JP2008226693A - Lithium-ion secondary battery - Google Patents

Lithium-ion secondary battery Download PDF

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JP2008226693A
JP2008226693A JP2007064752A JP2007064752A JP2008226693A JP 2008226693 A JP2008226693 A JP 2008226693A JP 2007064752 A JP2007064752 A JP 2007064752A JP 2007064752 A JP2007064752 A JP 2007064752A JP 2008226693 A JP2008226693 A JP 2008226693A
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active material
positive electrode
secondary battery
ion secondary
lithium ion
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JP5103961B2 (en
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Kaoru Osada
かおる 長田
Tetsuo Minamino
哲郎 南野
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Panasonic Holdings Corp
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Matsushita Electric Industrial 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium-ion secondary battery with a high capacity and safety having no deterioration in cycle characteristics and preservation characteristics, in particular, a lithium ion secondary battery improved in safety at the time of overcharge. <P>SOLUTION: This is a non-aqueous secondary battery in which an electrode group is constructed by winding or laminating through a separator a positive electrode plate and a negative electrode plate in which an active material layer capable of storing and releasing lithium ion is installed on a current collector. The lithium-ion secondary battery has the active material to be charged at 4.3 V or less in Li/Li+ standard and a substance which generates oxygen gas at the time of overcharge existing in the positive electrode plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、リチウムイオン二次電池に関し、特に安全性を向上したものに関する。   The present invention relates to a lithium ion secondary battery, and particularly relates to an improved safety.

近年、パソコン、携帯電話などの電子機器のモバイル化が急速に進んでおり、これらの駆動電源として、小型で軽量かつ高容量な二次電池が必要とされている。このような理由から高エネルギー密度が可能なリチウムイオン二次電池の開発が広くなされている。そこで、高エネルギー密度化に伴い、電池の安全性確保はますます重要となっている。   In recent years, electronic devices such as personal computers and mobile phones are rapidly becoming mobile, and a small, light and high capacity secondary battery is required as a driving power source for these devices. For these reasons, lithium ion secondary batteries capable of high energy density have been widely developed. Therefore, as the energy density increases, ensuring the safety of batteries is becoming more and more important.

電池が過充電された場合、負極でのリチウムイオン吸蔵量が過剰になるとリチウム金属が析出し、セパレータを貫通して正極に達し短絡する恐れがある。また、過充電により溶媒の分解が生じると、電池が発熱したり、分解によるガスにより電池の内圧が上昇したりする恐れがある。さらに、電池が発熱すること、また、正極活物質から過剰にリチウムイオンが放出されることにより、活物質自体が電解液と反応しやすくなり発煙にいたる恐れがある。   When the battery is overcharged, if the amount of occlusion of lithium ions at the negative electrode becomes excessive, lithium metal may be deposited, penetrate the separator, reach the positive electrode, and short circuit. In addition, when the solvent is decomposed due to overcharge, the battery may generate heat, or the internal pressure of the battery may increase due to gas generated by the decomposition. Further, the battery generates heat, and excessive release of lithium ions from the positive electrode active material may cause the active material itself to easily react with the electrolytic solution, resulting in smoke generation.

このような課題を解決するために、特許文献１には、４V級の高い放電電圧が得られるリチウムとマンガンとマンガン以外の金属からなるスピネル構造の酸化物と、リチウムとニッケルコバルトとニッケルとマンガン以外の金属を含む酸化物を混合することで、高エネルギー密度で容量維持率が高くサイクル特性の良好な活物質が提案されている。   In order to solve such a problem, Patent Document 1 discloses an oxide having a spinel structure made of a metal other than lithium, manganese, and manganese, and lithium, nickel cobalt, nickel, and manganese. An active material having a high energy density, a high capacity retention rate, and a good cycle characteristic has been proposed by mixing an oxide containing a metal other than the above.

また、特許文献２には、マンガンを含み、かつアルミニウムまたはマグネシウムを含むリチウム酸化物とＬｉxＣｏＭｇyＡｌzＯ2（１≦ｘ≦１．０３、０．００５≦ｙ≦０．１、０．００１≦ｚ≦０．０２）からなる2種類の活物質を混合することで、充電電位が４．３〜４．４Ｖである充電を行っても、マンガンの溶出量を抑え、安全性を確保する方法が開示されている。 Further, Patent Document 2, includes a manganese and lithium oxide and Li x CoMg y Al z O 2 (1 ≦ x ≦ 1.03,0.005 ≦ y ≦ containing aluminum or magnesium 0.1, .001 ≦ z ≦ 0.02) by mixing two kinds of active materials, even when charging with a charging potential of 4.3 to 4.4 V, the elution amount of manganese is suppressed and safety is improved. A method of ensuring is disclosed.

また、特許文献３には、 異種元素を導入したリチウム複合ニッケル酸化物と異種元素を導入したリチウム複合コバルト酸化物の2種類を少なくとも含むことで、過放電特性、過充電安全性、保存特性が優れた活物質が提案されている。
特開２０００−３１５５０３号公報 特開２００４−２０７１２０号公報 特開２００２−３１９３９８号公報 Patent Document 3 includes at least two types of lithium composite nickel oxide into which different elements are introduced and lithium composite cobalt oxide into which different elements are introduced, thereby providing overdischarge characteristics, overcharge safety, and storage characteristics. Excellent active materials have been proposed.
JP 2000-315503 A JP 2004-207120 A JP 2002-319398 A

しかしながら、特許文献１のように、活物質として、マンガンとそれ以外の金属を含むスピネル構造の酸化物を用いた場合、高エネルギー密度で容量維持率が高くなるものの、過充電により溶媒の分解が生じた場合の、電池が発熱したり、分解によるガスにより電池の内圧が上昇したりする問題を解決するのものではなかった。   However, as in Patent Document 1, when an oxide having a spinel structure containing manganese and other metals is used as the active material, the capacity retention rate is high at a high energy density, but the solvent is decomposed by overcharging. When this occurs, it does not solve the problem that the battery generates heat or the internal pressure of the battery rises due to gas due to decomposition.

