JP2010192230A - Nonaqueous electrolyte secondary battery - Google Patents

Nonaqueous electrolyte secondary battery Download PDF

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JP2010192230A
JP2010192230A JP2009034852A JP2009034852A JP2010192230A JP 2010192230 A JP2010192230 A JP 2010192230A JP 2009034852 A JP2009034852 A JP 2009034852A JP 2009034852 A JP2009034852 A JP 2009034852A JP 2010192230 A JP2010192230 A JP 2010192230A
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negative electrode
secondary battery
lithium
electrolyte secondary
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JP5321116B2 (en
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Hideki Kitao
英樹 北尾
Akihito Yamato
亮仁 大和
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Murata Manufacturing 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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Abstract

<P>PROBLEM TO BE SOLVED: To improve output characteristics of a nonaqueous electrolytic solution secondary battery. <P>SOLUTION: The nonaqueous electrolytic solution secondary battery to contain nonaqueous electrolytic solution formed by dissolving an electrolyte into a nonaqueous solvent includes a negative electrode active material layer 122 arranged on a surface of a negative electrode current collector 121, and an additional layer 14 arranged on the surface of the negative electrode active material layer 122 and including lithium to contain titanium oxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

この発明は、一般的に非水系溶媒に電解質を溶解させた非水系電解液を含む非水電解液二次電池に関し、特定的には出力特性を改善した非水電解液二次電池に関するものである。   The present invention generally relates to a non-aqueous electrolyte secondary battery including a non-aqueous electrolyte obtained by dissolving an electrolyte in a non-aqueous solvent, and more particularly to a non-aqueous electrolyte secondary battery having improved output characteristics. is there.

従来から、高出力、高エネルギー密度の二次電池として、非水電解液を用い、リチウムイオンを正極と負極との間で移動させて、充放電を行うようにした非水電解液二次電池が利用されている。   Conventionally, a non-aqueous electrolyte secondary battery that uses a non-aqueous electrolyte as a secondary battery with a high output and a high energy density and moves lithium ions between the positive electrode and the negative electrode to perform charge / discharge. Is being used.

また、近年においては、このような非水電解液二次電池を電気自動車の電源など、様々な分野に利用することが検討されている。非水電解液二次電池を電気自動車の電源などの様々な分野に利用する場合、高い出力特性が非水電解液二次電池に要求される。   In recent years, the use of such non-aqueous electrolyte secondary batteries in various fields such as power sources for electric vehicles has been studied. When the nonaqueous electrolyte secondary battery is used in various fields such as a power source of an electric vehicle, high output characteristics are required for the nonaqueous electrolyte secondary battery.

上記の要求に応えるために、たとえば、特開平５−１２１０６６号公報（以下、特許文献１という）には、非水電解液二次電池の高容量化のためにドープ量が大きく、電流効率のよい特定の炭素質材料を用いた負極の構成が提案されている。この負極においては、負極の活物質は、炭素網面の面間隔ｄ００２が０．３３７ｎｍ未満の黒鉛状炭素質を炭素網面の面間隔ｄ００２が０．３３７ｎｍ以上の炭素質で被覆してなる複合炭素質である。このように負極を構成することにより、電流効率が高く、かつ容量の大きな非水電解液二次電池が得られることが特許文献１に記載されている。すなわち、特許文献１では、出力特性を向上させるために、負極を形成する炭素粒子の表面に低結晶性炭素を被覆して、炭素と電解液界面の直流抵抗を低減するという方法が提案されている。 In order to meet the above requirements, for example, Japanese Patent Laid-Open No. 5-121066 (hereinafter referred to as Patent Document 1) has a large dope amount for increasing the capacity of a non-aqueous electrolyte secondary battery, and has a current efficiency. A configuration of a negative electrode using a good specific carbonaceous material has been proposed. In this negative electrode, the active material of the negative electrode is obtained by coating a graphitic carbonaceous material having a carbon network surface spacing d 002 of less than 0.337 nm with a carbonaceous material having a carbon network surface spacing d 002 of 0.337 nm or more. It is a composite carbonaceous material. Patent Document 1 describes that a nonaqueous electrolyte secondary battery with high current efficiency and large capacity can be obtained by configuring the negative electrode in this way. That is, in Patent Document 1, in order to improve output characteristics, a method is proposed in which the surface of carbon particles forming a negative electrode is coated with low crystalline carbon to reduce the DC resistance at the interface between the carbon and the electrolyte. Yes.

特開平５−１２１０６６号公報Japanese Patent Laid-Open No. 5-121066

しかし、特許文献１で提案された方法を採用しても、非水電解液二次電池の出力特性を十分に向上させることができなかった。   However, even if the method proposed in Patent Document 1 is adopted, the output characteristics of the non-aqueous electrolyte secondary battery cannot be sufficiently improved.

そこで、この発明の目的は、非水電解液二次電池の出力特性を向上させることである。   Accordingly, an object of the present invention is to improve the output characteristics of a non-aqueous electrolyte secondary battery.

この発明に従った非水電解液二次電池は、非水系溶媒に電解質を溶解させた非水系電解液を含む非水電解液二次電池であって、負極集電体の表面上に配置された負極活物質層と、この負極活物質層の表面上に配置され、リチウム含有チタン酸化物を含む付加層とを備える。   A non-aqueous electrolyte secondary battery according to the present invention is a non-aqueous electrolyte secondary battery including a non-aqueous electrolyte obtained by dissolving an electrolyte in a non-aqueous solvent, and is disposed on the surface of a negative electrode current collector. A negative electrode active material layer, and an additional layer disposed on the surface of the negative electrode active material layer and including a lithium-containing titanium oxide.

この発明の非水電解液二次電池においては、負極活物質層の表面上にリチウム含有チタン酸化物を含む付加層が配置されている。これにより、作動電位の高いリチウム含有チタン酸化物が負極活物質層の表面上に均一に配置されるので、直流抵抗が特異的に低減されるものと推測される。その結果、非水電解液二次電池の出力特性を向上させることができる。   In the non-aqueous electrolyte secondary battery of the present invention, an additional layer containing lithium-containing titanium oxide is disposed on the surface of the negative electrode active material layer. As a result, the lithium-containing titanium oxide having a high operating potential is evenly disposed on the surface of the negative electrode active material layer, so that it is presumed that the direct current resistance is specifically reduced. As a result, the output characteristics of the nonaqueous electrolyte secondary battery can be improved.

