JP2020202149A - Additive agent for electrolyte, electrolyte for lithium secondary battery, and lithium secondary battery - Google Patents
Additive agent for electrolyte, electrolyte for lithium secondary battery, and lithium secondary battery Download PDFInfo
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- JP2020202149A JP2020202149A JP2019110272A JP2019110272A JP2020202149A JP 2020202149 A JP2020202149 A JP 2020202149A JP 2019110272 A JP2019110272 A JP 2019110272A JP 2019110272 A JP2019110272 A JP 2019110272A JP 2020202149 A JP2020202149 A JP 2020202149A
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- secondary battery
- lithium secondary
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 92
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 239000003792 electrolyte Substances 0.000 title claims abstract description 75
- 239000000654 additive Substances 0.000 title claims abstract description 20
- 230000000996 additive effect Effects 0.000 title claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 title abstract 3
- 150000001875 compounds Chemical class 0.000 claims abstract description 40
- 125000005843 halogen group Chemical group 0.000 claims abstract description 11
- 125000004430 oxygen atom Chemical group O* 0.000 claims abstract description 6
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 125000004434 sulfur atom Chemical group 0.000 claims abstract description 5
- 239000002000 Electrolyte additive Substances 0.000 claims description 37
- 229910052782 aluminium Inorganic materials 0.000 claims description 16
- 125000002029 aromatic hydrocarbon group Chemical group 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 229910052749 magnesium Inorganic materials 0.000 claims description 8
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 5
- 125000003118 aryl group Chemical group 0.000 abstract description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical group C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract 2
- 239000011244 liquid electrolyte Substances 0.000 description 34
- FIQMHBFVRAXMOP-UHFFFAOYSA-N triphenylphosphane oxide Chemical compound C=1C=CC=CC=1P(C=1C=CC=CC=1)(=O)C1=CC=CC=C1 FIQMHBFVRAXMOP-UHFFFAOYSA-N 0.000 description 28
- 238000012360 testing method Methods 0.000 description 22
- 239000011888 foil Substances 0.000 description 21
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 15
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 15
- 238000007599 discharging Methods 0.000 description 14
- 238000004146 energy storage Methods 0.000 description 14
- 229910013870 LiPF 6 Inorganic materials 0.000 description 13
- 239000007773 negative electrode material Substances 0.000 description 13
- 239000007774 positive electrode material Substances 0.000 description 13
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 12
- 239000011149 active material Substances 0.000 description 10
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- XKTYXVDYIKIYJP-UHFFFAOYSA-N 3h-dioxole Chemical compound C1OOC=C1 XKTYXVDYIKIYJP-UHFFFAOYSA-N 0.000 description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 9
- 229910014422 LiNi1/3Mn1/3Co1/3O2 Inorganic materials 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 239000011734 sodium Substances 0.000 description 8
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 7
- 239000004743 Polypropylene Substances 0.000 description 7
- 210000004027 cell Anatomy 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 229920001155 polypropylene Polymers 0.000 description 7
- 125000003710 aryl alkyl group Chemical group 0.000 description 6
- 125000004432 carbon atom Chemical group C* 0.000 description 6
- 239000011889 copper foil Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000007784 solid electrolyte Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 239000010936 titanium Substances 0.000 description 5
- 229910015222 Ni1/3Mn1/3Co1/3O2 Inorganic materials 0.000 description 4
- 238000002848 electrochemical method Methods 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- RIOQSEWOXXDEQQ-UHFFFAOYSA-N triphenylphosphine Chemical compound C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 RIOQSEWOXXDEQQ-UHFFFAOYSA-N 0.000 description 4
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 description 2
- 125000000094 2-phenylethyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])C([H])([H])* 0.000 description 2
- 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 2
- 229910013716 LiNi Inorganic materials 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 125000005428 anthryl group Chemical group [H]C1=C([H])C([H])=C2C([H])=C3C(*)=C([H])C([H])=C([H])C3=C([H])C2=C1[H] 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 2
- 125000001797 benzyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])* 0.000 description 2
- 125000002529 biphenylenyl group Chemical group C1(=CC=CC=2C3=CC=CC=C3C12)* 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000417 fungicide Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 230000016507 interphase Effects 0.000 description 2
- 239000004611 light stabiliser Substances 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 125000001624 naphthyl group Chemical group 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 125000005561 phenanthryl group Chemical group 0.000 description 2
- 239000000049 pigment Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000002798 polar solvent Substances 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000003755 preservative agent Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 125000002221 trityl group Chemical group [H]C1=C([H])C([H])=C([H])C([H])=C1C([*])(C1=C(C(=C(C(=C1[H])[H])[H])[H])[H])C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical group [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical group [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910013684 LiClO 4 Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910013275 LiMPO Inorganic materials 0.000 description 1
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 1
- 229910015965 LiNi0.8Mn0.1Co0.1O2 Inorganic materials 0.000 description 1
- 229910003249 Na3Zr2Si2PO12 Inorganic materials 0.000 description 1
- 229910020808 NaBF Inorganic materials 0.000 description 1
- 229910021201 NaFSI Inorganic materials 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910018207 SeS Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- IUPSCJLUPXHTNI-UHFFFAOYSA-M [O-]P(O)(O)=O.F.F.F.F.F.F.[Na+] Chemical compound [O-]P(O)(O)=O.F.F.F.F.F.F.[Na+] IUPSCJLUPXHTNI-UHFFFAOYSA-M 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005576 amination reaction Methods 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000004651 carbonic acid esters Chemical class 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910000664 lithium aluminum titanium phosphates (LATP) Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- VCCATSJUUVERFU-UHFFFAOYSA-N sodium bis(fluorosulfonyl)azanide Chemical compound FS(=O)(=O)N([Na])S(F)(=O)=O VCCATSJUUVERFU-UHFFFAOYSA-N 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- YLKTWKVVQDCJFL-UHFFFAOYSA-N sodium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Na+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F YLKTWKVVQDCJFL-UHFFFAOYSA-N 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002759 woven fabric Substances 0.000 description 1
- 229910009161 xLi2S-(1-x)P2S5 Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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
Abstract
Description
本発明は、電解質用添加剤、リチウム二次電池用電解質及びリチウム二次電池に関する。 The present invention relates to an additive for an electrolyte, an electrolyte for a lithium secondary battery, and a lithium secondary battery.
次世代のリチウム二次電池等の二次電池に対する要求は年々高まっている。近年では、高い安全性に加えて、高いエネルギー貯蔵密度を実現することができる二次電池の構築が求められている。例えば、リチウム金属をアノード（負極）とするリチウム二次電池は、現在主流のリチウムイオン二次電池と比較して高いエネルギー貯蔵密度を有することから、次世代二次電池の有望な候補とされている。 The demand for secondary batteries such as next-generation lithium secondary batteries is increasing year by year. In recent years, there has been a demand for the construction of a secondary battery capable of achieving a high energy storage density in addition to high safety. For example, a lithium secondary battery using a lithium metal as an anode (negative electrode) has a higher energy storage density than the current mainstream lithium ion secondary battery, and is therefore regarded as a promising candidate for a next-generation secondary battery. There is.
しかしながら、リチウム二次電池においては、リチウム金属表面でのとげ状突起、いわゆるデンドライトの形成に伴う電池の内部ショートの危険性や、充放電サイクル耐性の低下が実用化の障害となってきた。この観点から、前述の次世代二次電池の高い要求に応えるべく、各種の電極材料を改良することのみならず、二次電池を構成する電解質及び電解質に含まれる添加剤（電解質用添加剤）を開発することも重要とされている。 However, in a lithium secondary battery, the risk of internal short circuit of the battery due to the formation of spiny protrusions on the surface of the lithium metal, so-called dendrites, and the decrease in charge / discharge cycle resistance have been obstacles to practical use. From this point of view, in order to meet the high demands of the above-mentioned next-generation secondary batteries, not only are various electrode materials improved, but also the electrolytes that make up the secondary batteries and the additives contained in the electrolytes (electrolyte additives). It is also important to develop.
