JP2005135864A - Nonaqueous electrolyte secondary battery and manufacturing method of the same - Google Patents

Nonaqueous electrolyte secondary battery and manufacturing method of the same Download PDF

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JP2005135864A
JP2005135864A JP2003373350A JP2003373350A JP2005135864A JP 2005135864 A JP2005135864 A JP 2005135864A JP 2003373350 A JP2003373350 A JP 2003373350A JP 2003373350 A JP2003373350 A JP 2003373350A JP 2005135864 A JP2005135864 A JP 2005135864A
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composite oxide
lithium
transition metal
secondary battery
electrolyte secondary
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Hideki Kitao
英樹 北尾
Toyoki Fujiwara
豊樹 藤原
Takaaki Ikemachi
隆明 池町
Toshiyuki Noma
俊之 能間
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Sanyo Electric Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery having a positive electrode containing lithium-transition metal complex oxide and lithium-manganese complex oxide as activators, with an improved high temperature preservation property. <P>SOLUTION: The nonaqueous electrolyte secondary battery has the positive electrode having a current collector containing lithium-transition metal complex oxide containing at least Ni and Mn on one surface, and lithium-manganese complex oxide on the other surface. The lithium-transition metal complex oxide contains Co, and has a spinel structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は非水電解質二次電池に関わり、特に高温保存耐久性の改善に関するものである。   The present invention relates to a non-aqueous electrolyte secondary battery, and particularly relates to improvement of high-temperature storage durability.

非水電解質二次電池の正極活物質の例としては、コバルト酸リチウム（ＬｉＣｏＯ2）が代表的なものとして挙げられ、既に非水電解質二次電池の正極活物質として実用化されている。しかし、コバルト酸リチウムを単独で用いた場合には、コバルト酸リチウムの構造劣化や正極表面における電解液の分解が原因となり、充放電サイクルに伴う容量低下が認められていた。 A typical example of a positive electrode active material for a non-aqueous electrolyte secondary battery is lithium cobaltate (LiCoO 2 ), which has already been put into practical use as a positive electrode active material for a non-aqueous electrolyte secondary battery. However, when lithium cobaltate was used alone, the capacity was reduced due to charge / discharge cycles due to structural deterioration of lithium cobaltate and decomposition of the electrolyte on the positive electrode surface.

そこで近年、正極活物質として、リチウムマンガン複合酸化物、特にスピネル構造を持つマンガン酸リチウムが注目されるようになった。リチウムマンガン複合酸化物は、コバルト酸リチウムのような層状構造とは異なる三次元のホスト構造を有するため理論容量の大部分が使用可能であり、サイクル特性に優れることが期待されている。しかしながら、リチウムマンガン複合酸化物を用いた電池においては、充電に伴う相変化による構造劣化が生じ、電池特性が低下するという問題があった。特許文献１においては、このようなリチウムマンガン複合酸化物であるマンガン酸リチウムにＬｉ−Ｎｉ−Ｃｏ複合酸化物を混合することにより、高温保存時の劣化を抑制する方法が提案されている。
特許第３０２４６３６号公報 上記に開示された正極は、正極活物質としてマンガン酸リチウムとＬｉ−Ｎｉ−Ｃｏ複合酸化物との混合物を使用し、電解液に対するマンガン酸リチウムの安定性の向上、すなわちマンガンの溶出、電解液との反応、酸素の放出等の抑制を図っているが、それでも十分な高温保存特性が得られたとは言い難く、さらなる特性の向上が求められている。 Accordingly, in recent years, lithium manganese composite oxides, particularly lithium manganate having a spinel structure, have attracted attention as positive electrode active materials. Since the lithium manganese composite oxide has a three-dimensional host structure different from the layered structure such as lithium cobaltate, most of the theoretical capacity can be used, and it is expected to have excellent cycle characteristics. However, a battery using a lithium manganese composite oxide has a problem that structural deterioration occurs due to a phase change accompanying charging, and battery characteristics are deteriorated. Patent Document 1 proposes a method for suppressing deterioration during high-temperature storage by mixing Li-Ni-Co composite oxide with lithium manganate, which is such a lithium manganese composite oxide.
Patent No. 3024636 The positive electrode disclosed above uses a mixture of lithium manganate and Li—Ni—Co composite oxide as the positive electrode active material, and improves the stability of lithium manganate relative to the electrolyte, ie, manganese. Although elution, reaction with the electrolytic solution, and release of oxygen are attempted, it is still difficult to say that sufficient high-temperature storage characteristics have been obtained, and further improvement of characteristics is required.

