JP4211542B2 - Lithium secondary battery - Google Patents

Lithium secondary battery Download PDF

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JP4211542B2
JP4211542B2 JP2003314537A JP2003314537A JP4211542B2 JP 4211542 B2 JP4211542 B2 JP 4211542B2 JP 2003314537 A JP2003314537 A JP 2003314537A JP 2003314537 A JP2003314537 A JP 2003314537A JP 4211542 B2 JP4211542 B2 JP 4211542B2
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transition metal
negative electrode
battery
lithium
aqueous electrolyte
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JP2005085545A (en
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陽心 八木
敏和 前島
健介 弘中
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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
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Description

本発明はリチウム二次電池に係り、特に、正極活物質に層状結晶構造を有するリチウム遷移金属複酸化物を用いた正極と、負極活物質に黒鉛質炭素を用いた負極と、をセパレータを介して配置し非水電解液に浸潤させたリチウム二次電池に関する。   The present invention relates to a lithium secondary battery, and in particular, a positive electrode using a lithium transition metal double oxide having a layered crystal structure as a positive electrode active material and a negative electrode using graphitic carbon as a negative electrode active material via a separator. The present invention relates to a lithium secondary battery arranged and infiltrated with a non-aqueous electrolyte.

従来、リチウム二次電池は、高エネルギー密度であるメリットを活かして、主にＶＴＲカメラやノートパソコン、携帯電話等のポータブル機器の電源に使用されている。一般的な円筒型リチウム二次電池の寸法は、直径１８ｍｍ、高さ６５ｍｍであり、１８６５０型と呼ばれ小形民生用リチウムイオン電池として広く普及している。１８６５０型リチウム二次電池では、正極活物質に高容量、長寿命を特徴とするコバルト酸リチウム、負極活物質に炭素材料がそれぞれ主として用いられており、電池容量はおおむね１．３Ａｈ〜１．７Ａｈ、出力はおよそ１０Ｗ程度である。   Conventionally, lithium secondary batteries have been used mainly as power sources for portable devices such as VTR cameras, notebook computers, and mobile phones, taking advantage of the high energy density. A general cylindrical lithium secondary battery has a diameter of 18 mm and a height of 65 mm, which is called 18650 type, and is widely used as a small-sized consumer lithium ion battery. In the 18650 type lithium secondary battery, a lithium cobaltate characterized by high capacity and long life is mainly used for the positive electrode active material, and a carbon material is mainly used for the negative electrode active material, and the battery capacity is approximately 1.3 Ah to 1.7 Ah. The output is about 10W.

リチウム二次電池の内部構造は、通常以下のような捲回式とされている。正負極はそれぞれ活物質が金属箔に塗着された帯状であり、セパレータを挟んで正負極が直接接触しないように断面渦巻状に捲回され、捲回群を形成している。この捲回群が円筒状の電池容器に収容され、非水電解液注液後、封口されている。そして、初充電によりリチウムイオンを負極に吸蔵させることで電池機能が付与される。   The internal structure of a lithium secondary battery is usually a winding type as follows. Each of the positive and negative electrodes is in the form of a band in which an active material is applied to a metal foil, and is wound in a cross-sectional spiral shape so that the positive and negative electrodes are not in direct contact across the separator, thereby forming a wound group. The wound group is accommodated in a cylindrical battery container and sealed after the non-aqueous electrolyte solution is injected. And a battery function is provided by making lithium ion occlude in a negative electrode by first charge.

一方、自動車産業界においては環境問題に対応すべく、排出ガスのない、動力源を電池のみにした電気自動車、内燃機関エンジンと電池との両方を動力源とするハイブリッド（電気）自動車が開発され、一部は実用化されている。リチウム二次電池を電気自動車用電源として用いるには、高容量だけではなく、加速性能などを左右する高出力化、つまり内部抵抗の低減や、電気自動車の長期使用に対応すべく長寿命化も求められる。ここでいう長寿命化は、容量、出力の低下を抑制し、電気自動車を走行させるに必要な電気エネルギー供給能力を長期に亘って満足することである。   On the other hand, in the automobile industry, in order to cope with environmental problems, electric vehicles without exhaust gas and using only a power source as a power source, and hybrid (electric) vehicles using both an internal combustion engine and a battery as a power source have been developed. Some have been put to practical use. In order to use lithium secondary batteries as power sources for electric vehicles, not only high capacity, but also high output that affects acceleration performance, etc., that is, reduction of internal resistance, and long life to support long-term use of electric vehicles Desired. The extension of the life here means that the decrease in capacity and output is suppressed and the electric energy supply capability necessary for running the electric vehicle is satisfied over a long period of time.

リチウム二次電池では、充電により非水電解液が負極活物質の炭素材料と接触することで還元され分解されるため、負極表面に局部的な被膜が形成される。この被膜は非水電解液と炭素材料との接触を妨げるため、被膜表面では非水電解液が分解しにくくなる。また、この被膜はリチウムイオンが通過可能ではあるが、被膜形成後非水電解液中に遷移金属イオンが含まれていると、充放電サイクルに伴い負極表面で非水電解液が分解され被膜の膜厚が増加しリチウムイオンの移動を阻害するので、容量や出力の低下を招く。   In the lithium secondary battery, the nonaqueous electrolyte solution is reduced and decomposed by contact with the carbon material of the negative electrode active material by charging, so that a local film is formed on the negative electrode surface. Since this coating prevents contact between the non-aqueous electrolyte and the carbon material, the non-aqueous electrolyte is difficult to decompose on the coating surface. In addition, lithium ion can pass through this coating, but if the transition metal ions are contained in the nonaqueous electrolyte after the coating is formed, the nonaqueous electrolyte is decomposed on the negative electrode surface along with the charge / discharge cycle, and the coating Since the film thickness increases and the movement of lithium ions is hindered, the capacity and output are reduced.

また、被膜形成後非水電解液中に遷移金属イオンが含まれていると、充放電サイクルに伴い負極で樹枝状に析出しセパレータを貫通させて正負極を短絡させるため、容量や出力を低下させ寿命の劣化を招く。これを解決するために、例えば、非水電解液中に混入する金属元素を排除する技術が開示されている（特許文献１参照）。   In addition, if transition metal ions are included in the non-aqueous electrolyte after film formation, the capacity and output are reduced because the negative electrode is dendriticly deposited on the negative electrode during the charge / discharge cycle and penetrates the separator to short-circuit the positive and negative electrodes. Cause life deterioration. In order to solve this, for example, a technique for eliminating metal elements mixed in a non-aqueous electrolyte is disclosed (see Patent Document 1).

