JP4952314B2 - Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same - Google Patents
Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same Download PDFInfo
- Publication number
- JP4952314B2 JP4952314B2 JP2007068410A JP2007068410A JP4952314B2 JP 4952314 B2 JP4952314 B2 JP 4952314B2 JP 2007068410 A JP2007068410 A JP 2007068410A JP 2007068410 A JP2007068410 A JP 2007068410A JP 4952314 B2 JP4952314 B2 JP 4952314B2
- Authority
- JP
- Japan
- Prior art keywords
- separator
- secondary battery
- electrode plate
- layer
- battery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000011148 porous material Substances 0.000 claims description 52
- 239000012982 microporous membrane Substances 0.000 claims description 28
- 229920000642 polymer Polymers 0.000 claims description 25
- 229920000098 polyolefin Polymers 0.000 claims description 7
- 239000010410 layer Substances 0.000 description 98
- 229920003235 aromatic polyamide Polymers 0.000 description 29
- 239000004760 aramid Substances 0.000 description 24
- 230000000052 comparative effect Effects 0.000 description 17
- 229920005989 resin Polymers 0.000 description 14
- 239000011347 resin Substances 0.000 description 14
- 239000004698 Polyethylene Substances 0.000 description 13
- 229920000573 polyethylene Polymers 0.000 description 13
- -1 polyethylene Polymers 0.000 description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 10
- 229910001416 lithium ion Inorganic materials 0.000 description 10
- 239000008151 electrolyte solution Substances 0.000 description 9
- 238000001556 precipitation Methods 0.000 description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 6
- 238000007599 discharging Methods 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000011149 active material Substances 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 238000000691 measurement method Methods 0.000 description 5
- 239000012528 membrane Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000007086 side reaction Methods 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 210000001787 dendrite Anatomy 0.000 description 4
- 239000011255 nonaqueous electrolyte Substances 0.000 description 4
- 239000003973 paint Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 230000008602 contraction Effects 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229920005672 polyolefin resin Polymers 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011883 electrode binding agent Substances 0.000 description 2
- 230000010220 ion permeability Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 description 1
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910014195 BM-400B Inorganic materials 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 239000004962 Polyamide-imide Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910004339 Ti-Si Inorganic materials 0.000 description 1
- 229910010978 Ti—Si Inorganic materials 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical class C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram 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
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 229920006015 heat resistant resin Polymers 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000003273 ketjen black Substances 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- 150000002642 lithium compounds Chemical class 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920002312 polyamide-imide Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910021484 silicon-nickel alloy Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Images
Classifications
-
- 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
Description
非水系二次電池用セパレータおよびこれを備えた非水系二次電池に関する。 The present invention relates to a separator for a non-aqueous secondary battery and a non-aqueous secondary battery including the same.
リチウムイオン二次電池は、軽量で高エネルギー密度を有することから、携帯電話、ノートパソコンなどのポータブル機器を中心に電源として実用化されている。これらの機器の高性能化および長時間駆動の要求からさらなる高エネルギー密度化の研究・開発が活発に行われている。このような開発の中で、安全性の確保が大きな課題の一つとなっている。安全性の確保に対して、セパレータの観点から、シャットダウン機能と耐熱性を両立させるために、シャットダウン機能を有するポリエチレン微多孔膜などに耐熱性樹脂からなる層をコーティングして一体化したセパレータが提案されている。これらは安全性の確保、あるいはそれと合せてセパレータのカールを防ぐなどのハンドリングを考慮したことに着目している（例えば、特許文献１参照のこと）。しかしながら、電池の高容量化に伴い、安全性の確保に加えて、二次電池として重要な特性であるサイクル特性や高温保存特性に着目した場合、安全性とこれらの特性を両立するセパレータとしては不十分である。 Lithium-ion secondary batteries are lightweight and have high energy density, and thus have been put to practical use as power sources mainly for portable devices such as mobile phones and notebook computers. Research and development of further higher energy density has been actively conducted due to the demand for higher performance and longer driving time for these devices. In such development, ensuring safety is one of the major issues. To ensure safety, from the perspective of the separator, in order to achieve both shutdown function and heat resistance, a separator that integrates a layer made of heat-resistant resin on a polyethylene microporous membrane with shutdown function is proposed. Has been. These focus on the consideration of handling such as ensuring safety or preventing curling of the separator in combination (for example, see Patent Document 1). However, as battery capacity increases, in addition to ensuring safety, when focusing on cycle characteristics and high-temperature storage characteristics, which are important characteristics for secondary batteries, as a separator that achieves both safety and these characteristics, It is insufficient.
また、ポリオレフィン系樹脂を用いたセパレータの孔径を制御し、電池性能を改善することが提案されている（例えば、特許文献２参照のこと）。電池を高容量にする場合、正極板および負極板の高密度化やセパレータの薄膜化などが実施されることが多い。この際に、電極表面の電解液の枯渇などを助長し、二次電池の重要特性であるサイクル特性や高温保存特性の低下をもたらすことがある。長期間充放電を繰り返すと極板の膨張によって極板間の電解液が押し出され、電極表面の電解液の枯渇などが起こる。さらには、電解液が副反応によりが分解し、分解生成物によって、セパレータが目詰まりし、電池性能が低下することが知られている。このため、セパレータの孔径は目詰まりし難くくするために、セパレータの孔が大きいのが望ましい。一方で、リチウム析出によるデンドライトおよび金属不純物の溶解析出による正・負極板間の内部短絡防止を考慮すると孔径は小さい方が望ましく、セパレータの孔径を制御することが述べられている。
しかし、近年の非水系二次電池、中でもリチウムイオン二次電池の高容量化によって、特許文献１のように、ポリオレフィン系微多孔膜の両面に耐熱性高分子からなる多孔質層が形成された耐熱性に優れたセパレータは、安全性の向上を主目的としている。安全性を向上させることはある程度可能であるが、電池の高容量化に伴って課題となる電池特性、具体的には、サイクル特性、リチウム析出によるデンドライト、および金属不純物の溶解析出による正・負極板間の内部短絡防止が十分にできないという課題がある。その理由は、セパレータ表面の孔径が小さすぎると、前述のように、セパレータが目詰まりしやすく、サイクル特性が低下してしまい、逆に、セパレータ表面の孔径が大きすぎると、前述の内部短絡の危険性が高く、信頼性を確保できず、セパレータの膜構造、特に孔径を考慮することが重要であるからである。そのため、サイクル特性や高温保存特性などの長期信頼性の確保が非常に困難である。
However, due to the recent increase in capacity of non-aqueous secondary batteries, particularly lithium ion secondary batteries, a porous layer made of a heat-resistant polymer was formed on both surfaces of a polyolefin microporous film as in
また、特許文献２はポリオレフィン系樹脂を用いたセパレータの孔径を規定し、これらの性能を改善するが提案されている。しかし、電池の高容量化に伴って、セパレータを薄膜化したり、正極板・負極板を高密度化することによって、セパレータの孔径を制御した
としてもポリオレフィン系樹脂そのものの柔らかさは変わらない。そのため、電池を充放電することで、極板の膨張収縮が起こり、その膨張に伴って柔らかいセパレータが圧縮されることになる。よって、電極表面に接しているセパレータ中に保持された電解液が枯渇し、サイクル特性の確保が困難となる。これはセパレータが厚み方向に対して、極板の膨張収縮に耐えられるだけの機械的強度を有していないことが課題である。
本発明は、シャットダウン機能を有する微多孔膜と耐熱性分子からなる多孔質膜とを有するセパレータで、シャットダウン機能を有する微多孔膜より厚み方向の機械的強度がある多孔質層であり、かつ孔質層の孔径を制御することにより、安全性、サイクル特性、および信頼性を兼ね備えた非水系二次電池を提供することを目的とする。 The present invention is a separator having a microporous membrane having a shutdown function and a porous membrane made of a heat-resistant molecule, and is a porous layer having a mechanical strength in the thickness direction as compared with the microporous membrane having a shutdown function, and pores An object of the present invention is to provide a non-aqueous secondary battery having safety, cycle characteristics, and reliability by controlling the pore diameter of the material layer.