本発明の目的は、リチウムマンガン複合酸化物とリチウム遷移金属複合酸化物とを正極活物質として用いた非水電解質二次電池において、高温保存特性に優れた非水電解質二次電池及びその正極を提供することにある。   An object of the present invention is to provide a nonaqueous electrolyte secondary battery using a lithium manganese composite oxide and a lithium transition metal composite oxide as a positive electrode active material, a nonaqueous electrolyte secondary battery excellent in high-temperature storage characteristics, and a positive electrode thereof. It is to provide.

本発明の非水電解質二次電池は、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とを活物質としてなる正極を有する非水電解質二次電池において、前記リチウム遷移金属複合酸化物と前記リチウムマンガン複合酸化物とがそれぞれ集電体の異なる面に配置されていることを特徴とする。   The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery having a positive electrode using a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide as active materials. The metal composite oxide and the lithium manganese composite oxide are respectively disposed on different surfaces of the current collector.

非水電解質二次電池の正極活物質として、リチウムマンガン複合酸化物とＬｉ−Ｎｉ−Ｃｏ複合酸化物、Ｌｉ−Ｎｉ−Ｍｎ複合酸化物などのＬｉ−Ｎｉ複合酸化物との混合物を用いて正極を作製する場合には、該混合物のスラリーを集電体に塗布して圧延する。この際、圧延しても充填されにくいリチウムマンガン複合酸化物よりも、加圧によって充填されやすいＬｉ−Ｎｉ複合酸化物が優先的に充填する。さらには、周囲のリチウムマンガン複合酸化物に押しつぶされＬｉ−Ｎｉ複合酸化物粒子が割れることが予想される。上記の理由により、十分な保存特性が得られないと考えられる。   As a positive electrode active material of a nonaqueous electrolyte secondary battery, a positive electrode using a mixture of a lithium manganese composite oxide and a Li—Ni composite oxide such as a Li—Ni—Co composite oxide or a Li—Ni—Mn composite oxide Is produced, the slurry of the mixture is applied to a current collector and rolled. At this time, the Li—Ni composite oxide that is easily filled by pressurization is preferentially filled rather than the lithium manganese composite oxide that is difficult to be filled even when rolled. Furthermore, it is expected that the Li—Ni composite oxide particles are cracked by being crushed by the surrounding lithium manganese composite oxide. For the above reasons, it is considered that sufficient storage characteristics cannot be obtained.

一方、本発明においては、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とを、それぞれ集電体の異なる面に配置しているため、前記リチウム遷移金属複合酸化物の割れを防止することができると考えられる。これにより、リチウムマンガン複合酸化物と前記遷移金属複合酸化物とを正極活物質として用いる効果、つまり、リチウムマンガン複合酸化物の電解液に対する安定性がより向上する。従って十分な保存特性が得られるのである。   On the other hand, in the present invention, the lithium transition metal composite oxide containing at least Ni and Mn and the lithium manganese composite oxide are disposed on different surfaces of the current collector, respectively. It is thought that the cracking of can be prevented. Thereby, the effect which uses lithium manganese complex oxide and the said transition metal complex oxide as a positive electrode active material, ie, the stability with respect to the electrolyte solution of lithium manganese complex oxide, improves more. Therefore, sufficient storage characteristics can be obtained.

本発明に用いるリチウム遷移金属複合酸化物は、遷移金属として少なくともＮｉとＭｎを含むものである。遷移金属としては、ＮｉやＭｎのほかに、Ｂ、Ｍｇ、Ａｌ、Ｔｉ、Ｖ、Ｆｅ、Ｃｏ、Ｃｕ、Ｚｎ、Ｇａ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｓｎ、ＰおよびＩｎから選択される少なくとも一種の元素をさらに含んでいても良いが、特に、コバルトを含むことが好ましい。従って、本発明におけるリチウム遷移金属複合酸化物は、式ＬｉaＭｎxＮｉyＣｏzＯ2（ここで、ａ、ｘ、ｙ及びｚは、０≦ａ≦１．２、ｘ＋ｙ＋ｚ＝１、ｘ≧０、ｙ≧０、及びｚ≧０を満足する数である。）で表わすことができる。 The lithium transition metal composite oxide used in the present invention contains at least Ni and Mn as transition metals. As the transition metal, in addition to Ni and Mn, at least selected from B, Mg, Al, Ti, V, Fe, Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Sn, P and In One kind of element may be further contained, but in particular, cobalt is preferably contained. Therefore, the lithium transition metal composite oxide in the present invention has the formula Li a Mn x Ni y Co z O 2 (where a, x, y and z are 0 ≦ a ≦ 1.2, x + y + z = 1, x ≧ 0, y ≧ 0, and z ≧ 0.).