例えば、非特許文献１では、アノードとしてグラファイトを用いたリチウムイオン二次電池において、電解質中に添加されたトリフェニルホスィン（TP）が酸化物カソード材料上で充電時の高電圧印加時に生成した酸素分子を除去することで、リチウムイオン二次電池の充放電サイクル耐性を向上させることを示している。また、非特許文献２では、炭酸エステル系の電解液へのトリフェニルホスフィンオキシド（TPO）の添加により、グラファイト/LiNi0.8Mn0.1Co0.1O2系のリチウムイオン二次電池性能を向上させることが報告されている。 For example, in Non-Patent Document 1, in a lithium ion secondary battery using graphite as an anode, triphenylphosine (TP) added to the electrolyte was generated when a high voltage was applied during charging on an oxide cathode material. It is shown that the charge / discharge cycle resistance of the lithium ion secondary battery is improved by removing oxygen molecules. Further, in Non-Patent Document 2, the addition of triphenylphosphine oxide (TPO) to a carbonic acid ester-based electrolytic solution can improve the performance of a graphite / LiNi 0.8 Mn 0.1 Co 0.1 O 2 based lithium ion secondary battery. It has been reported.
しかしながら、上述のような従来の電解質用添加剤はリチウムイオン二次電池に適用した例が知られるのみで、リチウム二次電池に適用しても効果があるかどうかは理解できない。特に、安全性に問題があるとされているリチウム二次電池に適用して安全性が向上するかどうかは示されていない。 However, it is only known that the conventional additives for electrolytes as described above are applied to lithium ion secondary batteries, and it cannot be understood whether or not they are effective even when applied to lithium secondary batteries. In particular, it has not been shown whether or not the safety is improved by applying it to a lithium secondary battery, which is said to have a safety problem.
本発明は、上記に鑑みてなされたものであり、安全性に優れ、容量に優れたリチウム二次電池を製造することができる電解質用添加剤、リチウム二次電池用電解質及びリチウム二次電池を提供することを目的とする。 The present invention has been made in view of the above, and provides an electrolyte additive, an electrolyte for a lithium secondary battery, and a lithium secondary battery capable of producing a lithium secondary battery having excellent safety and excellent capacity. The purpose is to provide.
本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、電解質用添加剤として、特定の化合物を組合せて使用した場合には、安全性に優れ、容量に優れたリチウム二次電池を製造することができることを見出した。本発明らは、このような知見に基づき、さらに研究を重ね、本発明を完成した。すなわち、本発明は、以下の構成を包含する。 As a result of diligent research to achieve the above object, the present inventors have excellent safety and excellent capacity when a specific compound is used in combination as an additive for an electrolyte. Found that it can be manufactured. Based on such findings, the present inventions have further studied and completed the present invention. That is, the present invention includes the following configurations.
項１．一般式（1）： Item 1. General formula (1):
［式中、M1は配位元素を示す。R1は同一又は異なって、1価の芳香族炭化水素基を示す。nは1以上の整数を示す。］
で表される化合物と、
一般式（2）：
[In the formula, M 1 indicates the coordination element. R 1 is the same or different and represents a monovalent aromatic hydrocarbon group. n indicates an integer greater than or equal to 1. ]
And the compound represented by
General formula (2):
［式中、M2は配位元素を示す。R2は同一又は異なって、1価の芳香族炭化水素基を示す。R3は酸素原子、硫黄原子又はハロゲン原子を示す。mは0以上の整数を示す。実線と破線で表される結合は単結合又は二重結合を示す。］
で表される化合物とを含有する、電解質用添加剤。
[In the formula, M 2 indicates the coordination element. R 2 is the same or different and represents a monovalent aromatic hydrocarbon group. R 3 represents an oxygen atom, a sulfur atom or a halogen atom. m indicates an integer greater than or equal to 0. Bonds represented by solid and dashed lines indicate single or double bonds. ]
An additive for an electrolyte containing a compound represented by.
項２．前記一般式（1）において、M1がMg、Al、Si、P又はBである、項１に記載の電解質用添加剤。 Item 2. Item 2. The electrolyte additive according to Item 1, wherein in the general formula (1), M 1 is Mg, Al, Si, P or B.
項３．前記一般式（2）において、M2がMg、Al、Si、P又はBである、項１又は２に記載の電解質用添加剤。 Item 3. Item 2. The electrolyte additive according to Item 1 or 2, wherein M 2 is Mg, Al, Si, P or B in the general formula (2).
項４．前記一般式（1）において、R1がフェニル基である、項１〜３のいずれか１項に記載の電解質用添加剤。 Item 4. Item 2. The additive for an electrolyte according to any one of Items 1 to 3, wherein R 1 is a phenyl group in the general formula (1).
項５．前記一般式（2）において、R2がフェニル基である、項１〜４のいずれか１項に記載の電解質用添加剤。 Item 5. Item 2. The additive for an electrolyte according to any one of Items 1 to 4, wherein R 2 is a phenyl group in the general formula (2).
項６．前記電解質用添加剤の総量を100モル%として、前記一般式（1）で表される化合物を10〜90モル%含有し、前記一般式（2）で表される化合物を90〜10モル%含有する、項１〜５のいずれか１項に記載の電解質用添加剤。 Item 6. Assuming that the total amount of the electrolyte additive is 100 mol%, the compound represented by the general formula (1) is contained in an amount of 10 to 90 mol%, and the compound represented by the general formula (2) is contained in an amount of 90 to 10 mol%. The additive for an electrolyte according to any one of Items 1 to 5, which is contained.
項７．項１〜６のいずれか１項に記載の電解質添加剤を含有する、リチウム二次電池用電解質。 Item 7. An electrolyte for a lithium secondary battery containing the electrolyte additive according to any one of Items 1 to 6.
項８．項７に記載のリチウム二次電池用電解質を備える、リチウム二次電池。 Item 8. A lithium secondary battery comprising the electrolyte for the lithium secondary battery according to item 7.
本発明によれば、安全性に優れ、容量に優れたリチウム二次電池を製造することができる。 According to the present invention, it is possible to manufacture a lithium secondary battery having excellent safety and excellent capacity.
本明細書において、「含有」は、「含む（comprise）」、「実質的にのみからなる（consist essentially of）」、及び「のみからなる（consist of）」のいずれも包含する概念である。また、本明細書において、数値範囲を「Ａ〜Ｂ」で示す場合、Ａ以上Ｂ以下を意味する。 As used herein, "contains" is a concept that includes any of "comprise," "consist essentially of," and "consist of." Further, in the present specification, when the numerical range is indicated by "A to B", it means A or more and B or less.
１．電解質用添加剤
本発明の電解質用添加剤は、一般式（1）：
1. 1. Additives for electrolytes The additives for electrolytes of the present invention have the general formula (1):
［式中、M1は配位元素を示す。R1は同一又は異なって、1価の芳香族炭化水素基を示す。nは1以上の整数を示す。］
で表される化合物と、
一般式（2）：
[In the formula, M 1 indicates the coordination element. R 1 is the same or different and represents a monovalent aromatic hydrocarbon group. n indicates an integer greater than or equal to 1. ]
And the compound represented by
General formula (2):
［式中、M2は配位元素を示す。R2は同一又は異なって、1価の芳香族炭化水素基を示す。R3は酸素原子、硫黄原子又はハロゲン原子を示す。mは1以上の整数を示す。実線と破線で表される結合は単結合又は二重結合を示す。］
で表される化合物とを含有する。
[In the formula, M 2 indicates the coordination element. R 2 is the same or different and represents a monovalent aromatic hydrocarbon group. R 3 represents an oxygen atom, a sulfur atom or a halogen atom. m indicates an integer greater than or equal to 1. Bonds represented by solid and dashed lines indicate single or double bonds. ]
Contains a compound represented by.
