JP4703121B2 - Non-aqueous electrolyte secondary battery - Google Patents
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- JP4703121B2 JP4703121B2 JP2004075110A JP2004075110A JP4703121B2 JP 4703121 B2 JP4703121 B2 JP 4703121B2 JP 2004075110 A JP2004075110 A JP 2004075110A JP 2004075110 A JP2004075110 A JP 2004075110A JP 4703121 B2 JP4703121 B2 JP 4703121B2
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- 239000011255 nonaqueous electrolyte Substances 0.000 title claims description 65
- 239000002131 composite material Substances 0.000 claims description 25
- 239000002904 solvent Substances 0.000 claims description 25
- 229910052782 aluminium Inorganic materials 0.000 claims description 16
- 239000000654 additive Substances 0.000 claims description 15
- 230000000996 additive effect Effects 0.000 claims description 13
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 239000011149 active material Substances 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- JKJWYKGYGWOAHT-UHFFFAOYSA-N bis(prop-2-enyl) carbonate Chemical compound C=CCOC(=O)OCC=C JKJWYKGYGWOAHT-UHFFFAOYSA-N 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 229910052733 gallium Inorganic materials 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 229910052712 strontium Inorganic materials 0.000 claims description 5
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 239000003792 electrolyte Substances 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims 1
- 239000007774 positive electrode material Substances 0.000 description 37
- 230000000052 comparative effect Effects 0.000 description 29
- 239000007789 gas Substances 0.000 description 23
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 22
- 239000008151 electrolyte solution Substances 0.000 description 16
- 239000012046 mixed solvent Substances 0.000 description 16
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 14
- -1 amorphous carbon Chemical compound 0.000 description 14
- 238000002360 preparation method Methods 0.000 description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 description 11
- 239000001569 carbon dioxide Substances 0.000 description 11
- 239000001257 hydrogen Substances 0.000 description 11
- 229910052739 hydrogen Inorganic materials 0.000 description 11
- 239000007773 negative electrode material Substances 0.000 description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 10
- 238000000354 decomposition reaction Methods 0.000 description 9
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 229910001416 lithium ion Inorganic materials 0.000 description 8
- 229910013870 LiPF 6 Inorganic materials 0.000 description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 7
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 5
- 239000002033 PVDF binder Substances 0.000 description 5
- 239000011888 foil Substances 0.000 description 5
- 239000011259 mixed solution Substances 0.000 description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 239000011889 copper foil Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 150000005678 chain carbonates Chemical class 0.000 description 3
- 150000005676 cyclic carbonates Chemical class 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 229910013928 LiCo0.95Mg0.05O2 Inorganic materials 0.000 description 2
- 229910015704 LiMn0.33Co0.33Ni0.33O2 Inorganic materials 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000003125 aqueous solvent Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- GAEKPEKOJKCEMS-UHFFFAOYSA-N gamma-valerolactone Chemical compound CC1CCC(=O)O1 GAEKPEKOJKCEMS-UHFFFAOYSA-N 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910012108 LiCo0.98Mg0.02O2 Inorganic materials 0.000 description 1
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 1
- 229910014689 LiMnO Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000005001 laminate film Substances 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- HNJBEVLQSNELDL-UHFFFAOYSA-N pyrrolidin-2-one Chemical compound O=C1CCCN1 HNJBEVLQSNELDL-UHFFFAOYSA-N 0.000 description 1
- 238000007142 ring opening reaction Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
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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
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- Battery Electrode And Active Subsutance (AREA)
Description
本発明は、非水電解液二次電池、特に、その正極活物質となる複合酸化物の改良と、非水電解液の添加剤との組み合わせに関するものである。 The present invention relates to a non-aqueous electrolyte secondary battery, and in particular, to a combination of an improved composite oxide serving as a positive electrode active material and a non-aqueous electrolyte additive.
非水電解液二次電池の代表的な電池として、リチウムイオン二次電池がある。リチウムイオン二次電池の正極活物質として、コバルト酸リチウム（以下、ＬｉＣｏＯ２と略す）、ニッケル酸リチウム（ＬｉＮｉＯ２）、マンガン酸リチウム（ＬｉＭｎ２Ｏ４，ＬｉＭｎＯ２）、および鉄酸リチウム（ＬｉＦｅＯ２）などの遷移金属酸化物が用いられている。負極活物質として、非晶質炭素、人造黒鉛、および天然黒鉛などのリチウムイオンを吸蔵・放出することができる材料が用いられている。非水電解液として、非水溶媒と溶質を混合したものが用いられている。非水溶媒として、環状炭酸エステル類、鎖状炭酸エステル類、および環状カルボン酸エステル類などが用いられている。 As a typical battery of the non-aqueous electrolyte secondary battery, there is a lithium ion secondary battery. As positive electrode active materials of lithium ion secondary batteries, lithium cobaltate (hereinafter abbreviated as LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 , LiMnO 2 ), and lithium ferrate (LiFeO) Transition metal oxides such as 2 ) are used. As the negative electrode active material, materials capable of occluding and releasing lithium ions such as amorphous carbon, artificial graphite, and natural graphite are used. As the non-aqueous electrolyte, a mixture of a non-aqueous solvent and a solute is used. As non-aqueous solvents, cyclic carbonates, chain carbonates, cyclic carboxylic acid esters and the like are used.
非水電解液は、電池特性を向上させるために、エチレンカーボネートやエチルメチルカーボネートを主溶媒とし、種々の添加剤を混合することが知られている。添加剤の中でも、ジアリルカーボネート（以下、ＤＡＣと略す）は、負極活物質表面に良好な皮膜を形成し、サイクル特性を向上させることが提案されている（特許文献１、２）。
従来のリチウムイオン二次電池において、非水電解液にＤＡＣを添加することにより、負極活物質表面に良好な皮膜を形成するため、常温におけるサイクル特性を向上させることができる。しかし、高温におけるサイクル特性や高温保存特性の試験をした場合に、ガス発生により、それらの特性が劣化するという問題がある。これは、ＤＡＣの分子構造において、ビニル基と酸素の間に挟まれたＣＨ２基から水素が引き抜かれ、水素ガスが発生するためと推定される。 In a conventional lithium ion secondary battery, by adding DAC to the non-aqueous electrolyte, a good film is formed on the surface of the negative electrode active material, so that the cycle characteristics at room temperature can be improved. However, when testing cycle characteristics at high temperatures and high temperature storage characteristics, there is a problem that these characteristics deteriorate due to gas generation. This is presumably because in the molecular structure of the DAC, hydrogen is extracted from the CH 2 group sandwiched between the vinyl group and oxygen to generate hydrogen gas.
そこで本発明は、このような従来の課題を解決するもので、高温におけるサイクル特性が良好で、かつ高温保存時のガス発生が少ない非水電解液二次電池を提供することを目的とする。 The present invention solves such conventional problems, and an object of the present invention is to provide a non-aqueous electrolyte secondary battery having good cycle characteristics at high temperatures and low gas generation during high-temperature storage.
