JPH11297310A - Lithium ion secondary battery, and first time charging method therefor - Google Patents
Lithium ion secondary battery, and first time charging method thereforInfo
- Publication number
- JPH11297310A JPH11297310A JP10102437A JP10243798A JPH11297310A JP H11297310 A JPH11297310 A JP H11297310A JP 10102437 A JP10102437 A JP 10102437A JP 10243798 A JP10243798 A JP 10243798A JP H11297310 A JPH11297310 A JP H11297310A
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- ion secondary
- lithium ion
- battery
- secondary 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.)
- Withdrawn
Links
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims description 12
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 23
- 239000007773 negative electrode material Substances 0.000 claims abstract description 20
- 239000000203 mixture Substances 0.000 claims description 34
- 229910052744 lithium Inorganic materials 0.000 description 15
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 14
- 238000012360 testing method Methods 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 11
- 238000007789 sealing Methods 0.000 description 11
- 239000011230 binding agent Substances 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 9
- -1 polytetrafluoroethylene Polymers 0.000 description 9
- 230000008021 deposition Effects 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000001066 destructive effect Effects 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000004743 Polypropylene Substances 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 239000008151 electrolyte solution Substances 0.000 description 5
- 229920001155 polypropylene Polymers 0.000 description 5
- 239000007774 positive electrode material Substances 0.000 description 5
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 3
- 239000006229 carbon black Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000012790 confirmation Methods 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 description 2
- OZJPLYNZGCXSJM-UHFFFAOYSA-N 5-valerolactone Chemical compound O=C1CCCCO1 OZJPLYNZGCXSJM-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 239000012752 auxiliary agent Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 description 1
- BFWCTCCSQMLOPL-UHFFFAOYSA-N 1-methoxycarbonyloxypropan-2-yl methyl carbonate Chemical compound COC(=O)OCC(C)OC(=O)OC BFWCTCCSQMLOPL-UHFFFAOYSA-N 0.000 description 1
- MYNUAGYBVSQRFN-UHFFFAOYSA-N 2-ethoxycarbonyloxyethyl ethyl carbonate Chemical compound CCOC(=O)OCCOC(=O)OCC MYNUAGYBVSQRFN-UHFFFAOYSA-N 0.000 description 1
- DOMLQXFMDFZAAL-UHFFFAOYSA-N 2-methoxycarbonyloxyethyl methyl carbonate Chemical compound COC(=O)OCCOC(=O)OC DOMLQXFMDFZAAL-UHFFFAOYSA-N 0.000 description 1
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- 229920002943 EPDM rubber Polymers 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- 229920000181 Ethylene propylene rubber Polymers 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229910013716 LiNi Inorganic materials 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 229920000459 Nitrile rubber Polymers 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 150000005678 chain carbonates Chemical class 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 239000003795 chemical substances by application 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
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- 229910001547 lithium hexafluoroantimonate(V) Inorganic materials 0.000 description 1
- 229910001540 lithium hexafluoroarsenate(V) Inorganic materials 0.000 description 1
- 229910002102 lithium manganese oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000009782 nail-penetration test Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、リチウムイオン二
次電池およびその初回充電方法に関し、さらに詳しく
は、サイクル特性が優れ、かつ安全性が優れたリチウム
イオン二次電池およびその初回充電方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium ion secondary battery and a first charging method thereof, and more particularly, to a lithium ion secondary battery having excellent cycle characteristics and excellent safety and a first charging method thereof.