一般式（1）で表される化合物は、リチウム二次電池の熱暴走を抑制し、一般式（2）で表される化合物は、その分解生成物が電極上で安定な界面層（Stable solid Electrolyte Interphase (SEI)）を形成し、電解質と電極との副反応を抑制し、デンドライト形成抑制効果を有する。これら一般式（1）で表される化合物と一般式（2）で表される化合物とを組合せた場合は、予想外にもこれらの効果が相乗的に向上し、安全性に優れ、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等に優れたリチウム二次電池を製造することができる。 The compound represented by the general formula (1) suppresses the thermal runaway of the lithium secondary battery, and the compound represented by the general formula (2) is a stable solid in which the decomposition product is stable on the electrode. It forms Electrolyte Interphase (SEI)), suppresses side reactions between the electrolyte and the electrodes, and has the effect of suppressing the formation of dendrites. When the compound represented by the general formula (1) and the compound represented by the general formula (2) are combined, these effects are unexpectedly improved synergistically, the safety is excellent, and the capacity ( In particular, it is possible to manufacture a lithium secondary battery having excellent discharge capacity), charge / discharge cycle resistance, energy storage density, Coulomb efficiency, and the like.
一般式（1）において、M1で示される配位元素としては、特に制限はないが、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、Mg、Al、Si、P、B等が好ましく、P、B等がより好ましい。 In the general formula (1), the coordinating element represented by M 1 is not particularly limited, but the safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density of the obtained lithium secondary battery, From the viewpoint of Coulomb efficiency and the like, Mg, Al, Si, P, B and the like are preferable, and P, B and the like are more preferable.
一般式（1）において、R1で示される1価の芳香族炭化水素基としては、例えば、アリール基、アラルキル基等が挙げられる。アリール基の炭素数は、６〜２０が好ましく、６〜１４がより好ましく、６〜１０がさらに好ましい。また、アラルキル基の炭素数は、７〜２０が好ましく、７〜１４がより好ましく、７〜１０がさらに好ましい。 In the general formula (1), examples of the monovalent aromatic hydrocarbon group represented by R 1 include an aryl group and an aralkyl group. The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 6 to 10 carbon atoms. The carbon number of the aralkyl group is preferably 7 to 20, more preferably 7 to 14, and even more preferably 7 to 10.
アリール基の具体例としては、例えば、フェニル基、ナフチル基、アントリル基、フェナントリル基、ビフェニレン基等が挙げられ、アラルキル基の具体例としては、例えば、ベンジル基、フェネチル基、トリチル基等が挙げられる。 Specific examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenylene group and the like, and specific examples of the aralkyl group include a benzyl group, a phenethyl group, a trityl group and the like. Be done.
なかでも、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、アリール基が好ましく、フェニル基がより好ましい。なお、nが2以上の整数である場合は、R1は同一でもよいし、異なっていてもよい。 Among them, an aryl group is preferable, and a phenyl group is more preferable, from the viewpoints of safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density, coulombic efficiency, etc. of the obtained lithium secondary battery. When n is an integer of 2 or more, R 1 may be the same or different.
一般式（1）においては、nは、1以上の整数であり、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、好ましくは2〜4の整数である。なお、nの好ましい数値はM1の種類によって異なる。具体的には、M1がMgの場合はnは2が好ましく、M1がAlの場合はnは3が好ましく、M1がSiの場合はnは4が好ましく、M1がPの場合はnは3が好ましく、M1がBの場合はnは3が好ましい。 In the general formula (1), n is an integer of 1 or more, and from the viewpoints of safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density, Coulomb efficiency, etc. of the obtained lithium secondary battery. , Preferably an integer of 2-4. The preferred value of n depends on the type of M 1 . Specifically, when M 1 is Mg, n is preferably 2, when M 1 is Al, n is preferably 3, when M 1 is Si, n is preferably 4, and when M 1 is P. N is preferably 3 and n is preferably 3 when M 1 is B.
上記のような条件を満たす一般式（1）で表される化合物としては、例えば、 Examples of the compound represented by the general formula (1) satisfying the above conditions include, for example.
等が挙げられ、単独で使用することもでき、2種以上を組合せて使用することもできる。 Etc., and can be used alone or in combination of two or more.
一般式（2）において、M2で示される金属元素としては、特に制限はないが、より安定な界面層が形成され、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、Mg、Al、Si、P、B等が好ましく、P、B等がより好ましい。なお、一般式（2）で表される化合物は、M2として、一般式（1）で表される化合物におけるM1と同じ化合物を使用することもできるし、異なる化合物を使用することもできる。 In the general formula (2), the metal element represented by M 2 is not particularly limited, but a more stable interface layer is formed, and the safety, capacity (particularly discharge capacity), and charge of the obtained lithium secondary battery are obtained. From the viewpoint of discharge cycle resistance, energy storage density, Coulomb efficiency and the like, Mg, Al, Si, P, B and the like are preferable, and P, B and the like are more preferable. As the compound represented by the general formula (2), the same compound as M 1 in the compound represented by the general formula (1) can be used as M 2 , or a different compound can be used. ..
一般式（2）において、R2で示される1価の芳香族炭化水素基としては、例えば、アリール基、アラルキル基等が挙げられる。アリール基の炭素数は、６〜２０が好ましく、６〜１４がより好ましく、６〜１０がさらに好ましい。また、アラルキル基の炭素数は、７〜２０が好ましく、７〜１４がより好ましく、７〜１０がさらに好ましい。 In the general formula (2), examples of the monovalent aromatic hydrocarbon group represented by R 2 include an aryl group and an aralkyl group. The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 6 to 10 carbon atoms. The carbon number of the aralkyl group is preferably 7 to 20, more preferably 7 to 14, and even more preferably 7 to 10.
アリール基の具体例としては、例えば、フェニル基、ナフチル基、アントリル基、フェナントリル基、ビフェニレン基等が挙げられ、アラルキル基の具体例としては、例えば、ベンジル基、フェネチル基、トリチル基等が挙げられる。 Specific examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a biphenylene group and the like, and specific examples of the aralkyl group include a benzyl group, a phenethyl group, a trityl group and the like. Be done.
なかでも、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、アリール基が好ましく、フェニル基がより好ましい。なお、一般式（2）で表される化合物は、R2として、一般式（1）で表される化合物におけるR1と同じ化合物を使用することもできるし、異なる化合物を使用することもできる。また、mが2以上の整数である場合は、R2は同一でもよいし、異なっていてもよい。 Among them, an aryl group is preferable, and a phenyl group is more preferable, from the viewpoints of safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density, coulombic efficiency, etc. of the obtained lithium secondary battery. As the compound represented by the general formula (2), the same compound as R 1 in the compound represented by the general formula (1) can be used as R 2 , or a different compound can be used. .. Further, when m is an integer of 2 or more, R 2 may be the same or different.
一般式（2）において、R3で示されるハロゲン原子としては、フッ素原子、塩素原子、臭素原子及びヨウ素原子が挙げられる。 In the general formula (2), examples of the halogen atom represented by R 3 include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点からは、R3としては、酸素原子が好ましい。 From the viewpoints of safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density, Coulomb efficiency, etc. of the obtained lithium secondary battery, an oxygen atom is preferable as R 3 .
一般式（2）において、実線と破線で表される結合は単結合又は二重結合であり、R3の種類によって異なる。具体的には、R3が酸素原子及び硫黄原子の場合は二重結合であり、R3がハロゲン原子の場合は単結合である。 In the general formula (2), the bond represented by the solid line and the broken line is a single bond or a double bond, and differs depending on the type of R 3 . Specifically, when R 3 is an oxygen atom and a sulfur atom, it is a double bond, and when R 3 is a halogen atom, it is a single bond.