また、特許文献２のように、Ｍｎの溶出を抑え安全性を確保しても、さらに、特許文献３のように、 異種元素を導入したリチウム複合ニッケル酸化物と異種元素を導入したリチウム複合コバルト酸化物の2種類を少なくとも含むことで、過充電安全性を向上させても、過充電により溶媒の分解が生じた場合の、電池が発熱したり、分解によるガスにより電池の内圧が上昇したりする問題を解決するのものではなかった。   Moreover, even if elution of Mn is suppressed and the safety is ensured as in Patent Document 2, a lithium composite nickel oxide into which a different element is introduced and a lithium composite cobalt into which a different element is introduced as in Patent Document 3. Even if the overcharge safety is improved by including at least two kinds of oxides, the battery may generate heat or the internal pressure of the battery may increase due to the gas due to the decomposition when the solvent is decomposed due to overcharge. It did not solve the problem.

また、特許文献２または３では、それぞれ、混合する活物質の相乗効果を含んで安全性の向上を図るものであり、その効果が見込める活物質同士の組み合わせが限定されていた。   Moreover, in patent document 2 or 3, the improvement of safety | security is aimed at including the synergistic effect of the active material to mix, respectively, The combination of the active materials which can anticipate the effect was limited.

本発明のリチウムイオン二次電池は、集電体にリチウムイオンを吸蔵放出可能な活物質層を設けた正極板と負極板とをセパレータを介して巻回または積層して電極群を構成し非水電解質とともにケースに封入してなるリチウムイオン二次電池であって、前記正極板にＬｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含み、過充電時に酸素ガスを発生する物質を存在させた構成であることを特徴とする。上記構成によれば、過充電時にガス発生により、正極活物質層と集電体間、または、正極極板とセパレータ間、または、正極層内が離れるため、充電を遮断し、電解液の分解、正極活物質の分解、また、負極側へのＬｉ析出による短絡を防ぐことができる。 The lithium ion secondary battery of the present invention comprises a positive electrode plate having a current collector provided with an active material layer capable of occluding and releasing lithium ions, and a negative electrode plate wound or laminated via a separator to form an electrode group. A lithium ion secondary battery encapsulated in a case together with a water electrolyte, wherein the positive electrode plate includes an active material that is charged at 4.3 V or less on the basis of Li / Li + , and a substance that generates oxygen gas when overcharged It is the structure which existed. According to the above configuration, due to gas generation at the time of overcharge, separation between the positive electrode active material layer and the current collector, or between the positive electrode plate and the separator, or the inside of the positive electrode layer is interrupted, so that charging is interrupted and the electrolytic solution is decomposed. In addition, decomposition of the positive electrode active material and short circuit due to Li deposition on the negative electrode side can be prevented.

本発明のリチウムイオン二次電池では、過充電時に酸素ガスを発生する正極活物質として、リチウム過剰正極活物質Ｌｉ［（Ｎｉ0.5Ｍｎ0.5）xＣｏy（Ｌｉ1/3Ｍｎ1/3）z］Ｏ2（ただし、ｘ+ｙ+ｚ＝1 ｚ＞０ ）またはＬｉαＮｉβＭｎγＯ2（αが１．１以上でβ：γ＝1：1）で示される活物質を用いることが好ましい。上記活物質を用いれば、Ｌｉ／Ｌｉ+基準において４．５Ｖ程度で、酸素ガスの発生が起こることにより、正極と負極の極間を広げることが可能となる。 In the lithium ion secondary battery of the present invention, a lithium-excess cathode active material Li [(Ni 0.5 Mn 0.5 ) x Co y (Li 1/3 Mn 1/3 ) z is used as a cathode active material that generates oxygen gas during overcharge. It is preferable to use an active material represented by O 2 (where x + y + z = 1 z> 0) or LiαNiβMnγO 2 (α is 1.1 or more and β: γ = 1: 1). If the above active material is used, the generation of oxygen gas occurs at about 4.5 V on the basis of Li / Li + , so that the gap between the positive electrode and the negative electrode can be widened.

また、本発明のリチウムイオン二次電池は、正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む正極活物質層と集電体との間に酸素ガスを発生する物質を設けた構成とすることができる。これによって過充電時に、集電体と活物質層との間に速やかに抵抗が生じ、充電を遮断することが出来る。 The lithium ion secondary battery of the present invention generates oxygen gas between the positive electrode active material layer containing the active material charged at 4.3 V or less on the basis of Li / Li + and the current collector as the positive electrode plate. It can be set as the structure which provided the substance. As a result, resistance is quickly generated between the current collector and the active material layer during overcharging, and charging can be interrupted.

本発明のリチウムイオン二次電池では、正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む、正極活物質の前記セパレータに対向する外表面に過充電時に酸素ガスを発生する物質を設けて構成することもできる。このような構成にすることによって急速に過充電状態になった場合にも、ガス発生で速やかに正負極間の空間を確保することが出来る。 In the lithium ion secondary battery of the present invention, the positive electrode plate contains an active material that is charged at 4.3 V or less on the basis of Li / Li + , and oxygen gas is supplied to the outer surface facing the separator of the positive electrode active material during overcharging. It is also possible to provide a material to be generated. With such a configuration, even when an overcharged state is rapidly reached, a space between the positive and negative electrodes can be secured quickly by gas generation.

また、本発明のリチウムイオン二次電池では、前記正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む、正極活物質層に過充電時に酸素ガスを発生する物質を混合した構成とすることが出来る。このような構成にすることによって、ガス発生が万遍なく起こり、過充電によるガス発生時に正極層内で空間を比較的均一に形成することが出来る。 Further, in the lithium ion secondary battery of the present invention, the positive electrode plate includes a material that generates an oxygen gas when overcharged in the positive electrode active material layer, including an active material charged at 4.3 V or less on the basis of Li / Li +. A mixed configuration can be obtained. With this configuration, gas generation occurs uniformly, and spaces can be formed relatively uniformly in the positive electrode layer when gas is generated due to overcharging.

本発明のリチウムイオン二次電池では、過充電時に酸素ガスを発生する物質が、活物質として１０％以上存在するのも好ましい。   In the lithium ion secondary battery of the present invention, it is preferable that a substance that generates oxygen gas at the time of overcharge is present as an active material in an amount of 10% or more.

本発明のリチウムイオン二次電池によれば、過充電時に酸素ガスを発生する正極活物質を正極極板に含むことにより、過充電時において正／負極板間の間隔を広げることができるので、高容量で、サイクル特性・保存特性が劣化することなく安全性の高い電池を提供することができる。   According to the lithium ion secondary battery of the present invention, by including a positive electrode active material that generates oxygen gas during overcharge in the positive electrode plate, the interval between the positive and negative electrode plates can be increased during overcharge, A battery having high capacity and high safety without deterioration in cycle characteristics and storage characteristics can be provided.