特開２００２−７５４６０号公報JP 2002-75460 A

しかしながら、上述した特許文献１の技術では、非水電解液中に混入する金属元素が排除されるため、樹枝状の析出は抑制されるが、充放電サイクルに伴う非水電解液の分解及び負極表面に形成された被膜の膜厚の増加を抑制することは難しい。従って、リチウム二次電池の充電により、充放電サイクルに伴う非水電解液の分解を抑制可能、かつ、リチウムイオンの通過可能な被膜を負極表面に形成させることができれば、容量や出力の低下を抑制すると共に、寿命の劣化を抑制することが期待できる。   However, in the technique of Patent Document 1 described above, metal elements mixed in the non-aqueous electrolyte are excluded, so that dendritic precipitation is suppressed, but decomposition of the non-aqueous electrolyte and the negative electrode accompanying the charge / discharge cycle are suppressed. It is difficult to suppress an increase in the thickness of the film formed on the surface. Therefore, if charging of the lithium secondary battery can suppress the decomposition of the non-aqueous electrolyte accompanying the charge / discharge cycle and a film capable of passing lithium ions can be formed on the negative electrode surface, the capacity and output are reduced. It is possible to suppress the deterioration of the lifetime as well as the suppression.

本発明は上記事案に鑑み、充放電サイクルに伴う容量や出力の維持率の低下を抑制でき、長寿命のリチウム二次電池を提供することを課題とする。   In view of the above-described case, an object of the present invention is to provide a long-life lithium secondary battery that can suppress a decrease in capacity and output retention rate associated with a charge / discharge cycle.

上記課題を解決するために、本発明は、正極活物質に層状結晶構造を有するリチウム遷移金属複酸化物を用いた正極と、負極活物質に黒鉛質炭素を用いた負極と、をセパレータを介して配置し非水電解液に浸潤させたリチウム二次電池において、初充電完了前に、前記非水電解液に含有された遷移金属イオンの濃度をＡｐｐｍ、前記負極の電極面積をＢｍ２としたときに、前記電極面積に対する前記遷移金属イオンの存在量Ａ／Ｂの範囲が１３５乃至２７０であり、かつ、前記遷移金属イオンの濃度Ａが１００ｐｐｍ乃至２００ｐｐｍであることを特徴とする。 In order to solve the above problems, the present invention provides a positive electrode using a lithium transition metal double oxide having a layered crystal structure as a positive electrode active material and a negative electrode using graphitic carbon as a negative electrode active material via a separator. In the lithium secondary battery placed and infiltrated with the non-aqueous electrolyte, the concentration of transition metal ions contained in the non-aqueous electrolyte was set to Appm and the electrode area of the negative electrode was set to Bm 2 before the first charge was completed. Occasionally, Ri range 135 to 270 der abundance a / B of the transition metal ion relative to the electrode area, and the concentration a of the transition metal ions, wherein the 100ppm to 200ppm der Rukoto.

本発明では、リチウム二次電池を初充電すると、遷移金属イオンが負極表面で還元され遷移金属の析出が起こる。析出した遷移金属が非水電解液の分解を促進する触媒作用を発揮して非水電解液を分解するため、負極表面に安定な被膜を形成する。非水電解液に含有された遷移金属イオンの濃度をＡｐｐｍ、負極の電極面積をＢｍ２としたときに、電極面積に対する遷移金属イオンの存在量Ａ／Ｂが１３５に満たないと、析出する遷移金属量が不十分なため安定な被膜が形成されないため、充放電サイクルに伴い非水電解液が分解され被膜が成長する。逆に、遷移金属イオンの存在量Ａ／Ｂが２７０を超えると、初充電では負極表面に遷移金属が析出しきれず、充放電サイクルに伴い遷移金属析出が継続され、局部的に被膜が成長して（リチウムイオンが通過可能な安定な被膜の維持ができず）容量や出力の低下が起こる。遷移金属イオンの濃度Ａが２００ｐｐｍを超えると、遷移金属が樹枝状に析出するため、セパレータを貫通させて正負極間に微小短絡を引き起こし電圧低下を招き、遷移金属イオンの濃度Ａが１００ｐｐｍに満たないと、充放電サイクルに伴い容量や出力の低下が起こる。 In the present invention, when a lithium secondary battery is initially charged, transition metal ions are reduced on the negative electrode surface, and transition metal is deposited. Since the deposited transition metal exhibits a catalytic action that promotes the decomposition of the nonaqueous electrolyte solution and decomposes the nonaqueous electrolyte solution, a stable coating is formed on the negative electrode surface. When the concentration of transition metal ions contained in the non-aqueous electrolyte is Appm and the electrode area of the negative electrode is Bm 2 , the transition metal ions are deposited if the amount A / B of the transition metal ions with respect to the electrode area is less than 135. Since the amount of metal is insufficient, a stable coating cannot be formed, and the non-aqueous electrolyte is decomposed and the coating grows with the charge / discharge cycle. Conversely, if the transition metal ion abundance A / B exceeds 270 , the transition metal cannot be deposited on the negative electrode surface during the initial charge, and the transition metal deposition continues with the charge / discharge cycle, and the film grows locally. (Stable coating that allows lithium ions to pass through cannot be maintained), resulting in a decrease in capacity and output. When the transition metal ion concentration A exceeds 200 ppm, the transition metal precipitates in a dendritic shape, causing a minute short-circuit between the positive and negative electrodes through the separator, resulting in a voltage drop, and the transition metal ion concentration A reaching 100 ppm. Otherwise, the capacity and output decrease with the charge / discharge cycle.

本発明によれば、負極の電極面積Ｂに対する遷移金属イオンの存在量Ａ／Ｂの範囲を１３５乃至２７０とし、かつ、遷移金属イオンの濃度Ａを１００ｐｐｍ乃至２００ｐｐｍとしたので、初充電により、遷移金属イオンが負極表面に遷移金属として析出すると共に、析出した遷移金属が負極表面に安定な被膜を形成・維持するため、非水電解液と黒鉛質炭素及び析出した遷移金属との接触が抑制され、充放電サイクルに伴う非水電解液の分解及び被膜の成長が起こりにくくなるので、容量や出力の低下を抑制でき寿命を向上させることができる。 According to the present invention, the range of the transition metal ion abundance A / B with respect to the electrode area B of the negative electrode is 135 to 270 , and the transition metal ion concentration A is 100 ppm to 200 ppm. Metal ions are deposited as transition metals on the negative electrode surface, and the deposited transition metals form and maintain a stable coating on the negative electrode surface, which prevents contact between the non-aqueous electrolyte and graphitic carbon and the deposited transition metal. Since the decomposition of the non-aqueous electrolyte and the growth of the coating are less likely to occur during the charge / discharge cycle, the capacity and output can be prevented from decreasing and the life can be improved.

この場合において、初充電完了前に非水電解液に含有された遷移金属イオンは、初充電完了後に、実質的に全て負極の表面に遷移金属として析出していることが好ましい。 In this case, it is preferable that substantially all transition metal ions contained in the non-aqueous electrolyte before completion of the initial charge are deposited as transition metals on the surface of the negative electrode after the completion of the initial charge.