前記課題を解決するために、本発明の非水電解液二次電池は、式ＬｉＡＯ2（式中、Ａは、Ｍｎ，Ｃｏ，およびＮｉからなる群より選択された少なくとも２種の元素を表す）で示される複合酸化物を活物質とする正極、負極、および主溶媒と溶質と添加剤としてＤＡＣを含む非水電解液を具備し、前記ＤＡＣの添加量は、非水電解液の主溶媒１００重量部に対して、０．５〜５．０重量部である。 In order to solve the above problems, the non-aqueous electrolyte secondary battery of the present invention has a formula LiAO 2 (wherein A represents at least two elements selected from the group consisting of Mn, Co, and Ni). ) And a non-aqueous electrolyte containing DAC as a main solvent, a solute, and an additive. The amount of the DAC added is the main solvent of the non-aqueous electrolyte. It is 0.5-5.0 weight part with respect to 100 weight part .
本発明の別の態様の非水電解液二次電池は、式ＬｉＢ1-wＣwＯ2（式中、Ｂは、Ｍｎ，Ｃｏ，およびＮｉからなる群より選択された少なくとも１種の元素、Ｃは、Ｍｇ，Ｃａ，Ｓｒ，Ａｌ，およびＧａからなる群より選択された少なくとも１種の元素を表し、０．００５≦ｗ≦０．１）で示される複合酸化物を活物質とする正極、負極、および主溶媒と溶質と添加剤としてＤＡＣを含む非水電解液を具備し、前記ＤＡＣの添加量は、非水電解液の主溶媒１００重量部に対して、０．５〜５．０重量部である。 A nonaqueous electrolyte secondary battery according to another aspect of the present invention has a formula LiB 1-w C w O 2 (wherein B is at least one element selected from the group consisting of Mn, Co, and Ni). , C represents at least one element selected from the group consisting of Mg, Ca, Sr, Al, and Ga, and a composite oxide represented by 0.005 ≦ w ≦ 0.1) is used as an active material A positive electrode, a negative electrode, and a main solvent, a solute, and a non-aqueous electrolyte containing DAC as an additive are provided. The amount of the DAC added is 0.5 to 5 with respect to 100 parts by weight of the main solvent of the non-aqueous electrolyte. 0.0 part by weight .
本発明の正極活物質と非水電解液の添加剤とを組み合わせることにより、高温におけるガス発生が抑制され、サイクル特性を向上させることができる。したがって、高信頼性の非水電解液二次電池を提供することができる。 By combining the positive electrode active material of the present invention and the non-aqueous electrolyte additive, gas generation at a high temperature can be suppressed and cycle characteristics can be improved. Therefore, a highly reliable non-aqueous electrolyte secondary battery can be provided.
本発明の非水電解液二次電池は、複合酸化物を活物質とする正極、負極、および非水電解液からなる。複合酸化物は、ＬｉＡＯ２で示され、Ａは、Ｍｎ，Ｃｏ，およびＮｉからなる群より選択された少なくとも２種の元素である。非水電解液は、主溶媒、溶質、および添加剤を含んでいる。添加剤は、ＤＡＣである。 The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte using a composite oxide as an active material. The composite oxide is represented by LiAO 2 , and A is at least two elements selected from the group consisting of Mn, Co, and Ni. The nonaqueous electrolytic solution includes a main solvent, a solute, and an additive. The additive is DAC.
本発明の別の態様の非水電解液二次電池は、複合酸化物を活物質とする正極、負極、および非水電解液からなる。複合酸化物は、ＬｉＢ１−ｗＣｗＯ２で示され、Ｂは、Ｍｎ，Ｃｏ，およびＮｉからなる群より選択された少なくとも１種の元素、Ｃは、Ｍｇ，Ｃａ，Ｓｒ，Ａｌ，およびＧａからなる群より選択された少なくとも１種の元素を表し、０．００５≦ｗ≦０．１である。非水電解液は、主溶媒、溶質、および添加剤を含んでいる。添加剤は、ＤＡＣである。 The non-aqueous electrolyte secondary battery according to another aspect of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte using a composite oxide as an active material. The composite oxide is represented by LiB 1-w C w O 2 , B is at least one element selected from the group consisting of Mn, Co, and Ni, and C is Mg, Ca, Sr, Al, And at least one element selected from the group consisting of Ga and 0.005 ≦ w ≦ 0.1. The nonaqueous electrolytic solution includes a main solvent, a solute, and an additive. The additive is DAC.
本発明の非水電解液二次電池は、以下の実施例で説明するように、高温におけるガス発生が抑制され、サイクル特性が向上する。このような効果が得られる理由については、必ずしも発明者の理論に拘束されるのを好むものではないが、発明者は次のように推察している。すなわち、正極活物質であるＬｉＡＯ２およびＬｉＢ１−ｗＣｗＯ２で示される複合酸化物は、その表面がアルカリ性を有するので、ＤＡＣの分解により発生する水素ガスを容易に吸収するのである。複合酸化物ＬｉＢ１−ｗＣｗＯ２中のＣとして、Ｍｇ，Ｃａ，Ｓｒ，Ａｌ，およびＧａからなる群より選択される少なくとも１種の元素を含む場合、これらの元素を含まない場合に比べて、複合酸化物の表面がアルカリ性になり易くなる。その結果、ＤＡＣの分解により発生する水素イオンをさらに吸収することができるためと考えられる。 In the nonaqueous electrolyte secondary battery of the present invention, gas generation at high temperature is suppressed and cycle characteristics are improved, as will be described in the following examples. The reason why such an effect is obtained is not necessarily limited by the inventor's theory, but the inventor presumes as follows. That is, since the surface of the composite oxide represented by LiAO 2 and LiB 1-w C w O 2 that are positive electrode active materials has alkalinity, it easily absorbs hydrogen gas generated by the decomposition of DAC. In the case where at least one element selected from the group consisting of Mg, Ca, Sr, Al, and Ga is included as C in the composite oxide LiB 1-w C w O 2 , when these elements are not included In comparison, the surface of the composite oxide tends to be alkaline. As a result, it is considered that hydrogen ions generated by the decomposition of the DAC can be further absorbed.
ＤＡＣの好ましい添加割合は、非水電解液の主溶媒１００重量部に対して、０．５〜５．０重量部である。
ＤＡＣの添加量が少ない場合は、負極活物質表面に良好な皮膜を形成し、サイクル特性を向上させるという効果が顕著に現れない。その反面、ＤＡＣの添加量が多い場合は、正極活物質となる複合酸化物が、ＤＡＣの分解によって発生する水素イオンを吸収できる能力を超えてしまい、水素ガスが多量に発生することとなる。このような視点から、ＤＡＣの添加量は、非水電解液の主溶媒１００重量部に対して、０．５〜５．０重量部が好ましい。
A preferable addition ratio of the DAC is 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the main solvent of the nonaqueous electrolytic solution.