以下、本発明を実施するための最良の形態について、図面を参照しながら説明する。   The best mode for carrying out the present invention will be described below with reference to the drawings.

本発明のリチウムイオン二次電池は正極板と負極板とをセパレータを介して巻回または積層して構成した電極群を非水電解質とともにケースに封入したものである。   In the lithium ion secondary battery of the present invention, an electrode group formed by winding or laminating a positive electrode plate and a negative electrode plate via a separator is enclosed in a case together with a non-aqueous electrolyte.

本発明のリチウムイオン二次電池は、過充電時に酸素ガスを発生する正極活物質が存在する活物質を用いる。   The lithium ion secondary battery of the present invention uses an active material in which a positive electrode active material that generates oxygen gas during overcharge is present.

本発明のリチウムイオン二次電池に用いる過充電時に酸素ガスを発生する正極活物質としては、Ｌｉ／Ｌｉ+を基準として、４．５Ｖ以上でガスを発生する活物質が好ましい。 As the positive electrode active material that generates oxygen gas at the time of overcharging used in the lithium ion secondary battery of the present invention, an active material that generates gas at 4.5 V or higher with respect to Li / Li + is preferable.

過充電時に酸素ガスを発生する正極活物質として、好ましくは、Ｍｎを多く含む方が、４．５Ｖ以上で酸素ガスを放出しやすいため良好である。   As the positive electrode active material that generates oxygen gas at the time of overcharge, it is preferable that a large amount of Mn is contained because oxygen gas is easily released at 4.5 V or higher.

具体的な好ましい例としてＬｉ［（Ｎｉ0.5Ｍｎ0.5）xＣｏy（Ｌｉ1/3Ｍｎ1/3）z］Ｏ2（ただし、ｘ+ｙ+ｚ＝1 ｚ＞０ ）またはＬｉαＮｉβＭｎγＯ2（αが１．１以上でβ：γ＝1：1）で示される活物質が、本発明のリチウムイオン二次電池に用いることができる。これら活物質は、層状構造に帰属されるリチウム過剰正極活物質であり、一般的にＬｉＭｅＯ2（Ｍｅは遷移金属）と表され、リチウム層、遷移金属層、酸素層が一軸方向に積層したリチウム遷移金属酸化物と同様の構造を有するもので、Ｒ３−Ｍ構造に帰属される活物質、または、Ｌｉ「Ｌｉ1/3Ｍｅ2/3」Ｏ2で表されるＬｉ層とＬｉ1/3Ｍｅ2/3層および酸素層が積層したＣ２／ｍ構造の活物質を指す。これらの活物質が好ましい活物質であるが、本発明はこれらの活物質に限定されるものではない。 As a specific preferred example, Li [(Ni 0.5 Mn 0.5 ) x Co y (Li 1/3 Mn 1/3 ) z ] O 2 (where x + y + z = 1 z> 0) or LiαNiβMnγO 2 (α Can be used in the lithium ion secondary battery of the present invention. These active materials are lithium-rich positive electrode active materials attributed to a layered structure, generally expressed as LiMeO 2 (Me is a transition metal), and lithium in which a lithium layer, a transition metal layer, and an oxygen layer are laminated in a uniaxial direction. An active material belonging to the R3-M structure, or a Li layer represented by Li “Li 1/3 Me 2/3 ” O 2 and Li 1/3 An active material having a C2 / m structure in which a Me 2/3 layer and an oxygen layer are stacked. These active materials are preferred active materials, but the present invention is not limited to these active materials.

また、過充電時に酸素ガスを発生する正極活物質は、混合されていてもよく、集電体側にあってもセパレータ側にあっても良い。   Moreover, the positive electrode active material which generates oxygen gas at the time of overcharge may be mixed, and may exist in the collector side or the separator side.

本発明のリチウムイオン二次電池は、図１に模式的に示すように、集電体２上にＬｉ／Ｌｉ+基準で４．３Ｖ以下でリチウムイオンを吸蔵放出可能な正極活物質と過充電時に酸素ガスを発生する正極活物質との混合正極活物質層１を設けた正極板を用いる。 As schematically shown in FIG. 1, the lithium ion secondary battery of the present invention is overcharged with a positive electrode active material capable of occluding and releasing lithium ions at 4.3 V or less on the basis of Li / Li + on a current collector 2. A positive electrode plate provided with a mixed positive electrode active material layer 1 with a positive electrode active material that sometimes generates oxygen gas is used.

また、図２に示すように、集電体２上に過充電時に酸素ガスを発生する正極活物質層４を設け、さらにその上にＬｉ／Ｌｉ+基準で４．３Ｖ以下でリチウムイオンを吸蔵放出可能な活物質層３を設けた正極板を用いる。 Further, as shown in FIG. 2, a positive electrode active material layer 4 that generates oxygen gas at the time of overcharge is provided on the current collector 2, and further, lithium ions are occluded at 4.3 V or less on the basis of Li / Li +. A positive electrode plate provided with a releasable active material layer 3 is used.

さらに別の形態としては、図３に示すように、集電体２上にＬｉ／Ｌｉ+基準で４．３Ｖ以下でリチウムイオンを吸蔵放出可能な活物質層３を設け、さらにその上に過充電時に酸素ガスを発生する正極活物質４の層を設けた正極板を用いる。 As yet another form, as shown in FIG. 3, an active material layer 3 capable of occluding and releasing lithium ions at 4.3 V or less on the basis of Li / Li + is provided on the current collector 2, and the active material layer 3 is further formed thereon. A positive electrode plate provided with a layer of the positive electrode active material 4 that generates oxygen gas during charging is used.

図１に示すように４．３Ｖ以下でリチウムイオンを吸蔵放出可能な正極活物質に過充電時に酸素ガスを発生する正極活物質が混合されていることにより、ガス発生が万遍なく起こり、過充電によるガス発生時に正極層内の空間を比較的均一に形成することが出来る。   As shown in FIG. 1, the cathode active material that can absorb and release lithium ions at 4.3 V or less is mixed with the cathode active material that generates oxygen gas at the time of overcharging. When the gas is generated by charging, the space in the positive electrode layer can be formed relatively uniformly.

また、図２に示すように過充電時に酸素ガスを発生する正極活物質を、集電体側に層状もしくはこれに準ずるよう高濃度で配することで、極端な過充電時における内部抵抗をより高くすることが出来る。   Further, as shown in FIG. 2, the positive electrode active material that generates oxygen gas at the time of overcharge is arranged on the current collector side in a layered manner or at a high concentration so that the internal resistance at the time of extreme overcharge is higher. I can do it.