本発明によれば、負極の電極面積Ｂに対する遷移金属イオンの存在量Ａ／Ｂの範囲を１３５乃至２７０とし、かつ、遷移金属イオンの濃度Ａを１００ｐｐｍ乃至２００ｐｐｍとしたので、初充電により、遷移金属イオンが負極表面に遷移金属として析出すると共に、析出した遷移金属が負極表面に安定な被膜を形成・維持するため、非水電解液と黒鉛質炭素及び析出した遷移金属との接触が抑制され、充放電サイクルに伴う非水電解液の分解及び被膜の成長が起こりにくくなるので、容量や出力の低下を抑制でき寿命を向上させることができる、という効果を得ることができる。 According to the present invention, the range of the transition metal ion abundance A / B with respect to the electrode area B of the negative electrode is 135 to 270 , and the transition metal ion concentration A is 100 ppm to 200 ppm. Metal ions are deposited as transition metals on the negative electrode surface, and the deposited transition metals form and maintain a stable coating on the negative electrode surface, which prevents contact between the non-aqueous electrolyte and graphitic carbon and the deposited transition metal. Since the decomposition of the non-aqueous electrolyte and the growth of the coating are less likely to occur during the charge / discharge cycle, it is possible to obtain an effect that the decrease in capacity and output can be suppressed and the life can be improved.

以下、図面を参照して、本発明をハイブリッド電気自動車用電源に用いられる円筒型リチウムイオン電池に適用した実施の形態について説明する。   Hereinafter, an embodiment in which the present invention is applied to a cylindrical lithium ion battery used for a power source for a hybrid electric vehicle will be described with reference to the drawings.

（正極板）
図１に示すように、正極活物質として層状結晶構造を有するリチウム遷移金属複酸化物であるコバルト酸リチウム（ＬｉＣｏＯ２）粉末と、導電材の黒鉛粉末及びアセチレンブラックと、バインダ（結着剤）のポリフッ化ビニリデン（以下、ＰＶＤＦという。）と、を質量比８５：９：２：４で混合し、これに分散溶媒のＮ−メチル−２−ピロリドン（以下、ＮＭＰという。）を添加、混練したスラリを、厚さ２０μｍのアルミニウム箔Ｗ１（正極集電体）の両面に塗布した。このとき、正極板長寸方向の一方の側縁に幅３０ｍｍの未塗布部を残した。その後乾燥、プレス、裁断して幅８２ｍｍ、長さ４１７ｃｍ、活物質合剤塗布部Ｗ２厚さ８３μｍの正極板を得た。正極活物質合剤層Ｗ２のかさ密度は２．６５ｇ／ｃｍ３とした。側縁に残した未塗布部に切り欠きを入れ、切り欠き残部を正極リード片２とした。隣り合う正極リード片２を５０ｍｍ間隔とし、正極リード片２の幅を５ｍｍとした。 (Positive electrode plate)
As shown in FIG. 1, lithium cobalt oxide (LiCoO 2 ) powder, which is a lithium transition metal double oxide having a layered crystal structure as a positive electrode active material, graphite powder and acetylene black as a conductive material, and a binder (binder) Of polyvinylidene fluoride (hereinafter referred to as PVDF) at a mass ratio of 85: 9: 2: 4, and N-methyl-2-pyrrolidone (hereinafter referred to as NMP) as a dispersion solvent was added thereto and kneaded. The slurry was applied to both sides of an aluminum foil W1 (positive electrode current collector) having a thickness of 20 μm. At this time, an uncoated portion with a width of 30 mm was left on one side edge in the longitudinal direction of the positive electrode plate. Thereafter, drying, pressing, and cutting were performed to obtain a positive electrode plate having a width of 82 mm, a length of 417 cm, and an active material mixture application part W2 thickness of 83 μm. The bulk density of the positive electrode active material mixture layer W2 was 2.65 g / cm 3 . A notch was left in the uncoated portion left on the side edge, and the remaining notch was used as the positive electrode lead piece 2. Adjacent positive electrode lead pieces 2 were spaced 50 mm apart, and the width of the positive electrode lead pieces 2 was 5 mm.

（負極板）
負極活物質として黒鉛粉末と、導電材としてアセチレンブラック粉末と、バインダのＰＶＤＦと、を質量比８８：５：７で混合し、更に分散溶媒のＮＭＰを添加、混練してスラリを得た。得られたスラリを厚さ１０μｍの圧延銅箔Ｗ３（負極集電体）の両面に塗布した。このとき、負極板長寸方向の一方の側縁に幅３０ｍｍの未塗布部を残した。その後乾燥、プレス、裁断して幅８６ｍｍ、長さ４２９ｃｍ、活物質合剤塗布部Ｗ４厚さの７９μｍ負極板を得た。負極活物質合剤層Ｗ４のかさ密度は１．００ｇ／ｃｍ３とした。側縁に残した未塗布部に正極板と同様に切り欠きを入れ、切り欠き残部を負極リード片３とした。隣り合う負極リード片３を５０ｍｍ間隔とし、負極リード片３の幅を５ｍｍとした。得られた負極板の電極面積Ｂは両面で、８６ｍｍ×４２９ｃｍ×２＝０．７４ｍ２となる。 (Negative electrode plate)
Graphite powder as a negative electrode active material, acetylene black powder as a conductive material, and PVDF as a binder were mixed at a mass ratio of 88: 5: 7, and NMP as a dispersion solvent was further added and kneaded to obtain a slurry. The obtained slurry was applied to both surfaces of a rolled copper foil W3 (negative electrode current collector) having a thickness of 10 μm. At this time, an uncoated portion having a width of 30 mm was left on one side edge in the longitudinal direction of the negative electrode plate. Thereafter, drying, pressing, and cutting were performed to obtain a 79 μm negative electrode plate having a width of 86 mm, a length of 429 cm, and an active material mixture coating portion W4 thickness. The bulk density of the negative electrode active material mixture layer W4 was 1.00 g / cm 3 . A notch was formed in the uncoated part left on the side edge in the same manner as the positive electrode plate, and the remaining part of the notch was used as the negative electrode lead piece 3. Adjacent negative electrode lead pieces 3 were spaced 50 mm apart, and the width of the negative electrode lead pieces 3 was 5 mm. Electrode area B of the obtained negative electrode plate a double-sided, the 86mm × 429cm × 2 = 0.74m 2 .