【０００２】[0002]
【従来の技術】近年、各種携帯機器の電源として、軽量
でかつ高容量密度のリチウムイオン二次電池が使用され
ている。最近では携帯機器の長時間使用へのニーズが高
まり、更なる高容量密度化が求められている。しかしな
がら、電池の高容量密度化を図るために、電極活物質を
高密度で充填したり、リチウムニッケル酸化物などの高
容量密度化が可能な正極活物質を使用すると、負極活物
質である炭素系材料の表面に金属リチウムが析出して、
サイクル特性が低下したり、通常の製品では遭遇しない
ような苛酷な条件下で破壊試験を試験的に行った場合に
安全性が悪くなるという問題があった。2. Description of the Related Art In recent years, lightweight and high capacity density lithium ion secondary batteries have been used as power sources for various portable devices. Recently, the need for long-term use of portable devices has increased, and further higher capacity density has been demanded. However, in order to increase the capacity of the battery, if the electrode active material is filled at a high density or if a positive electrode active material such as lithium nickel oxide capable of increasing the capacity is used, the carbon as the negative electrode active material is reduced. Metallic lithium precipitates on the surface of the base material,
There has been a problem that the cycle characteristics are deteriorated and the safety is deteriorated when a destructive test is conducted on a test under severe conditions which are not encountered in a normal product.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、上記のよう
な従来技術の問題点を解決し、負極活物質に炭素系材料
を含み、容量密度が４００Ｗｈ／ｌ以上の高容量のリチ
ウムイオン二次電池において、負極合剤の密度や初回充
電方法を制御することにより、炭素系材料の表面への金
属リチウムの析出を抑制し、サイクル特性が優れ、かつ
安全性が優れたリチウムイオン二次電池を提供すること
を目的とする。SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and comprises a high-capacity lithium ion secondary battery containing a carbon-based material as a negative electrode active material and having a capacity density of 400 Wh / l or more. By controlling the density of the negative electrode mixture and the initial charging method in the secondary battery, the deposition of metallic lithium on the surface of the carbon-based material is suppressed, and the lithium ion secondary battery has excellent cycle characteristics and excellent safety. The purpose is to provide.
【０００４】[0004]
【課題を解決するための手段】本発明者らは、上記課題
を解決するため鋭意検討を重ねた結果、負極活物質に炭
素系材料を含み、容量密度が４００Ｗｈ／ｌ以上のリチ
ウムイオン二次電池において、上記負極活物質を含む負
極合剤の密度を１．５５ｇ／ｃｍ3 以下にすることによ
って、負極活物質の炭素系材料の表面への金属リチウム
の析出を抑制し、サイクル特性が優れ、かつ通常の製品
では遭遇しないような苛酷な条件下で破壊試験を試験的
に行った場合においても、安全性の優れたリチウムイオ
ン二次電池を得ることができることを見出した。Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have found that a lithium ion secondary material containing a carbon-based material in the negative electrode active material and having a capacity density of 400 Wh / l or more is used. In the battery, by setting the density of the negative electrode mixture containing the negative electrode active material to 1.55 g / cm 3 or less, deposition of metallic lithium on the surface of the carbon-based material of the negative electrode active material is suppressed, and the cycle characteristics are excellent. Also, it has been found that a lithium ion secondary battery having excellent safety can be obtained even when a destructive test is conducted on a trial basis under severe conditions that are not encountered in ordinary products.
【０００５】また、本発明者らは、負極活物質に炭素系
材料を含み、容量密度が４００Ｗｈ／ｌのリチウムイオ
ン二次電池の初回充電にあたり、充電初期の正極の単位
面積当たりの電流密度を０．３ｍＡ／ｃｍ2 以下にして
初回充電することにより、サイクル特性が優れ、かつ通
常の製品では遭遇しないような苛酷な条件下で破壊試験
を試験的に行った場合においても、安全性の優れたリチ
ウムイオン二次電池を得ることができることも見出し
た。In addition, the inventors of the present invention have proposed that when a negative electrode active material contains a carbon-based material and has a capacity density of 400 Wh / l for the first charge of a lithium ion secondary battery, the current density per unit area of the positive electrode at the initial stage of charge is reduced. By charging the battery for the first time at 0.3 mA / cm 2 or less, it has excellent cycle characteristics and excellent safety even when a destructive test is conducted under severe conditions that are not encountered in ordinary products. That a lithium ion secondary battery can be obtained.