また、図３に示すように過充電時に酸素ガスを発生する正極活物質を、セパレータ側に層状もしくはこれに準ずるように高濃度で配することで、急速に過充電状態になった場合にも、ガス発生で速やかに正負極間の空間を確保することができる。   Also, as shown in FIG. 3, the positive electrode active material that generates oxygen gas during overcharge is arranged in a layered or high concentration on the separator side so that it can be overcharged rapidly. The space between the positive and negative electrodes can be secured quickly by gas generation.

なお、図２〜３において、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下でリチウムを吸蔵放出可能
な正極活物質層３と、過充電時に酸素ガスを発生する正極活物質層４に明瞭な境界は必ずしも必要ではなく、徐々に過充電時に酸素ガスを発生する正極活物質の濃度が変化する構成であっても良い。 In FIGS. 2 to 3, there is a clear boundary between the positive electrode active material layer 3 that can occlude and release lithium at 4.3 V or less on the basis of Li / Li + and the positive electrode active material layer 4 that generates oxygen gas during overcharge. A configuration in which the concentration of the positive electrode active material that generates oxygen gas at the time of overcharging gradually changes may be used.

過充電時に酸素ガスを発生する正極活物質と同時に用いるＬｉ／Ｌｉ+基準で４．３Ｖ以下でリチウムを吸蔵放出可能な正極活物質は、具体的には、ＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＮｉ1/2Ｍｎ1/2Ｏ2、ＬｉＮｉＣｏＯ2などの活物質を好ましく用いることができるが、本発明はこれらの活物質に限定されるものではない。 The positive electrode active material capable of occluding and releasing lithium at 4.3 V or less on the basis of Li / Li + used simultaneously with the positive electrode active material that generates oxygen gas at the time of overcharge is specifically LiCoO 2 , LiNiO 2 , LiNi 1 / Active materials such as 2 Mn 1/2 O 2 and LiNiCoO 2 can be preferably used, but the present invention is not limited to these active materials.

また、過充電時に酸素ガスを発生する正極活物質は、Ｌｉ／Ｌｉ＋基準で４．３Ｖ以下でリチウムを吸蔵放出可能な正極活物質と比較し、活物質の重量比１０％以上含まれることが好ましい。１０％未満の場合、酸素ガス発生による効果が十分に発揮できない場合がある。   In addition, the positive electrode active material that generates oxygen gas during overcharge may be included in a weight ratio of 10% or more of the active material as compared with a positive electrode active material capable of occluding and releasing lithium at 4.3 V or less on the basis of Li / Li +. preferable. If it is less than 10%, the effect of oxygen gas generation may not be sufficiently exhibited.

正極集電体の材質としては、アルミニウム、ステンレス鋼、ニッケルメッキ、チタン、タンタル等の金属材料やカーボンペーパーなどの炭素材料が用いられる。中でも、金属材料が好ましく、アルミニウムが特に好ましい。   As a material of the positive electrode current collector, a metal material such as aluminum, stainless steel, nickel plating, titanium, or tantalum, or a carbon material such as carbon paper is used. Among these, a metal material is preferable, and aluminum is particularly preferable.

以下、本発明を実施例により更に詳しく説明するが、本発明はこれらの実施例により制限されるものではない。   EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not restrict | limited by these Examples.

（実施例１）
正極板の製造方法を説明する。 (Example 1)
A method for manufacturing the positive electrode plate will be described.

まず、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2を合成した。硫酸ニッケルと硫酸マンガンとをニッケルとマンガンの比が１：１となるようにてイオン交換水に溶かし、これを、ＬｉＯＨをイオン交換水に溶解しｐＨ＝１３としたアルカリ水溶液に滴下し、ニッケルとマンガンの水酸化物を作製した。この水酸化物をＬｉＯＨと化学量論比にあうように混合し、４８０℃３時間にて焼成したあと粉砕し、さらに９００℃３時間で焼成しＬｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2を合成した。 First, Li 1.2 Ni 0.4 Mn 0.4 O 2 was synthesized. Nickel sulfate and manganese sulfate were dissolved in ion-exchange water so that the ratio of nickel to manganese was 1: 1, and this was dropped into an alkaline aqueous solution in which LiOH was dissolved in ion-exchange water and adjusted to pH = 13. And manganese hydroxide were prepared. This hydroxide was mixed with LiOH so as to have a stoichiometric ratio, calcined at 480 ° C. for 3 hours, pulverized, and further calcined at 900 ° C. for 3 hours to synthesize Li 1.2 Ni 0.4 Mn 0.4 O 2 .

このＬｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2粉末をＬｉＣｏＯ2粉末と重量比で１：１となるように混合した。混合した粉末３ｋｇを、呉羽化学（株）製ＰＶＤＦ＃１３２０（固形分１２重量％のＮ−メチルピロリドン（ＮＭＰ）溶液）１．５ｋｇ、アセチレンブラック１２０ｇおよび適量のＮＭＰとともに双腕式練合機にて攪拌し、正極ペーストを作製した。このペーストを図１に示すように２０μｍ厚のアルミニウム箔に塗布乾燥した。総厚が１６０μｍとなるように圧延した後、１８６５０型の円筒電池に挿入可能な幅にスリットし、正極フープを得た。 This Li 1.2 Ni 0.4 Mn 0.4 O 2 powder was mixed with the LiCoO 2 powder at a weight ratio of 1: 1. 3 kg of the mixed powder was added to a double-arm kneader together with 1.5 kg of PVDF # 1320 (N-methylpyrrolidone (NMP) solution with a solid content of 12% by weight), 120 g of acetylene black and an appropriate amount of NMP. And stirred to prepare a positive electrode paste. As shown in FIG. 1, this paste was applied to an aluminum foil having a thickness of 20 μm and dried. After rolling to a total thickness of 160 μm, it was slit to a width that could be inserted into a 18650-type cylindrical battery to obtain a positive electrode hoop.