上記課題を解決するために、本発明の非水系二次電池用セパレータは、シャットダウン機能を有する微多孔膜の両面に耐熱性高分子からなる多孔質層が形成され、前記微多孔膜の片面には前記耐熱性高分子からなるの多孔質層の平均孔径が０．０１〜０．０５μｍであり、かつもう一方の面には前記耐熱性高分子からなる多孔質層の平均孔径が０．２〜１μｍである。 In order to solve the above-described problems, the separator for a non-aqueous secondary battery according to the present invention has a porous layer made of a heat-resistant polymer formed on both sides of a microporous membrane having a shutdown function. Has an average pore diameter of the porous layer made of the heat-resistant polymer of 0.01 to 0.05 μm, and the other surface has an average pore diameter of 0.2 μm of the porous layer made of the heat-resistant polymer. ˜1 μm.
本発明によれば、安全性、サイクル特性、および信頼性に優れた高容量非水系二次電池を提供することが可能となる。 ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the high capacity | capacitance non-aqueous secondary battery excellent in safety | security, cycling characteristics, and reliability.
本発明の非水系二次電池用セパレータの実施の形態は、シャットダウン機能を有する微多孔膜の両面に耐熱性高分子からなる多孔質層が形成され、片面の多孔質層が平均孔径０．０１〜０．０５μｍ、もう片面の多孔質層が平均孔径０．２〜１μｍである膜構造を有している。シャットダウン機能を有する微多孔膜の両面に耐熱性高分子からなる多孔質層がない場合、充放電時の極板の膨張収縮により、微多孔膜が圧縮され、微多孔膜中に保持された電解液が枯渇し、サイクル特性が低下してしまう。そのため、シャットダウン機能を有する微多孔膜より厚み方向の機械的強度がある多孔質層が必要である。耐熱性高分子からなる多孔質層の平均孔径が０．０１μｍより小さい場合、イオン透過性が得られず、平均孔径が１μｍ以上の場合、耐熱性高分子からなる多孔質層の製膜性が悪く、剥離し易いため良くない。このような非水系二次電池用セパレータを非水系二次電池に使った場合において、本発明の非水系二次電池の実施の形態は、正極板、負極板、およびシャットダウン機能を有する微多孔膜を有する非水系二次電池において、微多孔膜は、両面に耐熱性高分子からなる多孔質層が形成され、微多孔膜の片面には耐熱性高分子からなる多孔質層の平均孔径が０．０１〜０．０５μｍであり、かつもう一方の面には前記耐熱性高分子からなる多孔質層の平均孔径が０．２〜１μｍである。 In an embodiment of the separator for a non-aqueous secondary battery of the present invention, a porous layer made of a heat-resistant polymer is formed on both surfaces of a microporous membrane having a shutdown function, and the porous layer on one side has an average pore diameter of 0.01. .About.0.05 .mu.m, and the other porous layer has a membrane structure having an average pore size of 0.2 to 1 .mu.m. When there is no porous layer made of heat-resistant polymer on both sides of the microporous membrane with shutdown function, the microporous membrane is compressed by the expansion and contraction of the electrode plate during charge and discharge, and the electrolysis retained in the microporous membrane The liquid is depleted and the cycle characteristics are degraded. For this reason, a porous layer having a mechanical strength in the thickness direction of the microporous membrane having a shutdown function is required. When the average pore size of the porous layer made of the heat resistant polymer is smaller than 0.01 μm, the ion permeability is not obtained, and when the average pore size is 1 μm or more, the film forming property of the porous layer made of the heat resistant polymer is high. It is not good because it is bad and easy to peel off. When such a non-aqueous secondary battery separator is used for a non-aqueous secondary battery, embodiments of the non-aqueous secondary battery of the present invention include a positive electrode plate, a negative electrode plate, and a microporous film having a shutdown function. In the non-aqueous secondary battery having a microporous membrane, a porous layer made of a heat resistant polymer is formed on both sides of the microporous membrane, and the average pore size of the porous layer made of the heat resistant polymer is 0 on one side of the microporous membrane. 0.01 to 0.05 μm, and on the other side, the porous layer made of the heat-resistant polymer has an average pore diameter of 0.2 to 1 μm.
耐熱性高分子からなる多孔質層の平均孔径を０．０５μｍ以下にすることにより、リチウム析出によるデンドライトおよび金属不純物の溶解析出によるブリッジの形成に起因する内部短絡防止に効果があり、非水系二次電池の信頼性が向上する。前述したイオン透過性を確保するために、平均孔径が０．０１μｍ以上が必要である。かつ、耐熱性高分子からなる多孔質層の平均孔径を０．２μｍ以上にすることにより、電解液の副反応による生成物が堆積することによるセパレータの目詰まりを抑制することが可能となり、サイクル特性が向上する。前述した多孔質層の製膜性の理由から、平均孔径が１μｍ以下が必要である。以上のことより、平均孔径０．０１〜０．０５μｍを有する多孔質層により、リチウム析出によるデンドライトおよび金属不純物の溶解析出によるブリッジの形成に起因する内部短絡防止に効果があり、信頼性が向上する。また、平均孔径０．２〜１μｍを有する多孔質層により、副反応による生成物が堆積することによるセパレータの目詰まりを抑
制することが可能となり、サイクル特性が向上する。
By setting the average pore size of the porous layer made of a heat-resistant polymer to 0.05 μm or less, it is effective in preventing internal short circuit due to the formation of bridges by dendrite by lithium precipitation and dissolution precipitation of metal impurities. The reliability of the secondary battery is improved. In order to ensure the above-mentioned ion permeability, the average pore diameter is required to be 0.01 μm or more. In addition, by setting the average pore size of the porous layer made of the heat-resistant polymer to 0.2 μm or more, it becomes possible to suppress clogging of the separator due to accumulation of products due to the side reaction of the electrolytic solution, and the cycle Improved characteristics. For the reason of the film forming property of the porous layer described above, the average pore size is required to be 1 μm or less. As described above, the porous layer having an average pore diameter of 0.01 to 0.05 μm is effective in preventing internal short circuit due to dendrite due to lithium precipitation and bridge formation due to dissolution and precipitation of metal impurities, improving reliability. To do. In addition, the porous layer having an average pore diameter of 0.2 to 1 μm can suppress clogging of the separator due to accumulation of products due to side reactions, and the cycle characteristics are improved.