【０００６】本発明が対象とするような、負極活物質に
炭素系材料を含み、容量密度が４００Ｗｈ／ｌ以上の高
容量密度のリチウムイオン二次電池においては、負極活
物質の炭素系材料の表面に金属リチウムが析出すると、
上記炭素系材料へのリチウムのインターカレーション・
ディインターカレーションの可逆性が悪くなり、サイク
ル特性が低下するものと考えられる。また、上記炭素系
材料の表面に析出した金属リチウムが電解液と反応しや
すいこともサイクル特性を低下させる原因になるものと
考えられる。In a high capacity density lithium ion secondary battery containing a carbon-based material in the negative electrode active material and having a capacity density of 400 Wh / l or more as the object of the present invention, the carbon-based material of the negative electrode active material is used. When metallic lithium precipitates on the surface,
Intercalation of lithium into the above carbon-based materials
It is considered that the reversibility of the deintercalation deteriorates and the cycle characteristics deteriorate. Further, it is considered that the fact that the metallic lithium precipitated on the surface of the carbon-based material easily reacts with the electrolytic solution also causes the deterioration of the cycle characteristics.
【０００７】ところが、容量密度が４００Ｗｈ／ｌ未満
の容量密度が低いリチウムイオン二次電池の場合、負極
の表面にわずかにリチウムが析出していても、サイクル
特性の著しい低下がなく、また、通常の製品では遭遇し
ないような苛酷な条件下で破壊試験を試験的に行って短
絡させた場合でも、安全性の著しい低下がなかった。こ
のことから、炭素系材料の表面への金属リチウムの析出
は、特に高容量密度の電池に影響を及ぼすものと考えら
れる。However, in the case of a lithium ion secondary battery having a low capacity density of less than 400 Wh / l, even if lithium is slightly precipitated on the surface of the negative electrode, the cycle characteristics are not remarkably lowered, and Even if the product was subjected to a destructive test under severe conditions that would not be encountered with the product and short-circuited, there was no significant reduction in safety. From this, it is considered that deposition of metallic lithium on the surface of the carbon-based material particularly affects a battery having a high capacity density.
【０００８】本発明の請求項１に記載の発明において、
負極合剤の密度を１．５５ｇ／ｃｍ 3 以下にすることに
よって、負極活物質の炭素系材料の表面への金属リチウ
ムの析出を抑制することが可能になる理由としては、負
極合剤の密度が１．５５ｇ／ｃｍ3 以下になると、負極
合剤中へのリチウムイオンの拡散が容易になり、負極の
表面に金属リチウムが析出しにくくなるためであると考
えられる。[0008] In the first aspect of the present invention,
The density of the negative electrode mixture is 1.55 g / cm ThreeTo be
Therefore, metal lithium on the surface of the carbon-based material of the negative electrode active material
The reason why it is possible to suppress the deposition of
The density of the mixture is 1.55 g / cmThreeWhen it becomes less, the negative electrode
The diffusion of lithium ions into the mixture becomes easier,
This is because it is difficult for metallic lithium to precipitate on the surface.
available.
【０００９】本発明の請求項２に記載の発明において、
初回充電時の充電初期の正極の単位面積当たりの電流密
度を０．３ｍＡ／ｃｍ2 以下にすることによって、負極
活物質の炭素系材料の表面への金属リチウムの析出を抑
制することが可能になる理由としては、電流密度を０．
３ｍＡ／ｃｍ2 以下にすると、初回充電時の充電初期の
正極の分極を小さくできるので正極の反応が均一にな
り、それによって正極と対向する負極の反応も均一にな
り、局部的な電流集中が少なくなることによるものと考
えられる。In the invention according to claim 2 of the present invention,
By reducing the current density per unit area of the positive electrode at the initial stage of charging at the time of initial charging to 0.3 mA / cm 2 or less, it is possible to suppress the deposition of lithium metal on the surface of the carbon-based material of the negative electrode active material. The reason is that the current density is set to 0.
When it is 3 mA / cm 2 or less, the polarization of the positive electrode at the initial stage of charging at the time of the initial charge can be reduced, so that the reaction of the positive electrode becomes uniform, so that the reaction of the negative electrode facing the positive electrode also becomes uniform, and local current concentration is reduced. It is considered that this is due to a decrease.