（電池組立）
作製した正極板と負極板とを、これら両極板が直接接触しないように幅９０ｍｍ、厚さ４０μｍのポリエチレン製セパレータＷ５と共に捲回した。捲回の中心には、ポリプロピレン製の中空円筒状の軸芯１を用いた。このとき、正極リード片２と負極リード片３とが、それぞれ捲回群６の互いに反対側の両端面に位置するようにした。 (Battery assembly)
The produced positive electrode plate and negative electrode plate were wound together with a polyethylene separator W5 having a width of 90 mm and a thickness of 40 μm so that the two electrode plates were not in direct contact with each other. A hollow cylindrical shaft core 1 made of polypropylene was used at the center of winding. At this time, the positive electrode lead piece 2 and the negative electrode lead piece 3 were respectively positioned on opposite end surfaces of the wound group 6.

正極リード片２を変形させ、その全てを、捲回群６の軸芯１のほぼ延長線上にある正極集電リング４の周囲から一体に張り出した鍔部周面付近に集合、接触させた後、正極リード片２と鍔部周面とを超音波溶接して正極リード片２を鍔部周面に接続した。一方、負極集電リング５と負極リード片３との接続操作も、正極集電リング４と正極リード片２との接続操作と同様に実施した。   After the positive electrode lead piece 2 is deformed, all of the positive electrode lead pieces 2 are gathered and brought into contact with the vicinity of the collar peripheral surface integrally projecting from the periphery of the positive electrode current collecting ring 4 substantially on the extension line of the axis 1 of the winding group 6 The positive electrode lead piece 2 and the flange peripheral surface were ultrasonically welded to connect the positive electrode lead piece 2 to the flange peripheral surface. On the other hand, the connection operation between the negative electrode current collection ring 5 and the negative electrode lead piece 3 was performed in the same manner as the connection operation between the positive electrode current collection ring 4 and the positive electrode lead piece 2.

その後、正極集電リング４の鍔部周面全周に絶縁被覆を施した。この絶縁被覆には、基材がポリイミドで、その片面にヘキサメタアクリレートからなる粘着剤を塗布した粘着テープを用いた。この粘着テープを鍔部周面から捲回群６外周面に亘って一重以上巻いて絶縁被覆とし、捲回群６を電池容器７内に挿入した。電池容器７には、ニッケルメッキが施されたスチール製の容器を用いた。   Thereafter, an insulation coating was applied to the entire circumference of the collar peripheral surface of the positive electrode current collecting ring 4. For this insulation coating, an adhesive tape in which the base material was polyimide and an adhesive made of hexamethacrylate was applied on one side thereof was used. One or more layers of this adhesive tape were wound from the circumferential surface of the collar portion to the outer circumferential surface of the wound group 6 to form an insulating coating, and the wound group 6 was inserted into the battery container 7. As the battery container 7, a steel container plated with nickel was used.

負極集電リング５には予め電気的導通のための負極リード板８を溶接しておき、電池容器７に捲回群６を挿入後、電池容器７の底部と負極リード板８とを溶接した。一方、正極集電リング４には、予め複数枚のアルミニウム製のリボンを重ね合わせて構成した正極リード９を溶接しておき、正極リード９の他端を、電池容器７を封口するための電池蓋の下面に溶接した。電池蓋には、円筒型リチウムイオン電池２０の内圧上昇に応じて開裂する内圧開放機構としての開裂弁１１が設けられている。開裂弁１１の開裂圧は、約９×１０５Ｐａに設定した。電池蓋は、蓋ケース１２と、蓋キャップ１３と、気密を保つ弁押え１４と、開裂弁１１とで構成されており、これらが積層されて蓋ケース１２の周縁をカシメることによって組立てられている。 A negative electrode lead plate 8 for electrical conduction is welded to the negative electrode current collecting ring 5 in advance, and after the winding group 6 is inserted into the battery container 7, the bottom of the battery container 7 and the negative electrode lead plate 8 are welded. . On the other hand, the positive electrode current collecting ring 4 is welded with a positive electrode lead 9 formed by previously superposing a plurality of aluminum ribbons, and a battery for sealing the battery container 7 at the other end of the positive electrode lead 9. Welded to the bottom of the lid. The battery lid is provided with a cleavage valve 11 as an internal pressure release mechanism that cleaves in accordance with an increase in internal pressure of the cylindrical lithium ion battery 20. The cleavage pressure of the cleavage valve 11 was set to about 9 × 10 5 Pa. The battery lid is composed of a lid case 12, a lid cap 13, an airtight valve presser 14, and a cleavage valve 11. The battery lid is laminated and assembled by crimping the periphery of the lid case 12. Yes.

電池容器７内に非水電解液を注液し、その後、正極リード９を折りたたむようにして電池蓋で電池容器７に蓋をし、ＥＰＤＭ樹脂製ガスケット１０を介してカシメて密封することにより円筒型リチウムイオン電池２０を完成させた。   A nonaqueous electrolyte solution is injected into the battery container 7, and then the battery container 7 is covered with a battery cover so that the positive electrode lead 9 is folded, and crimped and sealed through an EPDM resin gasket 10 to form a cylinder. Type lithium ion battery 20 was completed.

非水電解液は次のように調製した。エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）とジエチルカーボネート（ＤＥＣ）とを体積比１：１：１の割合で混合した混合溶媒中へ６フッ化リン酸リチウム（ＬｉＰＦ６）を１モル／リットルとなるように溶解させた。更に、遷移金属の６フッ化リン酸塩である、６フッ化リン酸マンガン、６フッ化リン酸コバルト又は６フッ化リン酸ニッケルを溶解させた。遷移金属の６フッ化リン酸塩の添加量は、非水電解液中の遷移金属イオンの濃度Ａが８０〜５２０ｐｐｍとなるようにした。これにより、上述したように負極の電極面積Ｂが０．７４ｍ２であることから、負極の電極面積Ｂに対する遷移金属イオンの存在量Ａ／Ｂは１０８〜７００となる。 The non-aqueous electrolyte was prepared as follows. 1 mol / liter of lithium hexafluorophosphate (LiPF 6 ) in a mixed solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1: 1. It was made to melt | dissolve. Further, transition metal hexafluorophosphate, manganese hexafluorophosphate, cobalt hexafluorophosphate or nickel hexafluorophosphate, was dissolved. The amount of transition metal hexafluorophosphate added was such that the concentration A of transition metal ions in the non-aqueous electrolyte was 80 to 520 ppm. Thereby, since the electrode area B of the negative electrode is 0.74 m 2 as described above, the transition metal ion abundance A / B with respect to the electrode area B of the negative electrode is 108 to 700.

次に、本実施形態に従って作製した円筒型リチウムイオン電池２０の実施例について説明する。なお、以下に説明する実施例のうち、実施例１、実施例５、実施例６は参考として示したものである。また、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, examples of the cylindrical lithium ion battery 20 manufactured according to the present embodiment will be described. Of the examples described below, Example 1, Example 5, and Example 6 are shown for reference. In addition, a comparative example battery manufactured for comparison is also shown.