本発明の非水系二次電池用セパレータおよび非水系二次電池の好ましい実施の形態は、微多孔膜がポリオレフィン系である。シャットダウン機能を有する微多孔膜の中でも、ポリオレフィン系は、特に優れたシャットダウン特性を有しており、かつ延伸性に優れており、微多孔膜自身の機械的な強度の確保の点からも好ましい。 In a preferred embodiment of the separator for a non-aqueous secondary battery and the non-aqueous secondary battery of the present invention, the microporous membrane is a polyolefin-based film. Among the microporous membranes having a shutdown function, polyolefins have particularly excellent shutdown properties and excellent stretchability, and are preferable from the viewpoint of securing the mechanical strength of the microporous membrane itself.
本発明の非水系二次電池の好ましい実施の形態は、多孔質層の平均孔径が小さい面を正極板側に配置し、平均孔径が大きい面を負極板側に配置する。こうすることにより、電解液の副反応の酸化還元反応による生成物の堆積は負極板側で顕著であるため、正極板側に面する多孔質層の平均孔径よりも負極側に面する多孔質層の平均孔径を大きくすることが目詰まりを抑制する効果が得られる。このような構成にすることで非水系二次電池のサイクル特性がさらに向上する。 In a preferred embodiment of the nonaqueous secondary battery of the present invention, the surface of the porous layer having a small average pore diameter is disposed on the positive electrode plate side, and the surface having a large average pore diameter is disposed on the negative electrode plate side. By doing so, the product deposition due to the oxidation-reduction reaction as a side reaction of the electrolytic solution is remarkable on the negative electrode plate side, so that the porous surface facing the negative electrode side is larger than the average pore diameter of the porous layer facing the positive electrode plate side. Increasing the average pore size of the layer has the effect of suppressing clogging. With such a configuration, the cycle characteristics of the non-aqueous secondary battery are further improved.
シャットダウン機能を有する微多孔膜は公知のポリオレフィン微多孔膜を好適に用いることが可能である。具体的には、膜厚は５〜２５μｍの範囲であり、目付けは５〜２５ｇ／ｍ２が好適である。空孔率は３０〜５０％の範囲が好ましく、ガーレ値（ＪＩＳ Ｐ８１１７）は８００秒／１００ｃｃ以下が好適であり、さらに６００秒以下が好ましい。材質としてはポリエチレンを主体とすることが好ましい。
A known polyolefin microporous membrane can be suitably used as the microporous membrane having a shutdown function. Specifically, the film thickness is in the range of 5 to 25 μm, and the basis weight is preferably 5 to 25 g /
シャットダウン機能を有する微多孔膜の両面に形成される耐熱性高分子からなる多孔質層については、融点２００℃以上を有するものが好ましい。具体的には、芳香族ポリアミド、ポリイミド、ポリアミドイミド、およびセラミックフィラー等が挙げられ、これらを混合して用いても構わない。 About the porous layer which consists of a heat resistant polymer formed in both surfaces of the microporous film which has a shutdown function, what has melting | fusing point 200 degreeC or more is preferable. Specific examples include aromatic polyamide, polyimide, polyamideimide, ceramic filler, and the like, and these may be used in combination.
また、本発明の耐熱性高分子からなる多孔質層の平均孔径は、水銀圧入法によって測定されるモード径のことである。 The average pore diameter of the porous layer made of the heat-resistant polymer of the present invention is a mode diameter measured by a mercury intrusion method.
本発明の非水系二次電池用セパレータの膜厚は１０〜３０μｍの範囲が好ましく、耐熱性高分子からなる多孔質層は各層とも１．０〜７．０ｇ／ｍ２の範囲で被覆することが好ましく、特に１．５〜４．０ｇ／ｍ２の範囲が好ましい。１．０ｇ／ｍ２未満の場合には、高温時にポリオレフィン系微多孔膜の収縮力の影響で短絡する可能性があり、安全性の確保が困難になる。また、７．０ｇ／ｍ２より大きい場合には、セパレータとして群構成時にクラックが入りやすく、耐熱性高分子からなる多孔質層が剥離する可能性がある。
The film thickness of the separator for a non-aqueous secondary battery of the present invention is preferably in the range of 10 to 30 μm, and the porous layer made of a heat-resistant polymer may be coated in the range of 1.0 to 7.0 g /
正極板については、活物質としてコバルト酸リチウムおよびその変性体・ニッケル酸リチウムおよびその変性体・マンガン酸リチウムおよびその変性体などの複合酸化物を挙げることができる。結着剤としてはＰＴＦＥやＰＶＤＦ等を単独または組み合わせて用いてもよい。導電材としてはアセチレンブラック、ケッチェンブラック（登録商標）、および各種グラファイトを単独あるいは組み合わせて用いてよい。 Regarding the positive electrode plate, examples of the active material include composite oxides such as lithium cobaltate and its modified body / lithium nickelate and its modified body / lithium manganate and its modified body. As the binder, PTFE, PVDF or the like may be used alone or in combination. As the conductive material, acetylene black, ketjen black (registered trademark), and various graphites may be used alone or in combination.
正極集電体の材料としてはアルミニウム、もしくはアルミニウム合金箔が好ましい。 The material for the positive electrode current collector is preferably aluminum or aluminum alloy foil.
負極板としてはその活物質としては、天然黒鉛、人造黒鉛、およびハードカーボン等の各種炭素材料またはリチウムと合金化可能な各種元素、例えば、Ａｌ、Ｓｉ、Ｚｎ、Ｇｅ、Ｃｄ、Ｓｎ、およびＰｂ等を挙げることができる。これらは単独で含まれていてもよく、２種以上が含まれていてもよい。また、ＳｎＯ、ＳｉＯｘ（０＜ｘ＜２）等の酸化物、Ｎｉ−Ｓｉ合金、およびＴｉ−Ｓｉ合金等の遷移金属元素を含む合金等、様々な材料を用いることができる。 The active material for the negative electrode plate includes various carbon materials such as natural graphite, artificial graphite, and hard carbon, or various elements that can be alloyed with lithium, such as Al, Si, Zn, Ge, Cd, Sn, and Pb. Etc. These may be contained independently and 2 or more types may be contained. In addition, various materials such as oxides such as SnO and SiOx (0 <x <2), Ni-Si alloys, alloys containing transition metal elements such as Ti-Si alloys, and the like can be used.
結着剤としてはＰＶＤＦおよびその変性体をはじめ各種樹脂材料を用いることができる。また、結着剤を用いずに、集電体上に蒸着などにより活物質層を形成してもよい。 As the binder, various resin materials including PVDF and modified products thereof can be used. Alternatively, the active material layer may be formed on the current collector by vapor deposition or the like without using a binder.
負極集電体の材料としては、銅箔が好ましい。 As a material for the negative electrode current collector, copper foil is preferable.