【００１０】[0010]
【発明の実施の形態】本発明の容量密度が４００Ｗｈ／
ｌ以上のリチウムイオン二次電池において、負極活物質
として用いる炭素系材料としては、例えば、天然黒鉛、
人造黒鉛、炭素繊維、乱層構造を有する炭素、低結晶炭
素、非晶質炭素などが挙げられるが、それら以外の炭素
系材料であってもよく、また、ホウ素、リンなどの他の
元素を含んだものであってもよい。さらに、２種類以上
の炭素系材料を併用してもよいし、電池の容量密度を４
００Ｗｈ／ｌ以上にできるものであれば、炭素系材料以
外のものを含んでいてもよい。DESCRIPTION OF THE PREFERRED EMBODIMENTS The capacity density of the present invention is 400 Wh /
l or more lithium ion secondary batteries, as the carbon-based material used as the negative electrode active material, for example, natural graphite,
Artificial graphite, carbon fiber, carbon having a turbostratic structure, low-crystalline carbon, amorphous carbon, etc. may be mentioned, but other carbon-based materials may be used, and other elements such as boron and phosphorus may be used. May be included. Further, two or more carbon-based materials may be used in combination, or the capacity density of the battery may be reduced to 4%.
Any material other than the carbon-based material may be included as long as it can be made 00 Wh / l or more.
【００１１】負極の作製は、例えば、上記炭素系材料か
らなる負極活物質に、必要に応じて、バインダーや、カ
ーボンブラック、グラファイトなどのような導電助剤な
どを加えて混合して負極合剤を調製し、溶剤でペースト
状にし（ただし、バインダーはあらかじめ溶剤に溶解さ
せておいてから負極活物質などと混合してもよい）、そ
の負極合剤ペーストを集電体に塗布し、乾燥して、上記
集電体の一方の面または両面に負極合剤の密度が１．５
５ｇ／ｃｍ3 以下になるように負極合剤層を形成するこ
とによって行われる（両面に負極合剤層を形成する場合
は、両面の負極合剤とも密度を１．５５ｇ／ｃｍ3 以下
にする）。ただし、負極の作製方法は上記例示の方法に
限られることはない。The negative electrode is prepared by, for example, adding a binder, a conductive auxiliary such as carbon black, graphite, or the like to the negative electrode active material made of the carbon-based material and mixing the mixture, if necessary. Prepared in a paste with a solvent (however, the binder may be dissolved in the solvent beforehand and then mixed with the negative electrode active material, etc.), and the negative electrode mixture paste is applied to the current collector, and dried. The density of the negative electrode mixture is 1.5% on one or both surfaces of the current collector.
When forming the negative electrode mixture layer (on both sides carried out by forming a negative electrode mixture layer so that the 5 g / cm 3 or less, the density on both sides of the negative electrode mixture to 1.55 g / cm 3 or less ). However, the method for manufacturing the negative electrode is not limited to the method described above.
【００１２】本発明においては、上記のように集電体の
一方の面または両面に形成される負極合剤層における負
極合剤の密度を１．５５ｇ／ｃｍ3 以下にするが、この
負極合剤の密度は小さいほど、負極活物質の炭素系材料
の表面への金属リチウムの析出を抑制するのに適してい
るが、負極合剤の密度があまりにも小さくなりすぎる
と、電池をサイクルさせた時に負極合剤の剥離が生じ、
容量が低下するおそれがあるので、負極合剤の密度とし
ては、上記のように１．５５ｇ／ｃｍ3 以下であって、
１．２０ｇ／ｃｍ3 以上が実用上適している。In the present invention, the density of the negative electrode mixture in the negative electrode mixture layer formed on one or both surfaces of the current collector is set to 1.55 g / cm 3 or less. The lower the density of the agent, the more suitable it is to suppress the deposition of metallic lithium on the surface of the carbon-based material of the negative electrode active material, but if the density of the negative electrode mixture becomes too small, the battery was cycled. Sometimes peeling of the negative electrode mixture occurs,
Since the capacity may decrease, the density of the negative electrode mixture is 1.55 g / cm 3 or less as described above,
1.20 g / cm 3 or more is practically suitable.