また、本発明において用いるリチウムマンガン複合酸化物は、式ＬｉaＭｎbＯ4（ここで、ａ及びｂは、０≦ａ≦１．２、０≦ｂ≦１．８を満足する数である。）で表わすことができる。 Further, the lithium manganese composite oxide used in the present invention has the formula Li a Mn b O 4 (where a and b are numbers satisfying 0 ≦ a ≦ 1.2 and 0 ≦ b ≦ 1.8). .)

特に、前記リチウムマンガン複合酸化物はスピネル構造を有することが好ましい。スピネル構造を有するリチウムマンガン複合酸化物は、リチウムマンガン複合酸化物の中でも、特に加圧による充填がされにくい。そのため、スピネル構造を有するリチウムマンガン複合酸化物とリチウム遷移金属複合酸化物とを混合して使用すると、リチウム遷移金属複合酸化物粒子が割れやすくなる。本発明のように、リチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とをそれぞれ集電体の異なる面に配置することによって、リチウム遷移金属複合酸化物粒子の割れを防止し、より高温保存特性が向上する。   In particular, the lithium manganese composite oxide preferably has a spinel structure. Lithium manganese composite oxide having a spinel structure is particularly difficult to be filled with pressure among lithium manganese composite oxides. Therefore, when a lithium manganese composite oxide having a spinel structure and a lithium transition metal composite oxide are mixed and used, the lithium transition metal composite oxide particles are easily cracked. Like the present invention, by arranging the lithium transition metal composite oxide and the lithium manganese composite oxide on different surfaces of the current collector, the lithium transition metal composite oxide particles are prevented from cracking and stored at higher temperatures. Will improve.

本発明において、少なくともＮｉとＭｎを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物は、リチウム遷移金属複合酸化物：リチウムマンガン複合酸化物の重量比が、９：１〜１：９の範囲内であることが好ましい。この範囲において、リチウム遷移金属複合酸化物の容量が大きいという利点と、リチウムマンガン酸化物の熱的安定性が高いという利点を共に満たすことができるためである。また、さらに好ましくは重量比９：１〜４：６であり、より好ましくは９：１〜６：４である。   In the present invention, the lithium transition metal composite oxide and the lithium manganese composite oxide containing at least Ni and Mn have a weight ratio of lithium transition metal composite oxide: lithium manganese composite oxide in the range of 9: 1 to 1: 9. It is preferable to be within. This is because, within this range, both the advantage that the lithium transition metal composite oxide has a large capacity and the advantage that the lithium manganese oxide has high thermal stability can be satisfied. More preferably, the weight ratio is 9: 1 to 4: 6, and more preferably 9: 1 to 6: 4.

本発明の二次電池において用いられる負極は、非水電解質二次電池の負極として用いることができるものであれば、特に限定されるものではない。負極材料としては、リチウムを吸蔵・放出することが可能な材料が用いられ、例えば、黒鉛材料、リチウム金属、リチウムを合金化し得る材料などが用いられるが、炭素材料であることが好ましい。炭素材料の中でも、特に黒鉛材料であることが好ましい。   The negative electrode used in the secondary battery of the present invention is not particularly limited as long as it can be used as the negative electrode of the nonaqueous electrolyte secondary battery. As the negative electrode material, a material capable of inserting and extracting lithium is used. For example, a graphite material, lithium metal, a material capable of alloying lithium, and the like are used, and a carbon material is preferable. Among carbon materials, graphite material is particularly preferable.

本発明に用いられる非水電解質としては、非水電解質二次電池に用いられる電解質を制限なく用いることができる。電解質の溶媒としては、特に限定されるものではないが、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネートなどの環状カーボネート、ジメチルカーボネート、メチルエチルカーボネート、ジエチルカーボネートなどの鎖状カーボネートとの混合溶媒が例示される。   As the non-aqueous electrolyte used in the present invention, an electrolyte used for a non-aqueous electrolyte secondary battery can be used without limitation. The electrolyte solvent is not particularly limited, but a mixed solvent with a cyclic carbonate such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, or a chain carbonate such as dimethyl carbonate, methyl ethyl carbonate, or diethyl carbonate. Illustrated.