一般式（2）においては、mは、0以上の整数であり、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、好ましくは1〜4の整数である。なお、mの好ましい数値はR3及びM2の種類によって異なる。具体的には、M2がMgの場合はmは0（ただしR3がハロゲン原子の場合は1）が好ましく、M2がAlの場合はmは1（ただしR3がハロゲン原子の場合は2）が好ましく、M2がSiの場合はmは2（ただしR3がハロゲン原子の場合は3）が好ましく、M2がPの場合はmは3（ただしR3がハロゲン原子の場合は4）が好ましく、M2がBの場合はmは1（ただしR3がハロゲン原子の場合は2）が好ましい。なお、一般式（2）で表される化合物は、mとして、一般式（1）で表される化合物におけるnと同じ化合物を使用することもできるし、異なる化合物を使用することもできる。 In the general formula (2), m is an integer of 0 or more, and from the viewpoints of safety, capacity (particularly discharge capacity), charge / discharge cycle resistance, energy storage density, Coulomb efficiency, etc. of the obtained lithium secondary battery. , Preferably an integer from 1 to 4. The preferred value of m depends on the type of R 3 and M 2 . Specifically, when M 2 is Mg, m is preferably 0 (however, when R 3 is a halogen atom, 1), and when M 2 is Al, m is 1 (however, when R 3 is a halogen atom). 2) is preferable, m is 2 when M 2 is Si (however, 3 when R 3 is a halogen atom), and m is 3 when M 2 is P (however, when R 3 is a halogen atom). 4) is preferable, and when M 2 is B, m is preferably 1 (however, when R 3 is a halogen atom, 2). As the compound represented by the general formula (2), the same compound as n in the compound represented by the general formula (1) can be used as m, or a different compound can be used.
上記のような条件を満たす一般式（2）で表される化合物としては、例えば、 Examples of the compound represented by the general formula (2) satisfying the above conditions include, for example.
等が挙げられ、単独で使用することもでき、2種以上を組合せて使用することもできる。 Etc., and can be used alone or in combination of two or more.
本発明の電解質用添加剤において、一般式（1）で表される化合物の含有量は、特に制限されるわけではないが、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、本発明の電解質用添加剤の総量を100モル%として、10〜90モル%含有することが好ましく、20〜80モル%含有することがより好ましく、30〜70モル%含有することがさらに好ましく、40〜60モル%含有することが特に好ましい。また、本発明の電解質用添加剤において、一般式（2）で表される化合物の含有量は、特に制限されるわけではないが、得られるリチウム二次電池の安全性、容量（特に放電容量）、充放電サイクル耐性、エネルギー貯蔵密度、クーロン効率等の観点から、本発明の電解質用添加剤の総量を100モル%として、10〜90モル%含有することが好ましく、20〜80モル%含有することがより好ましく、30〜70モル%含有することがさらに好ましく、40〜60モル%含有することが特に好ましい。 In the electrolyte additive of the present invention, the content of the compound represented by the general formula (1) is not particularly limited, but the safety, capacity (particularly discharge capacity) of the obtained lithium secondary battery, and so on. From the viewpoint of charge / discharge cycle resistance, energy storage density, Coulomb efficiency, etc., the total amount of the electrolyte additive of the present invention is 100 mol%, and it is preferably contained in an amount of 10 to 90 mol%, preferably 20 to 80 mol%. Is more preferable, and 30 to 70 mol% is more preferable, and 40 to 60 mol% is particularly preferable. Further, in the electrolyte additive of the present invention, the content of the compound represented by the general formula (2) is not particularly limited, but the safety and capacity (particularly discharge capacity) of the obtained lithium secondary battery are not particularly limited. ), Charge / discharge cycle resistance, energy storage density, Coulomb efficiency, etc., the total amount of the electrolyte additive of the present invention is 100 mol%, preferably 10 to 90 mol%, and 20 to 80 mol%. It is more preferable to contain 30 to 70 mol%, and it is particularly preferable to contain 40 to 60 mol%.
本発明の電解質用添加剤には、本発明の効果が阻害されない程度であれば、その他の成分を含むことができる。その他の成分としては、例えば、光安定剤、酸化防止剤、防腐剤、重合阻害剤、顔料、着色剤、防カビ剤等が挙げられる。また、その他の成分として、公知の電解質用添加剤を含むこともできる。本発明の電解質用添加剤がその他成分を含む場合、その他成分の含有量は、本発明の電解質用添加剤の総量を100質量%として、0〜5質量%が好ましく、0.01〜1質量%がより好ましい。なお、本発明の電解質用添加剤は、上記した一般式（1）で表される化合物及び一般式（2）で表される化合物のみで構成されていてもよい。 The electrolyte additive of the present invention may contain other components as long as the effects of the present invention are not impaired. Examples of other components include light stabilizers, antioxidants, preservatives, polymerization inhibitors, pigments, colorants, fungicides and the like. Further, as other components, known electrolyte additives may be included. When the electrolyte additive of the present invention contains other components, the content of the other components is preferably 0 to 5% by mass, preferably 0.01 to 1% by mass, with the total amount of the electrolyte additives of the present invention being 100% by mass. More preferred. The electrolyte additive of the present invention may be composed of only the compound represented by the above general formula (1) and the compound represented by the general formula (2).
本発明の電解質用添加剤は、例えば、二次電池に使用される電解質への添加剤として使用することができ、特にはリチウム二次電池用の電解質への添加剤として使用することができる。本発明の電解質用添加剤を含有する電解質を二次電池、特にリチウム二次電池に適用することで、二次電池、特にリチウム二次電池の安全性を高め、優れた容量（特に放電容量）、エネルギー貯蔵密度、クーロン効率等をもたらすことができる。 The electrolyte additive of the present invention can be used, for example, as an additive to an electrolyte used in a secondary battery, and in particular, can be used as an additive to an electrolyte used in a lithium secondary battery. By applying the electrolyte containing the electrolyte additive of the present invention to a secondary battery, particularly a lithium secondary battery, the safety of the secondary battery, especially the lithium secondary battery, is enhanced, and excellent capacity (particularly discharge capacity) is achieved. , Energy storage density, Coulomb efficiency, etc. can be provided.
本発明の電解質用添加剤は、固体電解質及び液体電解質のいずれにも適用することができ、いずれの場合においても二次電池、特にリチウム二次電池の安全性を高め、優れた容量（特に放電容量）、エネルギー貯蔵密度、クーロン効率等をもたらすことができる。特に、本発明の電解質用添加剤を液体電解質に適用した場合、この液体電解質を備える二次電池（特にリチウム二次電池）は、優れた充放電サイクル耐性を有することもできる。 The electrolyte additive of the present invention can be applied to both solid electrolytes and liquid electrolytes, and in either case, it enhances the safety of secondary batteries, especially lithium secondary batteries, and has excellent capacity (particularly discharge). Capacity), energy storage density, Coulomb efficiency, etc. can be provided. In particular, when the electrolyte additive of the present invention is applied to a liquid electrolyte, a secondary battery (particularly a lithium secondary battery) provided with this liquid electrolyte can also have excellent charge / discharge cycle resistance.
本発明の電解質用添加剤を電解質に含有させる方法は特に限定されず。公知の電解質用添加剤の添加方法を広く採用することができる。なお、電解質の種類は後述する。 The method for incorporating the electrolyte additive of the present invention into the electrolyte is not particularly limited. A known method for adding an electrolyte additive can be widely adopted. The type of electrolyte will be described later.
本発明の電解質用添加剤の製造方法は特に限定されず、例えば、公知の製造方法を広く採用することができる。また、上記した一般式（1）で表される化合物及び一般式（2）で表される化合物は、市販品からも入手することができる。 The method for producing the electrolyte additive of the present invention is not particularly limited, and for example, a known production method can be widely adopted. Further, the compound represented by the general formula (1) and the compound represented by the general formula (2) described above can also be obtained from commercially available products.