（実施例１）
下表１に示すように、実施例１では、遷移金属をマンガン（Ｍｎ）とし、非水電解液に６フッ化リン酸マンガンを溶解した。非水電解液中のマンガンイオン濃度Ａは８０ｐｐｍとした。このとき、負極の電極面積Ｂ（０．７４ｍ２）に対するマンガンイオンの存在量Ａ／Ｂは１０８である。なお、表１において、Ｍｎはマンガンを、Ｃｏはコバルトを、Ｎｉはニッケルをそれぞれ示している。 Example 1
As shown in Table 1 below, in Example 1, manganese (Mn) was used as the transition metal, and manganese hexafluorophosphate was dissolved in the non-aqueous electrolyte. The manganese ion concentration A in the non-aqueous electrolyte was 80 ppm. At this time, the abundance A / B of manganese ions with respect to the electrode area B (0.74 m 2 ) of the negative electrode is 108. In Table 1, Mn represents manganese, Co represents cobalt, and Ni represents nickel.

（実施例２〜実施例６）
表１に示すように、実施例２〜実施例６では、マンガンイオンの濃度Ａを変更する以外は実施例１と同様にした。実施例２では１００ｐｐｍ、実施例３では１５０ｐｐｍ、実施例４では２００ｐｐｍ、実施例５では２５０ｐｐｍ、実施例６では５２０ｐｐｍとした。このとき、存在量Ａ／Ｂは、実施例２では１３５、実施例３では２０２、実施例４では２７０、実施例５では３３８、実施例６では７００である。 (Example 2 to Example 6)
As shown in Table 1, Example 2 to Example 6 were the same as Example 1 except that the manganese ion concentration A was changed. Example 2 was 100 ppm, Example 3 was 150 ppm, Example 4 was 200 ppm, Example 5 was 250 ppm, and Example 6 was 520 ppm. At this time, the abundance A / B is 135 in the second embodiment, 202 in the third embodiment, 270 in the fourth embodiment, 338 in the fifth embodiment, and 700 in the sixth embodiment.

（実施例７〜実施例８）
表１に示すように、実施例７〜実施例８では、遷移金属を変更する以外は実施例３と同様にした。実施例７では、遷移金属をコバルト（Ｃｏ）とし、６フッ化リン酸コバルトを溶解し、実施例８では、遷移金属をニッケル（Ｎｉ）とし、６フッ化リン酸ニッケルを溶解した。 (Example 7 to Example 8)
As shown in Table 1, Examples 7 to 8 were the same as Example 3 except that the transition metal was changed. In Example 7, the transition metal was cobalt (Co) and cobalt hexafluorophosphate was dissolved, and in Example 8, the transition metal was nickel (Ni) and nickel hexafluorophosphate was dissolved.

（比較例１）
表１に示すように、比較例１では、遷移金属の６フッ化リン酸塩を添加しないこと以外は実施例１と同様にした。 (Comparative Example 1)
As shown in Table 1, Comparative Example 1 was the same as Example 1 except that no transition metal hexafluorophosphate was added.

＜試験・評価＞
次に、作製した実施例及び比較例の各電池について、次の条件で初期化した後、以下の一連の試験を行った。
（１）４．１Ｖ定電圧充電、制限電流５．５Ａ、２．５時間、２５°Ｃ
（２）２Ａ定電流放電、終止電圧２．７Ｖ、２５°Ｃ
（３）４．１Ｖ定電圧、制限電流５．５Ａ、２．５時間、２５°Ｃ
（４）２Ａ定電流放電、終止電圧２．７Ｖ、２５°Ｃ
（５）３．７Ｖ定電圧、制限電流５．５Ａ、２．５時間、２５°Ｃ <Test and evaluation>
Next, for each of the batteries of the produced examples and comparative examples, the following series of tests were performed after initialization under the following conditions.
(1) 4.1V constant voltage charge, limit current 5.5A, 2.5 hours, 25 ° C
(2) 2A constant current discharge, final voltage 2.7V, 25 ° C
(3) 4.1V constant voltage, limiting current 5.5A, 2.5 hours, 25 ° C
(4) 2A constant current discharge, final voltage 2.7V, 25 ° C
(5) 3.7V constant voltage, limiting current 5.5A, 2.5 hours, 25 ° C

初期化した後、２２．５±２．５°Ｃの温度雰囲気下に各電池を２１日間放置した。このとき、放置１４日目から２１日目までに低下した電圧を７で除算し、一日あたりの電圧低下率（ｍＶ／ｄａｙ）を算出した。   After initialization, each battery was left in a temperature atmosphere of 22.5 ± 2.5 ° C. for 21 days. At this time, the voltage dropped from the 14th day to the 21st day was divided by 7 to calculate the voltage drop rate (mV / day) per day.

次に各電池を充電した後放電し、環境温度２５±２°Ｃの雰囲気下において、初期放電容量を測定した。充電条件は、４．１Ｖ定電圧、制限電流５．５Ａ、２．５時間とし、放電条件は、２Ａ定電流、終止電圧２．７Ｖとした。   Next, each battery was charged and then discharged, and the initial discharge capacity was measured in an atmosphere having an environmental temperature of 25 ± 2 ° C. The charging conditions were 4.1V constant voltage, limiting current 5.5A, 2.5 hours, and the discharging conditions were 2A constant current, final voltage 2.7V.

また、各電池を上述した充電条件で充電（満充電状態）した後、環境温度２５±２°Ｃの雰囲気下において、初期出力を測定した。測定条件は１０Ａ、３０Ａ、９０Ａの電流値で各１０秒間放電し、横軸電流に対して、各５秒目の電池電圧値を縦軸にプロットし、３点を直線近似した直線が終止電圧である２．７Ｖと交差する点の電流値を読み取り、この電流値と２．７Ｖとの積をその電池の出力とした。   Moreover, after each battery was charged under the above-described charging conditions (fully charged state), the initial output was measured in an atmosphere having an environmental temperature of 25 ± 2 ° C. Measurement conditions were 10A, 30A, and 90A current values for 10 seconds each, and the horizontal axis current was plotted on the vertical axis for the 5th second battery voltage value. The current value at the point where the voltage intersects with 2.7V was read, and the product of this current value and 2.7V was used as the output of the battery.

パルスサイクル試験は、５０±３°Ｃの雰囲気下において各電池に約５０Ａの高負荷電流を充電方向及び放電方向ともに約５秒通電し、休止時間も含め１サイクル約３０秒のパルスサイクル試験を連続して１０万回繰り返した。   In the pulse cycle test, a high load current of about 50 A was applied to each battery for about 5 seconds in both the charge and discharge directions in an atmosphere of 50 ± 3 ° C, and a pulse cycle test of about 30 seconds per cycle including the rest period was performed. Repeated 100,000 times continuously.