また、電解質の溶質としては、特に限定されるものではないが、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＣＦ3ＳＯ3、ＬｉＮ（ＣＦ3ＳＯ2)2、ＬｉＮ（Ｃ2Ｆ5ＳＯ2)2、ＬｉＮ（ＣＦ3ＳＯ2)(Ｃ4Ｆ9ＳＯ2)、ＬｉＣ（ＣＦ3ＳＯ2)3、ＬｉＣ（Ｃ2Ｆ5ＳＯ2)3、ＬｉＡｓＦ6、ＬｉＣｌＯ4、Ｌｉ2Ｂ10Ｃｌ10、Ｌｉ2Ｂ12Ｃｌ12など及びそれらの混合物が挙げられる。 Further, the electrolyte solute is not particularly limited, but LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN ( CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (CF 3 SO 2 ) 3 , LiC (C 2 F 5 SO 2 ) 3 , LiAsF 6 , LiClO 4 , Li 2 B 10 Cl 10 , Li 2 B And 12 Cl 12 and mixtures thereof.

また、本発明における非水電解質二次電池の製造方法は、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とをアルミニウムからなる集電体の異なる面に配置した後、両面から加圧して正極としたことを特徴とする。   Further, in the method for producing a nonaqueous electrolyte secondary battery in the present invention, a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide are disposed on different surfaces of a current collector made of aluminum. The positive electrode is formed by pressing from both sides.

本発明における非水電解質二次電池の製造方法により、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物との混合物を加圧することがないので、該混合物の加圧に伴うリチウム遷移金属複合酸化物粒子の割れを防止することができる。   The method for producing a non-aqueous electrolyte secondary battery in the present invention does not pressurize a mixture of a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide. The cracking of the accompanying lithium transition metal composite oxide particles can be prevented.

さらに、本発明における非水電解質二次電池の製造方法においては、前記リチウム遷移金属複合酸化物と前記リチウムマンガン複合酸化物の充填密度が2.0〜3.7g／ccとなるように加圧していることが好ましい。   Furthermore, in the method for producing a non-aqueous electrolyte secondary battery in the present invention, pressurization is performed so that a filling density of the lithium transition metal composite oxide and the lithium manganese composite oxide is 2.0 to 3.7 g / cc. Is preferred.

上記の範囲となるように加圧した場合、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物との混合物を加圧する場合と比較して、リチウム遷移金属複合酸化物粒子の割れを防止する効果が大きくなる。   Lithium transition metal composite oxide particles when pressed to be in the above range, compared to when pressing a mixture of a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide The effect of preventing cracking is increased.

本発明によれば、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とを正極活物質として用いた非水電解質二次電池において、前記リチウム遷移金属酸化粒子の加圧による割れを防止し、優れた高温保存特性を得ることが出来る。   According to the present invention, in a non-aqueous electrolyte secondary battery using a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide as a positive electrode active material, pressurization of the lithium transition metal oxide particles Can be prevented, and excellent high-temperature storage characteristics can be obtained.

以下、本発明を実施例に基づいてさらに詳細に説明するが、本発明は以下の実施例に何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能なものである。   Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof. Is.