When the amount of DAC added is small, the effect of forming a good film on the surface of the negative electrode active material and improving the cycle characteristics does not appear significantly. On the other hand, when the amount of DAC added is large, the composite oxide serving as the positive electrode active material exceeds the ability to absorb hydrogen ions generated by the decomposition of the DAC, and a large amount of hydrogen gas is generated. From such a viewpoint, the amount of DAC added is preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the main solvent of the nonaqueous electrolytic solution.
本発明の好ましい実施の形態において、非水電解液は、さらに添加剤としてビニレンカーボネート（以下、ＶＣと略す）を含む。
ＶＣは、負極活物質表面に良好な皮膜を形成し、サイクル特性を向上させるという効果がある。ＤＡＣとＶＣの両方を添加すると、ＤＡＣの分解によって発生する水素イオンを減少させ、水素ガスの発生を減少させることができる。さらに、ＶＣの分解反応によって発生する炭酸ガスも抑制することができる。水素ガスの発生が減少する理由は、ＶＣの分子構造における不飽和結合の部分に水素イオンが付加されるためであると考えられる。炭酸ガスの発生が減少する理由は、ＤＡＣの分解によって発生する水素イオンが、正極活物質となる複合酸化物の表面で中和され、その表面でのＶＣの開環反応が進行しなくなるためと推定される。このことから、ＤＡＣとＶＣの両方を添加するのが好ましい。
In a preferred embodiment of the present invention, the non-aqueous electrolyte further contains vinylene carbonate (hereinafter abbreviated as VC) as an additive.
VC has an effect of forming a good film on the surface of the negative electrode active material and improving cycle characteristics. When both DAC and VC are added, hydrogen ions generated by the decomposition of DAC can be reduced, and generation of hydrogen gas can be reduced. Furthermore, carbon dioxide gas generated by the decomposition reaction of VC can also be suppressed. The reason why the generation of hydrogen gas is reduced is considered to be because hydrogen ions are added to the unsaturated bond portion in the molecular structure of VC. The reason why the generation of carbon dioxide gas decreases is that hydrogen ions generated by the decomposition of DAC are neutralized on the surface of the composite oxide serving as the positive electrode active material, and the ring-opening reaction of VC on the surface does not proceed. Presumed. For this reason, it is preferable to add both DAC and VC.
ＶＣの好ましい添加割合は、非水電解液の主溶媒１００重量部に対して、０．５〜１０．０重量部である。
ＶＣの添加量が少ない場合は、負極活物質表面に良好な皮膜を形成し、サイクル特性を向上させるという効果が顕著に現れない。その反面、ＶＣの添加量が多い場合は、正極活物質となる複合酸化物の表面でＶＣの分解反応により炭酸ガスが多量に発生することとなる。このような視点から、ＶＣの添加量は、非水電解液の主溶媒１００重量部に対して、０．５〜１０．０重量部が好ましい。
A preferable addition ratio of VC is 0.5 to 10.0 parts by weight with respect to 100 parts by weight of the main solvent of the nonaqueous electrolytic solution.
When the amount of VC added is small, the effect of forming a good film on the surface of the negative electrode active material and improving the cycle characteristics does not appear significantly. On the other hand, when the amount of VC added is large, a large amount of carbon dioxide gas is generated by the decomposition reaction of VC on the surface of the composite oxide serving as the positive electrode active material. From such a viewpoint, the addition amount of VC is preferably 0.5 to 10.0 parts by weight with respect to 100 parts by weight of the main solvent of the nonaqueous electrolytic solution.
非水電解液の主溶媒としては、環状炭酸エステル類、鎖状炭酸エステル類、環状カルボン酸エステル類などが挙げられる。環状炭酸エステル類としては、プロピレンカーボネート、エチレンカーボネート（以下、ＥＣと略す）などが代表的なものである。鎖状炭酸エステル類としては、ジエチルカーボネート（以下、ＤＥＣと略す）、エチルメチルカーボネート（以下、ＥＭＣと略す）、およびジメチルカーボネートなどがある。環状カルボン酸エステル類としては、γ−ブチロラクトン、γ−バレロラクトンなどがある。溶質としては、六フッ化リン酸リチウム（以下、ＬｉＰＦ６と略す）、四フッ化ホウ酸リチウム（ＬｉＢＦ４）、およびビストリフルオロメチルスルホン酸イミドリチウム（ＬｉＮ（ＣＦ３ＳＯ２）２）などがある。 Examples of the main solvent for the non-aqueous electrolyte include cyclic carbonates, chain carbonates, and cyclic carboxylic acid esters. Typical cyclic carbonates include propylene carbonate, ethylene carbonate (hereinafter abbreviated as EC) and the like. Examples of the chain carbonates include diethyl carbonate (hereinafter abbreviated as DEC), ethyl methyl carbonate (hereinafter abbreviated as EMC), and dimethyl carbonate. Examples of cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone. Examples of the solute include lithium hexafluorophosphate (hereinafter abbreviated as LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), and lithium bistrifluoromethylsulfonate (LiN (CF 3 SO 2 ) 2 ). is there.
図１に、本発明の一実施例である非水電解液二次電池としてリチウムイオン二次電池の断面概略図を示す。 In FIG. 1, the cross-sectional schematic of a lithium ion secondary battery is shown as a nonaqueous electrolyte secondary battery which is one Example of this invention.
このリチウムイオン二次電池は以下のようにして作製する。まず、アルミニウム箔集電体１に正極活物質層３を塗布して形成した正極板５と、銅箔集電体２に負極活物質層４を塗布して形成した負極板６との間にポリプロピレン製微多孔セパレータ１１を配置する。それらを挟むようにアルミニウム集電板７と、銅集電板８を積層し極板群１２を構成する。アルミニウム集電板７と銅集電板８には、それぞれアルミニウム製正極リード９と銅製負極リード１０が溶接されている。また、正極板５と負極板６の活物質層塗布面はセパレータ１１に対向させている。２つのリード９、１０を相対する方向になるように配置させ、極板群１２をテープ（図示せず）で固定する。さらに、アルミニウム箔を含むポリプロピレンのラミネートフィルムからなるチューブ１３に上記極板群１２を収納する。一方の正極リード９を引き出したチューブ１３の開口部を正極リード９と共に熱溶着し、封止する。もう一方の負極リード１０を引き出したチューブ１３の開口部から、非水電解液を注入する。封止前処理として、定電流７ｍＡで１時間充電し、減圧脱気（−７５０ｍｍＨｇ、１０秒間）する。その後、チューブ１３の開口部を負極リード１０と共に熱溶着し、封止する。
This lithium ion secondary battery is manufactured as follows. First, between the
そして、予備充放電として、定電流７ｍＡ、上限電圧４．２Ｖと下限電圧３．０Ｖの間で充放電を５回繰り返す。さらに、定電流２５ｍＡで４．２Ｖまで充電し、定電圧４．２Ｖで保持する。定電流および定電圧の充電時間の合計は２時間とする。この後に、定電流７ｍＡで放電する。 And as preliminary charging / discharging, charging / discharging is repeated 5 times between constant current 7mA, upper limit voltage 4.2V, and lower limit voltage 3.0V. Further, the battery is charged to 4.2 V with a constant current of 25 mA and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage is 2 hours. Thereafter, the battery is discharged at a constant current of 7 mA.