この発明の非水電解液二次電池において、付加層の厚みは、１０μｍ以上５０μｍ以下であることが好ましい。   In the nonaqueous electrolyte secondary battery of the present invention, the thickness of the additional layer is preferably 10 μm or more and 50 μm or less.

このように付加層の厚みを限定することにより、直流抵抗をより効果的に低減させることができる。   Thus, by limiting the thickness of the additional layer, the direct current resistance can be more effectively reduced.

また、この発明の非水電解液二次電池において、リチウム含有チタン酸化物の平均粒径が、０．５μｍ以上１０μｍ以下であることが好ましい。   In the nonaqueous electrolyte secondary battery of the present invention, it is preferable that the lithium-containing titanium oxide has an average particle size of 0.5 μm or more and 10 μm or less.

このようにリチウム含有チタン酸化物の平均粒径を限定することにより、直流抵抗をより効果的に低減させることができる。   Thus, direct current resistance can be reduced more effectively by limiting the average particle diameter of the lithium-containing titanium oxide.

さらに、この発明の非水電解液二次電池において、負極活物質層は炭素材料を含むことが好ましい。さらにまた、炭素材料は、結晶化度の高い炭素からなる芯材と、この芯材の表面の少なくとも一部を被覆し、結晶化度の低い炭素からなる表面層とを含むことが好ましい。   Furthermore, in the nonaqueous electrolyte secondary battery of the present invention, the negative electrode active material layer preferably contains a carbon material. Furthermore, the carbon material preferably includes a core material made of carbon with a high degree of crystallinity and a surface layer made of carbon with a low degree of crystallinity covering at least a part of the surface of the core material.

このように負極活物質層を構成することにより、直流抵抗をより効果的に低減させることができる。   By configuring the negative electrode active material layer in this manner, the direct current resistance can be more effectively reduced.

以上のようにこの発明によれば、非水溶媒に電解質を溶解させた非水系電解液を含む非水電解液二次電池において、直流抵抗を特異的に低減させることができるので、出力特性を向上させることができる。   As described above, according to the present invention, in the non-aqueous electrolyte secondary battery including the non-aqueous electrolyte solution in which the electrolyte is dissolved in the non-aqueous solvent, the direct current resistance can be specifically reduced. Can be improved.

本発明の非水電解液二次電池の一つの実施の形態である非水電解液二次電池の一例としてリチウムイオン二次電池の電池要素を示す断面図である。It is sectional drawing which shows the battery element of a lithium ion secondary battery as an example of the nonaqueous electrolyte secondary battery which is one embodiment of the nonaqueous electrolyte secondary battery of this invention.

以下、この発明の非水電解液二次電池の実施の形態を説明する。   Embodiments of the non-aqueous electrolyte secondary battery of the present invention will be described below.

図１は、本発明の非水電解液二次電池の一つの実施の形態である非水電解液二次電池の一例としてリチウムイオン二次電池の電池要素を示す断面図である。   FIG. 1 is a cross-sectional view showing a battery element of a lithium ion secondary battery as an example of a nonaqueous electrolyte secondary battery which is one embodiment of the nonaqueous electrolyte secondary battery of the present invention.

図１に示すように、電池要素１０では、複数の短冊状の正極１１と複数の短冊状の負極１２とが、複数の短冊状のセパレータ１３を介して、交互に積層されて形成されている。   As shown in FIG. 1, in the battery element 10, a plurality of strip-shaped positive electrodes 11 and a plurality of strip-shaped negative electrodes 12 are alternately stacked via a plurality of strip-shaped separators 13. .

ここで、正極１１は、正極集電体１１１の両面に正極活物質層１１２が積層されて形成されている。一例として、正極集電体１１１はアルミニウムからなり、正極活物質層１１２はコバルト酸リチウム複合酸化物（ＬＣＯ）からなる。   Here, the positive electrode 11 is formed by laminating a positive electrode active material layer 112 on both surfaces of a positive electrode current collector 111. As an example, the positive electrode current collector 111 is made of aluminum, and the positive electrode active material layer 112 is made of lithium cobalt oxide composite oxide (LCO).

一方、負極１２は、負極集電体１２１の両面に負極活物質層１２２が積層されて形成されている。一例として、負極集電体１２１は銅からなり、負極活物質層１２２は炭素材料からなる。   On the other hand, the negative electrode 12 is formed by laminating a negative electrode active material layer 122 on both surfaces of a negative electrode current collector 121. As an example, the negative electrode current collector 121 is made of copper, and the negative electrode active material layer 122 is made of a carbon material.

付加層１４が、負極活物質層１２２の表面上に積層されて形成され、リチウム含有チタン酸化物を含む。言い換えれば、付加層１４は、セパレータ１３と負極活物質層１２２との間に形成されている。一例として、付加層１４は、チタン酸リチウム層からなる。付加層１４の厚みは１０μｍ以上５０μｍ以下であるのが好ましい。付加層１４に含まれるリチウム含有チタン酸化物の平均粒径は０．５μｍ以上１０μｍ以下であるのが好ましい。図１では、付加層１４は、負極活物質層１２２の表面上に直接形成されているが、負極活物質層１２２の表面上に中間層を介在させて形成されていてもよく、付加層１４は、負極活物質層１２２の表面の上に少なくとも配置されていればよい。   The additional layer 14 is formed by being laminated on the surface of the negative electrode active material layer 122 and includes a lithium-containing titanium oxide. In other words, the additional layer 14 is formed between the separator 13 and the negative electrode active material layer 122. As an example, the additional layer 14 includes a lithium titanate layer. The thickness of the additional layer 14 is preferably 10 μm or more and 50 μm or less. The average particle size of the lithium-containing titanium oxide contained in the additional layer 14 is preferably 0.5 μm or more and 10 μm or less. In FIG. 1, the additional layer 14 is formed directly on the surface of the negative electrode active material layer 122. However, the additional layer 14 may be formed on the surface of the negative electrode active material layer 122 with an intermediate layer interposed therebetween. May be disposed at least on the surface of the negative electrode active material layer 122.

