochemical cell used for the measurement of the initial charge capacity of the positive electrode active material and negative electrode active material which are used for the lithium ion secondary battery of embodiment which can apply this invention. 実施形態の円筒型リチウムイオン二次電池の断面図である。It is sectional drawing of the cylindrical lithium ion secondary battery of embodiment.

符号の説明Explanation of symbols

１１ 正極
１２ 負極
２０ 円筒型リチウムイオン二次電池（リチウムイオン二次電池） 11 Positive electrode 12 Negative electrode 20 Cylindrical lithium ion secondary battery (lithium ion secondary battery)

Claims (5)

正極活物質を含む正極合剤が塗着された正極及び負極活物質を含む負極合剤が塗着された負極を非水電解液に浸潤させたリチウムイオン二次電池において、前記正極活物質が組成式ＬｉＮｉＸＭｎＹＣｏＺＭαＯ２（Ｍ：Ｆｅ、Ｃｒ、Ｃｕ、Ａｌ、Ｍｇ、Ｓｉ、Ｘ＋Ｙ＋Ｚ＋α＝１、０．２５≦Ｘ≦０．５５、０．２５≦Ｙ≦０．５５、０．１５≦Ｚ≦０．４、０≦α≦０．１）で表される六方晶系の層状結晶構造の複合酸化物であり、前記正極合剤の塗着量が８．０ｍｇ／ｃｍ２以上１４．５ｍｇ／ｃｍ２以下であることを特徴とするリチウムイオン二次電池。 In a lithium ion secondary battery in which a positive electrode coated with a positive electrode mixture containing a positive electrode active material and a negative electrode coated with a negative electrode mixture containing a negative electrode active material are infiltrated into a non-aqueous electrolyte, the positive electrode active material is composition formula LiNi X Mn Y Co Z M α O 2 (M: Fe, Cr, Cu, Al, Mg, Si, X + Y + Z + α = 1,0.25 ≦ X ≦ 0.55,0.25 ≦ Y ≦ 0.55 , 0.15 ≦ Z ≦ 0.4, 0 ≦ α ≦ 0.1), a composite oxide having a layered crystal structure of a hexagonal system, and the coating amount of the positive electrode mixture is 8.0 mg / A lithium ion secondary battery characterized by having a density of cm 2 or more and 14.5 mg / cm 2 or less. 前記負極活物質が、主として非晶質炭素であることを特徴とする請求項１に記載のリチウムイオン二次電池。   The lithium ion secondary battery according to claim 1, wherein the negative electrode active material is mainly amorphous carbon. 前記正極の初充電容量に対する前記負極の初充電容量の比が、０．８０以上１．１１以下であることを特徴とする請求項１又は請求項２に記載のリチウムイオン二次電池。   3. The lithium ion secondary battery according to claim 1, wherein a ratio of an initial charge capacity of the negative electrode to an initial charge capacity of the positive electrode is 0.80 or more and 1.11 or less. 前記正極合剤の塗着量に対する前記負極合剤の塗着量の割合が、０．２７以上０．４１以下であることを特徴とする請求項１乃至請求項３のいずれか１項に記載のリチウムイオン二次電池。   4. The ratio of the coating amount of the negative electrode mixture to the coating amount of the positive electrode mixture is 0.27 or more and 0.41 or less. 5. Lithium ion secondary battery. 前記非水電解液を構成する溶媒が、環状又は直鎖状のカーボネート類を主成分とすることを特徴とする請求項１乃至請求項４のいずれか１項に記載のリチウムイオン二次電池。   The lithium ion secondary battery according to any one of claims 1 to 4, wherein a solvent constituting the non-aqueous electrolyte contains a cyclic or linear carbonate as a main component.
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WO2006054604A1 (en) * 2004-11-19 2006-05-26 Matsushita Electric Industrial Co., Ltd. Nonaqueous electrolyte secondary battery
JP2007134218A (en) * 2005-11-11 2007-05-31 Kansai Electric Power Co Inc:The Nonaqueous electrolyte secondary battery
JP2008091041A (en) * 2006-09-29 2008-04-17 Sanyo Electric Co Ltd Nonaqueous secondary battery
JP2009266708A (en) * 2008-04-28 2009-11-12 Hitachi Vehicle Energy Ltd Lithium secondary battery
JP2010251189A (en) * 2009-04-17 2010-11-04 Gs Yuasa Corp Active material for lithium secondary battery, electrode for lithium secondary battery, and lithium secondary battery
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JP2011192404A (en) * 2010-03-11 2011-09-29 Toyota Central R&D Labs Inc Anode active material for nonaqueous secondary battery, nonaqueous secondary battery and using method
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US9184447B2 (en) 2011-05-23 2015-11-10 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high power density