電解液については、塩としてＬｉＰＦ６およびＬｉＢＦ４などの各種リチウム化合物を用いることができる。また、溶媒としてエチレンカーボネート（ＥＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、およびエチルメチルカーボネート（ＥＭＣ）を単独および組み合わせて用いることができる。 For the electrolytic solution, it is possible to use various lithium compounds such as LiPF 6 and LiBF 4 as a salt. Further, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) can be used alone or in combination as a solvent.
以上のような構成とすることで、安全性、サイクル特性、および信頼性に優れた高容量非水系二次電池を得ることができる。 By setting it as the above structures, the high capacity | capacitance non-aqueous secondary battery excellent in safety | security, cycling characteristics, and reliability can be obtained.
次に、円筒型リチウムイオン二次電池の作製方法について詳細に述べる。 Next, a method for manufacturing a cylindrical lithium ion secondary battery will be described in detail.
（ａ）正極板の作製
正極活物質としてコバルト酸リチウム３ｋｇと、正極結着剤として呉羽化学（株）製の「＃１３２０（商品名）」（ＰＶＤＦを１２重量％含むＮＭＰ溶液）１ｋｇと、導電剤としてアセチレンブラック９０ｇと、適量のＮＭＰとを、双腕式練合機にて攪拌し、正極合剤塗料を調製した。この塗料を正極集電体である厚み１５μｍのアルミニウム箔の両面に、正極リードの接続部を除いて塗布し、乾燥後の塗膜をローラで圧延し、活物質密度が３．６ｇ／ｃｍ３の正極合剤層を形成した。この際、アルミニウム箔および正極合剤層からなる極板の厚みを１５０μｍに制御した。その後、円筒型電池（直径１８ｍｍ、長さ６５ｍｍ）の電池缶に挿入可能な幅に極板を極板幅５７．５ｍｍにスリットし、正極板のフープを得た。
(A) Production of positive electrode plate 3 kg of lithium cobalt oxide as a positive electrode active material, 1 kg of “# 1320 (trade name)” (NMP solution containing 12% by weight of PVDF) manufactured by Kureha Chemical Co., Ltd. as a positive electrode binder, 90 g of acetylene black as a conductive agent and an appropriate amount of NMP were stirred with a double-arm kneader to prepare a positive electrode mixture paint. This paint was applied to both sides of a 15 μm thick aluminum foil as a positive electrode current collector, excluding the connecting portion of the positive electrode lead, and the dried coating film was rolled with a roller to obtain an active material density of 3.6 g / cm 3. The positive electrode mixture layer was formed. Under the present circumstances, the thickness of the electrode plate which consists of aluminum foil and a positive mix layer was controlled to 150 micrometers. Thereafter, the electrode plate was slit to a width of 57.5 mm so that the electrode plate could be inserted into a cylindrical battery (diameter 18 mm, length 65 mm) battery can to obtain a hoop of the positive electrode plate.
（ｂ）負極板の作製
負極活物質として人造黒鉛３ｋｇと、負極結着剤として日本ゼオン（株）製の「ＢＭ−４００Ｂ（商品名）」（スチレン−ブタジエン共重合体の変性体を４０重量％含む水性分散液）７５ｇと、増粘剤としてカルボキシメチルセルロース（ＣＭＣ）を３０ｇと、適量の水とを、双腕式練合機にて攪拌し、負極合剤塗料を調製した。この塗料を負極集電体である厚さ１０μｍの銅箔の両面に、負極リード接続部を除いて塗布し、乾燥後の塗膜をローラで圧延して、活物質層密度が１．６ｇ／ｃｍ３になるように負極合剤層を形成した。この際、銅箔および負極合剤層からなる極板の厚みが１５０μｍになるようにした。その後、上述した円筒型リチウムイオン二次電池の電池缶に挿入可能な幅（極板幅５８．５ｍｍ）の極板にスリットし、負極板のフープを得た。
(B) Production of negative electrode plate 3 kg of artificial graphite as the negative electrode active material, and “BM-400B (trade name)” manufactured by Nippon Zeon Co., Ltd. as the negative electrode binder (40 weight of modified styrene-butadiene copolymer) % Aqueous dispersion), 30 g of carboxymethyl cellulose (CMC) as a thickener, and an appropriate amount of water were stirred with a double-arm kneader to prepare a negative electrode mixture paint. This paint was applied to both sides of a 10 μm-thick copper foil as a negative electrode current collector, excluding the negative electrode lead connection portion, and the dried coating film was rolled with a roller to obtain an active material layer density of 1.6 g / The negative electrode mixture layer was formed so as to be cm 3 . At this time, the thickness of the electrode plate made of the copper foil and the negative electrode mixture layer was set to 150 μm. Then, it slit into the electrode plate of the width | variety (electrode plate width 58.5mm) which can be inserted in the battery can of the cylindrical lithium ion secondary battery mentioned above, and obtained the hoop of the negative electrode plate.
（ｃ）セパレータの作製
まず、セパレータの構成について説明する。図１に示すように、セパレータには三層あり、正極板に面している層をＡ層、負極板に面している層をＣ層、真ん中の層をＢ層と呼ぶことにする。
(C) Production of Separator First, the configuration of the separator will be described. As shown in FIG. 1, the separator has three layers. The layer facing the positive electrode plate is called A layer, the layer facing the negative electrode plate is called C layer, and the middle layer is called B layer.
（Ｂ層の作製）
原料として重量平均分子量６０万の高密度ポリエチレン３５重量部、重量平均分子量２０万の低密度ポリエチレン１０重量部、可塑剤ジオクチルフタレート５５重量部を混合造粒した後、先端にＴ−ダイを装着した押出機中で溶融混練し、厚さ１００μｍのシートを作製した。このシートをメチルエチルケトン（ＭＥＫ）溶媒に浸漬させジオクチルフタレートを抽出除去し、乾燥させて延伸前の多孔膜を得た。この多孔膜を１１５〜１２５℃に加熱された槽で二軸方向に７．０倍×７．０倍に延伸し、その後１００℃に加熱された槽
で熱処理を行い、ポリエチレン微多孔膜を得た。
(Preparation of layer B)
After mixing and granulating 35 parts by weight of high density polyethylene having a weight average molecular weight of 600,000, 10 parts by weight of low density polyethylene having a weight average molecular weight of 200,000, and 55 parts by weight of a plasticizer dioctyl phthalate as a raw material, a T-die was attached to the tip. It was melt-kneaded in an extruder to produce a sheet having a thickness of 100 μm. This sheet was immersed in a methyl ethyl ketone (MEK) solvent to extract and remove dioctyl phthalate, and dried to obtain a porous film before stretching. The porous film was stretched 7.0 times to 7.0 times in a biaxial direction in a tank heated to 115 to 125 ° C, and then heat-treated in a tank heated to 100 ° C to obtain a polyethylene microporous film. It was.