なお、複数の正極１１を構成する複数の正極集電体１１１の端部が集約された正極集端部１１３は、正極接続端子に電気的に接続されており、複数の負極１２を構成する複数の負極集電体１２１の端部が集約された負極集端部１２３は、負極接続端子に電気的に接続されている。   The positive electrode collecting end portion 113 in which the end portions of the plurality of positive electrode current collectors 111 constituting the plurality of positive electrodes 11 are aggregated is electrically connected to the positive electrode connection terminal, and the plurality of negative electrode 12 constituting the plurality of negative electrode 12 is configured. The negative electrode collecting end portion 123 in which the end portions of the negative electrode current collector 121 are integrated is electrically connected to the negative electrode connection terminal.

上記の付加層１４に含まれるリチウム含有チタン酸化物としては、一般的に組成式Ｌｉ４Ｔｉ５−ｘＭｅｘＯ１２（ｘ＝０〜１、Ｍｅは、Ｍｇ，Ａｌ，Ｔｉ，Ｚｒ，Ｍｏ，Ｎｂ，Ｓｒ，Ｎｉ，Ｃｏ，Ｍｎ，Ｗのうち少なくとも一種）を用いることができる。 The lithium-containing titanium oxide contained in the additional layer 14 is generally represented by the composition formula Li 4 Ti 5-x Me x O 12 (x = 0 to 1, Me is Mg, Al, Ti, Zr, Mo). , Nb, Sr, Ni, Co, Mn, and W).

上記の負極活物質層１２２の材料としては、炭素材料、シリコン（Ｓｉ）、スズ（Ｓｎ）、ゲルマニウム（Ｇｅ）、アルミニウム（Ａｌ）、リチウム（Ｌｉ）などを用いることができる。いずれの材料を用いた場合においても本発明の効果を得ることができるが、コストの観点から負極活物質層１２２の材料としては炭素材料を使うことが好ましい。炭素材料としては、黒鉛、ソフトカーボン、ハードカーボン、コークスなどを用いることができる。   As a material of the negative electrode active material layer 122, a carbon material, silicon (Si), tin (Sn), germanium (Ge), aluminum (Al), lithium (Li), or the like can be used. Although the effect of the present invention can be obtained when any material is used, it is preferable to use a carbon material as the material of the negative electrode active material layer 122 from the viewpoint of cost. As the carbon material, graphite, soft carbon, hard carbon, coke and the like can be used.

負極活物質層１２２の材料として炭素材料を用いる場合、負極活物質層１２２は、結晶化度の高い炭素からなる芯材と、この芯材の表面の少なくとも一部を被覆し、結晶化度の低い炭素からなる表面層とからなる炭素材料を含むことが好ましい。この場合、結晶化度の高い炭素からなる芯材としての黒鉛と、その黒鉛の表面の少なくとも一部を被覆し、結晶化度の低い炭素からなる表面層とからなる低結晶性炭素被覆黒鉛としては、ラマン分光法により求められる１３５０／ｃｍの強度ＩＡと、１５８０／ｃｍの強度ＩＢとの強度比（ＩＡ／ＩＢ）が０．２〜０．３の範囲のものを用いることが好ましい。ここで、１５８０／ｃｍのピークは黒鉛構造に近い六方対称性をもった積層に起因して得られるピークであり、１３５０／ｃｍのピークは炭素局部の乱れた低結晶性構造に起因して得られるピークであり、上記のＩＡ／ＩＢの値が大きいほど、表面における低結晶性炭素の割合が大きくなる。そして、上記のＩＡ／ＩＢの値が０．２未満になると、黒鉛の表面における低結晶性炭素の割合が少なくなって、リチウムイオンの受け入れ性を十分に高めることが困難になる。一方、ＩＡ／ＩＢの値が０．３を越えると、低結晶性炭素の量が多くなって黒鉛の割合が低下し、負極活物質層１２２の構成に起因して電池容量が低下する。   In the case where a carbon material is used as the material of the negative electrode active material layer 122, the negative electrode active material layer 122 covers a core material made of carbon having a high degree of crystallinity and at least a part of the surface of the core material. It is preferable to include a carbon material composed of a surface layer composed of low carbon. In this case, as a low-crystalline carbon-coated graphite comprising graphite as a core material made of carbon having a high degree of crystallinity, and a surface layer made of carbon having a low degree of crystallinity, covering at least part of the surface of the graphite. Preferably uses an intensity ratio (IA / IB) between the intensity IA of 1350 / cm determined by Raman spectroscopy and the intensity IB of 1580 / cm in the range of 0.2 to 0.3. Here, the peak of 1580 / cm is a peak obtained due to the lamination having hexagonal symmetry close to the graphite structure, and the peak of 1350 / cm is obtained due to the disordered low crystalline structure of the local carbon. As the IA / IB value increases, the proportion of low crystalline carbon on the surface increases. When the value of IA / IB is less than 0.2, the proportion of low crystalline carbon on the surface of the graphite decreases, and it becomes difficult to sufficiently increase the acceptability of lithium ions. On the other hand, when the value of IA / IB exceeds 0.3, the amount of low crystalline carbon increases, the proportion of graphite decreases, and the battery capacity decreases due to the configuration of the negative electrode active material layer 122.

また、本発明における非水電解液二次電池において、非水電解液の非水系溶媒としては、たとえば、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、ブチレンカーボネート（ＢＣ）、ジエチルカーボネート（ＤＥＣ）、ジメチルカーボネート（ＤＭＣ）、エチルメチルカーボネート（ＥＭＣ）、ガンマブチロラクトン（ＧＢＬ）、１，２−ジメトキシエタン（ＤＭＥ）、メチルアセテート（ＭＡ）、メチルプロピネート（ＭＰ）、エチルアセテート（ＥＡ）等を単独または２種類以上混合させて使用することができる。また、非水電解液二次電池のサイクル性能をさらに向上させるために、非水電解液の非水系溶媒にビニレンカーボネート（ＶＣ）やビニルエチレンカーボネート（ＶＥＣ）を混合させることが好ましい。ビニレンカーボネート（ＶＣ）またはビニルエチレンカーボネート（ＶＥＣ）の混合量は、サイクル性能の観点から、非水電解液の総重量に対し、０．１重量部〜５重量部であることが好ましい。その混合量が０．１重量部より少ないと、サイクル特性向上の効果が得られにくく、５重量部より多いと、負極上で非水系溶媒の還元分解生成物が多くなりすぎて、電池の出力性能が低下する。   In the non-aqueous electrolyte secondary battery of the present invention, examples of the non-aqueous solvent for the non-aqueous electrolyte include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and diethyl carbonate (DEC). Dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), gamma butyrolactone (GBL), 1,2-dimethoxyethane (DME), methyl acetate (MA), methyl propionate (MP), ethyl acetate (EA), etc. It can be used alone or in combination of two or more. In order to further improve the cycle performance of the non-aqueous electrolyte secondary battery, it is preferable to mix vinylene carbonate (VC) or vinyl ethylene carbonate (VEC) with the non-aqueous solvent of the non-aqueous electrolyte. The amount of vinylene carbonate (VC) or vinyl ethylene carbonate (VEC) mixed is preferably 0.1 to 5 parts by weight with respect to the total weight of the non-aqueous electrolyte from the viewpoint of cycle performance. If the mixing amount is less than 0.1 parts by weight, it is difficult to obtain the effect of improving the cycle characteristics. If the mixing amount is more than 5 parts by weight, the reductive decomposition product of the non-aqueous solvent is excessively increased on the negative electrode. Performance decreases.