負極板６は以下のようにして作製する。負極活物質層４の負極活物質として人造黒鉛粉末を７５重量部、導電剤としてアセチレンブラックを２０重量部、および結着剤としてポリフッ化ビニリデン（以下、ＰＶＤＦと略す）のＮ−メチル−２−ピロリドン（以下、ＮＭＰと略す）溶液をＰＶＤＦが５重量部相当を混合する。この混合物を厚み２０μｍの銅箔集電体２の片面に、塗布、乾燥して厚みが８０μｍの負極活物質層４を形成する。これを３５ｍｍ×３５ｍｍサイズに切り出し、銅箔集電体２と負極リード１０の付いた銅集電板８とを超音波溶接する。この電池の設計容量は、３５ｍＡｈである。
The negative electrode plate 6 is produced as follows. The negative electrode active material of the negative electrode
以下に、正極板５の作製と非水電解液の調製について説明する。
《実施例１》
（１）正極板の作製
正極板５は以下のようにして作製した。正極活物質としてＬｉＭｎ０．３３Ｃｏ０．３３Ｎｉ０．３３Ｏ２粉末を８５重量部、導電剤としてアセチレンブラックを１０重量部、および結着剤としてＰＶＤＦのＮＭＰ溶液をＰＶＤＦが５重量部相当を混合した。この混合物を厚み２０μｍのアルミニウム箔集電体１の片面に、塗布、乾燥して厚みが８０μｍの正極活物質層３を形成した。これを３５ｍｍ×３５ｍｍサイズに切り出し、アルミニウム箔集電体１と正極リード９の付いたアルミニウム集電板７とを超音波溶接した。
Below, preparation of the
Example 1
(1) Production of positive electrode plate The
（２）非水電解液の調製
非水電解液は以下のようにして調製した。溶媒として、ＥＣとＥＭＣとを体積比１：３で混合した混合溶媒１００重量部に、ＤＡＣ２重量部を添加した。この混合液に、ＬｉＰＦ６を１．２５ｍｏｌ／Ｌの濃度で溶解した。
このように作製した正極板と非水電解液を用いて、図１のようなリチウムイオン二次電池を作製した。
(2) Preparation of non-aqueous electrolyte The non-aqueous electrolyte was prepared as follows. As a solvent, 2 parts by weight of DAC was added to 100 parts by weight of a mixed solvent in which EC and EMC were mixed at a volume ratio of 1: 3. LiPF 6 was dissolved in this mixture at a concentration of 1.25 mol / L.
A lithium ion secondary battery as shown in FIG. 1 was produced using the positive electrode plate thus produced and a non-aqueous electrolyte.
《比較例１》
正極活物質として、ＬｉＣｏＯ２を用いた以外は実施例１と同様にして電池を作製した。
<< Comparative Example 1 >>
A battery was fabricated in the same manner as in Example 1 except that LiCoO 2 was used as the positive electrode active material.
実施例１と比較例１の電池について、定電流２５ｍＡで４．２Ｖまで充電し、定電圧４．２Ｖで保持した。定電流および定電圧の充電時間の合計は２時間とした。そして、８５℃で１日保存し、保存直後の電池内の水素ガス量を測定した。その結果を表１に示す。 The batteries of Example 1 and Comparative Example 1 were charged to 4.2 V at a constant current of 25 mA and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage was 2 hours. And it preserve | saved for one day at 85 degreeC, and measured the hydrogen gas amount in the battery immediately after preservation | save. The results are shown in Table 1.
表１の結果から、実施例１の正極活物質の複合酸化物ＬｉＭｎ０．３３Ｃｏ０．３３Ｎｉ０．３３Ｏ２を用いた場合は、比較例１の正極活物質の複合酸化物ＬｉＣｏＯ２を用いた場合に比べ、高温保存における水素ガスの発生量が少なくなっている。 From the results of Table 1, when the composite oxide LiMn 0.33 Co 0.33 Ni 0.33 O 2 of the positive electrode active material of Example 1 was used, the composite oxide LiCoO 2 of the positive electrode active material of Comparative Example 1 was used. Compared to the case of using hydrogen, the amount of hydrogen gas generated during high-temperature storage is reduced.
《実施例２》
正極活物質として、以下に説明する表２に示したものを用いた以外は実施例１と同様にして電池を作製した。
Example 2
A battery was fabricated in the same manner as in Example 1 except that the positive electrode active material shown in Table 2 described below was used.
実施例２の電池について、実施例１と同様の評価を行った。その結果を表２に示す。 The battery of Example 2 was evaluated in the same manner as in Example 1. The results are shown in Table 2.
表２の結果から、表２に示した正極活物質の複合酸化物とＤＡＣとの組み合わせにおいて、高温保存後の水素ガスの発生が抑制されていることがわかる。 From the results of Table 2, it can be seen that in the combination of the composite oxide of the positive electrode active material and DAC shown in Table 2, the generation of hydrogen gas after high-temperature storage is suppressed.
《実施例３》
（１）正極板の作製
正極活物質として、以下に説明する表３に示したものを用いた。
Example 3
(1) Production of positive electrode plate The positive electrode active material shown in Table 3 described below was used.
（２）非水電解液の調製
ＥＣとＥＭＣとの混合溶媒１００重量部にＤＡＣおよびＶＣをそれぞれ２重量部および１重量部添加して、非水電解液を調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of Nonaqueous Electrolytic Solution A nonaqueous electrolytic solution was prepared by adding 2 parts by weight and 1 part by weight of DAC and VC to 100 parts by weight of a mixed solvent of EC and EMC, respectively. Otherwise, the battery was fabricated in the same manner as in Example 1.
実施例３の電池について、実施例１と同様の評価を行った。その結果を表３に示す。 The battery of Example 3 was evaluated in the same manner as in Example 1. The results are shown in Table 3.
表３の結果から、実施例１、２と同じ正極活物質の複合酸化物を用いた場合に比べ、非水電解液にＤＡＣ以外にＶＣを添加することで、高温保存後の水素ガスの発生がさらに抑制されていることがわかる。 From the results in Table 3, generation of hydrogen gas after high-temperature storage is achieved by adding VC in addition to DAC to the non-aqueous electrolyte as compared with the case where the composite oxide of the same positive electrode active material as in Examples 1 and 2 is used. It can be seen that is further suppressed.