このポリエチレン微多孔膜を基材として、表面にアラミド樹脂を塗着し、アラミド−ポリエチレン微多孔積層膜とした。以下にアラミド−ポリエチレン微多孔積層膜の作製方法を示す。 Using this polyethylene microporous membrane as a base material, an aramid resin was applied to the surface to obtain an aramid-polyethylene microporous laminated membrane. A method for producing an aramid-polyethylene microporous laminated film is shown below.
（Ａ層、Ｃ層の作製）
ＮＭＰ４２００ｇに塩化カルシウム２７２．６５ｇを溶解した後、パラフェニレンジアミン１３２．９１ｇを添加して完全に溶解させた。得られた溶液に、テレフタル酸ジクロライド（以下、ＴＰＣと略す）２４３．３２ｇを徐々に添加してパラアラミドを重合させ、さらにＮＭＰで希釈して、濃度２．０重量％のパラアラミド溶液を得た。なお、得られたパラアラミド溶液からパラアラミド樹脂を分離し、その固有粘度を求めたところ、２０１ｃｍ３／ｇであった。
(Preparation of A layer and C layer)
After 272.65 g of calcium chloride was dissolved in 4200 g of NMP, 132.91 g of paraphenylenediamine was added and completely dissolved. To the obtained solution, 243.32 g of terephthalic acid dichloride (hereinafter abbreviated as TPC) was gradually added to polymerize para-aramid, and further diluted with NMP to obtain a para-aramid solution having a concentration of 2.0% by weight. In addition, when para-aramid resin was isolate | separated from the obtained para-aramid solution and the intrinsic viscosity was calculated | required, it was 201 cm < 3 > / g.
得られたパラアラミド溶液に、アルミナ粉末（平均粒子径０．１６μｍ）を添加し、分散させ、様々なアラミド樹脂の含有率を有するＡ層の原料スラリーを調製した。 To the obtained para-aramid solution, alumina powder (average particle size 0.16 μm) was added and dispersed to prepare a raw material slurry of layer A having various aramid resin contents.
次に、ポリエチレンフィルム（Ｂ層）の片面に、所定量のＡ層の原料スラリーを塗布し、温度６０℃、湿度７０％の雰囲気で、アラミド樹脂を析出させた。その後、析出したアラミド樹脂を水洗し、乾燥させた。その結果、Ｂ層およびＢ層の片面に形成されたＡ層からなり、Ａ層がアラミド樹脂とアルミナ粉末とを含むセパレータが得られた。さらに、所定量のＣ層の原料スラリーを塗布し、温度６０℃、湿度７０％の雰囲気で、アラミド樹脂を析出させた。その後、析出したアラミド樹脂を水洗し、乾燥させた。その結果、Ｂ層のもう片面にアラミド樹脂とアルミナ粉末とを含むＣ層が形成され、Ｂ層の両面にＡ層、Ｃ層からなるセパレータが得られた。 Next, a predetermined amount of the raw material slurry of the A layer was applied to one side of the polyethylene film (B layer), and an aramid resin was deposited in an atmosphere at a temperature of 60 ° C. and a humidity of 70%. Thereafter, the precipitated aramid resin was washed with water and dried. As a result, there was obtained a separator comprising the B layer and the A layer formed on one side of the B layer, and the A layer containing an aramid resin and alumina powder. Furthermore, a predetermined amount of the raw material slurry for the C layer was applied, and an aramid resin was deposited in an atmosphere at a temperature of 60 ° C. and a humidity of 70%. Thereafter, the precipitated aramid resin was washed with water and dried. As a result, a C layer containing an aramid resin and alumina powder was formed on the other side of the B layer, and a separator composed of the A layer and the C layer was obtained on both sides of the B layer.
アラミド樹脂とアルミナ粉末との合計に占めるアラミド樹脂の含有率を様々に変化させて孔径の異なる多孔膜を含むセパレータが得られた。 A separator including porous films having different pore diameters was obtained by varying the content of the aramid resin in the total of the aramid resin and the alumina powder.
（ｄ）非水電解液の調製
ＥＣとＤＭＣとＥＭＣとを体積比２：３：３で含む非水溶媒の混合物に、ＬｉＰＦ６を１．２ｍｏｌ／Ｌの濃度で溶解した後、ＶＣを非水電解液１００重量部あたり３重量部添加し、非水電解液を調整した。
(D) Preparation of non-aqueous electrolyte solution After dissolving LiPF 6 at a concentration of 1.2 mol / L in a mixture of non-aqueous solvent containing EC, DMC, and EMC at a volume ratio of 2: 3: 3, VC is not added. A non-aqueous electrolyte was prepared by adding 3 parts by weight per 100 parts by weight of the water electrolyte.
（ｅ）電池の作製
上述の正極板、負極板、セパレータおよび非水電解液を用いて、以下の要領で円筒型電池を作製した。まず、正極板のフープと負極板のフープとをそれぞれ所定の長さに切断し、正極リード接続部には正極リードの一端を、負極リード接続部には負極リードの一端をそれぞれ接続した。その後、正極板、負極板、セパレータを用いて捲回し、最外周がセパレータで覆われた円柱状の電極群を構成した。ここでセパレータのフープを巻き解く速度を２個／分（荷重は５００ｇｆ）とした。
(E) Production of Battery A cylindrical battery was produced in the following manner using the positive electrode plate, the negative electrode plate, the separator, and the non-aqueous electrolyte. First, the hoop of the positive electrode plate and the hoop of the negative electrode plate were each cut to a predetermined length, and one end of the positive electrode lead was connected to the positive electrode lead connection portion, and one end of the negative electrode lead was connected to the negative electrode lead connection portion. Then, it rolled using the positive electrode plate, the negative electrode plate, and the separator, and comprised the cylindrical electrode group by which the outermost periphery was covered with the separator. Here, the unwinding speed of the separator hoop was set to 2 pieces / minute (load is 500 gf).
この電極群を上部絶縁リングと下部絶縁リングで挟み、電池缶に収容した。次いで、上記の非水電解液５ｇを電池缶内に注入した後１３３Ｐａに減圧し、電極群表面に電解液の残渣が確認されなくなるまで放置し、電極群に電解液を含浸させた。 This electrode group was sandwiched between an upper insulating ring and a lower insulating ring and accommodated in a battery can. Next, 5 g of the above non-aqueous electrolyte solution was poured into the battery can, and then the pressure was reduced to 133 Pa. The electrode group surface was left until no electrolyte residue was observed, and the electrode group was impregnated with the electrolyte solution.
その後、正極リードを電池蓋の裏面に、負極リードを電池缶の内底面にそれぞれ溶接し、最後に周縁に絶縁パッキンが配された電池蓋で電池缶の開口部を塞ぎ、容量２５００ｍＡｈの１８６５０サイズの円筒型リチウムイオン二次電池を作製した。これを実施例とする。 After that, the positive electrode lead is welded to the back surface of the battery lid and the negative electrode lead is welded to the inner bottom surface of the battery can. A cylindrical lithium ion secondary battery was prepared. This is an example.
（セパレータの厚み）
厚みは、ＪＩＳ規格Ｋ７１３０−１９９２による方法に準じて測定した。また、多孔質層の厚みについては、断面ＳＥＭ写真で確認した。
(Separator thickness)
The thickness was measured according to a method according to JIS standard K7130-1992. Moreover, about the thickness of the porous layer, it confirmed with the cross-sectional SEM photograph.