上記の非水電解液において、非水系溶媒に溶解させる電解質としては、非水電解液二次電池において一般に使用されているものを用いることができ、たとえば、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＮ（Ｃ２Ｆ６ＳＯ２）２、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ４Ｆ９ＳＯ２）、ＬｉＣ（Ｃ２Ｆ５ＳＯ２）３、ＬｉＡｓＦ６、ＬｉＣｌＯ４等を単独または２種類以上混合させて使用することができる。電解質の量は溶媒総重量に対して、０．５ｍｏｌ％〜１．５ｍｏｌ％であることが好ましい。電解質の量が０．５ｍｏｌ％以下であると、十分な電解液の伝導率が得られず、出力特性が低下し、１．５ｍｏｌ％以上であると、電解液の粘度が高くなりすぎ、イオン拡散速度が低下し、電池の出力特性が低下する。 In the above non-aqueous electrolyte, as the electrolyte dissolved in the non-aqueous solvent, those generally used in non-aqueous electrolyte secondary batteries can be used. For example, LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 6 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 LiClO 4 or the like can be used alone or in admixture of two or more. The amount of the electrolyte is preferably 0.5 mol% to 1.5 mol% with respect to the total weight of the solvent. If the amount of the electrolyte is 0.5 mol% or less, sufficient conductivity of the electrolytic solution cannot be obtained, and output characteristics are deteriorated. If the amount is 1.5 mol% or more, the viscosity of the electrolytic solution becomes too high, and the ion The diffusion rate is lowered, and the output characteristics of the battery are lowered.

また、上記の非水電解液に含有させるオキサラト錯体をアニオンとするリチウム塩としては、具体的にはリチウム−ビス（オキサラト）ボレート、ジフルオロ（オキサラト）ホウ酸リチウム、テトラフルオロ（オキサラト）リン酸リチウム等を用いることができる。   Moreover, as lithium salt which uses the oxalato complex contained in said non-aqueous electrolyte as an anion, specifically, lithium-bis (oxalato) borate, difluoro (oxalato) lithium borate, tetrafluoro (oxalato) lithium phosphate Etc. can be used.

正極１１と負極１２を電気的に絶縁するセパレータ１３としては、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、ポリエチレンテレフタレート（ＰＥＴ）から選ばれる１種以上から構成される微多孔膜を用いることができる。この微多孔膜には、アルミナ(Ａｌ２Ｏ３)、シリカ(ＳｉＯ２)、チタニア(ＴｉＯ２)などのフィラーが含まれていてもよい。上記のフィラーとバインダとしての樹脂とのみからセパレータが形成されていてもよい。 As the separator 13 that electrically insulates the positive electrode 11 and the negative electrode 12, a microporous film composed of at least one selected from polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) can be used. This microporous film may contain a filler such as alumina (Al 2 O 3 ), silica (SiO 2 ), and titania (TiO 2 ). The separator may be formed only from the filler and the resin as the binder.

本発明の非水電解液二次電池において、正極１１に用いる正極活物質層１１２の材料としては、非水電解液二次電池において一般に使用されているものを用いることができ、たとえば、コバルト酸リチウム（ＬｉＣｏＯ２）、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）、ニッケル酸リチウム（ＬｉＮｉＯ２）等のリチウム遷移金属複合酸化物や、リン酸鉄リチウム（ＬｉＦｅＰＯ４）等のリチウム含有リン酸塩等を用いることができる。また、正極活物質層１１２の材料としては、上記のリチウム遷移金属複合酸化物における遷移金属の一部を他の金属元素で置換させたものを用いることも可能であり、このような金属元素としては、コバルト（Ｃｏ）、ニッケル（Ｎｉ）、バナジウム（Ｖ）、マンガン（Ｍｎ）、ジルコニウム（Ｚｒ）、チタン（Ｔｉ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、鉄（Ｆｅ）、ニオブ（Ｎｂ）、モリブデン（Ｍｏ）から選択される１種又は２種以上を用いることができる。さらに、正極活物質層１１２の材料としては、上記のような正極活物質を混合したものを用いることも可能である。 In the non-aqueous electrolyte secondary battery of the present invention, as the material of the positive electrode active material layer 112 used for the positive electrode 11, those generally used in non-aqueous electrolyte secondary batteries can be used. For example, cobalt acid Lithium transition metal composite oxides such as lithium (LiCoO 2 ), lithium manganate (LiMn 2 O 4 ), lithium nickelate (LiNiO 2 ), lithium-containing phosphates such as lithium iron phosphate (LiFePO 4 ), etc. Can be used. Further, as the material of the positive electrode active material layer 112, a material obtained by substituting a part of the transition metal in the lithium transition metal composite oxide with another metal element can be used. Is cobalt (Co), nickel (Ni), vanadium (V), manganese (Mn), zirconium (Zr), titanium (Ti), zinc (Zn), aluminum (Al), iron (Fe), niobium (Nb) 1 type, or 2 or more types selected from molybdenum (Mo). Further, as the material of the positive electrode active material layer 112, a mixture of the positive electrode active materials as described above can be used.