《実施例４》
（１）正極板の作製
正極活物質として、以下に説明する表４に示したものを用いた。
Example 4
(1) Production of positive electrode plate The positive electrode active material shown in Table 4 described below was used.
（２）非水電解液の調製
ＥＣとＥＭＣとの混合溶媒１００重量部にＤＡＣおよびＶＣをそれぞれ１重量部および２重量部添加して、非水電解液を調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of non-aqueous electrolyte A non-aqueous electrolyte was prepared by adding 1 and 2 parts by weight of DAC and VC to 100 parts by weight of a mixed solvent of EC and EMC, respectively. Otherwise, the battery was fabricated in the same manner as in Example 1.
《比較例２》
（１）正極板の作製
実施例４または比較例１と同じ正極活物質を用いた。
<< Comparative Example 2 >>
(1) Production of positive electrode plate The same positive electrode active material as in Example 4 or Comparative Example 1 was used.
（２）非水電解液の調製
ＥＣとＥＭＣとの混合溶媒１００重量部にＶＣを２重量部添加して、非水電解液を調製した。さらに、正極活物質がＬｉＣｏＯ２の場合は、ＥＣとＥＭＣとの混合溶媒１００重量部にＤＡＣおよびＶＣをそれぞれ１重量部および２重量部添加した非水電解液も調製した。
それ以外は、実施例４と同様にして電池を作製した。
(2) Preparation of Nonaqueous Electrolyte Solution A nonaqueous electrolyte solution was prepared by adding 2 parts by weight of VC to 100 parts by weight of a mixed solvent of EC and EMC. Furthermore, when the positive electrode active material was LiCoO 2 , a non-aqueous electrolyte was prepared by adding 1 part by weight and 2 parts by weight of DAC and VC to 100 parts by weight of a mixed solvent of EC and EMC, respectively.
Otherwise, the battery was fabricated in the same manner as in Example 4.
実施例４と比較例２の電池について、定電流２５ｍＡで４．２Ｖまで充電し、定電圧４．２Ｖで保持した。定電流および定電圧の充電時間の合計は２時間とした。そして、８５℃で１日保存し、保存後電池内の炭酸ガス量を測定した。その結果を表４に示す。 The batteries of Example 4 and Comparative Example 2 were charged to 4.2 V at a constant current of 25 mA and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage was 2 hours. And it preserve | saved at 85 degreeC for 1 day, and the amount of carbon dioxide in a battery was measured after the preservation | save. The results are shown in Table 4.
表４の結果から、正極活物質の複合酸化物ＬｉＣｏＯ２を用い、ＤＡＣとＶＣを添加した場合でも、ＶＣの分解による炭酸ガスの抑制効果は認められなかった。実施例４と同じ正極活物質である複合酸化物を用いても、非水電解液にＤＡＣを添加しない場合は、ＶＣの分解による炭酸ガスの抑制効果は認められなかった。これに対し、実施例４の正極活物質の複合酸化物にＤＡＣとＶＣを添加した場合の組み合わせにおいては、炭酸ガスの発生が抑制されていることがわかる。 From the results in Table 4, even when the composite oxide LiCoO 2 of the positive electrode active material was used and DAC and VC were added, the carbon dioxide suppression effect due to the decomposition of VC was not recognized. Even when the composite oxide, which is the same positive electrode active material as in Example 4, was used, when no DAC was added to the non-aqueous electrolyte, the carbon dioxide suppression effect due to the decomposition of VC was not recognized. On the other hand, in the combination of DAC and VC added to the composite oxide of the positive electrode active material of Example 4, it can be seen that the generation of carbon dioxide gas is suppressed.
《実施例５》
正極活物質として、ＬｉＣｏ０．９５Ｍｇ０．０５Ｏ２を用いた以外は、実施例１と同様にして電池を作製した。
Example 5
A battery was fabricated in the same manner as in Example 1 except that LiCo 0.95 Mg 0.05 O 2 was used as the positive electrode active material.
《比較例３》
ＥＣとＥＭＣとの混合溶媒に対してＤＡＣを添加しない非水電解液を用いた以外は、実施例５と同様にして電池を作製した。
<< Comparative Example 3 >>
A battery was fabricated in the same manner as in Example 5 except that a nonaqueous electrolytic solution in which DAC was not added to the mixed solvent of EC and EMC was used.
《比較例４》
比較例１と同じ正極活物質を用いた以外は、実施例５と同様にして電池を作製した。
<< Comparative Example 4 >>
A battery was fabricated in the same manner as in Example 5 except that the same positive electrode active material as in Comparative Example 1 was used.
《比較例５》
（１）正極板の作製
比較例１と同じ正極活物質を用いた。
<< Comparative Example 5 >>
(1) Production of positive electrode plate The same positive electrode active material as in Comparative Example 1 was used.
（２）非水電解液の調整
ＥＣとＥＭＣとの混合溶媒に対してＤＡＣを添加しない非水電解液を用いた以外は、実施例５と同様にして電池を作製した。
(2) Preparation of non-aqueous electrolyte A battery was fabricated in the same manner as in Example 5 except that a non-aqueous electrolyte without adding DAC to the mixed solvent of EC and EMC was used.
実施例５と比較例３、４および５の電池について、４５℃で充放電を繰り返した。充電条件として、定電流２５ｍＡで上限電圧４．２Ｖまで充電し、定電圧４．２Ｖで保持した。定電流および定電圧の充電時間の合計は２時間とする。放電条件として、定電流３６ｍＡで下限電圧３．０Ｖまで放電した。これら充放電を繰り返し、電池容量が初期の７０％になった時点のサイクル数をサイクル寿命とした。その結果を表５に示す。 The batteries of Example 5 and Comparative Examples 3, 4 and 5 were repeatedly charged and discharged at 45 ° C. As charging conditions, the battery was charged at a constant current of 25 mA to an upper limit voltage of 4.2 V and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage is 2 hours. As a discharge condition, the battery was discharged to a lower limit voltage of 3.0 V at a constant current of 36 mA. These charge / discharge cycles were repeated, and the cycle number when the battery capacity reached 70% of the initial value was defined as the cycle life. The results are shown in Table 5.
表５の結果から、実施例５のように、正極活物質としてＬｉＣｏ０．９５Ｍｇ０．０５Ｏ２を用い、非水電解液にＤＡＣを添加した場合にのみ、高温におけるサイクル寿命が向上している。 From the results in Table 5, the cycle life at high temperature is improved only when LiCo 0.95 Mg 0.05 O 2 is used as the positive electrode active material and DAC is added to the non-aqueous electrolyte as in Example 5. ing.
《実施例６》
（１）正極板の作製
実施例５と同じ正極活物質を用いた。
Example 6
(1) Production of positive electrode plate The same positive electrode active material as in Example 5 was used.