パルスサイクル試験後の放電容量及び出力を上述した方法と同様にして測定した。初期放電容量に対するパルスサイクル試験後の放電容量の割合を百分率で求め、容量維持率とし、初期出力に対するパルスサイクル試験後の出力の割合を百分率で求め、出力維持率とした。実施例及び比較例の電池の電圧低下率、容量維持率及び出力維持率の試験結果を下表２に示す。   The discharge capacity and output after the pulse cycle test were measured in the same manner as described above. The ratio of the discharge capacity after the pulse cycle test with respect to the initial discharge capacity was obtained as a percentage to obtain the capacity maintenance ratio, and the ratio of the output after the pulse cycle test with respect to the initial output was obtained as a percentage to obtain the output maintenance ratio. Table 2 below shows the test results of the voltage drop rate, capacity retention rate, and output retention rate of the batteries of Examples and Comparative Examples.

表２に示すように、非水電解液に遷移金属イオンを含有させていない比較例１の電池は出力維持率が８０．５％となり、十分な性能を得ることができなかった。これに対して、非水電解液に遷移金属イオンを含有させた実施例１〜実施例８の各電池は、出力維持率がいずれも８２．０％以上の高い結果を示した。マンガンイオンを含有させた実施例１〜実施例６の各電池では、出力維持率が８２．０〜９１．２％であった。また、マンガンイオンに代えて、コバルトイオンを含有させた実施例７の電池では出力維持率が９１．５％を示し、ニッケルイオンを含有させた実施例８の電池では出力維持率が９１．７％を示した。従って、実施例１〜実施例８の各電池は、長寿命の電池であった。   As shown in Table 2, the battery of Comparative Example 1 in which the transition metal ion was not contained in the nonaqueous electrolytic solution had an output maintenance ratio of 80.5%, and sufficient performance could not be obtained. In contrast, each of the batteries of Examples 1 to 8 in which transition metal ions were included in the non-aqueous electrolyte showed a high output maintenance ratio of 82.0% or more. In each battery of Examples 1 to 6 containing manganese ions, the output retention rate was 82.0 to 91.2%. In addition, in the battery of Example 7 containing cobalt ions instead of manganese ions, the output maintenance rate was 91.5%, and in the battery of Example 8 containing nickel ions, the output maintenance rate was 91.7%. %showed that. Therefore, the batteries of Examples 1 to 8 were long-life batteries.

また、負極の電極面積に対する遷移金属イオンの存在量Ａ／Ｂが１３５より小さい実施例１の電池は、出力維持率は良好だったものの、容量維持率が８８．５％と若干低い値となった。また、存在量Ａ／Ｂが２７０より大きい実施例５及び実施例６の電池は、容量維持率がそれぞれ８８．１％及び８４．０％と若干低い値となった。これに対して、存在量Ａ／Ｂを１３５〜２７０の範囲とした実施例２〜実施例４の各電池は、出力維持率が９０．１〜９１．２％、容量維持率が９３．１〜９５．２％の優れた電池であった。   In addition, the battery of Example 1 having a transition metal ion abundance A / B smaller than 135 with respect to the electrode area of the negative electrode had a good output maintenance ratio, but the capacity maintenance ratio was a slightly low value of 88.5%. It was. Further, the batteries of Example 5 and Example 6 in which the abundance A / B is greater than 270 have capacity retention rates of 88.1% and 84.0%, which are slightly low values, respectively. On the other hand, each battery of Examples 2 to 4 having the abundance A / B in the range of 135 to 270 has an output maintenance ratio of 90.1 to 91.2% and a capacity maintenance ratio of 93.1. It was an excellent battery of ˜95.2%.

更に、遷移金属イオンの非水電解液中の濃度Ａを５２０ｐｐｍとした実施例６の電池は、電圧低下率が５．３ｍＶ／ｄａｙと他の実施例の電池に比べて大きくなった。これに対して、遷移金属イオンの濃度Ａを５２０ｐｐｍ未満とした実施例１〜実施例５及び実施例７〜実施例８の各電池は、２．０〜２．１ｍＶ／ｄａｙの電圧低下率であった。   Further, the battery of Example 6 in which the transition metal ion concentration A in the non-aqueous electrolyte was 520 ppm was 5.3 mV / day, which was larger than the batteries of the other examples. In contrast, each of the batteries of Examples 1 to 5 and Examples 7 to 8 having a transition metal ion concentration A of less than 520 ppm had a voltage drop rate of 2.0 to 2.1 mV / day. there were.

本実施形態の円筒型リチウムイオン電池２０では、非水電解液に遷移金属イオンが含有される。遷移金属イオンは、初充電により負極表面で還元され遷移金属として実質的に全て析出する。析出した遷移金属は非水電解液の分解を促進する触媒作用を発揮し非水電解液を分解するため、負極表面に被膜が形成される。この被膜は、充放電を繰り返しても分解、溶解することなく充放電に対して安定である。また、この被膜はリチウムイオンが通過可能であり充放電を阻害せず、負極活物質の黒鉛炭素及び充電により析出した遷移金属を被覆して、非水電解液との接触を抑制する。このため、充放電サイクルに伴う非水電解液の分解が抑制され、被膜の成長が起こりにくくなるので、容量、出力の低下を抑制して電池寿命を向上させることができる。   In the cylindrical lithium ion battery 20 of the present embodiment, transition metal ions are contained in the nonaqueous electrolytic solution. The transition metal ions are reduced on the negative electrode surface by the initial charge, and substantially all of the transition metal ions are deposited. The deposited transition metal exhibits a catalytic action that promotes the decomposition of the non-aqueous electrolyte and decomposes the non-aqueous electrolyte, so that a coating is formed on the negative electrode surface. This coating is stable against charge and discharge without being decomposed or dissolved even after repeated charge and discharge. Further, this coating allows lithium ions to pass therethrough and does not inhibit charging / discharging, and covers the negative electrode active material graphite carbon and a transition metal deposited by charging, thereby suppressing contact with the non-aqueous electrolyte. For this reason, since decomposition | disassembly of the nonaqueous electrolyte accompanying a charging / discharging cycle is suppressed and the growth of a film becomes difficult to occur, the fall of a capacity | capacitance and an output can be suppressed and battery life can be improved.