本発明の非水電解液二次電池において、正極１１の正極活物質層１１２を作製するにあたっては、上記のような正極活物質の他に、炭素材料などの導電剤と、ポリフッ化ビニリデンなどの結着剤を加えた正極合剤を用いることができる。そして、この正極合剤中に導電剤として炭素材料を加える場合、正極合剤中における炭素材料の量を３重量％〜１５重量％の範囲内にすることが好ましい。また、正極活物質層１１２中における上記の導電剤と結着剤との合計量は、エネルギー密度を確保する観点から、１０重量％以下であることが好ましい。また、導電剤に用いる炭素材料としては、たとえば、アセチレンブラック等の塊状炭素や繊維状炭素等を用いることができる。   In preparing the positive electrode active material layer 112 of the positive electrode 11 in the non-aqueous electrolyte secondary battery of the present invention, in addition to the positive electrode active material as described above, a conductive agent such as a carbon material and polyvinylidene fluoride or the like A positive electrode mixture to which a binder is added can be used. And when adding a carbon material as a electrically conductive agent in this positive electrode mixture, it is preferable to make the quantity of the carbon material in a positive electrode mixture into the range of 3 weight%-15 weight%. Moreover, it is preferable that the total amount of said electrically conductive agent and binder in the positive electrode active material layer 112 is 10 weight% or less from a viewpoint of ensuring an energy density. Further, as the carbon material used for the conductive agent, for example, bulk carbon such as acetylene black, fibrous carbon, or the like can be used.

以下のようにして作製した正極１１と負極１２と非水電解液とを用いて、付加層１４としてのチタン酸リチウム層の厚みやチタン酸リチウムの平均粒径を表１に示すように異ならせることにより、付加層１４を形成した実施例１〜１２の非水電解液二次電池を作製した。また、付加層１４を形成しない比較例１〜２の非水電解液二次電池も作製した。   Using the positive electrode 11, the negative electrode 12, and the non-aqueous electrolyte produced as follows, the thickness of the lithium titanate layer as the additional layer 14 and the average particle diameter of the lithium titanate are varied as shown in Table 1. Thereby, the nonaqueous electrolyte secondary battery of Examples 1-12 in which the additional layer 14 was formed was produced. In addition, non-aqueous electrolyte secondary batteries of Comparative Examples 1 and 2 in which the additional layer 14 was not formed were also produced.

（実施例１）
実施例１においては、以下のようにして作製した正極１１と負極１２と非水電解液とを用い、図１に示すような積層型の電池要素１０を備え、電池容量が２０ｍＡｈである非水電解液二次電池を作製した。 Example 1
In Example 1, a non-aqueous battery having a stacked battery element 10 as shown in FIG. 1 and a battery capacity of 20 mAh using a positive electrode 11, a negative electrode 12, and a non-aqueous electrolyte prepared as follows. An electrolyte secondary battery was produced.

［正極の作製］
正極活物質としてＬｉ１．０１（Ｎｉ０．３３Ｃｏ０．３３Ｍｎ０．３３）Ｏ２を用い、この正極活物質と、導電剤の炭素材料と、結着剤のポリフッ化ビニリデンを溶解させたＮ−メチル−２−ピロリドン（ＮＭＰ）溶液とを、正極活物質と導電剤と結着剤との重量比が９０：５：５になるように調製した。この調製されたものを混練して正極合剤スラリーを作製した。この正極合剤スラリーをアルミニウム箔からなる正極集電体１１１の上に塗布したものを乾燥させて圧延ローラーにより圧延し、これに集電タブを取り付けて正極１１を作製した。 [Production of positive electrode]
Li 1.01 (Ni 0.33 Co 0.33 Mn 0.33 ) O 2 was used as the positive electrode active material, and this positive electrode active material, the carbon material of the conductive agent, and the polyvinylidene fluoride of the binder were dissolved. The N-methyl-2-pyrrolidone (NMP) solution was prepared so that the weight ratio of the positive electrode active material, the conductive agent, and the binder was 90: 5: 5. The prepared mixture was kneaded to prepare a positive electrode mixture slurry. What apply | coated this positive mix slurry on the positive electrode collector 111 which consists of aluminum foil was dried, and it rolled with the rolling roller, and the current collection tab was attached to this, and the positive electrode 11 was produced.

このときの単位面積あたりの正極合材の目付け量を６．５ｍｇ／ｃｍ２、充填密度を２．８ｇ／ｃｃとした。正極１１の寸法を５０ｍｍ×５０ｍｍとした。この正極１１の単位容量を、電解液の電解質として１ｍｏｌ／ＬのＬｉＰＦ６、溶媒としてエチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）とを３：７の体積比で混合した混合溶媒を用い、対極にリチウム金属を用いて、充電１０ｍＡ−４．３Ｖ、放電１０ｍＡ−２．５Ｖにて測定した。その結果、１ｇ当たり１５０ｍＡｈの単位容量を得た。 At this time, the basis weight of the positive electrode mixture per unit area was 6.5 mg / cm 2 , and the packing density was 2.8 g / cc. The dimension of the positive electrode 11 was 50 mm × 50 mm. The unit capacity of the positive electrode 11 is 1 mol / L LiPF 6 as an electrolyte of an electrolytic solution, and a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 3: 7 as a solvent. Using lithium metal, the measurement was performed at a charge of 10 mA-4.3 V and a discharge of 10 mA-2.5 V. As a result, a unit capacity of 150 mAh per 1 g was obtained.

［負極の作製］
負極活物質として、低結晶性炭素で被覆された平均粒径１５μｍの球状天然黒鉛粒子を用いた。そして、この低結晶性炭素被覆天然黒鉛からなる負極活物質と、結着剤のポリアクリロニトリル変性体（ＰＡＮ）をＮ−メチル−２−ピロリドン溶液に溶解させた溶液とを、負極活物質と結着剤の重量比が９５：５になるように調製した。この調製されたものを混練して負極合剤スラリーを作製した。この負極合剤スラリーを銅箔からなる負極集電体１２１の上に塗布したものを温度１２０℃で乾燥した。 [Production of negative electrode]
As the negative electrode active material, spherical natural graphite particles having an average particle diameter of 15 μm and coated with low crystalline carbon were used. Then, a negative electrode active material comprising the low crystalline carbon-coated natural graphite and a solution obtained by dissolving a polyacrylonitrile modified PAN (PAN) as a binder in an N-methyl-2-pyrrolidone solution are combined with the negative electrode active material. The weight ratio of the adhesive was adjusted to 95: 5. The prepared mixture was kneaded to prepare a negative electrode mixture slurry. What apply | coated this negative mix slurry on the negative electrode collector 121 which consists of copper foils was dried at the temperature of 120 degreeC.