２．リチウム二次電池用電解質
本発明のリチウム二次電池用電解質は、本発明の電解質用添加剤を含有する。本発明のリチウム二次電池用電解質は、例えば、リチウム二次電池等の各種二次電池に好適に使用することができる。特に、電解質が本発明の電解質用添加剤を含むことで、電解質自体の性能が増強される。
2. 2. Electrolyte for Lithium Secondary Battery The electrolyte for lithium secondary battery of the present invention contains the additive for the electrolyte of the present invention. The electrolyte for a lithium secondary battery of the present invention can be suitably used for various secondary batteries such as a lithium secondary battery. In particular, when the electrolyte contains the additive for the electrolyte of the present invention, the performance of the electrolyte itself is enhanced.
本発明の電解質用添加剤が適用できる固体電解質及び液体電解質は、特に限定されず、公知の電解質を広く適用することができる。 The solid electrolyte and the liquid electrolyte to which the additive for the electrolyte of the present invention can be applied are not particularly limited, and known electrolytes can be widely applied.
固体電解質としては、例えば、Li10GeP2S12、xLi2S-(1-x)P2S5（0.6≦x≦0.85）、Na11Sn2PS12等の硫化物電解質；Na3PSe4；Li3xLa2/3-xTiO3（0≦x≦0.16）等の酸化物電解質；Li1+xAlxTi2-x(PO4)3（0≦x≦0.5）（LATP）；LixLa3M2O12（3≦x≦7.5、M= Ta, Nb, Zr）；Na3Zr2Si2PO12；ポリマーベースの電解質等が挙げられる。ポリマーベースの電解質としては、例えば、ポリエチレンオキサイド（PEO）、ポリビニリデンフルオライド（PVDF）等をベースとする電解質が挙げられる。ポリマーベースの電解質は、必要に応じて、LiPF6、LiClO4、リチウムビストリフルオロメチルスルホニルイミド（LiTFSI）、NaClO4、NaBF4等の公知の電解質を含むことができる。その他、固体電解質としては、公知の無機電解質と混合してなるハイブリッド電解質を挙げることもできる。 Examples of solid electrolytes include sulfide electrolytes such as Li 10 GeP 2 S 12 , xLi 2 S- (1-x) P 2 S 5 (0.6 ≤ x ≤ 0.85), and Na 11 Sn 2 PS 12 ; Na 3 PSe. 4 ; Oxide electrolytes such as Li 3x La 2 / 3-x TiO 3 (0 ≤ x ≤ 0.16); Li 1 + x Al x Ti 2-x (PO 4 ) 3 (0 ≤ x ≤ 0.5) (LATP) Li x La 3 M 2 O 12 (3 ≤ x ≤ 7.5, M = Ta, Nb, Zr); Na 3 Zr 2 Si 2 PO 12 ; Polymer-based electrolytes and the like. Examples of the polymer-based electrolyte include electrolytes based on polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), and the like. The polymer-based electrolyte can optionally include known electrolytes such as LiPF 6 , LiClO 4 , Lithium Bistrifluoromethylsulfonylimide (LiTFSI), NaClO 4 , NaBF 4 . In addition, as the solid electrolyte, a hybrid electrolyte obtained by mixing with a known inorganic electrolyte can also be mentioned.
液体電解質としては、極性溶媒に溶解したリチウム塩又はナトリウム塩が挙げられる。極性溶媒としては、例えば、プロピレンカーボネート、エチレンカーボネート（EC）、ジメチルカーボネート（DMC）、エチルメチルカーボネート、ジエチルカーボネート（DEC）等のカーボネート化合物；1,3-ジオキソラン（DOL）、1,2-ジメトキシエタン（DME）等のエーテル化合物等を挙げることができる。リチウム塩としては、例えば、六フッ化リン酸リチウム（LiPF6）、リチウムビスフルオロスルホニルイミド（LiFSI）、リチウムビストリフルオロメタンスルホニルイミド（LiTFSI）等が挙げられる。ナトリウム塩としては、例えば、六フッ化リン酸ナトリウム（NaPF6）、ナトリウムビスフルオロスルホニルイミド（NaFSI）、ナトリウムビストリフルオロメタンスルホニルイミド（NaTFSI）等が挙げられる。液体電解質の具体例としては、例えば、LiPF6のエチレンカーボネート（EC）及びジエチルカーボネート（DEC）の混合溶液、LiTFSIのエチレンカーボネート（EC）及びジエチルカーボネート（DEC）の混合溶液、LiPF6の1,3-ジオキソラン（DOL）及び1,2-ジメトキシエタン（DME）の混合溶液、LiTFSIの1,3-ジオキソラン（DOL）及び1,2-ジメトキシエタン（DME）の混合溶液等を挙げることができる。 Examples of the liquid electrolyte include a lithium salt or a sodium salt dissolved in a polar solvent. Examples of the polar solvent include carbonate compounds such as propylene carbonate, ethylene carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate and diethyl carbonate (DEC); 1,3-dioxolane (DOL) and 1,2-dimethoxy. Examples thereof include ether compounds such as ethane (DME). Examples of the lithium salt include lithium hexafluorophosphate (LiPF 6 ), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI) and the like. Examples of the sodium salt include sodium hexafluoride phosphate (NaPF 6 ), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI) and the like. Specific examples of the liquid electrolyte, for example, a mixed solution of the mixed solution of ethylene carbonate LiPF 6 (EC) and diethyl carbonate (DEC), ethylene carbonate LiTFSI (EC) and diethyl carbonate (DEC), 1 of LiPF 6, Examples thereof include a mixed solution of 3-dioxolane (DOL) and 1,2-dimethoxyethane (DME), a mixed solution of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) of LiTFSI, and the like.
本発明のリチウム二次電池用電解質中の本発明の電解質用添加剤の含有量は特に限定されない。例えば、本発明のリチウム二次電池用電解質が液体である場合、当該液体電解質中の本発明の電解質用添加剤の濃度は0.005〜0.5mol/Lが好ましく、0.01〜0.2mol/Lがより好ましい。 The content of the electrolyte for the present invention in the electrolyte for the lithium secondary battery of the present invention is not particularly limited. For example, when the electrolyte for a lithium secondary battery of the present invention is a liquid, the concentration of the electrolyte additive of the present invention in the liquid electrolyte is preferably 0.005 to 0.5 mol / L, more preferably 0.01 to 0.2 mol / L. ..
また、本発明のリチウム二次電池用電解質が固体である場合、当該固体電解質の総量を100質量%として、本発明の電解質用添加剤の含有量は、0.01〜50質量%が好ましく、0.3〜3質量%がより好ましい。 When the electrolyte for a lithium secondary battery of the present invention is a solid, the content of the electrolyte additive of the present invention is preferably 0.01 to 50% by mass, preferably 0.3 to 50% by mass, assuming that the total amount of the solid electrolyte is 100% by mass. 3% by mass is more preferable.
本発明のリチウム二次電池用電解質には、本発明の効果が阻害されない程度であれば、その他の成分を含むことができる。その他の成分としては、例えば、光安定剤、酸化防止剤、防腐剤、重合阻害剤、顔料、着色剤、防カビ剤等が挙げられる。本発明のリチウム二次電池用電解質がその他成分を含む場合、その他成分の含有量は、本発明のリチウム二次電池用電解質の総量を100質量%として、0〜5質量%が好ましく、0.01〜1質量%がより好ましい。 The electrolyte for a lithium secondary battery of the present invention may contain other components as long as the effects of the present invention are not impaired. Examples of other components include light stabilizers, antioxidants, preservatives, polymerization inhibitors, pigments, colorants, fungicides and the like. When the electrolyte for a lithium secondary battery of the present invention contains other components, the content of the other components is preferably 0 to 5% by mass, preferably 0.01 to 5% by mass, with the total amount of the electrolyte for a lithium secondary battery of the present invention being 100% by mass. 1% by mass is more preferable.