また、負極の電極面積Ｂｍ２に対する非水電解液に含有された遷移金属イオンの濃度Ａｐｐｍ（遷移金属イオンの存在量Ａ／Ｂ）が１０８に満たないと、析出する遷移金属量が不十分となり、安定な被膜が形成されず、負極表面で非水電解液が分解されるため、充放電の繰り返しに伴い被膜が成長し、容量維持率が低下する。逆に存在量Ａ／Ｂが７００を超えると、非水電解液に含有された遷移金属イオンが初充電で析出しきれず、充放電を繰り返す度に遷移金属の析出が起こるため、この遷移金属の触媒作用により被膜が成長し続け、容量維持率が低下する。従って、負極の電極面積に対する遷移金属イオンの存在量Ａ／Ｂは１０８〜７００とすることが好ましく、１３５〜２７０とすることがより好ましい。また、初充電完了後に、遷移金属イオンが遷移金属として負極表面に析出してしまい非水電解液に残存しないので、その後の充放電による遷移金属の析出を防止することができる。 Further, if the concentration Appm of transition metal ions (abundance of transition metal ions A / B) contained in the non-aqueous electrolyte with respect to the electrode area Bm 2 of the negative electrode is less than 108, the amount of transition metal deposited becomes insufficient. Since a stable coating is not formed and the nonaqueous electrolyte is decomposed on the negative electrode surface, the coating grows with repeated charge and discharge, and the capacity retention rate decreases. Conversely, if the abundance A / B exceeds 700, transition metal ions contained in the non-aqueous electrolyte cannot be deposited by the initial charge, and transition metal deposition occurs every time charging and discharging are repeated. The film continues to grow due to the catalytic action, and the capacity retention rate decreases. Accordingly, the transition metal ion abundance A / B with respect to the electrode area of the negative electrode is preferably 108 to 700, more preferably 135 to 270. In addition, after completion of the initial charge, transition metal ions are deposited on the surface of the negative electrode as a transition metal and do not remain in the non-aqueous electrolyte, so that it is possible to prevent the transition metal from being deposited due to subsequent charge and discharge.

更に、遷移金属イオンの非水電解液中の濃度が５２０ｐｐｍ以上では、遷移金属が樹枝状に析出することから、セパレータを貫通させて短絡を引き起こすため、電圧低下率を増加させてしまう。遷移金属イオンの非水電解液中の濃度を５２０ｐｐｍ未満とすることで、樹枝状の析出が減少するので、電圧低下率を低減して長寿命の電池を実現することができる。   Furthermore, when the concentration of the transition metal ion in the non-aqueous electrolyte is 520 ppm or more, the transition metal precipitates in a dendritic shape, causing a short circuit by penetrating the separator, thereby increasing the voltage drop rate. By setting the concentration of the transition metal ions in the non-aqueous electrolyte to be less than 520 ppm, dendritic precipitation is reduced, so that the voltage drop rate can be reduced and a long-life battery can be realized.

また、本実施形態では、正極活物質に層状結晶構造のリチウム遷移金属複酸化物が用いられる。層状結晶構造は、酸素層間にリチウム単独の二次元拡散層を有しているためリチウムの拡散係数が小さい。このため、リチウムの挿入、脱離が容易となり内部抵抗が低減するので、高出力のリチウム二次電池を得ることができる。更に、本実施形態では、負極活物質に黒鉛が用いられる。黒鉛は層状の結晶構造を有しており、リチウムの挿入、脱離が容易となるため、高出力のリチウム二次電池を得ることができる。   In this embodiment, a lithium transition metal double oxide having a layered crystal structure is used as the positive electrode active material. The layered crystal structure has a small lithium diffusion coefficient because it has a lithium two-dimensional diffusion layer between oxygen layers. For this reason, since insertion and extraction of lithium are facilitated and the internal resistance is reduced, a high-power lithium secondary battery can be obtained. Furthermore, in this embodiment, graphite is used for the negative electrode active material. Since graphite has a layered crystal structure and lithium can be easily inserted and removed, a high-power lithium secondary battery can be obtained.

なお、本実施形態では、非水電解液中へ添加する遷移金属イオンにＭｎ、Ｃｏ、Ｎｉのイオンを例示したが、本発明はこれらに限定されるものではなく、これら以外の遷移金属元素、例えば、銅（Ｃｕ）、銀（Ａｇ）、クロム（Ｃｒ）、鉄（Ｆｅ）等のイオンを用いてもよい。また、非水電解液に添加する物質として遷移金属の６フッ化リン酸塩を例に挙げたが、過塩素酸塩、６フッ化ヒ酸塩、４フッ化ホウ酸塩、４フェニルホウ酸塩、メチルスルホン酸塩、３フッ化メチルスルホン酸塩等やこれらの混合物を用いることもできる。   In the present embodiment, the transition metal ions added to the non-aqueous electrolyte are exemplified by Mn, Co, and Ni ions, but the present invention is not limited to these, and other transition metal elements, For example, ions such as copper (Cu), silver (Ag), chromium (Cr), and iron (Fe) may be used. Moreover, although the transition metal hexafluorophosphate was cited as an example of the substance to be added to the non-aqueous electrolyte, perchlorate, hexafluoroarsenate, tetrafluoroborate, and 4-phenylborate , Methyl sulfonate, trifluoromethyl sulfonate, and the like, and mixtures thereof can also be used.

また、本実施形態では、正極活物質にコバルト酸リチウムを用いた例を示したが、本発明のリチウム二次電池用正極活物質としては、リチウムイオンを挿入・脱離可能な材料であり、予め十分な量のリチウムイオンを挿入した層状結晶構造を有するリチウム遷移金属複酸化物であればよく、マンガン酸リチウム（ＬｉＭｎＯ２）、ニッケル酸リチウム（ＬｉＮｉＯ２）等でも同様の効果を得ることができる。更に、これらのリチウム遷移金属複酸化物結晶中の遷移金属やリチウムの一部をそれら以外の元素、例えば、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｒ、Ａ１、Ｍｇ、等の元素で置換あるいはドープした材料や結晶中の酸素の一部をＳ、Ｐ等の元素で置換あるいはドープした材料を使用するようにしてもよい。更には、電池電圧として５Ｖ級が可能なリチウムマンガン複酸化物を用いても、本発明の効果には変わりない。 Further, in the present embodiment, an example in which lithium cobaltate is used as the positive electrode active material is shown, but the positive electrode active material for a lithium secondary battery of the present invention is a material that can insert and desorb lithium ions, Any lithium transition metal double oxide having a layered crystal structure in which a sufficient amount of lithium ions has been inserted in advance may be used, and the same effect can be obtained with lithium manganate (LiMnO 2 ), lithium nickelate (LiNiO 2 ), or the like. it can. Furthermore, a material obtained by substituting or doping a part of the transition metal or lithium in these lithium transition metal double oxide crystals with an element other than those elements, for example, Fe, Co, Ni, Cr, A1, Mg, etc. A material in which a part of oxygen in the crystal is substituted or doped with an element such as S or P may be used. Furthermore, the effect of the present invention does not change even if a lithium manganese double oxide capable of 5V class as the battery voltage is used.