（セパレータの平均孔径）
島津製作所製ポアサイザー９３２０型を用いて、サンプル重量０．０２〜０．０４ｍｇを前処理として真空脱気を５分間行った後、初期圧２．０ｐｓｉａより測定した。得られた細孔径分布データから、４μｍ以下で圧入体積の最も大きい点（モード径）を平均孔径とした。
(Average pore size of separator)
Using a pore sizer 9320 manufactured by Shimadzu Corporation, vacuum degassing was performed for 5 minutes using a sample weight of 0.02 to 0.04 mg as a pretreatment, and then measured from an initial pressure of 2.0 psia. From the obtained pore diameter distribution data, the point (mode diameter) having the largest injection volume at 4 μm or less was defined as the average pore diameter.
《実施例１》
以下で説明する表１に示したセパレータを用いた。セパレータはポリエチレン微多孔膜（Ｂ層）の両面にアラミド多孔質層（Ａ、Ｃ層）を形成し、Ａ層の平均孔径が０．０２μｍ、Ｃ層の平均孔径が０．５μｍであるものを用いた。このセパレータを用いて円筒型リチウムイオン二次電池を作製した。
Example 1
The separator shown in Table 1 described below was used. The separator is formed by forming an aramid porous layer (A, C layer) on both sides of a polyethylene microporous membrane (B layer), the average pore diameter of the A layer being 0.02 μm, and the average pore diameter of the C layer being 0.5 μm. Using. A cylindrical lithium ion secondary battery was produced using this separator.
《実施例２》
Ａ層の平均孔径が０．０５μｍ、Ｃ層の平均孔径が１μｍであるセパレータを用いた以外は実施例１と同様の電池を作製した。
Example 2
A battery was prepared in the same manner as in Example 1 except that a separator having an average pore size of layer A of 0.05 μm and an average pore size of layer C of 1 μm was used.
《実施例３》
Ｂ層にポリプロピレン微多孔膜を用いた以外は実施例１と同様の電池を作製した。
Example 3
A battery was prepared in the same manner as in Example 1 except that a polypropylene microporous film was used for the B layer.
《実施例４》
Ａ層の平均孔径が０．５μｍ、Ｃ層の平均孔径が０．０２μｍであるセパレータを用いた以外は実施例１と同様の電池を作製した。
Example 4
A battery was prepared in the same manner as in Example 1 except that a separator having an average pore diameter of the A layer of 0.5 μm and an average pore diameter of the C layer of 0.02 μm was used.
《比較例１》
Ｂ層のみのポリエチレン微多孔膜のセパレータを用いた電池を作製した。
<< Comparative Example 1 >>
A battery using a polyethylene microporous membrane separator having only a B layer was produced.
《比較例２》
Ａ層の平均孔径が０．１μｍ、Ｃ層の平均孔径が０．５μｍであるセパレータを用いた以外は実施例１と同様の電池を作製した。
<< Comparative Example 2 >>
A battery was prepared in the same manner as in Example 1 except that a separator having an average pore diameter of the A layer of 0.1 μm and an average pore diameter of the C layer of 0.5 μm was used.
《比較例３》
Ａ層の平均孔径が０．０５μｍ、Ｃ層の平均孔径が１．５μｍであるセパレータを用いた以外は実施例１と同様の電池を作製した。しかし、電池作製時において、セパレータのＣ層の剥離が発生したため、電池を作ることができなかった。
<< Comparative Example 3 >>
A battery was prepared in the same manner as in Example 1 except that a separator having an average pore diameter of the A layer of 0.05 μm and an average pore diameter of the C layer of 1.5 μm was used. However, when the battery was produced, peeling of the C layer of the separator occurred, so that the battery could not be produced.
以下に、電池の評価方法として、電池の電圧不良の測定方法、初期容量の測定方法、およびサイクル特性の評価方法について示します。 The following are the battery evaluation methods: battery voltage failure measurement method, initial capacity measurement method, and cycle characteristic evaluation method.
（電池の評価方法）
（電圧不良の測定方法）
組み立てられた電池に定電流０．２５Ｃで電池電圧４．１Ｖまで充電を行い、定電流１Ｃで電池電圧３．０Ｖまで放電し、これら充放電を３サイクル行った。再度、定電流０．２５Ｃで電池電圧が４．１Ｖに到達するまで充電し、さらに定電圧４．１Ｖで２時間充電した。その後、充電状態で恒温４５℃で７日間エージングを行った後、電池が２５℃になった状態で電池電圧を測定し、測定数の平均値より２ｍＶ低いものを不良とし、各々の電
池について不良率を算出した。
(Battery evaluation method)
(Measurement method of voltage failure)
The assembled battery was charged to a battery voltage of 4.1 V at a constant current of 0.25 C, discharged to a battery voltage of 3.0 V at a constant current of 1 C, and these charging and discharging were performed for 3 cycles. The battery was charged again at a constant current of 0.25 C until the battery voltage reached 4.1 V, and further charged at a constant voltage of 4.1 V for 2 hours. Then, after aging at a constant temperature of 45 ° C. for 7 days in the charged state, the battery voltage was measured in a state where the battery was at 25 ° C. The rate was calculated.
（初期容量の測定方法）
作製した電池を２５℃の環境下に置き、設計容量を基準にして、定電流０．１Ｃで電池電圧が４．２Ｖに到達するまで充電し、さらに定電圧４．２Ｖで５時間充電した。その後、定電流０．１Ｃで放電し、２５℃における初期容量（Ｃ０）を測定した。得られた初期容量を基準にして、以下に説明するサイクル特性と加熱試験を評価した。
(Measurement method of initial capacity)
The produced battery was placed in an environment of 25 ° C., charged with a constant current of 0.1 C until the battery voltage reached 4.2 V, and charged at a constant voltage of 4.2 V for 5 hours, based on the design capacity. Thereafter, the battery was discharged at a constant current of 0.1 C, and the initial capacity (C 0 ) at 25 ° C. was measured. The cycle characteristics and heating test described below were evaluated based on the obtained initial capacity.
（サイクル特性の測定方法）
２５℃環境温度で、以下の条件で電池の充放電を繰り返した。
(Measurement method of cycle characteristics)
The battery was repeatedly charged and discharged under the following conditions at an ambient temperature of 25 ° C.
まず、定電流０．１Ｃで、電池電圧が４．２Ｖになるまで充電し、その後、定電圧４．２Ｖで、充電カット電流が５０ｍＡになるまで充電した。充電後の電池を３０分間休止させた。その後、定電流１Ｃで、電池電圧が３．０Ｖになるまで放電した。放電後の電池を３０分間休止させた。この充放電を１サイクルとして、放電容量が初期容量（Ｃ０）の５０％になるまで、充放電サイクルを繰り返した。その時のサイクル数を５０％維持サイクル数として求めた。 First, the battery was charged at a constant current of 0.1 C until the battery voltage reached 4.2 V, and then charged at a constant voltage of 4.2 V until the charge cut current reached 50 mA. The battery after charging was paused for 30 minutes. Thereafter, the battery was discharged at a constant current of 1 C until the battery voltage reached 3.0V. The discharged battery was paused for 30 minutes. This charging / discharging was made into 1 cycle, and the charging / discharging cycle was repeated until discharge capacity became 50% of initial capacity ( C0 ). The number of cycles at that time was determined as the number of 50% maintenance cycles.