３．リチウム二次電池
本発明のリチウム二次電池は本発明のリチウム二次電池用電解質を備える。つまり、本発明のリチウム二次電池は、本発明の電解質用添加剤を含有するリチウム二次電池用電解質を構成要素として含むことができる。本発明のリチウム二次電池は、本発明のリチウム二次電池用電解質に本発明の電解質用添加剤が含まれる限りは、その他の構成は特に限定されず、例えば、公知と同様の構成とすることができる。例えば、本発明のリチウム二次電池は、本発明の電解質用添加剤が含まれるリチウム二次電池用電解質に加えて、カソード、アノード及びセパレータを備えることができる。電池の大きさ及び形状は、リチウム二次電池の用途に応じて適宜決定することができる。
3. 3. Lithium secondary battery The lithium secondary battery of the present invention includes the electrolyte for the lithium secondary battery of the present invention. That is, the lithium secondary battery of the present invention can include an electrolyte for a lithium secondary battery containing the electrolyte for the present invention as a constituent element. The lithium secondary battery of the present invention is not particularly limited in other configurations as long as the electrolyte for the lithium secondary battery of the present invention contains the additive for the electrolyte of the present invention, and has, for example, the same configuration as known. be able to. For example, the lithium secondary battery of the present invention may include a cathode, an anode, and a separator in addition to the electrolyte for a lithium secondary battery containing the electrolyte additive of the present invention. The size and shape of the battery can be appropriately determined according to the use of the lithium secondary battery.
カソードは、例えば、金属箔に活物質が担持された構造を有することができる。金属箔としては、アルミニウム、チタン、白金、モリブデン、ステンレス、銅等が挙げられる。金属箔の形状は、例えば、多孔質体、箔、板、繊維からなるメッシュ等が挙げられる。カソードの活物質としては、公知の活物質を広く適用することができ、例えば、LiFePO4、LiCoO2、LiNixMnyCozO2（0.3≦x≦0.95、0.025≦y≦0.4、0.025≦y≦0.4）、LiNi1-y-zCoyAlzO2（0.05≦y≦0.15、0<z≦0.05）、LiMn2O4、LiMPO4（M= Co、Ni）、Li2FePO4F、V2O5、LixV3O8（1.5≦x≦5.5）、Li1-xVOPO4（0.5≦x≦0.92）、Li4Ti5O12、LiFeMO4（M= Mn、Si）、S、Se、SeS2、O2、Na3V2(PO4)3、Na2MnP2O7、NaFePO4、Na3MnZr(PO4)3等を挙げることができる。 The cathode can have, for example, a structure in which an active material is supported on a metal foil. Examples of the metal foil include aluminum, titanium, platinum, molybdenum, stainless steel, and copper. Examples of the shape of the metal foil include a porous body, a foil, a plate, and a mesh made of fibers. The cathode active material, can be applied widely known active materials, for example, LiFePO 4, LiCoO 2, LiNi x Mn y Co z O 2 (0.3 ≦ x ≦ 0.95,0.025 ≦ y ≦ 0.4,0.025 ≦ y ≦ 0.4), LiNi 1- yz Co y Al z O 2 (0.05 ≦ y ≦ 0.15,0 <z ≦ 0.05), LiMn 2 O 4, LiMPO 4 (M = Co, Ni), Li 2 FePO 4 F, V 2 O 5 , Li x V 3 O 8 (1.5 ≤ x ≤ 5.5), Li 1-x VOPO 4 (0.5 ≤ x ≤ 0.92), Li 4 Ti 5 O 12 , LiFeMO 4 (M = Mn, Si), S, Se, SeS 2 , O 2 , Na 3 V 2 (PO 4 ) 3 , Na 2 MnP 2 O 7 , NaFePO 4 , Na 3 MnZr (PO 4 ) 3, etc. can be mentioned.
アノードは、本発明はリチウム二次電池における課題を解決するものであるため、リチウム金属を採用することができる。なお、リチウム金属以外にも、例えば、金属箔に活物質が担持された構造を採用することもできる。金属箔としては、アルミニウム、チタン、白金、モリブデン、ステンレス、銅等が挙げられる。金属箔の形状は、例えば、多孔質体、箔、板、繊維からなるメッシュ等が挙げられる。アノードの活物質としては、Li、Na、K、Mg、Al、Zn等の金属；グラファイトおよび他の炭素材料；Si(C)ベース、Si(O)ベース又はSnベースの合金あるいは金属酸化物；Li4Ti5O12等を挙げることができる。 As the anode, a lithium metal can be adopted because the present invention solves the problems in the lithium secondary battery. In addition to lithium metal, for example, a structure in which an active material is supported on a metal foil can also be adopted. Examples of the metal foil include aluminum, titanium, platinum, molybdenum, stainless steel, and copper. Examples of the shape of the metal foil include a porous body, a foil, a plate, and a mesh made of fibers. As the active material of the anode, metals such as Li, Na, K, Mg, Al, Zn; graphite and other carbon materials; Si (C) -based, Si (O) -based or Sn-based alloys or metal oxides; Li 4 Ti 5 O 12 etc. can be mentioned.
セパレータとしては、リチウム二次電池に適用されている公知のセパレータを使用することができ、例えば、ポリエチレン、ポリプロピレン等のポリオレフィン樹脂；ポリイミド；ポリビニルアルコール；末端アミノ化ポリエチレンオキシドポリテトラフルオロエチレン等のフッ素樹脂；アクリル樹脂；ナイロン；芳香族アラミド；無機ガラス；セラミックス等の材質からなり、多孔質膜、不織布、織布等の形態の材料を用いることができる。 As the separator, a known separator applied to a lithium secondary battery can be used, and for example, a polyolefin resin such as polyethylene and polypropylene; polyimide; polyvinyl alcohol; and fluorine such as terminal amination polyethylene oxide polytetrafluoroethylene. Resin; Acrylic resin; Nylon; Aromatic aramid; Inorganic glass; Ceramics and other materials, and materials in the form of porous films, non-woven fabrics, woven fabrics and the like can be used.
リチウム二次電池を組み立てる方法も特に制限はなく、公知のリチウム二次電池の組み立て方法と同様の方法でリチウム二次電池を得ることができる。 The method for assembling the lithium secondary battery is also not particularly limited, and the lithium secondary battery can be obtained by the same method as the known method for assembling the lithium secondary battery.
以下、実施例により本発明をより具体的に説明するが、本発明はこれら実施例の態様に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the aspects of these Examples.
実施例における電解質用添加剤に使用する化合物として、シグマ−アルドリッチジャパン製のトリフェニルホスフィン（TP）及びトリフェニルホスフィンオキシド（TPO）を準備し、TP及びTPOの使用の有無による電解質の性能評価を行った。 Triphenylphosphine (TP) and triphenylphosphine oxide (TPO) manufactured by Sigma-Aldrich Japan were prepared as compounds used for the electrolyte additive in the examples, and the performance of the electrolyte was evaluated depending on the presence or absence of TP and TPO. went.
［試験例１；「1M LiPF6 in EC: DEC」ベース］
実施例１：TP及びTPO使用
CR2025型のLiNi1/3Mn1/3Co1/3O2｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiNi1/3Mn1/3Co1/3O2（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiNi1/3Mn1/3Co1/3O2；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、トリフェニルホスィン（TP）及びトリフェニルホスィンオキシド（TPO）をシグマ−アルドリッチジャパンより購入した市販の電解液（1M LiPF6 in EC: DEC (1: 1 vol.%) (50μL)）にそれぞれ0.025Mの濃度となるように溶解した。この液体電解質をLiPF6+ 5%TP-TPO in EC: DECと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.7〜4.3Vとして30℃で充放電試験を行った。
[Test Example 1; "1M LiPF 6 in EC: DEC" base]
Example 1: Use of TP and TPO
CR2025 type LiNi 1/3 Mn 1/3 Co 1/3 O 2 | Li Metal coin battery was constructed. In this coin battery, the bipolar active materials were Li Ni 1/3 Mn 1/3 Co 1/3 O 2 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. .. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. As the liquid electrolyte, a commercially available electrolyte (1M LiPF 6 in EC: DEC (1: 1 vol.%) (50 μL) obtained by purchasing triphenylphosphine (TP) and triphenylphosphine oxide (TPO) from Sigma-Aldrich Japan. )) Was dissolved to a concentration of 0.025 M. This liquid electrolyte was designated as LiPF 6 + 5% TP-TPO in EC: DEC. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.7 to 4.3V.