US9263737B2 (en) 2011-05-23 2016-02-16 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high power density
US9385372B2 (en) 2011-05-23 2016-07-05 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high energy density
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WO2006054604A1 (en) * 2004-11-19 2006-05-26 Matsushita Electric Industrial Co., Ltd. Nonaqueous electrolyte secondary battery
JP2007134218A (en) * 2005-11-11 2007-05-31 Kansai Electric Power Co Inc:The Nonaqueous electrolyte secondary battery
JP2008091041A (en) * 2006-09-29 2008-04-17 Sanyo Electric Co Ltd Nonaqueous secondary battery
JP2009266708A (en) * 2008-04-28 2009-11-12 Hitachi Vehicle Energy Ltd Lithium secondary battery
JP2010251189A (en) * 2009-04-17 2010-11-04 Gs Yuasa Corp Active material for lithium secondary battery, electrode for lithium secondary battery, and lithium secondary battery
JP2011192404A (en) * 2010-03-11 2011-09-29 Toyota Central R&D Labs Inc Anode active material for nonaqueous secondary battery, nonaqueous secondary battery and using method
WO2011114534A1 (en) * 2010-03-19 2011-09-22 トヨタ自動車株式会社 Lithium secondary battery and cathode active material for said lithium secondary battery
CN102804459A (en) * 2010-03-19 2012-11-28 丰田自动车株式会社 Lithium secondary battery and cathode active material for said lithium secondary battery
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JPWO2011114534A1 (en) * 2010-03-19 2013-06-27 トヨタ自動車株式会社 Lithium secondary battery and positive electrode active material for lithium secondary battery
CN104701525A (en) * 2010-03-19 2015-06-10 丰田自动车株式会社 Lithium secondary battery and positive electrode active substance for lithium secondary battery
JP5574195B2 (en) * 2010-03-19 2014-08-20 トヨタ自動車株式会社 Lithium secondary battery and positive electrode active material for lithium secondary battery
US9985278B2 (en) 2011-05-23 2018-05-29 Lg Chem, Ltd. Lithium secondary battery of high energy density with improved energy property
JP2017027947A (en) * 2011-05-23 2017-02-02 エルジー ケム． エルティーディ． High output lithium secondary battery with enhanced output density characteristics
US9184447B2 (en) 2011-05-23 2015-11-10 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high power density
US9203081B2 (en) 2011-05-23 2015-12-01 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high power density
US9263737B2 (en) 2011-05-23 2016-02-16 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high power density
US9385372B2 (en) 2011-05-23 2016-07-05 Lg Chem, Ltd. Lithium secondary battery of high power property with improved high energy density
WO2012161474A3 (en) * 2011-05-23 2013-01-17 주식회사 엘지화학 High-power lithium secondary battery having improved output density properties
US9601756B2 (en) 2011-05-23 2017-03-21 Lg Chem, Ltd. Lithium secondary battery of high energy density with improved energy property
EP2720302A4 (en) * 2011-07-13 2014-11-26 Lg Chemical Ltd High-energy lithium secondary battery having improved energy density characteristics
US9525167B2 (en) 2011-07-13 2016-12-20 Lg Chem, Ltd. Lithium secondary battery of high energy with improved energy property
JP2016213205A (en) * 2011-07-13 2016-12-15 エルジー・ケム・リミテッド High-energy lithium secondary battery improved in energy density characteristic
EP2720302A2 (en) * 2011-07-13 2014-04-16 LG Chem, Ltd. High-energy lithium secondary battery having improved energy density characteristics
CN110676514A (en) * 2018-07-03 2020-01-10 国家能源投资集团有限责任公司 Lithium ion battery monomer and formation method thereof
WO2021010085A1 (en) * 2019-07-12 2021-01-21 株式会社村田製作所 Secondary battery
JPWO2021010085A1 (en) * 2019-07-12 2021-01-21

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