一方、人造黒鉛３ｋｇを、日本ゼオン（株）製スチレン−ブタジエン共重合体ゴム粒子結着剤ＢＭ−４００Ｂ（固形分４０重量％）２００ｇ、ＣＭＣ５０ｇおよび適量の水とともに双腕式練合機にて攪拌し、負極ペーストを作製した。このペーストを１２μｍ厚の銅箔に塗布乾燥し、総厚が１６０μｍとなるように圧延した後、１８６５０型の円筒電池に挿入可能な幅にスリットし、負極フープを得た。セパレータと前記正負極を捲回構成し、所定の長さで切断して電槽缶内に挿入し、エチレンカーボネート（ＥＣ）／メチルエチルカーボネート（ＭＥＣ）＝１／３の混合溶媒にＬｉＰＦ6を１．５Ｍの濃度で溶解させた電解液を５ｇ添加して封口し、１８６５０型のリチウムイオン電池を作製した。 On the other hand, 3 kg of artificial graphite was mixed with Nippon Zeon Co., Ltd. styrene-butadiene copolymer rubber particle binder BM-400B (solid content 40% by weight) 200 g, CMC 50 g and an appropriate amount of water in a double arm kneader. Stirring to prepare a negative electrode paste. This paste was applied and dried on a 12 μm thick copper foil, rolled to a total thickness of 160 μm, and then slit into a width that could be inserted into a 18650-type cylindrical battery to obtain a negative electrode hoop. The separator and the positive and negative electrodes are wound, cut into a predetermined length, inserted into a battery case, and LiPF 6 is added to a mixed solvent of ethylene carbonate (EC) / methyl ethyl carbonate (MEC) = 1/3. 5 g of an electrolytic solution dissolved at a concentration of 1.5 M was added and sealed to produce a 18650 type lithium ion battery.

（実施例２）
まず、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2粉末１．５ｋｇ、ＬｉＣｏＯ2粉末１．５ｋｇを、それぞれ呉羽化学（株）製ＰＶＤＦ＃１３２０（固形分１２重量％のＮ−メチルピロリドン（ＮＭＰ）溶液）０．７５ｋｇ、アセチレンブラック６０ｇおよび適量のＮＭＰとともに双腕式練合機にて攪拌し、正極ペーストを２種類作製した。Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2のペーストをまず２０μｍ厚のアルミニウム箔に塗布乾燥した。つぎに、ＬｉＣｏＯ2のペーストを、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2が塗工された極板にさらに塗布乾燥し、図２に示すような正極板を作製した。総厚が１６０μｍとなるように圧延した後、１８６５０型の円筒電池に挿入可能な幅にスリットし、正極フープを得た。その後の工程は、実施例１と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Example 2)
First, 1.5 kg of Li 1.2 Ni 0.4 Mn 0.4 O 2 powder and 1.5 kg of LiCoO 2 powder were respectively converted into PVDF # 1320 (N-methylpyrrolidone (NMP) solution having a solid content of 12% by weight) manufactured by Kureha Chemical Co., Ltd. Two types of positive electrode pastes were prepared by stirring with a double arm kneader together with .75 kg, acetylene black 60 g and an appropriate amount of NMP. First, a paste of Li 1.2 Ni 0.4 Mn 0.4 O 2 was applied to an aluminum foil having a thickness of 20 μm and dried. Next, the LiCoO 2 paste was further applied and dried on the electrode plate coated with Li 1.2 Ni 0.4 Mn 0.4 O 2 to produce a positive electrode plate as shown in FIG. After rolling to a total thickness of 160 μm, it was slit to a width that could be inserted into a 18650-type cylindrical battery to obtain a positive electrode hoop. Subsequent steps were carried out in the same manner as in Example 1, and a 18650 type lithium ion battery was produced.

（実施例３）
実施例２と同様に、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2のペーストとＬｉＣｏＯ2のペーストの２種類を作製した。ＬｉＣｏＯ2のペーストをまず２０μｍ厚のアルミニウム箔に塗布乾燥した。つぎに、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2のペーストを、ＬｉＣｏＯ2が塗工された極板にさらに塗布乾燥し、図３に示すような正極板を作製した。その後の工程は、実施例２と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Example 3)
In the same manner as in Example 2, two types of pastes were prepared: Li 1.2 Ni 0.4 Mn 0.4 O 2 paste and LiCoO 2 paste. First, a LiCoO 2 paste was applied to an aluminum foil having a thickness of 20 μm and dried. Next, a paste of Li 1.2 Ni 0.4 Mn 0.4 O 2 was further applied to and dried on the electrode plate coated with LiCoO 2 to prepare a positive electrode plate as shown in FIG. Subsequent steps were performed in the same manner as in Example 2 to produce a 18650 type lithium ion battery.

（実施例４）
まず、 Ｌｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3)1/3]Ｏ2（ｘ＝５／１２、ｙ＝１／４、ｚ＝１／３のとき）を合成した。 Example 4
First, Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3) 1/3 ] O 2 (x = 5/12, y = 1/4, z = 1 / 3) was synthesized.

硫酸ニッケルと硫酸マンガンと硫酸コバルトをマンガンとニッケルとコバルトの比が０．６０：０．３６：０．２５となるようにしてイオン交換水に溶かし、これを、ＬｉＯＨをイオン交換水に溶解しｐＨ＝１３としたアルカリ水溶液に滴下し、ニッケルとマンガンとコバルトの水酸化物を作製した。この水酸化物をＬｉＯＨと化学量論比にあうように混合し、４８０℃３時間にて焼成したあと粉砕し、さらに９００℃３時間で焼成しＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を合成した。 Nickel sulfate, manganese sulfate, and cobalt sulfate were dissolved in ion exchange water so that the ratio of manganese, nickel, and cobalt was 0.60: 0.36: 0.25, and this was dissolved in ion exchange water. The solution was dropped into an alkaline aqueous solution having pH = 13 to produce a hydroxide of nickel, manganese and cobalt. This hydroxide was mixed with LiOH so as to have a stoichiometric ratio, calcined at 480 ° C. for 3 hours, pulverized, further calcined at 900 ° C. for 3 hours, and Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 was synthesized.

Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2の代わりにＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を用いた以外は、実施例１と同様にして１８６５０型のリチウムイオン電池を作製した。 Example except that Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 was used instead of Li 1.2 Ni 0.4 Mn 0.4 O 2 In the same manner as in Example 1, a 18650 type lithium ion battery was produced.

（実施例５）
Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2の代わりにＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を用いた以外は、実施例２と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Example 5)
Example except that Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 was used instead of Li 1.2 Ni 0.4 Mn 0.4 O 2 In the same manner as in Example 2, a 18650 type lithium ion battery was produced.