比較例１：TP及びTPO不使用
CR2025型のLiNi1/3Mn1/3Co1/3O2｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiNi1/3Mn1/3Co1/3O2（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiNi1/3Mn1/3Co1/3O2；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、シグマ−アルドリッチジャパンより購入した市販の電解液（1M LiPF6 in EC: DEC (1: 1 vol.%) (50μL)）を使用した。この液体電解質をLiPF6 in EC: DECと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.7〜4.3Vとして30℃で充放電試験を行った。
Comparative Example 1: TP and TPO not used
CR2025 type LiNi 1/3 Mn 1/3 Co 1/3 O 2 | Li Metal coin battery was constructed. In this coin battery, the bipolar active materials were Li Ni 1/3 Mn 1/3 Co 1/3 O 2 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. .. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. As the liquid electrolyte, a commercially available electrolyte (1M LiPF 6 in EC: DEC (1: 1 vol.%) (50 μL)) purchased from Sigma-Aldrich Japan was used. This liquid electrolyte was described as LiPF 6 in EC: DEC. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.7 to 4.3V.
比較例２：TP使用
CR2025型のLiNi1/3Mn1/3Co1/3O2｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiNi1/3Mn1/3Co1/3O2（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiNi1/3Mn1/3Co1/3O2；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、トリフェニルホスィン（TP）をシグマ−アルドリッチジャパンより購入した市販の電解液（1M LiPF6 in EC: DEC (1: 1 vol.%) (50μL)）に0.05Mの濃度となるように溶解した。この液体電解質をLiPF6+ 5%TP in EC: DECと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.7〜4.3Vとして30℃で充放電試験を行った。
Comparative example 2: Use of TP
CR2025 type LiNi 1/3 Mn 1/3 Co 1/3 O 2 | Li Metal coin battery was constructed. In this coin battery, the bipolar active materials were Li Ni 1/3 Mn 1/3 Co 1/3 O 2 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. .. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. The liquid electrolyte has a concentration of 0.05M in a commercially available electrolyte (1M LiPF 6 in EC: DEC (1: 1 vol.%) (50 μL)) obtained by purchasing triphenylphosine (TP) from Sigma-Aldrich Japan. Dissolved as. This liquid electrolyte was written as LiPF 6 + 5% TP in EC: DEC. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.7 to 4.3V.
比較例３：TPO使用
CR2025型のLiNi1/3Mn1/3Co1/3O2｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiNi1/3Mn1/3Co1/3O2（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiNi1/3Mn1/3Co1/3O2；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、トリフェニルホスィンオキシド（TPO）をシグマ−アルドリッチジャパンより購入した市販の電解液（1M LiPF6 in EC: DEC (1: 1 vol.%) (50μL)）に0.05Mの濃度となるように溶解した。この液体電解質をLiPF6+ 5%TPO in EC: DECと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.7〜4.3Vとして30℃で充放電試験を行った。
Comparative Example 3: Using TPO
CR2025 type LiNi 1/3 Mn 1/3 Co 1/3 O 2 | Li Metal coin battery was constructed. In this coin battery, the bipolar active materials were Li Ni 1/3 Mn 1/3 Co 1/3 O 2 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiNi 1/3 Mn 1/3 Co 1/3 O 2 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. .. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. The liquid electrolyte is a commercially available electrolyte (1M LiPF 6 in EC: DEC (1: 1 vol.%) (50 μL)) purchased from Sigma-Aldrich Japan with triphenylphosphine oxide (TPO) at a concentration of 0.05 M. Dissolved so that This liquid electrolyte was designated as LiPF 6 + 5% TPO in EC: DEC. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.7 to 4.3V.
［試験例２；「1M LiTFSI in DOL: DME」ベース］
実施例２：TP及びTPO使用
CR2025型のLiFePO4｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiFePO4（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiFePO4；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、トリフェニルホスィン（TP）及びトリフェニルホスィンオキシド（TPO）をXiamen Tob New Energy Technology Co., Ltd. Chinaより購入した市販の電解液（1M LiTFSI in DOL: DME (1: 1 vol.%) (50μL)）にそれぞれ0.025Mの濃度となるように溶解した。この液体電解質をLiTFSI + 5%TP-TPO in DOL: DMEと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.5〜4.0Vとして30℃で充放電試験を行った。
[Test Example 2; "1M LiTFSI in DOL: DME" base]
Example 2: Use of TP and TPO
A CR2025 type LiFePO 4 | Li metal coin battery was constructed. In this coin battery, the bipolar active materials were LiFePO 4 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiFePO 4 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. As the liquid electrolyte, a commercially available electrolyte (1M LiTFSI in DOL: DME (1: 1)) obtained by purchasing triphenylphosin (TP) and triphenylphosin oxide (TPO) from Xiamen Tob New Energy Technology Co., Ltd. China. It was dissolved in vol.%) (50 μL)) to a concentration of 0.025 M, respectively. This liquid electrolyte was described as LiTFSI + 5% TP-TPO in DOL: DME. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.5 to 4.0 V.
比較例４：TP及びTPO不使用
CR2025型のLiFePO4｜Li金属コイン電池を構築した。このコイン電池において、両極活物質はLiFePO4（正極活物質）及びLi（負極活物質）とした。正極は、塗工済正極板（正極活物質LiFePO4；正極集電体アルミホイル；容量1.5mAh/cm2）を宝泉（株）から購入した。また、負極は、負極集電体として銅箔の上に負極活物質としてリチウム金属箔を構成した。液体電解質は、Xiamen Tob New Energy Technology Co., Ltd. Chinaより購入した市販の電解液（1M LiTFSI in DOL: DME (1: 1 vol.%) (50μL)）を使用した。この液体電解質をLiTFSI in DOL: DMEと表記した。この液体電解質で湿らせたポリプロピレン製セパレータと、前記両極を用い、公知の方法でCR2025型のコイン電池に封入した。得られたリチウム二次電池は、Wuhan LAND electronics社の充放電装置（LAND batteries testing system）を使用して、充放電の電圧範囲を2.5〜4.0Vとして30℃で充放電試験を行った。
Comparative Example 4: TP and TPO not used
A CR2025 type LiFePO 4 | Li metal coin battery was constructed. In this coin battery, the bipolar active materials were LiFePO 4 (positive electrode active material) and Li (negative electrode active material). For the positive electrode, a coated positive electrode plate (positive electrode active material LiFePO 4 ; positive electrode current collector aluminum foil; capacity 1.5 mAh / cm 2 ) was purchased from Hosen Co., Ltd. Further, as the negative electrode, a lithium metal foil was formed as a negative electrode active material on a copper foil as a negative electrode current collector. As the liquid electrolyte, a commercially available electrolyte (1M LiTFSI in DOL: DME (1: 1 vol.%) (50 μL)) purchased from Xiamen Tob New Energy Technology Co., Ltd. China was used. This liquid electrolyte was referred to as LiTFSI in DOL: DME. Using a polypropylene separator moistened with this liquid electrolyte and the two poles, the battery was sealed in a CR2025 type coin cell by a known method. The obtained lithium secondary battery was subjected to a charge / discharge test at 30 ° C. using a charging / discharging device (LAND batteries testing system) manufactured by Wuhan LAND electronics, with a charging / discharging voltage range of 2.5 to 4.0 V.