＜実験1＞
（実施例1）
[正極の作製]
ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2の組成式で示されるリチウム遷移金属複合酸化物の粉末と導電剤としての人造黒鉛を重量比９:１でらいかい機で混合し、この混合物を５重量％の結着剤としてのポリフッ化ビニリデン（ＰＶｄＦ）を含むＮ−メチル−２−ピロリドン（ＮＭＰ）溶液に添加して混合してスラリーを調整した。このスラリーを厚み20μmのアルミニウム箔の片面にドクターブレード法により塗布した。さらに、ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2と同様にして、Ｌｉ1.1Ｍｎ1.9Ｏ4のスラリーを調整し、アルミニウム箔のもう一方の片面に塗布した。この際、ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2：Ｌｉ1.1Ｍｎ1.9Ｏ4の重量比が６：４となるように塗布した。そして両面に配置した正極活物質の充填密度が2．8g／ccとなるまで圧延を行った。さらにこれを１５０℃で２時間真空乾燥して、正極を作製した。 <Experiment 1>
(Example 1)
[Preparation of positive electrode]
Lithium transition metal composite oxide powder represented by the composition formula of LiNi 0.4 Co 0.3 Mn 0.3 O 2 and artificial graphite as a conductive agent were mixed at a weight ratio of 9: 1 with a coarse machine, and this mixture was mixed at 5% by weight. A slurry was prepared by adding and mixing to an N-methyl-2-pyrrolidone (NMP) solution containing polyvinylidene fluoride (PVdF) as a binder. This slurry was applied to one side of an aluminum foil having a thickness of 20 μm by a doctor blade method. Further, a slurry of Li 1.1 Mn 1.9 O 4 was prepared in the same manner as LiNi 0.4 Co 0.3 Mn 0.3 O 2 and applied to the other side of the aluminum foil. At this time, the coating was performed so that the weight ratio of LiNi 0.4 Co 0.3 Mn 0.3 O 2 : Li 1.1 Mn 1.9 O 4 was 6: 4. And it rolled until the packing density of the positive electrode active material arrange | positioned on both surfaces was set to 2.8g / cc. Furthermore, this was vacuum-dried at 150 degreeC for 2 hours, and the positive electrode was produced.

[負極の作製]
バインダーであるＰＶｄＦをＮＭＰに溶解し、この溶液に、黒鉛粉末とＰＶｄＦの重量比が８５：１５となるように黒鉛粉末を添加混合して、スラリーを調製した。得られたスラリーを厚み２０μｍの銅箔の両面にドクターブレード法により塗布し、１５０℃で２時間真空乾燥して、負極を作製した。 [Preparation of negative electrode]
PVdF as a binder was dissolved in NMP, and graphite powder was added to and mixed with this solution so that the weight ratio of the graphite powder to PVdF was 85:15 to prepare a slurry. The obtained slurry was applied to both sides of a 20 μm thick copper foil by a doctor blade method and vacuum dried at 150 ° C. for 2 hours to produce a negative electrode.

[電解液の作製]
エチレンカーボネートとジエチルカーボネートを体積比１：１の割合となるように混合した溶媒に、ＬｉＰＦ6を１モル／リットルの割合となるように溶解して、電解液を調製した。 [Preparation of electrolyte]
LiPF 6 was dissolved in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 to a ratio of 1 mol / liter to prepare an electrolytic solution.

[電池の組立]
上記で作製した正極を作用極１として、対極３および作用極１にリチウム金属を用い、図１に示す三電極式ビーカーセルを作製し、上記電解液を注入し本発明電池Ａ１を作製した。 [Battery assembly]
Using the positive electrode prepared above as the working electrode 1, lithium metal was used for the counter electrode 3 and the working electrode 1, and the three-electrode beaker cell shown in FIG. 1 was prepared, and the electrolyte solution was injected to prepare the battery A1 of the present invention.

（比較例１）
ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2とＬｉ1.1Ｍｎ1.9Ｏ4とを重量比６：４で混合した正極活物質を集電体の両面に塗布したこと以外は実施例1と同様にして比較電池Ｓ１を作製した。 (Comparative Example 1)
Comparative battery S1 in the same manner as in Example 1 except that a positive electrode active material obtained by mixing LiNi 0.4 Co 0.3 Mn 0.3 O 2 and Li 1.1 Mn 1.9 O 4 at a weight ratio of 6: 4 was applied to both sides of the current collector. Was made.

（比較例２）
ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2を正極活物質として用い集電体の両面に塗布したこと以外は実施例1と同様にして、比較電池Ｓ２を作製した。 (Comparative Example 2)
A comparative battery S2 was produced in the same manner as in Example 1 except that LiNi 0.4 Co 0.3 Mn 0.3 O 2 was used as the positive electrode active material and applied to both sides of the current collector.

（比較例３）
Ｌｉ1.1Ｍｎ1.9Ｏ4を正極活物質として用い集電体の両面に塗布したこと以外は実施例1と同様にして、比較電池Ｓ３を作製した。 (Comparative Example 3)
Comparative battery S3 was produced in the same manner as in Example 1 except that Li 1.1 Mn 1.9 O 4 was used as the positive electrode active material and applied to both sides of the current collector.