（実施例６）
Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2の代わりにＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を用いた以外は、実施例３と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Example 6)
Example except that Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 was used instead of Li 1.2 Ni 0.4 Mn 0.4 O 2 In the same manner as in Example 3, a 18650 type lithium ion battery was produced.

（実施例７）
Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2粉末０．３ｋｇ、ＬｉＣｏＯ2粉末２．７ｋｇを用いて、それぞれ正極ペーストを２種類作製した。ＬｉＣｏＯ２のペーストをまず２０μｍ厚のアルミニウム箔に塗布乾燥した。つぎに、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2のペーストを、ＬｉＣｏＯ2が塗工された極板にさらに塗布乾燥し、図３に示すような正極板を作製した。その後の工程は、実施例１と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Example 7)
Two types of positive electrode pastes were prepared using 0.3 kg of Li 1.2 Ni 0.4 Mn 0.4 O 2 powder and 2.7 kg of LiCoO 2 powder. LiCoO 2 paste was first applied to an aluminum foil having a thickness of 20 μm and dried. Next, a paste of Li 1.2 Ni 0.4 Mn 0.4 O 2 was further applied to and dried on the electrode plate coated with LiCoO 2 to prepare a positive electrode plate as shown in FIG. Subsequent steps were carried out in the same manner as in Example 1, and a 18650 type lithium ion battery was produced.

（比較例１）
ＬｉＣｏＯ2粉末のみを用いて、実施例１と同様にして、１８６５０型のリチウムイオン電池を作製した。 (Comparative Example 1)
A 18650 type lithium ion battery was produced in the same manner as in Example 1 using only LiCoO 2 powder.

（比較例２）
まず、 ＬｉＮｉ0.5Ｍｎ0.5Ｏ2を合成した。 (Comparative Example 2)
First, LiNi 0.5 Mn 0.5 O 2 was synthesized.

硫酸ニッケルと硫酸マンガンとをニッケルとマンガンの比が１：１となるようにてイオン交換水に溶かし、これを、ＬｉＯＨをイオン交換水に溶解しｐＨ＝１３としたアルカリ水溶液に滴下し、ニッケルとマンガンの水酸化物を作製した。この水酸化物をＬｉＯＨと化学量論比にあうように混合し、４８０℃３時間にて焼成したあと粉砕し、さらに９００℃３時間で焼成しＬｉＮｉ0.5Ｍｎ0.5Ｏ2を合成した。 Nickel sulfate and manganese sulfate were dissolved in ion-exchange water so that the ratio of nickel to manganese was 1: 1, and this was dropped into an alkaline aqueous solution in which LiOH was dissolved in ion-exchange water and adjusted to pH = 13. And manganese hydroxide were prepared. This hydroxide was mixed with LiOH so as to have a stoichiometric ratio, calcined at 480 ° C. for 3 hours, pulverized, and further calcined at 900 ° C. for 3 hours to synthesize LiNi 0.5 Mn 0.5 O 2 .

Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2の代わりにＬｉＮｉ0.5Ｍｎ0.5Ｏ2を用いた以外は、実施例１と同様にして１８６５０型のリチウムイオン電池を作製した。 A 18650 type lithium ion battery was produced in the same manner as in Example 1 except that LiNi 0.5 Mn 0.5 O 2 was used instead of Li 1.2 Ni 0.4 Mn 0.4 O 2 .

（比較例３）
まず、 Ｌｉ（Ｎ1/3Ｍｎ1/3Ｃｏ1/3）Ｏ2を合成した。 (Comparative Example 3)
First, Li (N 1/3 Mn 1/3 Co 1/3 ) O 2 was synthesized.

硫酸ニッケルと硫酸マンガンと硫酸コバルトをマンガンとニッケルとコバルトの比が０．３３：０．３３：０．３３となるようにしてイオン交換水に溶かし、これを、ＬｉＯＨをイオン交換水に溶解しｐＨ＝１３としたアルカリ水溶液に滴下し、ニッケルとマンガンとコバルトの水酸化物を作製した。この水酸化物をＬｉＯＨと化学量論比にあうように混合し、４８０℃３時間にて焼成したあと粉砕し、さらに９００℃３時間で焼成しＬｉ（Ｎ1/3Ｍｎ1/3Ｃｏ1/3）Ｏ2を合成した。 Nickel sulfate, manganese sulfate, and cobalt sulfate were dissolved in ion-exchanged water so that the ratio of manganese, nickel, and cobalt was 0.33: 0.33: 0.33, and LiOH was dissolved in ion-exchanged water. The solution was dropped into an alkaline aqueous solution having pH = 13 to produce a hydroxide of nickel, manganese and cobalt. This hydroxide was mixed with LiOH so as to have a stoichiometric ratio, calcined at 480 ° C. for 3 hours, pulverized, further calcined at 900 ° C. for 3 hours, and Li (N 1/3 Mn 1/3 Co 1 / 3 ) O 2 was synthesized.

Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2の代わりにＬｉ（Ｎ1/3Ｍｎ1/3Ｃｏ1/3）Ｏ2を用いた以外は、実施例１と同様にして１８６５０型のリチウムイオン電池を作製した。 A 18650 type lithium ion battery was produced in the same manner as in Example 1 except that Li (N 1/3 Mn 1/3 Co 1/3 ) O 2 was used instead of Li 1.2 Ni 0.4 Mn 0.4 O 2 . .

（比較例４）
Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2粉末０．２７ｋｇ、ＬｉＣｏＯ2粉末２．７３ｋｇを用いた以外は、実施例７と同様にして１８６５０型のリチウムイオン電池を作製した。 (Comparative Example 4)
A 18650 type lithium ion battery was fabricated in the same manner as in Example 7 except that 0.27 kg of Li 1.2 Ni 0.4 Mn 0.4 O 2 powder and 2.73 kg of LiCoO 2 powder were used.

（放電容量）
実施例１〜６、比較例１の３．０〜４．２Ｖで０．０５Ｃレートの定電流で充放電を行った時の放電容量を表１に示す。 (Discharge capacity)
Table 1 shows discharge capacities when charging and discharging were performed at a constant current of 0.05 C rate at 3.0 to 4.2 V in Examples 1 to 6 and Comparative Example 1.

Figure 2008226693
Figure 2008226693

実施例１〜６では、放電容量が比較例１〜４に対し、若干減少するものの、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2とＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2がそれぞれ充放電に寄与していることがわかった。 In Examples 1 to 6, Li 1.2 Ni 0.4 Mn 0.4 O 2 and Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1 / 3 Mn 2/3 ) 1/3 ] O 2 was found to contribute to charge / discharge.