【００１３】本発明において、正極活物質としては、例
えば、リチウムコバルト酸化物、リチウムニッケル酸化
物、リチウムマンガン酸化物などが挙げられるが、これ
らはＭｇ、Ｔｉ、Ａｌなどの他の元素を含んでいてもよ
く、また、２種類以上を併用してもよい。正極の作製
は、例えば、上記正極活物質に、必要に応じ、バインダ
ーや導電助剤を加えて混合し、溶剤でペースト状にし
（ただし、バインダーはあらかじめ溶剤に溶解させてお
いてから正極活物質などと混合してもよい）、その正極
合剤ペーストを集電体に塗布し、乾燥して、上記集電体
の一方の面または両面に正極合剤層を形成することによ
って行われる。ただし、正極の作製方法は上記例示の方
法に限られることはない。In the present invention, the positive electrode active material includes, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide and the like, and these include other elements such as Mg, Ti and Al. Or two or more of them may be used in combination. For the production of the positive electrode, for example, a binder or a conductive auxiliary agent is added to the above-mentioned positive electrode active material, if necessary, mixed and made into a paste with a solvent (provided that the binder is dissolved in the solvent in advance, and then the positive electrode active material is mixed). The positive electrode mixture paste is applied to a current collector, dried, and a positive electrode mixture layer is formed on one or both surfaces of the current collector. However, the method for manufacturing the positive electrode is not limited to the method described above.
【００１４】正極や負極のバインダーとしては、例え
ば、ポリフッ化ビニリデン、ポリテトラフルオロエチレ
ン、ポリビニルアルコール、エチルセルロース、ポリエ
チレンオキサイド、ポリビニルブチラール、ポリメチル
メタクリレート、ポリエチレングリコール、ポリプロピ
レングリコール、フッ素ゴム、エチレンプロピレンジエ
ンゴム、エチレンプロピレンゴム、スチレンブタジエン
ゴム、アクリロニトリルブタジエンゴムなどが挙げら
れ、これらはそれぞれ単独で用いてもよいし、２種類以
上を併用してもよい。また、導電助剤としては、例え
ば、カーボンブラック、グラファイト、Ｔｉ、Ａｌ、Ｎ
ｉなどの金属粉末などが用いられる。Examples of the binder for the positive electrode and the negative electrode include polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, ethyl cellulose, polyethylene oxide, polyvinyl butyral, polymethyl methacrylate, polyethylene glycol, polypropylene glycol, fluorine rubber, and ethylene propylene diene rubber. , Ethylene propylene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, etc., each of which may be used alone or in combination of two or more. Examples of the conductive aid include carbon black, graphite, Ti, Al, and N.
Metal powder such as i is used.
【００１５】正極や負極の集電体としては、例えば、ア
ルミニウム、ステンレス鋼、チタン、銅などの金属の
網、パンチドメタル、エキスパンドメタル、フォームメ
タル、箔などが用いられる。As the current collector for the positive electrode and the negative electrode, for example, a metal net such as aluminum, stainless steel, titanium, and copper, punched metal, expanded metal, foam metal, foil, and the like are used.
【００１６】電解液としては、有機溶媒に電解質を溶解
させた有機溶媒系の電解液が用いられる。上記の電解質
としては、例えば、ＬｉＣｌＯ4 、ＬｉＰＦ6 、ＬｉＢ
Ｆ4、ＬｉＡｓＦ6 、ＬｉＳｂＦ6 、ＬｉＣＦ3 Ｓ
Ｏ3 、ＬｉＣ4 Ｆ9 ＳＯ3 、ＬｉＣＦ3 ＣＯ2 、Ｌｉ2
Ｃ2 Ｆ4 （ＳＯ3 ）2 、ＬｉＮ（Ｒ1 ）（Ｒ2 ）（Ｒ1
＝ＣX Ｆ2X+1ＳＯ2 、Ｒ2 ＝Ｃy Ｆ2yＳＯ2 、ｘ＋ｙ≧
２）、ＬｉＣ（ＣＦ3 ＳＯ 2 ）3 、ＬｉＣn Ｆ2n+1ＳＯ
3 （ｎ≧２）などが単独でまたは２種以上混合して用い
られる。電解液中における電解質の濃度は、特に限定さ
れているものではないが、０．３〜１．７ｍｏｌ／ｌ、
特に０．７〜１．５ｍｏｌ／ｌ程度が好ましい。As an electrolytic solution, an electrolyte is dissolved in an organic solvent.