[電池の保存前定格容量測定]
上記実施例１並びに比較例１〜比較例２の各電池について、９．３７ｍＡで４．３Ｖまで充電した後休止し、さらに３．１２ｍＡで４．３Ｖまで充電した後、９．３７ｍＡで３．１Ｖまで放電し、このときの放電容量を保存前定格容量Ｐとした。 [Battery rated capacity measurement before storage]
About each battery of the said Example 1 and Comparative Example 1- Comparative Example 2, after charging to 4.3V at 9.37 mA, it rests, and after charging to 4.3V at 3.12 mA, it is 3.37 mA at 3.37 mA. The battery was discharged to 1 V, and the discharge capacity at this time was defined as the rated capacity P before storage.

[保存特性試験]
本発明電池Ａ１及び比較電池Ｓ１〜Ｓ３について、上記の定格容量測定試験後、９．３７ｍＡで４．３Ｖまで充電した後休止し、さらに３．１２ｍＡで４．３Ｖまで充電して、４５℃に保った恒温保存槽中で１０日間放置した。放置後、９．３７ｍＡで３．１Ｖまで放電した。そして、保存後放電した９．３７ｍＡで４．３Ｖまで充電した後休止し、さらに３．１２ｍＡで４．３Ｖまで充電した後、９．３７ｍＡで３．１Ｖまで放電し、このときの放電容量を保存後の定格容量ＱｍＡｈとし、以下の式により容量復帰率を求めた。 [Storage characteristics test]
About this invention battery A1 and comparative battery S1-S3, after said rated capacity measurement test, after charging to 4.3V at 9.37 mA, it pauses, and also it charges to 4.3V at 3.12 mA, and is 45 degreeC. It was left to stand for 10 days in a kept constant temperature storage tank. After standing, the battery was discharged at 9.37 mA to 3.1V. Then, after storage, the battery was charged to 4.3 V at 9.37 mA discharged, then paused, charged to 4.3 V at 3.12 mA, discharged to 3.1 V at 9.37 mA, and the discharge capacity at this time was The rated capacity after storage was set to QmAh, and the capacity recovery rate was determined by the following formula.

容量復帰率（％）＝保存後定格容量Ｑ／保存前定格容量Ｐ×１００
容量復帰率の測定結果を表１に示す。 Capacity recovery rate (%) = Rated capacity after storage Q / Rated capacity before storage P x 100
Table 1 shows the measurement results of the capacity recovery rate.

Figure 2005135864
Figure 2005135864

表１から明らかなように、本発明電池Ａ１は、比較電池Ｓ１〜Ｓ３よりも容量復帰率が向上し、高温保存特性に優れていることがわかる。つまり、本発明電池Ａ１では、リチウム遷移金属複合化合物であるＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2とリチウムマンガン複合酸化物であるＬｉ1.1Ｍｎ1.9Ｏ4をそれぞれ集電体の異なる面に塗布することにより、これらを混合して塗布した比較電池Ｓ１よりも高温保存特性に優れている。 As is apparent from Table 1, it can be seen that the battery A1 of the present invention has a higher capacity recovery rate than the comparative batteries S1 to S3 and is excellent in high-temperature storage characteristics. That is, in the battery A1 of the present invention, LiNi 0.4 Co 0.3 Mn 0.3 O 2 which is a lithium transition metal composite compound and Li 1.1 Mn 1.9 O 4 which is a lithium manganese composite oxide are respectively applied to different surfaces of the current collector. These are superior in high-temperature storage characteristics than the comparative battery S1 in which these are mixed and applied.

本発明電池Ａ１においては、ＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2とＬｉ1.1Ｍｎ1.9Ｏ4とを、それぞれ集電体の異なる面に塗布しているため、正極合剤圧延時に、Ｌｉ1.1Ｍｎ1.9Ｏ4に押しつぶされることによる、充填されやすいＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2粒子の割れを防止することができると推測される。これにより、Ｌｉ1.1Ｍｎ1.9Ｏ4とＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2とを正極活物質として用いる効果、つまり、電解液に対するＬｉ1.1Ｍｎ1.9Ｏ4の安定性がより向上し、十分な保存特性が得られるものと考えられる。 In the present invention battery A1, since LiNi 0.4 Co 0.3 Mn 0.3 O 2 and Li 1.1 Mn 1.9 O 4 are respectively applied to different surfaces of the current collector, during the positive electrode mixture rolling, Li 1.1 Mn 1.9 O It is presumed that cracking of LiNi 0.4 Co 0.3 Mn 0.3 O 2 particles that are easily filled by being crushed to 4 can be prevented. Thereby, the effect of using Li 1.1 Mn 1.9 O 4 and LiNi 0.4 Co 0.3 Mn 0.3 O 2 as the positive electrode active material, that is, the stability of Li 1.1 Mn 1.9 O 4 with respect to the electrolyte is further improved, and sufficient storage characteristics Is considered to be obtained.