このときの単位面積あたりの負極合材の目付け量を４ｍｇ／ｃｍ２、充填密度を１．５ｇ／ｃｃとした。負極１２の寸法を５２ｍｍ×５２ｍｍとした。この負極１２の単位容量は、電解液の電解質として１ｍｏｌ／ＬのＬｉＰＦ６、溶媒としてエチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）とを３：７の体積比で混合した混合溶媒を用い、対極にリチウム金属を用いて、充電１０ｍＡ−０．０１Ｖ、放電１０ｍＡ−１．０Ｖにて測定した。その結果、１ｇ当たり３５０ｍＡｈの単位容量を得た。 At this time, the basis weight of the negative electrode mixture per unit area was 4 mg / cm 2 , and the packing density was 1.5 g / cc. The dimension of the negative electrode 12 was set to 52 mm × 52 mm. The unit capacity of the negative electrode 12 is 1 mol / L LiPF 6 as the electrolyte of the electrolytic solution, and a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 3: 7 as the solvent. Using lithium metal, the measurement was performed at a charge of 10 mA-0.01 V and a discharge of 10 mA-1.0 V. As a result, a unit capacity of 350 mAh per 1 g was obtained.

[リチウム含有チタン酸化物層の作製]
リチウム含有チタン酸化物として平均粒径が５μｍのチタン酸リチウム（Ｌｉ４Ｔｉ５Ｏ１２）と、結着剤としてのポリアクリロニトリル変性体とを重量比率が９７．５：２．５になるようにＮ−メチル−２−ピロリドンに溶解させて、固形分濃度が３０重量％となるようにＮ−メチル−２−ピロリドン溶液を作製した。その後、上記で作製した負極１２の負極活物質層１２２の表面上に、ドクターブレード法により、付加層１４としてのチタン酸リチウム層の乾燥後厚みが１０μｍとなるように上記の溶液を塗布した後、温度１２０℃で乾燥したものをロールプレス機により圧延し、これに集電リードを取り付けて、両面に付加層１４が形成された負極１２を作製した。 [Preparation of lithium-containing titanium oxide layer]
The lithium titanate (Li 4 Ti 5 O 12 ) having an average particle size of 5 μm as the lithium-containing titanium oxide and the polyacrylonitrile modified product as the binder are adjusted to have a weight ratio of 97.5: 2.5. An N-methyl-2-pyrrolidone solution was prepared by dissolving in N-methyl-2-pyrrolidone to a solid content concentration of 30% by weight. Then, after apply | coating said solution on the surface of the negative electrode active material layer 122 of the negative electrode 12 produced above by the doctor blade method so that the thickness after drying of the lithium titanate layer as the additional layer 14 may become 10 micrometers. What was dried at a temperature of 120 ° C. was rolled with a roll press, and current collecting leads were attached thereto, thereby producing a negative electrode 12 having an additional layer 14 formed on both sides.

［非水電解液の作製］
非水系溶媒として、エチレンカーボネート（ＥＣ）と鎖状カーボネートであるジエチルカーボネート（ＤＥＣ）とを１：２の体積比で混合した混合溶媒を用い、この混合溶媒に電解質のＬｉＰＦ６を１ｍｏｌ／Ｌの濃度になるように溶解させて、非水電解液を作製した。 [Preparation of non-aqueous electrolyte]
As a non-aqueous solvent, a mixed solvent in which ethylene carbonate (EC) and chain carbonate diethyl carbonate (DEC) were mixed at a volume ratio of 1: 2 was used. In this mixed solvent, electrolyte LiPF 6 was added at 1 mol / L. It was made to melt | dissolve so that it might become a density | concentration, and the nonaqueous electrolyte solution was produced.

［電池の作製］
電池を作製するにあたっては、図１に示すように、上記のようにして作製した正極１１と負極１２との間に、セパレータ１３としてリチウムイオン透過性のポリエチレン製の微多孔膜を介在させ、これらを重ね合わせて、電池要素１０を形成した。この電池要素１０を、長方形のアルミニウムラミネートフィルムに封入し、三方辺を温度８０℃で熱融着した後、上記で作製した０．３ｇの非水電解液をアルミニウムラミネートフィルムの開口部から注入して、アルミニウムラミネートフィルムの開口部を熱融着することにより、リチウムイオン二次電池を作製した。 [Production of battery]
In producing the battery, as shown in FIG. 1, a lithium ion-permeable polyethylene microporous film is interposed as a separator 13 between the positive electrode 11 and the negative electrode 12 produced as described above, The battery element 10 was formed by superimposing. The battery element 10 was sealed in a rectangular aluminum laminate film, and three sides were heat-sealed at a temperature of 80 ° C., and then 0.3 g of the non-aqueous electrolyte prepared above was injected from the opening of the aluminum laminate film. Thus, a lithium ion secondary battery was manufactured by heat-sealing the opening of the aluminum laminate film.

[電池容量測定]
上記で作製したリチウムイオン二次電池に、充電電流を１０ｍＡとして電圧が４．２Ｖになるまで充電して、１０分間放置した後、放電電流を１０ｍＡとして電圧が３．０Ｖになるまで放電した。このときに得られた放電容量を電池容量とした。 [Battery capacity measurement]
The lithium ion secondary battery produced above was charged with a charging current of 10 mA until the voltage reached 4.2 V, allowed to stand for 10 minutes, and then discharged with a discharge current of 10 mA until the voltage reached 3.0 V. The discharge capacity obtained at this time was defined as the battery capacity.

[出力特性測定]
上記の電池容量の測定を５回繰り返した後、リチウムイオン二次電池に、電圧が４．２Ｖになるまで充電し、１０分間放置した。その後、放電電流を１０ｍＡ、２０ｍＡ、３０ｍＡとして、各放電電流にて１０秒間放電した際の到達電圧を電流値に対してプロットしたときの傾きから直流抵抗（ＤＣＲ）を算出した。 [Output characteristics measurement]
After the above battery capacity measurement was repeated five times, the lithium ion secondary battery was charged until the voltage reached 4.2 V and left for 10 minutes. Thereafter, the discharge current was set to 10 mA, 20 mA, and 30 mA, and the direct current resistance (DCR) was calculated from the slope when the ultimate voltage at the time of discharging for 10 seconds at each discharge current was plotted against the current value.

（実施例２）
付加層１４の形成において、チタン酸リチウムの平均粒径を１０μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 2)
In the formation of the additional layer 14, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the average particle size of lithium titanate was 10 μm, and the DCR was calculated.