（２）非水電解液の調製
ＥＣ、ＥＭＣ、およびＤＥＣを体積比３：５：２で混合した混合溶媒１００重量部に、以下で説明する表６に示した量のＤＡＣを添加した。この混合液に、ＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解して非水電解液を調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of non-aqueous electrolyte The amount of DAC shown in Table 6 described below was added to 100 parts by weight of a mixed solvent in which EC, EMC, and DEC were mixed at a volume ratio of 3: 5: 2. LiPF 6 was dissolved in this mixed solution at a concentration of 1.0 mol / L to prepare a nonaqueous electrolytic solution. Otherwise, the battery was fabricated in the same manner as in Example 1.
実施例６の電池について、実施例５と同じ評価を行った。その結果を表６に示す。 For the battery of Example 6, the same evaluation as in Example 5 was performed. The results are shown in Table 6.
表６の結果から、ＤＡＣの添加割合が増すと、高温におけるサイクル寿命が向上するが、主溶媒に対する添加量が５重量部を超えると、サイクル寿命向上の効果が上がらず、ＤＡＣの量が１０重量部で、サイクル寿命がかなり低下している。このことから、ＤＡＣの添加量は、主溶媒１００重量部に対して、０．５〜５重量部の範囲が好ましいことがわかる。 From the results of Table 6, when the addition ratio of DAC increases, the cycle life at high temperature is improved, but when the addition amount with respect to the main solvent exceeds 5 parts by weight, the effect of improving the cycle life is not improved, and the amount of DAC is 10 By weight, the cycle life is considerably reduced. This shows that the addition amount of DAC is preferably in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the main solvent.
《実施例７》
（１）正極板の作製
実施例５と同じ正極活物質を用いた。
Example 7
(1) Production of positive electrode plate The same positive electrode active material as in Example 5 was used.
（２）非水電解液の調製
ＥＣ、ＥＭＣ、およびＤＥＣを体積比３：５：２で混合した混合溶媒１００重量部に、以下で説明する表７に示した量のＤＡＣとＶＣとを添加した。この混合液に、ＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解して非水電解液を調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of non-aqueous electrolyte The amount of DAC and VC shown in Table 7 described below is added to 100 parts by weight of a mixed solvent in which EC, EMC, and DEC are mixed at a volume ratio of 3: 5: 2. did. LiPF 6 was dissolved in this mixed solution at a concentration of 1.0 mol / L to prepare a nonaqueous electrolytic solution. Otherwise, the battery was fabricated in the same manner as in Example 1.
《比較例６》
ＥＣ、ＥＭＣ、およびＤＥＣの混合溶媒１００重量部にＶＣを２重量部添加した非水電解液を用いた以外は、実施例７と同様にして電池を作製した。
<< Comparative Example 6 >>
A battery was fabricated in the same manner as in Example 7, except that a nonaqueous electrolytic solution in which 2 parts by weight of VC was added to 100 parts by weight of a mixed solvent of EC, EMC, and DEC was used.
《比較例７》
ＥＣ、ＥＭＣ、およびＤＥＣの混合溶媒にＤＡＣもＶＣも添加しない非水電解液を用いた以外は、実施例７と同様にして電池を作製した。
<< Comparative Example 7 >>
A battery was fabricated in the same manner as in Example 7 except that a nonaqueous electrolyte solution in which neither DAC nor VC was added to the mixed solvent of EC, EMC, and DEC was used.
実施例７と比較例６、７の電池について、８５℃で放置した後の電池の残存容量と、８５℃で放置した直後の電池内の水素や炭酸ガスなどを含む全ガス発生量を測定した。これらの評価は別々の電池で行った。８５℃に放置する前に、２０℃で、定電流２５ｍＡで上限電圧４．２Ｖまで充電し、定電圧４．２Ｖで保持した。定電流および定電圧の充電時間の合計は２時間とした。充電後の電池を開回路状態で、８５℃で１日間放置した。その後、それらの電池の半数を２０℃に戻し、定電流７ｍＡで下限電圧３．０Ｖまで放電した時の残存容量を測定した。それらの電池の残りは、８５℃で放置した直後の電池内の水素や炭酸ガスなどを含む全ガス発生量を測定した。その結果を表７に示す。 For the batteries of Example 7 and Comparative Examples 6 and 7, the remaining capacity of the battery after being left at 85 ° C. and the total gas generation amount including hydrogen and carbon dioxide in the battery immediately after being left at 85 ° C. were measured. . These evaluations were performed on separate batteries. Before leaving at 85 ° C., the battery was charged at 20 ° C. with a constant current of 25 mA up to an upper limit voltage of 4.2 V and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage was 2 hours. The battery after charging was left in an open circuit state at 85 ° C. for 1 day. Thereafter, half of the batteries were returned to 20 ° C., and the remaining capacity when discharged to a lower limit voltage of 3.0 V at a constant current of 7 mA was measured. The remaining amount of these batteries was measured for the total gas generation amount including hydrogen and carbon dioxide gas in the batteries immediately after being left at 85 ° C. The results are shown in Table 7.
表７の結果から、実施例７と比較例６とを比べると、ＤＡＣが含まれない非水電解液を用いた比較例６は、残存容量は実施例７と同等であるが、ガス発生量は実施例７より多くなっている。また、実施例７と比較例７とを比べると、ＤＡＣもＶＣも添加されていない非水電解液を用いた比較例７は、全ガス発生量は比較例６より少なくなっているが、実施例７よりも残存容量は小さくなっている。全残存容量とガス発生量の視点から、非水電解液にＤＡＣとＶＣとの両方を添加するのが好ましい。 From the results of Table 7, when Example 7 and Comparative Example 6 are compared, Comparative Example 6 using a non-aqueous electrolyte that does not contain DAC has the same residual capacity as Example 7, but the amount of gas generated Is larger than Example 7. Further, when Example 7 and Comparative Example 7 are compared, Comparative Example 7 using a non-aqueous electrolyte to which neither DAC nor VC is added has a smaller total gas generation amount than Comparative Example 6, but The remaining capacity is smaller than in Example 7. From the viewpoint of the total remaining capacity and the amount of gas generated, it is preferable to add both DAC and VC to the non-aqueous electrolyte.
実施例７において、ＶＣの量が０．５〜１０．０重量部を添加した場合は、０．３重量部以下、および１５．０重量部以上を添加した場合に比べ、残存容量が大きく、全ガス発生量が少なくなっている。このことから、ＤＡＣの添加量は、主溶媒１００重量部に対して、０．５〜１０．０重量部の範囲が好ましいことがわかる。 In Example 7, when the amount of VC was 0.5 to 10.0 parts by weight, the remaining capacity was larger than when 0.3 parts by weight or less and 15.0 parts by weight or more were added. Total gas generation is low. This shows that the addition amount of DAC is preferably in the range of 0.5 to 10.0 parts by weight with respect to 100 parts by weight of the main solvent.
《実施例８》
（１）正極板の作製
正極活物質として、以下に説明する表８に示したものを用いた。
Example 8
(1) Production of positive electrode plate The positive electrode active material shown in Table 8 described below was used.