（加熱試験）
電池を加熱槽に設置し、加熱槽を５℃／分の昇温速度で１５０℃まで上昇させ、１５０℃で１０分間放置した。その後、電池の温度をモニターし、電池の最高温度を測定した。
(Heating test)
The battery was placed in a heating tank, and the heating tank was raised to 150 ° C. at a temperature rising rate of 5 ° C./min and left at 150 ° C. for 10 minutes. Thereafter, the temperature of the battery was monitored, and the maximum temperature of the battery was measured.
それらの結果を表１と２に示した。 The results are shown in Tables 1 and 2.
以下、結果について説明する。 Hereinafter, the results will be described.
まず、電圧不良については、実施例１〜４は不良率が１％以上の比較例１、２と比べて大きく改善している。この原因として次の２つのように考えている。１つ目は、比較例１はセパレータがポリエチレン単層であり、アルミナを含むアラミド樹脂層よりも柔らかく、極板の膨張によりセパレータが圧縮され易くなっている。そのため、セパレータ中に保持されている電解液量が減少するに伴って、極板間の距離が小さくなったためと考えている。また、２つ目は、正極板あるいは負極板表面の微多孔膜の平均孔径が０．２μｍと０．０５μｍも大きいため、金属不純物の溶解析出によるブリッジが形成し易いと考えられる。以上、２つの要因から、電圧不良が高くなったと推定している。 First, regarding voltage failures, Examples 1 to 4 are greatly improved compared to Comparative Examples 1 and 2 having a failure rate of 1% or more. There are two possible causes for this. First, in Comparative Example 1, the separator is a polyethylene single layer, which is softer than the aramid resin layer containing alumina, and is easily compressed by the expansion of the electrode plate. For this reason, it is considered that the distance between the electrode plates is reduced as the amount of the electrolytic solution held in the separator is reduced. Second, since the average pore diameter of the microporous film on the surface of the positive electrode plate or the negative electrode plate is as large as 0.2 μm and 0.05 μm, it is considered that a bridge due to dissolution and precipitation of metal impurities is easily formed. From the above two factors, it is estimated that the voltage failure has increased.
また、比較例２については、セパレータの圧縮の影響は受け難いが、セパレータの多孔質層の平均孔径の小さい方の平均孔径が０．１μｍであることにより、前述した金属不純物の溶解析出によるブリッジが形成し易いことに起因すると考えられる。 Further, in Comparative Example 2, although not easily affected by the compression of the separator, the smaller average pore diameter of the porous layer of the separator is 0.1 μm. This is thought to be due to the ease of forming.
次に、２５℃サイクル寿命特性について説明する。 Next, the 25 ° C. cycle life characteristics will be described.
まず、ポリエチレン微多孔膜（Ｂ層）の両面にアラミド多孔質層（Ａ、Ｃ層）がない比較例１と比較例２を比べた場合、アラミド多孔質層がある比較例２は、アラミド多孔質層がない比較例１に比べ、サイクル特性が良好である。これは、比較例１のようにアラミド多孔質層がない場合、充放電を繰り返すサイクル試験において、極板の膨張によりセパレータが圧縮され、セパレータ中に保持されている電解液量が減少することによってリチウムイオンが通り難くなるためと考えられる。これに対して、アラミド多孔質層がある比較例２は、アラミド多孔質層を有しているため、極板が膨張しても一定の厚みを保持できる。このことから、一定の多孔度を維持しながら、かつ電解液の保持量が低下しないためサイクル特性が良好であると考えられる。 First, when Comparative Example 1 and Comparative Example 2 having no aramid porous layers (A and C layers) on both sides of a polyethylene microporous membrane (B layer) are compared, Comparative Example 2 having an aramid porous layer is aramid porous. The cycle characteristics are better than those of Comparative Example 1 having no quality layer. This is because, when there is no aramid porous layer as in Comparative Example 1, in the cycle test in which charging and discharging are repeated, the separator is compressed due to the expansion of the electrode plate, and the amount of electrolyte retained in the separator decreases. This is probably because lithium ions are difficult to pass. On the other hand, since the comparative example 2 with an aramid porous layer has an aramid porous layer, even if the electrode plate expands, a constant thickness can be maintained. From this, it is considered that the cycle characteristics are good because the amount of retained electrolyte does not decrease while maintaining a certain porosity.
また、いずれもアラミド多孔質層がある実施例１〜４と比較例２において、実施例１〜３および比較例２は、実施例４に比べ、サイクル特性が良好である。これは、実施例４は、負極板側に対向するアラミド多孔質層Ｃ層の平均孔径が０．０２μｍと小さいため、電解液の副反応による反応生成物が負極板表面に析出し、被膜形成され、セパレータの目詰まりを起こしている。このことから、セパレータの抵抗が大きくなり、分極が大きくなり、容量の低下を引き起こしたものと考えられる。これに対して、実施例１〜３および比較例２は、負極板側に対向するアラミド多孔質層Ｃ層の平均孔径が０．１μｍ以上あることで、セパレータの目詰まりによる分極の増大が抑制され、サイクル特性が大きく向上していると考えられる。 In Examples 1 to 4 and Comparative Example 2 each having an aramid porous layer, Examples 1 to 3 and Comparative Example 2 have better cycle characteristics than Example 4. In Example 4, since the average pore diameter of the aramid porous layer C layer facing the negative electrode plate side is as small as 0.02 μm, a reaction product due to a side reaction of the electrolytic solution is deposited on the surface of the negative electrode plate to form a film. As a result, the separator is clogged. From this, it is considered that the resistance of the separator is increased, the polarization is increased, and the capacity is reduced. In contrast, in Examples 1 to 3 and Comparative Example 2, the average pore diameter of the aramid porous layer C layer facing the negative electrode plate side is 0.1 μm or more, thereby suppressing an increase in polarization due to the clogging of the separator. Therefore, it is considered that the cycle characteristics are greatly improved.
次に、加熱試験について説明する。 Next, the heating test will be described.
ポリエチレン微多孔膜（Ｂ層）の両面にアラミド多孔質層（Ａ、Ｃ層）がない比較例１のみ最高温度１７０℃まで到達したが、アラミド多孔質層がある実施例１〜４および比較例２については、いずれも最高到達温度が１５５℃以下と低く、ポリエチレンよりも耐熱性のある樹脂層があるため、高温下でのセパレータの収縮が抑制されていると考えられる。 Although only the comparative example 1 which does not have an aramid porous layer (A, C layer) on both surfaces of a polyethylene microporous film (B layer) reached | attained the maximum temperature of 170 degreeC, Examples 1-4 and a comparative example with an aramid porous layer As for No. 2, since the maximum temperature reached is as low as 155 ° C. or lower and there is a resin layer that is more heat resistant than polyethylene, it is considered that the shrinkage of the separator at high temperatures is suppressed.