（実施例３）
付加層１４の形成において、チタン酸リチウムの平均粒径を１μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 3)
In the formation of the additional layer 14, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the average particle size of lithium titanate was 1 μm, and the DCR was calculated.

（実施例４）
付加層１４の形成において、チタン酸リチウムの平均粒径を０．５μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 Example 4
In the formation of the additional layer 14, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the average particle size of lithium titanate was 0.5 μm, and the DCR was calculated.

（実施例５）
付加層１４の形成において、チタン酸リチウムを含む上記の溶液を塗布するときに、チタン酸リチウム層の乾燥後厚みを３０μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 5)
In the formation of the additional layer 14, a lithium ion secondary battery was fabricated in the same manner as in Example 1 except that when the above solution containing lithium titanate was applied, the thickness after drying of the lithium titanate layer was 30 μm. Prepared and calculated DCR.

（実施例６）
付加層１４の形成において、チタン酸リチウムを含む上記の溶液を塗布するときに、チタン酸リチウム層の乾燥後厚みを５０μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 6)
In the formation of the additional layer 14, a lithium ion secondary battery was fabricated in the same manner as in Example 1 except that when the above solution containing lithium titanate was applied, the thickness after drying of the lithium titanate layer was 50 μm. Prepared and calculated DCR.

（実施例７）
チタン酸リチウムを含む上記の溶液を塗布するときに乾燥後厚みが１０μｍとなるように、付加層１４としてのチタン酸リチウム層を、セパレータ１３としてのポリエチレン製の微多孔膜の片面に形成したものを作製し、このチタン酸リチウム層が負極１２と対向するようにリチウムイオン二次電池を組み立てたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 7)
What formed the lithium titanate layer as the additional layer 14 on one side of the microporous film made of polyethylene as the separator 13 so that the thickness after drying was 10 μm when the above solution containing lithium titanate was applied A lithium ion secondary battery was produced in the same manner as in Example 1 except that the lithium ion secondary battery was assembled so that the lithium titanate layer faced the negative electrode 12, and the DCR was calculated.

（実施例８）
付加層１４の形成において、チタン酸リチウムの平均粒径を２０μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 8)
In the formation of the additional layer 14, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the average particle size of lithium titanate was 20 μm, and the DCR was calculated.

（実施例９）
付加層１４の形成において、チタン酸リチウムの平均粒径を０．１μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 Example 9
In the formation of the additional layer 14, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the average particle diameter of lithium titanate was 0.1 μm, and the DCR was calculated.

（実施例１０）
付加層１４の形成において、チタン酸リチウムを含む上記の溶液を塗布するときに、チタン酸リチウム層の乾燥後厚みを５μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 10)
In the formation of the additional layer 14, a lithium ion secondary battery was fabricated in the same manner as in Example 1 except that when the above solution containing lithium titanate was applied, the thickness after drying of the lithium titanate layer was 5 μm. Prepared and calculated DCR.

（実施例１１）
付加層１４の形成において、チタン酸リチウムを含む上記の溶液を塗布するときに、チタン酸リチウム層の乾燥後厚みを１００μｍとしたこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Example 11)
In the formation of the additional layer 14, a lithium ion secondary battery was fabricated in the same manner as in Example 1 except that when the above solution containing lithium titanate was applied, the thickness after drying of the lithium titanate layer was 100 μm. Prepared and calculated DCR.

（実施例１２）
負極１２の作製において、負極活物質として、低結晶性炭素で被覆していない黒鉛材料を用いたこと以外は実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 Example 12
In the production of the negative electrode 12, a lithium ion secondary battery was produced in the same manner as in Example 1 except that a graphite material not coated with low crystalline carbon was used as the negative electrode active material, and DCR was calculated.

（比較例１）
負極１２の作製において、付加層１４を形成しなかったこと以外は、実施例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Comparative Example 1)
In the production of the negative electrode 12, a lithium ion secondary battery was produced in the same manner as in Example 1 except that the additional layer 14 was not formed, and the DCR was calculated.

（比較例２）
負極１２の作製において、実施例１で用いた低結晶性炭素で被覆された黒鉛と平均粒径が５μｍのチタン酸リチウム粒子とを重量比２：１で混合したものと、結着剤としてのポリアクリロニトリル（ＰＡＮ）とをＮ−メチル−２−ピロリドンに溶解させたものを、低結晶性炭素で被覆された黒鉛およびチタン酸リチウムを含有する溶液とした。この溶液においては、低結晶性炭素で被覆された黒鉛とチタン酸リチウムの混合物と結着剤との重量比が９５：５になるように調製されている。この調製されたものを混練して負極合剤スラリーを作製したこと以外は、比較例１と同様にしてリチウムイオン二次電池を作製し、ＤＣＲを算出した。 (Comparative Example 2)
In the production of the negative electrode 12, a mixture of the graphite coated with the low crystalline carbon used in Example 1 and lithium titanate particles having an average particle diameter of 5 μm in a weight ratio of 2: 1 and a binder A solution of polyacrylonitrile (PAN) dissolved in N-methyl-2-pyrrolidone was used as a solution containing graphite coated with low crystalline carbon and lithium titanate. This solution is prepared so that the weight ratio of the mixture of graphite and lithium titanate coated with low crystalline carbon to the binder is 95: 5. A lithium ion secondary battery was prepared in the same manner as in Comparative Example 1 except that the prepared mixture was kneaded to prepare a negative electrode mixture slurry, and DCR was calculated.

以上の実施例１〜１２と比較例１〜２で算出したＤＣＲを表１に示す。   Table 1 shows the DCR calculated in Examples 1-12 and Comparative Examples 1-2.