（２）非水電解液の調製
ＥＣ、ＥＭＣ、およびＤＥＣを体積比３：５：２で混合した混合溶媒１００重量部に、ＤＡＣ２重量部を添加した。この混合液に、ＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解して非水電解液を調製した。これ以外は、実施例１と同様にした。
(2) Preparation of Nonaqueous
実施例８の電池について、実施例５と同様な評価を行った。その結果を表８に示す。 The battery of Example 8 was evaluated in the same manner as in Example 5. The results are shown in Table 8.
表８の結果から、正極活物質の複合酸化物の式ＬｉＢ１−ｗＣｗＯ２において、式中ＢをＣｏとし、式中ＣをＭｇ，Ｃａ，Ｓｒ，Ａｌ，およびＧａとした（ａ）〜（ｅ）の正極活物質と、ＤＡＣを添加した非水電解液とを組み合わせることにより、前述した比較例４の電池に比べて、高温におけるサイクル寿命が優れた電池が得られた。（ｈ）と（ｉ）のように式中Ｂを２種類の元素、（ｊ）のように式中Ｂを３種類の元素、（ｋ）にように式中Ｃを２種類の元素からなる正極活物質と、ＤＡＣを添加した非水電解液とを組み合わせた場合でも、高温におけるサイクル寿命が優れた電池が得られた。 From the results of Table 8, in the formula LiB 1-w C w O 2 of the composite oxide of the positive electrode active material, B in the formula is Co, and C is Mg, Ca, Sr, Al, and Ga (a ) To (e) were combined with the non-aqueous electrolyte to which the DAC was added, thereby obtaining a battery having an excellent cycle life at a high temperature as compared with the battery of Comparative Example 4 described above. As shown in (h) and (i), B in the formula consists of two kinds of elements, as shown in (j), B in the formula consists of three kinds of elements, and as shown in (k), C in the formula consists of two kinds of elements. Even when the positive electrode active material and the non-aqueous electrolyte to which DAC was added were combined, a battery having excellent cycle life at high temperatures was obtained.
《実施例９》
正極活物質として、以下に説明する表９に示したＬｉＮｉ０．８−ｘＣｏ０．２ＡｌｘＯ２粉末を用いた以外は、実施例８と同様にして電池を作製した。
Example 9
A battery was fabricated in the same manner as in Example 8 except that LiNi 0.8-x Co 0.2 Al x O 2 powder shown in Table 9 described below was used as the positive electrode active material.
実施例９の電池について、実施例５と同じ評価を行った。その結果を表９に示す。 The battery of Example 9 was evaluated in the same manner as Example 5. The results are shown in Table 9.
表９の結果から、正極活物質の複合酸化物として、ＬｉＮｉ０．８−ｘＣｏ０．２ＡｌｘＯ２と、ＤＡＣを添加した非水電解液とを組み合わせることにより、高温におけるサイクル寿命において、（ｃ）〜（ｇ）は、（ａ）と（ｂ）および（ｈ）と（ｉ）に比べて優れている。このことから、０．００５≦ｘ≦０．１００の範囲が好ましいことがわかる。 From the results of Table 9, by combining LiNi 0.8-x Co 0.2 Al x O 2 and a non-aqueous electrolyte to which DAC is added as a composite oxide of the positive electrode active material, the cycle life at high temperature can be improved. , (C) to (g) are superior to (a) and (b) and (h) and (i). This shows that the range of 0.005 ≦ x ≦ 0.100 is preferable.
《実施例１０》
（１）正極板の作製
正極活物質として、ＬｉＣｏ０．９８Ｍｇ０．０２Ｏ２粉末を用いた。
Example 10
(1) Production of positive electrode plate As the positive electrode active material, LiCo 0.98 Mg 0.02 O 2 powder was used.
（２）非水電解液の調製
ＥＣ、ＥＭＣ、およびＤＥＣを体積比３：５：２で混合した混合溶媒１００重量部に、以下で説明する表１０に示した量のＤＡＣを添加した。この混合液に、ＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解し調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of Nonaqueous Electrolytic Solution The amount of DAC shown in Table 10 described below was added to 100 parts by weight of a mixed solvent in which EC, EMC, and DEC were mixed at a volume ratio of 3: 5: 2. LiPF 6 was dissolved and prepared in this mixed solution at a concentration of 1.0 mol / L. Otherwise, the battery was fabricated in the same manner as in Example 1.
実施例１０の電池について、実施例５と同じ評価を行った。その結果を表１０に示す。 For the battery of Example 10, the same evaluation as in Example 5 was performed. The results are shown in Table 10.
表１０の結果から、ＤＡＣの添加割合が増すと、高温におけるサイクル寿命が向上するが、主溶媒に対する添加量が５重量部を超えると、サイクル寿命向上の効果が上がらず、ＤＡＣの量が１０重量部で、サイクル寿命がかなり低下している。このことから、ＤＡＣの添加量は、主溶媒１００重量部に対して、０．５〜５重量部の範囲が好ましいことがわかる。 From the results of Table 10, the cycle life at high temperature is improved when the addition ratio of DAC is increased, but when the addition amount to the main solvent exceeds 5 parts by weight, the effect of improving the cycle life is not improved, and the amount of DAC is 10 By weight, the cycle life is considerably reduced. This shows that the addition amount of DAC is preferably in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the main solvent.
《実施例１１》
（１）正極板の作製
実施例１０と同じ正極板を用いた。
Example 11
(1) Production of positive electrode plate The same positive electrode plate as in Example 10 was used.
（２）非水電解液の調整
ＥＣ、ＥＭＣ、およびＤＥＣを体積比３：５：２で混合した混合溶媒１００重量部に、以下で説明する表１１に示した量のＤＡＣとＶＣとを添加した。この混合液に、ＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解し調製した。それ以外は、実施例１と同様にして電池を作製した。
(2) Preparation of non-aqueous electrolyte The amount of DAC and VC shown in Table 11 described below is added to 100 parts by weight of a mixed solvent obtained by mixing EC, EMC, and DEC at a volume ratio of 3: 5: 2. did. LiPF 6 was dissolved and prepared in this mixed solution at a concentration of 1.0 mol / L. Otherwise, the battery was fabricated in the same manner as in Example 1.
《比較例８》
ＥＣ、ＥＭＣ、およびＤＥＣの混合溶媒１００重量部に対してＶＣを２重量部添加した非水電解液を用いた以外は、実施例１１と同様にして電池を作製した。
<< Comparative Example 8 >>
A battery was fabricated in the same manner as in Example 11 except that a nonaqueous electrolytic solution in which 2 parts by weight of VC was added to 100 parts by weight of a mixed solvent of EC, EMC, and DEC was used.
《比較例９》
ＥＣ、ＥＭＣ、およびＤＥＣの混合溶媒にＤＡＣもＶＣも添加しない以外は、実施例１１と同様にして電池を作製した。
<< Comparative Example 9 >>
A battery was fabricated in the same manner as in Example 11 except that neither DAC nor VC was added to the mixed solvent of EC, EMC, and DEC.