（過充電安全性）
電池充放電特性評価後の電池について、８０００ｍＡの電流で最大印加電圧１０Ｖの条件で過充電を行った。 (Overcharge safety)
About the battery after battery charging / discharging characteristic evaluation, it overcharged on the conditions of the maximum applied voltage 10V with the electric current of 8000 mA.

このときの発熱状態を観測し、電池側面温度の最高到達温度を（表２）中に示した。   The heat generation state at this time was observed, and the maximum reached temperature of the battery side surface temperature is shown in (Table 2).

以下、順を追って評価結果を記す。   The evaluation results are described below in order.

Figure 2008226693
Figure 2008226693

実施例１〜６の電池は充電中、４．５Ｖあたりから急激に電圧上昇が起こり、比較例１〜４よりも短時間で最高電圧に到達した。   The batteries of Examples 1 to 6 suddenly increased in voltage from around 4.5 V during charging, and reached the maximum voltage in a shorter time than Comparative Examples 1 to 4.

過充電後、実施例１〜６、比較例１の電池の分解を行ったところ、実施例１〜６では、小さな気泡がいくつか正極極板に見えたが比較例１では見られなかった。   After overcharging, the batteries of Examples 1 to 6 and Comparative Example 1 were disassembled. In Examples 1 to 6, some small bubbles were seen in the positive electrode plate, but were not seen in Comparative Example 1.

また、過充電後の電池はいずれも膨れ上がっていた。ガス分析を行ったところ、実施例１〜６までの電池は、いずれも酸素ガスが最も多く含まれ、比較例１〜４では、二酸化炭素ガス、水素ガスが多かった。   In addition, all the batteries after overcharging were swollen. As a result of gas analysis, all of the batteries of Examples 1 to 6 contained the largest amount of oxygen gas, and Comparative Examples 1 to 4 contained a large amount of carbon dioxide gas and hydrogen gas.

急激な電圧上昇が起こった理由は、実施例１〜３では、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2から酸素ガスが、実施例４〜６では、Ｌｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2から酸素ガスが放出されることによって、イオン・電子の伝導パスが遮断され、急激な電圧上昇を引き起こしたと考えられる。この伝導パスが遮断されることにより、正極活物質から引き抜かれるＬｉ量は、伝導パスが遮断されなかった活物質より、減少するため活物質自体の熱安定性は保たれると予測できる。 The reason for the rapid voltage increase is that in Examples 1 to 3, oxygen gas was generated from Li 1.2 Ni 0.4 Mn 0.4 O 2 , and in Examples 4 to 6, Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1 / 4 (Li 1/3 Mn 2/3 ) 1/3 ] The release of oxygen gas from O 2 is considered to have interrupted the ion / electron conduction path, causing a rapid voltage increase. It can be predicted that the thermal stability of the active material itself is maintained because the amount of Li extracted from the positive electrode active material is smaller than that of the active material where the conduction path is not blocked by blocking this conduction path.

また、４．５Ｖ程度から電解液の分解が発熱を伴いながらが起こるが、実施例１〜６では、急激に電圧上昇が起こるため、分解が起こりにくくなり、表２に示すように、比較例１〜４よりも電池側面温度の最高到達温度が低くなった理由と考えられる。また、実施例１〜３よりも実施例４〜６の方が電池側面温度の最高到達温度が低い理由は、Ｌｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2の方が、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2より、Ｍｎ量が多く、酸素を放出したためと考えられる。 In addition, although the decomposition of the electrolyte solution occurs while generating heat from about 4.5 V, in Examples 1 to 6, since the voltage rises suddenly, the decomposition is difficult to occur. This is considered to be the reason why the maximum temperature of the battery side surface temperature is lower than 1-4. The reason why the maximum temperature of the battery side surface temperature is lower in Examples 4 to 6 than in Examples 1 to 3 is that Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 is considered to have a larger amount of Mn and release oxygen than Li 1.2 Ni 0.4 Mn 0.4 O 2 .

比較例２のＬｉＮｉ0.5Ｍｎ0.5Ｏ2を含む電池では、実施例１のＬｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2より最高到達温度が高く、二酸化炭素ガス、水素ガスの放出が多かった。よって、ＬｉαＮｉβＭｎγＯ2の活物質でβ：γ＝1：1の時、αが１．１以上であることが好ましい。 In the battery containing LiNi 0.5 Mn 0.5 O 2 of Comparative Example 2, the maximum temperature reached was higher than that of Li 1.2 Ni 0.4 Mn 0.4 O 2 of Example 1, and carbon dioxide gas and hydrogen gas were released more. Therefore, when β: γ = 1: 1 in the LiαNiβMnγO 2 active material, α is preferably 1.1 or more.

比較例３のＬｉ（Ｎ1/3Ｍｎ1/3Ｃｏ1/3）Ｏ2を含む電池では、実施例２のＬｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を含む電池より、最高到達温度が高く、酸化炭素ガス、水素ガスの放出が多かった。よって、Ｌｉ［（Ｎｉ0.5Ｍｎ0.5）xＣｏy（Ｌｉ1/3Ｍｎ1/3）z］Ｏ2（ただし、ｘ+ｙ+ｚ＝1 ｚ＞０ ）であることが好ましい。 In the battery containing Li (N 1/3 Mn 1/3 Co 1/3 ) O 2 of Comparative Example 3, Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] The highest temperature was higher than the battery containing O 2, and the release of carbon oxide gas and hydrogen gas was more. Therefore, Li [(Ni 0.5 Mn 0.5 ) x Co y (Li 1/3 Mn 1/3 ) z ] O 2 (where x + y + z = 1 z> 0) is preferable.

比較例４のＬｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2粉末とＬｉＣｏＯ2粉末を重量比で９：９１とした場合では、電池側面温度の最高到達温度が実施例７より高くなった。酸素ガスの放出量が少なかったことが理由と考えられる。したがって、過充電時に酸素ガスが発生する活物質は、活物質の重量比で１０％以上含まれることが好ましい。 When the Li 1.2 Ni 0.4 Mn 0.4 O 2 powder and the LiCoO 2 powder of Comparative Example 4 were in a weight ratio of 9:91, the maximum battery side temperature reached higher than that in Example 7. The reason is that the amount of released oxygen gas was small. Therefore, it is preferable that the active material that generates oxygen gas during overcharge is contained in an active material weight ratio of 10% or more.