更に、本実施形態では、負極活物質に黒鉛を用いた例を示したが、本発明はこれに限定されるものではなく、黒鉛質炭素であればよい。ここでいう黒鉛質炭素は、必ずしも高結晶性の黒鉛を示すのではなく、メソフェーズ系黒鉛のような、Ｘ線回折による層間距離ｄ００２が０.３３５４ｎｍを超える黒鉛でもよい。また、Ｘ線回折で、ｈｋｌ指数付けが可能な回折線が現れるものでもよい。更に、粒子形状においても、鱗片状、球状、繊維状、塊状等、特に制限されるものではない。 Furthermore, in this embodiment, although the example which used graphite for the negative electrode active material was shown, this invention is not limited to this, What is necessary is just graphite carbon. The graphitic carbon here does not necessarily indicate highly crystalline graphite, but may be graphite such as mesophase-type graphite in which the interlayer distance d 002 by X-ray diffraction exceeds 0.3354 nm. In addition, diffraction lines that can be indexed by hkl may appear by X-ray diffraction. Further, the particle shape is not particularly limited, such as a scale shape, a spherical shape, a fiber shape, or a lump shape.

また更に、本実施形態では、エチレンカーボネート、ジメチルカーボネート、ジエチルカーボネートを体積比１：１：１で混合した混合溶媒にＬｉＰＦ６を溶解した非水電解液を例示したが、一般的なリチウム塩を電解質とし、これを有機溶媒に溶解した非水電解液を用いてもよく、本発明は用いられるリチウム塩や有機溶媒には特に制限されない。例えば、電解質としては、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＢ（Ｃ６Ｈ５）４、ＣＨ３ＳＯ３Ｌｉ、ＣＦ３ＳＯ３Ｌｉ等やこれらの混合物を用いることができる。また、有機溶媒としては、プロピレンカーボネート、１，２−ジメトキシエタン、１，２−ジエトキシエタン、γ−ブチロラクトン、テトラヒドロフラン、１，３−ジオキソラン、４−メチル−１，３−ジオキソラン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリル、プロピオニトリル等、又はこれらの２種類以上を混合した混合溶媒を用いることができ、更に、混合配合比についても限定されるものではない。このような非水電解液を用いることにより電池容量の向上や寒冷地での使用にも適合させることが可能となる。 Furthermore, in the present embodiment, a non-aqueous electrolyte solution in which LiPF 6 is dissolved in a mixed solvent in which ethylene carbonate, dimethyl carbonate, and diethyl carbonate are mixed at a volume ratio of 1: 1: 1 is exemplified. A non-aqueous electrolytic solution in which the electrolyte is dissolved in an organic solvent may be used, and the present invention is not particularly limited to the lithium salt or organic solvent used. For example, as the electrolyte, LiClO 4 , LiAsF 6 , LiBF 4 , LiB (C 6 H 5 ) 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, or a mixture thereof can be used. Examples of the organic solvent include propylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, Sulfolane, methyl sulfolane, acetonitrile, propionitrile, etc., or a mixed solvent in which two or more of these are mixed can be used, and the mixing ratio is not limited. By using such a non-aqueous electrolyte, it is possible to improve battery capacity and adapt to use in cold regions.

更にまた、本実施形態では、円筒型リチウムイオン電池２０について例示したが、本発明は電池の形状については限定されず、角形、その他の多角形の電池にも適用可能である。また、本発明の適用可能な構造としては、上述した電池容器に電池蓋がカシメによって封口されている構造の電池以外であっても構わない。このような構造の一例として正負外部端子が電池蓋を貫通し、電池容器内で軸芯を介して正負外部端子が押し合っている状態の電池を挙げることができる。更に本発明は、正極及び負極を捲回式の構造とせず、積層式の構造としたリチウム二次電池にも適用可能である。   Furthermore, in the present embodiment, the cylindrical lithium ion battery 20 has been exemplified, but the present invention is not limited to the shape of the battery, and can be applied to a rectangular or other polygonal battery. In addition, the structure to which the present invention can be applied may be other than a battery having a structure in which a battery lid is sealed by caulking on the battery container described above. As an example of such a structure, a battery in which positive and negative external terminals penetrate the battery lid and the positive and negative external terminals are pressed against each other via an axis in the battery container can be cited. Further, the present invention can be applied to a lithium secondary battery in which the positive electrode and the negative electrode have a stacked structure instead of a wound structure.

そして、本実施形態では、正極、負極集電体に金属箔（アルミニウム箔、銅箔）を用いた例を示したが、本発明はこれに限定されるものではなく、メッシュ状の金属集電体を用いてもよい。   And in this embodiment, although the example which used metal foil (aluminum foil, copper foil) for the positive electrode and the negative electrode collector was shown, this invention is not limited to this, A mesh-shaped metal collector is shown. The body may be used.

本発明に係るリチウム二次電池によれば、充放電サイクルに伴う容量や出力の維持率の低下を抑制でき、長寿命なため、製造、販売等に寄与し、産業上利用することができる。   According to the lithium secondary battery according to the present invention, it is possible to suppress a decrease in capacity and output maintenance ratio associated with the charge / discharge cycle, and to have a long life, so that it contributes to production, sales, etc., and can be utilized industrially.

本発明が適用可能な実施形態の円筒型リチウムイオン電池の断面図である。It is sectional drawing of the cylindrical lithium ion battery of embodiment which can apply this invention.

符号の説明Explanation of symbols

６ 捲回群
２０ 円筒型リチウムイオン電池（リチウム二次電池） 6 Winding group 20 Cylindrical lithium ion battery (lithium secondary battery)

Claims (2)

正極活物質に層状結晶構造を有するリチウム遷移金属複酸化物を用いた正極と、負極活物質に黒鉛質炭素を用いた負極と、をセパレータを介して配置し非水電解液に浸潤させたリチウム二次電池において、初充電完了前に、前記非水電解液に含有された遷移金属イオンの濃度をＡｐｐｍ、前記負極の電極面積をＢｍ２としたときに、前記電極面積に対する前記遷移金属イオンの存在量Ａ／Ｂの範囲が１３５乃至２７０であり、かつ、前記遷移金属イオンの濃度Ａが１００ｐｐｍ乃至２００ｐｐｍであることを特徴とするリチウム二次電池。 Lithium in which a positive electrode using a lithium transition metal double oxide having a layered crystal structure as a positive electrode active material and a negative electrode using graphitic carbon as a negative electrode active material are placed through a separator and infiltrated into a non-aqueous electrolyte in the secondary battery, before initial charge complete, the concentration of the transition metal ions contained in the nonaqueous electrolytic solution appm, the electrode area of the negative electrode when the Bm 2, of the transition metal ion relative to the electrode area range of abundance a / B is Ri 135 to 270 der, and a lithium secondary battery concentration a of the transition metal ions, wherein the 100ppm to 200ppm der Rukoto. 前記初充電完了前に前記非水電解液に含有された遷移金属イオンが、初充電完了後に、実質的に全て前記負極の表面に遷移金属として析出していることを特徴とする請求項１に記載のリチウム二次電池。 The transition metal ions contained in the nonaqueous electrolytic solution before the initial charging is completed, after the initial charging is completed, to claim 1, characterized in that it is deposited as substantially all transition metal on the surface of the negative electrode The lithium secondary battery as described.
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