実施例１１と比較例８、９の電池について、８５℃で放置した後の電池の残存容量と、８５℃で放置した直後の電池内の水素や炭酸ガスなどを含む全ガス発生量を測定した。これらの評価は別々の電池で行った。８５℃に放置する前に、２０℃で、定電流２５ｍＡで上限電圧４．２Ｖまで充電し、定電圧４．２Ｖで保持した。定電流および定電圧の充電時間の合計は２時間とした。充電後の電池を開回路状態で、８５℃で１日間放置した。その後、それらの電池の半数を２０℃に戻し、定電流７ｍＡで下限電圧３．０Ｖまで放電した時の残存容量を測定した。それらの電池の残りは、８５℃で放置した直後の電池内の水素や炭酸ガスなどを含む全ガス発生量を測定した。その結果を表１１に示す。 For the batteries of Example 11 and Comparative Examples 8 and 9, the remaining capacity of the battery after being left at 85 ° C. and the total gas generation amount including hydrogen and carbon dioxide in the battery immediately after being left at 85 ° C. were measured. . These evaluations were performed on separate batteries. Before leaving at 85 ° C., the battery was charged at 20 ° C. with a constant current of 25 mA up to an upper limit voltage of 4.2 V and held at a constant voltage of 4.2 V. The total charging time for constant current and constant voltage was 2 hours. The battery after charging was left in an open circuit state at 85 ° C. for 1 day. Thereafter, half of the batteries were returned to 20 ° C., and the remaining capacity when discharged to a lower limit voltage of 3.0 V at a constant current of 7 mA was measured. The remaining amount of these batteries was measured for the total gas generation amount including hydrogen and carbon dioxide gas in the batteries immediately after being left at 85 ° C. The results are shown in Table 11.
表１１の結果から、実施例１１と比較例８とを比べると、ＤＡＣが添加されていない非水電解液を用いた比較例８は、残存容量は実施例１１と同等であるが、全ガス発生量は実施例１１より多くなっている。また、実施例１１と比較例９とを比べると、ＤＡＣもＶＣも添加されていない非水電解液を用いた比較例９は、全ガス発生量については比較例７より少なくなっているが、残存容量は実施例１１より小さくなっている。残存容量と全ガス発生量の視点から、非水電解液にＤＡＣとＶＣの両方を添加するのが好ましいことがわかる。 From the results of Table 11, when Example 11 and Comparative Example 8 are compared, Comparative Example 8 using a non-aqueous electrolyte to which no DAC is added has a residual capacity equivalent to that of Example 11, but the total gas The amount generated is larger than that in Example 11. Further, when Example 11 and Comparative Example 9 are compared, Comparative Example 9 using a non-aqueous electrolyte to which neither DAC nor VC is added has a smaller total gas generation amount than Comparative Example 7, The remaining capacity is smaller than in Example 11. From the viewpoint of the remaining capacity and the total gas generation amount, it can be seen that it is preferable to add both DAC and VC to the non-aqueous electrolyte.
実施例１１において、ＶＣの量が０．５〜１０．０重量部を添加した場合は、０．３重量部以下、および１５．０重量部以上を添加した場合に比べ、残存容量が大きく、全ガス発生量が少なくなっている。このことから、ＤＡＣの添加量は、主溶媒１００重量部に対して、０．５〜１０．０重量部の範囲が好ましいことがわかる。 In Example 11, when the amount of VC was 0.5 to 10.0 parts by weight, the residual capacity was larger than when 0.3 parts by weight or less and 15.0 parts by weight or more were added. Total gas generation is low. This shows that the addition amount of DAC is preferably in the range of 0.5 to 10.0 parts by weight with respect to 100 parts by weight of the main solvent.
なお、正極活物質の複合酸化物の式ＬｉＢ１−ｗＣｗＯ２において、実施例８では、式中ＢとＣの元素を組み合わせた場合について説明し、実施例９では、式中Ｂの元素をＮｉとＣｏとし、式中Ｃの元素をＡｌとし、好ましい範囲は０．００５≦ｗ≦０．１００であることについて説明した。これら以外の元素の組み合わせにおいても同様の効果が得られる。
実施例の非水電解液二次電池の負極には、リチウムの吸蔵・放出が可能な炭素材料を用いたが、他のリチウムと合金化する単金属や合金、複合酸化物を用いても、また、リチウムやナトリウムなどのアルカリ金属を用いても、同様な効果が得られる。
In addition, in the formula LiB 1-w C w O 2 of the composite oxide of the positive electrode active material, Example 8 describes the case where the elements of B and C in the formula are combined, and Example 9 describes the case of B in the formula It has been described that the elements are Ni and Co, the element of C in the formula is Al, and the preferred range is 0.005 ≦ w ≦ 0.100. Similar effects can be obtained with combinations of other elements.
For the negative electrode of the non-aqueous electrolyte secondary battery of the example, a carbon material capable of occluding and releasing lithium was used, but using a single metal or alloy alloyed with other lithium or a composite oxide, The same effect can be obtained by using an alkali metal such as lithium or sodium.
本発明によれば、高温におけるガス発生が抑制され、サイクル特性が向上させることができ、高信頼性の非水電解液二次電池を提供することができる。この非水電解液二次電池は、ノートパソコン、携帯電話、デジタルスチルカメラなどの電子機器の駆動電源として有用である。 According to the present invention, gas generation at a high temperature is suppressed, cycle characteristics can be improved, and a highly reliable non-aqueous electrolyte secondary battery can be provided. This non-aqueous electrolyte secondary battery is useful as a drive power source for electronic devices such as notebook computers, mobile phones, and digital still cameras.
１ アルミニウム箔集電体
２ 銅箔集電体
３ 正極活物質層
４ 負極活物質層
５ 正極板
６ 負極板
７ アルミニウム集電板
８ 銅集電板
９ アルミニウム製正極リード
１０ 銅製負極リード
１１ ポリプロピレン製微多孔セパレータ
１２ 極板群
１３ チューブ
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| KR102272265B1 (en) * | 2014-11-21 | 2021-07-05 | 삼성에스디아이 주식회사 | Positive active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including same |
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| JP2002208434A (en) * | 2000-12-15 | 2002-07-26 | Wilson Greatbatch Ltd | Organic carbonate additives for nonaqueous electrolite rechargeable electrochemical cell |
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| JP2003017060A (en) * | 2001-04-25 | 2003-01-17 | Sony Corp | Positive electrode active material and non-aqueous electrolyte battery |
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| JP2005285722A (en) * | 2004-03-04 | 2005-10-13 | Mitsubishi Chemicals Corp | Non-aqueous electrolytic solution and lithium secondary battery |
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|---|---|
| JP2005267911A (en) | 2005-09-29 |
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