Figure 2010192230
Figure 2010192230

表１から、付加層１４中のチタン酸リチウムの平均粒径が０．５μｍ〜１０μｍ（実施例１〜実施例４）、チタン酸リチウム層の乾燥後厚みが１０μｍ〜５０μｍ（実施例１、実施例５、実施例６）の範囲において、比較例１に示すように付加層１４が形成されない負極１２を用いたリチウムイオン二次電池と比べて、飛躍的にＤＣＲが低減され、出力特性が向上することがわかる。   From Table 1, the average particle diameter of lithium titanate in the additional layer 14 is 0.5 μm to 10 μm (Example 1 to Example 4), and the thickness after drying of the lithium titanate layer is 10 μm to 50 μm (Example 1, Implementation). In the range of Example 5 and Example 6), as shown in Comparative Example 1, compared with the lithium ion secondary battery using the negative electrode 12 in which the additional layer 14 is not formed, the DCR is drastically reduced and the output characteristics are improved. I understand that

実施例９では、チタン酸リチウムの平均粒径が小さすぎると、チタン酸リチウムと負極１２の表面との接触点が増加し、バインダ量が不足するため、十分な密着ができず、出力特性が低下していることが考えられ、実施例８では、チタン酸リチウムの平均粒径が大きすぎると、負極１２の表面への電解液の拡散をチタン酸リチウムが阻害し、出力特性が低下するものと考えられる。また、実施例７では、付加層１４としてのチタン酸リチウム層を負極活物質層側ではなく、セパレータに形成した場合でも実施例１と遜色のない結果が得られた。   In Example 9, if the average particle size of lithium titanate is too small, the contact point between the lithium titanate and the surface of the negative electrode 12 increases, and the amount of the binder is insufficient, so that sufficient adhesion cannot be achieved and the output characteristics are low. In Example 8, when the average particle size of lithium titanate is too large, the lithium titanate inhibits the diffusion of the electrolytic solution to the surface of the negative electrode 12 and the output characteristics are deteriorated. it is conceivable that. Moreover, in Example 7, even when the lithium titanate layer as the additional layer 14 was formed not on the negative electrode active material layer side but on the separator, the same result as in Example 1 was obtained.

また、実施例１０では、チタン酸リチウム層の乾燥後厚みが薄いと、負極界面抵抗を低減する効果が得られがたく、実施例１１では、チタン酸リチウム層の乾燥後厚みが厚いと、正負極の極間距離が大きくなり、出力特性が低下するものと考えられる。   In Example 10, it is difficult to obtain the effect of reducing the negative electrode interface resistance when the thickness of the lithium titanate layer after drying is small. In Example 11, when the thickness of the lithium titanate layer after drying is large, It is considered that the distance between the negative electrodes increases and the output characteristics deteriorate.

さらに、実施例１２では、負極活物質として黒鉛の表面を低結晶性炭素で被覆していない材料を用いた場合、出力特性が低減しなかった理由は不明であるが、結晶性の高い黒鉛とチタン酸リチウムが直接接触することによって、チタン酸リチウムが黒鉛の電位と平均化されていることが要因であると推測される。   Furthermore, in Example 12, when the material in which the surface of graphite is not coated with low crystalline carbon is used as the negative electrode active material, it is unclear why the output characteristics were not reduced. It is assumed that the lithium titanate is in direct contact with the lithium titanate and is averaged with the potential of graphite.

なお、比較例２に示すように、黒鉛とチタン酸リチウムを混合した材料からなる負極１２を用いたリチウムイオン二次電池では、黒鉛が正極１１に対向する負極１２の面に露出してしまうために、チタン酸リチウムによる電位降下抑制の効果が得られないので、出力特性が低下するものと考えられる。   As shown in Comparative Example 2, in the lithium ion secondary battery using the negative electrode 12 made of a material in which graphite and lithium titanate are mixed, graphite is exposed on the surface of the negative electrode 12 facing the positive electrode 11. Furthermore, since the effect of suppressing the potential drop by lithium titanate cannot be obtained, it is considered that the output characteristics are deteriorated.

以上のように、表１に示す結果から、本発明の構成を採用することにより、出力特性が飛躍的に向上したリチウムイオン二次電池を作製することが可能となることがわかる。   As described above, it can be seen from the results shown in Table 1 that by adopting the configuration of the present invention, it is possible to manufacture a lithium ion secondary battery with greatly improved output characteristics.

今回開示された実施の形態や実施例はすべての点で例示であって制限的なものではないと考慮されるべきである。本発明の範囲は以上の実施の形態や実施例ではなく、特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての修正や変形を含むものであることが意図される。   It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments or examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

例えば、電池要素１０として短冊状の正極、負極、セパレータが積層されて構成されたものに代えて、長尺状の正極、負極、セパレータを巻回した構造としてもよい。   For example, instead of the battery element 10 formed by laminating strip-shaped positive electrodes, negative electrodes, and separators, a structure in which long positive electrodes, negative electrodes, and separators are wound may be used.

１０：電池要素、１１：正極、１２：負極、１３：セパレータ、１４：付加層、１１１：正極集電体、１１２：正極活物質層、１１３：正極集端部、１２１：負極集電体、１２２：負極活物質層、１２３：負極集端部。


10: battery element, 11: positive electrode, 12: negative electrode, 13: separator, 14: additional layer, 111: positive electrode current collector, 112: positive electrode active material layer, 113: positive electrode current collector, 121: negative electrode current collector, 122: negative electrode active material layer, 123: negative electrode collecting portion.


Claims (5)

非水系溶媒に電解質を溶解させた非水系電解液を含む非水電解液二次電池であって、
負極集電体の表面上に配置された負極活物質層と、
前記負極活物質層の表面上に配置され、リチウム含有チタン酸化物を含む付加層とを備えた、非水電解液二次電池。 A non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte obtained by dissolving an electrolyte in a non-aqueous solvent,
A negative electrode active material layer disposed on the surface of the negative electrode current collector;
A non-aqueous electrolyte secondary battery comprising an additional layer disposed on a surface of the negative electrode active material layer and including a lithium-containing titanium oxide. 前記付加層の厚みが、１０μｍ以上５０μｍ以下である、請求項１に記載の非水電解液二次電池。   The nonaqueous electrolyte secondary battery according to claim 1, wherein the additional layer has a thickness of 10 μm or more and 50 μm or less. 前記リチウム含有チタン酸化物の平均粒径が、０．５μｍ以上１０μｍ以下である、請求項１または請求項２に記載の非水電解液二次電池。   The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein an average particle size of the lithium-containing titanium oxide is 0.5 µm or more and 10 µm or less. 前記負極活物質層は炭素材料を含む、請求項１に記載の非水電解液二次電池。   The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode active material layer includes a carbon material. 前記炭素材料は、結晶化度の高い炭素からなる芯材と、前記芯材の表面の少なくとも一部を被覆し、結晶化度の低い炭素からなる表面層とを含む、請求項４に記載の非水電解液二次電池。   5. The carbon material according to claim 4, comprising: a core material made of carbon with a high degree of crystallinity; and a surface layer made of carbon with a low degree of crystallinity covering at least a part of the surface of the core material. Non-aqueous electrolyte secondary battery.
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