なお、試験例１及び２での電池の構築においては、グローブボックス（（株）美和製作所製）を不活性雰囲気下での電池製作のために使用し、H2O及びO2濃度がいずれも0.1ppm以下であるArガス雰囲気下で行った。また、試験例１及び２での電池製作に使用したセパレータは直径16mm、厚さ0.025mmとし、負極活物質（リチウム金属箔）は、直径12mm、厚さ0.1mmとし、負極集電体（銅箔）は、直径12mm、厚さ0.01mmとし、正極板（正極活物質塗工済）は、直径12mm、厚さ0.05mmとした。 In the construction of the batteries in Test Examples 1 and 2, a glove box (manufactured by Miwa Seisakusho Co., Ltd.) was used for manufacturing the batteries in an inert atmosphere, and the H 2 O and O 2 concentrations were both. This was performed under an Ar gas atmosphere of 0.1 ppm or less. The separator used for manufacturing the batteries in Test Examples 1 and 2 had a diameter of 16 mm and a thickness of 0.025 mm, and the negative electrode active material (lithium metal leaf) had a diameter of 12 mm and a thickness of 0.1 mm, and a negative electrode current collector (copper). The foil) had a diameter of 12 mm and a thickness of 0.01 mm, and the positive electrode plate (coated with the positive electrode active material) had a diameter of 12 mm and a thickness of 0.05 mm.
（評価結果）
図１は、試験例１（実施例１及び比較例１）で得た液体電解質を備えるリチウム二次電池の電気化学測定（放電容量及び充放電サイクル耐性）の結果を示す。図１から、液体電解質がTP及びTPOの双方を含むことで、電解質用添加剤を無添加の場合と比較して高い放電容量を有するとともに、100サイクルの充放電後に高い容量保持率を示した。特に、高い充放電レート（0.5C）において、充放電サイクルの繰り返しに伴う容量の低下が少ないことがわかる。これは、液体電解液中に添加したTP及びTPOの混合物が、電極表面上に安定な界面層（SEI；Solid Electrolyte Interphase）を形成し、電極表面上での電解質と電極の反応による電解質分解等の副反応やリチウムデンドライトの形成を抑制したためと推察される。
(Evaluation results)
FIG. 1 shows the results of electrochemical measurement (discharge capacity and charge / discharge cycle resistance) of a lithium secondary battery provided with a liquid electrolyte obtained in Test Example 1 (Example 1 and Comparative Example 1). From FIG. 1, since the liquid electrolyte contains both TP and TPO, it has a higher discharge capacity as compared with the case where no electrolyte additive is added, and also shows a high capacity retention rate after 100 cycles of charging and discharging. .. In particular, at a high charge / discharge rate (0.5C), it can be seen that there is little decrease in capacity due to repeated charge / discharge cycles. This is because the mixture of TP and TPO added to the liquid electrolyte forms a stable interface layer (SEI; Solid Electrolyte Interphase) on the electrode surface, and the electrolyte is decomposed by the reaction between the electrolyte and the electrode on the electrode surface. It is presumed that this was due to the suppression of side reactions and the formation of lithium electrolytes.
図２は、試験例２（実施例２及び比較例４）で得た液体電解質を備えるリチウム二次電池の電気化学測定（放電容量及び充放電サイクル耐性）の結果を示す。図２からも、液体電解質がTP及びTPOの双方を含むことで、電解質用添加剤を無添加の場合と比較して高い放電容量を有するとともに、70サイクルの充放電後に高い容量保持率を示した。この結果から、液体電解質中に添加TP及びTPOを添加することによる放電容量及び充放電サイクル耐性改善効果は、電解質の種類を問わず有効であると推察される。 FIG. 2 shows the results of electrochemical measurement (discharge capacity and charge / discharge cycle resistance) of the lithium secondary battery provided with the liquid electrolyte obtained in Test Example 2 (Example 2 and Comparative Example 4). Also from FIG. 2, since the liquid electrolyte contains both TP and TPO, it has a higher discharge capacity as compared with the case where no electrolyte additive is added, and also shows a high capacity retention rate after 70 cycles of charging and discharging. It was. From this result, it is inferred that the effect of improving the discharge capacity and the charge / discharge cycle resistance by adding the added TP and TPO to the liquid electrolyte is effective regardless of the type of electrolyte.
図３は、試験例１（実施例１及び比較例１〜３）で製作したリチウム二次電池の充放電曲線を示す。図３から、TP及びTPOの双方を添加した場合（実施例１）の総量と同量のTPを単独で電解液に添加した場合（比較例２）、セルはTPの酸化に伴う過充電挙動を示した。この過程では、TPの酸化に伴い、カソード−液体電解質間に、安定なカソード−電解質中間相（CEI；Cathode Electrolyte Interface）が形成されているものと推測される。加えて、TPは過充電時に生成する酸素ガスを効果的に除去しているものと考えられる。このような効果により、TPの添加により、電池により高い電圧が印加されることが許容されるようになる。 FIG. 3 shows a charge / discharge curve of the lithium secondary battery manufactured in Test Example 1 (Example 1 and Comparative Examples 1 to 3). From FIG. 3, when both TP and TPO were added (Example 1) and the same amount of TP as the total amount was added to the electrolytic solution alone (Comparative Example 2), the cell overcharged due to the oxidation of TP. showed that. In this process, it is presumed that a stable cathode-electrolyte intermediate phase (CEI; Cathode Electrolyte Interface) is formed between the cathode and the liquid electrolyte due to the oxidation of TP. In addition, TP is considered to effectively remove the oxygen gas generated during overcharging. Due to such an effect, the addition of TP allows a higher voltage to be applied to the battery.
一方で、TP及びTPOの双方を添加した場合（実施例１）の総量と同量のTPOを単独で添加した場合（比較例３）、観測された充放電曲線から、カソード及びアノードの両表面に安定化被膜が形成されていると推測され、これらが高い放電容量とクーロン効率を生じさせていると考えられる。 On the other hand, when both TP and TPO were added (Example 1) and the same amount of TPO was added alone (Comparative Example 3), both the cathode and anode surfaces were found from the observed charge / discharge curves. It is presumed that a stabilizing film is formed on the surface, which is considered to cause high discharge capacity and Coulomb efficiency.
それに対して、TP及びTPOの双方を添加した場合（実施例１）、上記の単独添加の場合に比べてよりスムースな充放電曲線と一層高い放電容量が観測されている。つまり、電極がより安定となり副生反応を抑制するとともに、放電容量及び充放電サイクル耐性が向上する。TP及びTPOの双方を添加した場合は、電解質用添加剤の量は同じであるにも関わらず、TPを単独で添加した場合及びTPOを単独で添加した場合のいずれと比較してもよりスムースな充放電曲線と一層高い放電容量が観測されており、これらの結果から、TP及びTPOの双方を添加する場合には、TPを単独で添加した場合及びTPOを単独で添加した場合の効果を単なる足し合わせたものではなく相乗効果が見られることが明らかとなった。 On the other hand, when both TP and TPO are added (Example 1), a smoother charge / discharge curve and a higher discharge capacity are observed as compared with the case of the above-mentioned single addition. That is, the electrode becomes more stable, the by-product reaction is suppressed, and the discharge capacity and the charge / discharge cycle resistance are improved. When both TP and TPO are added, the amount of the electrolyte additive is the same, but it is smoother than when TP is added alone or when TPO is added alone. A smooth charge / discharge curve and a higher discharge capacity have been observed. From these results, when both TP and TPO are added, the effects when TP is added alone and when TPO is added alone are shown. It became clear that a synergistic effect was seen, not just a combination.
以上より、一般式（1）で表される化合物と一般式（2）で表される化合物の双方を含む電解質用添加剤は、リチウム二次電池に高い放電容量をもたらすことができ、しかも、優れた充放電サイクル耐性をもたらすことができることが実証された。 From the above, the electrolyte additive containing both the compound represented by the general formula (1) and the compound represented by the general formula (2) can bring a high discharge capacity to the lithium secondary battery, and moreover. It has been demonstrated that it can provide excellent charge / discharge cycle resistance.
Claims (8)
で表される化合物と、
一般式（2）：
で表される化合物とを含有する、電解質用添加剤。 General formula (1):
And the compound represented by
General formula (2):
An additive for an electrolyte containing a compound represented by.
A lithium secondary battery comprising the electrolyte for a lithium secondary battery according to claim 7.
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