なお、前述した実施例については、円筒型リチウムイオン二次電池について説明したが、正極板および負極板が、セパレータを介して渦巻状に捲かれて極板群を構成しているものであればよく、角型リチウムイオン電池でも同様の効果が確認された。本発明のリチウムイオン二次電池の形状はこれに限定されるものではない。 In addition, about the Example mentioned above, although the cylindrical lithium ion secondary battery was demonstrated, if the positive electrode plate and the negative electrode plate were wound around the separator and comprised the electrode plate group, Well, the same effect was confirmed also in the prismatic lithium ion battery. The shape of the lithium ion secondary battery of the present invention is not limited to this.
本発明の非水系二次電池は、高容量でなおかつ優れたサイクル特性、安全性、信頼性を有し、携帯電話、ノートパソコンなどのポータブル電子機器の電源などとして有用である。 The non-aqueous secondary battery of the present invention has a high capacity and excellent cycle characteristics, safety and reliability, and is useful as a power source for portable electronic devices such as mobile phones and laptop computers.
１ 正極板
２ 負極板
Ａ 正極板に面する耐熱性高分子からなる多孔質層
Ｂ シャットダウン機能を有する微多孔膜
Ｃ 負極板に面する耐熱性高分子からなる多孔質層
DESCRIPTION OF
Claims (5)
前記微多孔膜は、両面に耐熱性高分子からなる多孔質層が形成され、前記微多孔膜の片面には前記耐熱性高分子からなる多孔質層の平均孔径が０．０１〜０．０５μｍであり、かつもう一方の面には前記耐熱性高分子からなる多孔質層の平均孔径が０．２〜１μｍである非水系二次電池。 In a non-aqueous secondary battery having a positive electrode plate, a negative electrode plate, and a microporous film having a shutdown function,
The microporous membrane is formed with a porous layer made of a heat resistant polymer on both sides, and an average pore size of the porous layer made of the heat resistant polymer is 0.01 to 0.05 μm on one side of the microporous membrane. And the other surface has a non-aqueous secondary battery in which the porous layer made of the heat-resistant polymer has an average pore diameter of 0.2 to 1 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007068410A JP4952314B2 (en) | 2007-03-16 | 2007-03-16 | Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007068410A JP4952314B2 (en) | 2007-03-16 | 2007-03-16 | Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2008234853A JP2008234853A (en) | 2008-10-02 |
| JP4952314B2 true JP4952314B2 (en) | 2012-06-13 |
Family
ID=39907434
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2007068410A Active JP4952314B2 (en) | 2007-03-16 | 2007-03-16 | Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4952314B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI431834B (en) | 2010-12-27 | 2014-03-21 | Ind Tech Res Inst | Lithium battery and electrode plate structure |
| JP5909633B2 (en) * | 2011-11-17 | 2016-04-27 | パナソニックＩｐマネジメント株式会社 | Hand dryer |
| JP5888079B2 (en) * | 2012-04-10 | 2016-03-16 | Tdk株式会社 | Separator and non-aqueous secondary battery using the same |
| WO2015122164A1 (en) * | 2014-02-17 | 2015-08-20 | 三洋電機株式会社 | Separator for non-aqueous electrolyte secondary batteries |
| US20180115015A1 (en) * | 2015-03-24 | 2018-04-26 | Nec Corporation | High safety and high energy density battery |
| WO2023127508A1 (en) * | 2021-12-27 | 2023-07-06 | パナソニックエナジ－株式会社 | Nonaqueous electrolyte secondary battery |
| CN114614200B (en) * | 2022-03-31 | 2023-12-19 | 宁德新能源科技有限公司 | Electrochemical device and electric equipment |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10302748A (en) * | 1997-04-28 | 1998-11-13 | Nitto Denko Corp | Non-aqueous electrolytic battery |
| JP2002231209A (en) * | 2001-01-31 | 2002-08-16 | Matsushita Electric Ind Co Ltd | Nonaqueous electrolyte secondary battery |
| DE10255121B4 (en) * | 2002-11-26 | 2017-09-14 | Evonik Degussa Gmbh | Separator with asymmetric pore structure for an electrochemical cell |
-
2007
- 2007-03-16 JP JP2007068410A patent/JP4952314B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2008234853A (en) | 2008-10-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4920423B2 (en) | Lithium ion secondary battery | |
| US10193117B2 (en) | Separator for nonaqueous secondary battery, and nonaqueous secondary battery | |
| TWI497790B (en) | Non-aqueous secondary battery separator and non-aqueous secondary battery | |
| JP5699576B2 (en) | Laminated microporous membrane, battery separator and non-aqueous electrolyte battery | |
| TWI497791B (en) | Non-aqueous secondary battery separator and non-aqueous secondary battery | |
| JP4487457B2 (en) | Nonaqueous electrolyte secondary battery separator and nonaqueous electrolyte secondary battery | |
| JP6143992B1 (en) | Non-aqueous secondary battery separator and non-aqueous secondary battery | |
| EP2696393B1 (en) | Nonaqueous secondary battery separator and nonaqueous secondary battery | |
| JP2019133940A (en) | Protective film, and separator and secondary battery using the same | |
| WO2017014245A1 (en) | Lithium ion secondary battery | |
| KR20180077190A (en) | Separator for non-aqueous secondary battery and non-aqueous secondary battery | |
| JP2007324073A (en) | Lithium secondary battery, its separator and its manufacturing method | |
| WO2007135952A1 (en) | Separator and nonaqueous electrolyte secondary battery | |
| JP2007294437A (en) | Separator for electrochemical cell, and lithium secondary battery | |
| JP4952314B2 (en) | Nonaqueous secondary battery separator and nonaqueous secondary battery equipped with the same | |
| US11398660B2 (en) | Flame retardant separator having asymmetric structure for secondary batteries | |
| JPWO2014021291A1 (en) | Nonaqueous electrolyte battery separator and nonaqueous electrolyte battery | |
| JP2015181110A (en) | Heat resistance microporous film, separator for lithium ion secondary batteries, and lithium ion secondary battery | |
| JPWO2012137374A1 (en) | Nonaqueous secondary battery separator and nonaqueous secondary battery | |
| WO2005067079A1 (en) | Lithium secondary battery | |
| JP2014026946A (en) | Separator for nonaqueous electrolyte battery, and nonaqueous electrolyte battery | |
| JP4649862B2 (en) | Lithium ion secondary battery and manufacturing method thereof | |
| JP2006228544A (en) | Lithium ion secondary battery | |
| JP2007242575A (en) | Nonaqueous electrolyte solution secondary battery | |
| JP2013196836A (en) | Separator for nonaqueous secondary battery and nonaqueous secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20100308 |
|
| RD01 | Notification of change of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7421 Effective date: 20100413 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20120208 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20120214 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20120227 |
|
| R151 | Written notification of patent or utility model registration |
Ref document number: 4952314 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R151 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20150323 Year of fee payment: 3 |