したがって、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2、Ｌｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2を正極極板に存在させた場合、安全性をさらに向上させた電池を作ることができる。 Therefore, Li 1.2 Ni 0.4 Mn 0.4 O 2 and Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 were present in the positive electrode plate. In this case, a battery with further improved safety can be produced.

さらに、Ｌｉ1.2Ｎｉ0.4Ｍｎ0.4Ｏ2、Ｌｉ[（Ｎｉ0.5Ｍｎ0.5）1/12Ｃｏ1/4（Ｌｉ1/3Ｍｎ2/3）1/3]Ｏ2ともに、ＬｉＣｏＯ2より活物質の電子抵抗が２桁ほど高いことから、これらの活物質を含むと極板抵抗が高くなり、なんらかの原因で内部短絡が生じた場合でも電池内にながれる電流を低減することが可能であり、内部短絡時の安全性にも有効と考えられる。 Further, Li 1.2 Ni 0.4 Mn 0.4 O 2 and Li [(Ni 0.5 Mn 0.5 ) 1/12 Co 1/4 (Li 1/3 Mn 2/3 ) 1/3 ] O 2 are more active materials than LiCoO 2 . Since the electronic resistance is about two orders of magnitude higher, if these active materials are included, the plate resistance increases, and even if an internal short circuit occurs for any reason, it is possible to reduce the current that flows in the battery. It is thought that it is effective for safety at the time.

さらに、電池の内圧がある一定以上となると充電が遮断される機能を備える電池において、電解液の分解によるガス発生のみならず、酸素ガスの発生も起こるため、電解液分解とこれに伴う発熱を抑えて、内圧を上昇させて充電を遮断することが可能であり、さらに安全性を高めることが可能である。   Furthermore, in a battery having a function of interrupting charging when the internal pressure of the battery exceeds a certain level, not only gas generation due to decomposition of the electrolyte solution but also generation of oxygen gas occurs. It is possible to suppress the charging by increasing the internal pressure, and it is possible to further improve the safety.

本発明にかかるリチウムイオン二次電池によれば安全性に優れたリチウムイオン二次電池を提供することができるため、パソコン、携帯電話などのモバイル化された電子機器の駆動電源等に有用である。   Since the lithium ion secondary battery according to the present invention can provide a lithium ion secondary battery with excellent safety, it is useful as a drive power source for mobile electronic devices such as personal computers and mobile phones. .

本発明の第１のリチウムイオン二次電池の模式図Schematic diagram of the first lithium ion secondary battery of the present invention 本発明の第２のリチウムイオン二次電池の模式図Schematic diagram of the second lithium ion secondary battery of the present invention 本発明の第３のリチウムイオン二次電池の模式図Schematic diagram of the third lithium ion secondary battery of the present invention

符号の説明Explanation of symbols

１ 混合正極活物質層
２ 集電体
３ リチウムを吸蔵放出可能な正極活物質層
４ 過充電時に酸素ガスを発生する正極活物質層 DESCRIPTION OF SYMBOLS 1 Mixed positive electrode active material layer 2 Current collector 3 Positive electrode active material layer which can occlude / release lithium 4 Positive electrode active material layer which generates oxygen gas at the time of overcharge

Claims (6)

集電体にリチウムイオンを吸蔵放出可能な活物質層を設けた正極板と負極板とをセパレータを介して巻回または積層して電極群を構成し非水電解質とともにケースに封入してなる非水系二次電池であって、前記正極板に、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質と過充電時に酸素ガスを発生する物質を存在させたリチウムイオン二次電池。 A positive electrode plate provided with an active material layer capable of occluding and releasing lithium ions on a current collector and a negative electrode plate are wound or laminated via a separator to form an electrode group, which is sealed in a case together with a non-aqueous electrolyte. A lithium ion secondary battery, which is an aqueous secondary battery, wherein an active material that is charged at 4.3 V or less on the basis of Li / Li + and a material that generates oxygen gas when overcharged are present on the positive electrode plate. 前記過充電時に酸素ガスを発生する物質として、Ｌｉ［（Ｎｉ0.5Ｍｎ0.5）xＣｏy（Ｌｉ1/3Ｍｎ1/3）z］Ｏ2（ただし、ｘ+ｙ+ｚ＝1 ｚ＞０ ）またはＬｉαＮｉβＭｎγＯ2（αが１．１以上でβ：γ＝１：１）で示される活物質を用いた請求項１記載のリチウムイオン二次電池。 As a substance that generates oxygen gas at the time of overcharge, Li [(Ni 0.5 Mn 0.5 ) x Co y (Li 1/3 Mn 1/3 ) z ] O 2 (where x + y + z = 1 z> 0 The lithium ion secondary battery according to claim 1, wherein an active material represented by Li) NiβMnγO 2 (α is 1.1 or more and β: γ = 1: 1) is used. 前記正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む正極活物質層と集電体との間に過充電時に酸素ガスを発生する物質を設けた構成とする請求項１記載のリチウムイオン二次電池。 The positive electrode plate has a configuration in which a material that generates oxygen gas at the time of overcharge is provided between a positive electrode active material layer containing an active material charged at 4.3 V or less on the basis of Li / Li + and a current collector. Item 2. A lithium ion secondary battery according to item 1. 前記正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む正極活物質層の前記セパレータに対向する外表面に、過充電時に酸素ガスを発生する物質を設けた構成とする請求項１記載のリチウムイオン二次電池。 A structure in which a material that generates oxygen gas at the time of overcharge is provided on the outer surface facing the separator of the positive electrode active material layer containing an active material that is charged at 4.3 V or less on the basis of Li / Li + as the positive electrode plate. The lithium ion secondary battery according to claim 1. 前記正極板として、Ｌｉ／Ｌｉ+基準で４．３Ｖ以下で充電する活物質を含む、正極活物質層内に、過充電時に酸素ガスを発生する物質を混合した構成とする請求項１記載のリチウムイオン二次電池。 2. The structure according to claim 1, wherein the positive electrode plate includes a positive electrode active material layer containing an active material charged at 4.3 V or less on the basis of Li / Li + , and a material that generates oxygen gas at the time of overcharge. Lithium ion secondary battery. 前記過充電時に酸素ガスを発生する物質が、活物質として１０％以上存在する請求項１記載のリチウムイオン二次電池。   The lithium ion secondary battery according to claim 1, wherein a substance that generates oxygen gas at the time of overcharge is present as an active material in an amount of 10% or more.
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