尚、本発明においては、リチウムマンガン複合酸化物と集電体の異なる面に配置する正極活物質として、少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物であるＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2を用いたが、リチウムマンガン複合酸化物よりも放電電位の低いリチウム遷移金属複合酸化物であれば、リチウムマンガン複合酸化物の電解液に対する安定性を向上させる効果があるので、本願発明と同様の効果が期待できる。 In the present invention, LiNi 0.4 Co 0.3 Mn 0.3 O 2 which is a lithium transition metal composite oxide containing at least Ni and Mn as a positive electrode active material disposed on different surfaces of the lithium manganese composite oxide and the current collector. However, the lithium transition metal composite oxide having a lower discharge potential than the lithium manganese composite oxide has the effect of improving the stability of the lithium manganese composite oxide with respect to the electrolytic solution. The effect can be expected.

実施例１において作製した三極式ビーカーセルの模式図。1 is a schematic diagram of a tripolar beaker cell manufactured in Example 1. FIG.

符号の説明Explanation of symbols

1・・・作用極
2・・・参照極
3・・・対極
4・・・電解液

1 ... Working electrode
2 ... Reference electrode
3 ... Counter electrode
4 ... Electrolyte

Claims (5)

少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とを活物質としてなる正極を有する非水電解質二次電池において、前記リチウム遷移金属複合酸化物と前記リチウムマンガン複合酸化物とがそれぞれ集電体の異なる面に配置されていることを特徴とする非水電解質二次電池。 In a non-aqueous electrolyte secondary battery having a positive electrode using a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide as active materials, the lithium transition metal composite oxide and the lithium manganese composite oxide Are disposed on different surfaces of the current collector, respectively. 前記リチウム遷移金属複合酸化物が、さらにＣｏを含むことを特徴とする請求項１に記載の非水電解質二次電池 The nonaqueous electrolyte secondary battery according to claim 1, wherein the lithium transition metal composite oxide further contains Co. 前記リチウムマンガン複合酸化物がスピネル構造を有することを特徴とする請求項１または２に記載の非水電解質二次電池。 The non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium manganese composite oxide has a spinel structure. 少なくともＮｉとＭｎとを含むリチウム遷移金属複合酸化物とリチウムマンガン複合酸化物とをアルミニウムからなる集電体の異なる面に配置した後、両面から加圧して正極としたことを特徴とする非水電解質二次電池の製造方法。 A non-aqueous solution characterized in that a lithium transition metal composite oxide containing at least Ni and Mn and a lithium manganese composite oxide are disposed on different surfaces of a current collector made of aluminum and then pressed from both surfaces to form a positive electrode. Manufacturing method of electrolyte secondary battery. 前記加圧が、前記リチウム遷移金属複合酸化物と前記リチウムマンガン複合酸化物の充填密度が2.0〜3.7g／ccとなるように加圧していることを特徴とする請求項４に記載の非水電解質二次電池の製造方法。



The non-water solution according to claim 4, wherein the pressurization is performed such that a filling density of the lithium transition metal composite oxide and the lithium manganese composite oxide is 2.0 to 3.7 g / cc. Manufacturing method of electrolyte secondary battery.



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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7816033B2 (en) 2006-05-29 2010-10-19 Lg Chem, Ltd. Cathode active material comprising mixture of lithium/manganese spinel oxide and lithium/nickel/cobalt/manganese oxide and lithium secondary battery containing same
CN109950547A (en) * 2019-03-27 2019-06-28 华中农业大学 A kind of three-dimensional collector being modified with base metal coating

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7816033B2 (en) 2006-05-29 2010-10-19 Lg Chem, Ltd. Cathode active material comprising mixture of lithium/manganese spinel oxide and lithium/nickel/cobalt/manganese oxide and lithium secondary battery containing same
CN109950547A (en) * 2019-03-27 2019-06-28 华中农业大学 A kind of three-dimensional collector being modified with base metal coating
CN109950547B (en) * 2019-03-27 2022-06-10 华中农业大学 Three-dimensional current collector decorated with non-noble metal coating

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