The used organic solvent-based electrolyte is used. The above electrolyte
As, for example, LiClOFour, LiPF6, LiB
FFour, LiAsF6, LiSbF6, LiCFThreeS
OThree, LiCFourF9SOThree, LiCFThreeCOTwo, LiTwo
CTwoFFour(SOThree)Two, LiN (R1) (RTwo) (R1
= CXF2X + 1SOTwo, RTwo= CyF2ySOTwo, X + y ≧
2), LiC (CFThreeSO Two)Three, LiCnF2n + 1SO
Three(N ≧ 2) used alone or in combination of two or more
Can be The concentration of the electrolyte in the electrolyte is not particularly limited
Although it is not a thing, 0.3-1.7 mol / l,
In particular, about 0.7 to 1.5 mol / l is preferable.
【００１７】また、上記電解液の有機溶媒としては、例
えば、エチレンカーボネート、プロピレンカーボネー
ト、ブチレンカーボネート、γ−ブチロラクトン、σ−
バレロラクトンなどの環状エステル、１，２−ビスメト
キシカルボニルオキシエタン、１，２−ビスエトキシカ
ルボニルオキシエタン、１，２−ビスメトキシカルボニ
ルオキシプロパン、１，２−ビスエトキシカルボニルオ
キシプロパンなどのアルキレンビスカーボネート化合
物、ジメチルカーボネート、ジエチルカーボネート、メ
チルエチルカーボネートなどの鎖状炭酸エステルや、
１，２−ジメトキシエタン、テトラヒドロフラン、２−
メチルテトラヒドロフラン、１，３−ジオキソラン、４
−メチル−１，３−ジオキソランなどのエーテルなどが
挙げられ、これらの中の１種のみを用いてもよいし、ま
た複数種を併用してもよいし、さらには、上記例示のも
の以外のものを用いてもよい。Examples of the organic solvent for the electrolyte include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and σ-
Cyclic esters such as valerolactone; alkylenebis such as 1,2-bismethoxycarbonyloxyethane, 1,2-bisethoxycarbonyloxyethane, 1,2-bismethoxycarbonyloxypropane, and 1,2-bisethoxycarbonyloxypropane Carbonate compounds, dimethyl carbonate, diethyl carbonate, chain carbonates such as methyl ethyl carbonate,
1,2-dimethoxyethane, tetrahydrofuran, 2-
Methyltetrahydrofuran, 1,3-dioxolane, 4
Ethers such as -methyl-1,3-dioxolan, and the like. One of these may be used, or a plurality of them may be used in combination. A thing may be used.
【００１８】セパレータとしては、例えば、微孔性のポ
リエチレンフィルム、微孔性のポリプロピレンフィル
ム、微孔性ポリエチレン−ポリプロピレン複合フィルム
などが好適に用いられるが、それら以外のものを用いて
もよい。As the separator, for example, a microporous polyethylene film, a microporous polypropylene film, a microporous polyethylene-polypropylene composite film and the like are suitably used, but other materials may be used.
【００１９】本発明の請求項２に記載の発明において
は、前記のように、放回充電の充電初期の正極の単位面
積当たりの電流密度を０．３ｍＡ／ｃｍ2 以下にして初
回充電を行うが、そのような０．３ｍＡ／ｃｍ2 以下で
充電する際の充電時間としては、電池容量の１／２０以
上が充電される時間まで行うことが好ましく、その後は
電池容量を５時間で放電するときの電流値（０．２Ｃ）
以下の電流で充電することが好ましい。ただし、初回充
電時の充電初期を超えて上記のような０．３ｍＡ／ｃｍ
2 以下の電流密度で充電してもよい。In the invention according to the second aspect of the present invention, as described above, the initial charge is performed with the current density per unit area of the positive electrode in the initial stage of the discharge charge being 0.3 mA / cm 2 or less. However, the charging time when charging at 0.3 mA / cm 2 or less is preferably performed up to a time at which 1/20 or more of the battery capacity is charged, and then the battery capacity is discharged in 5 hours. Current value at the time (0.2C)
It is preferable to charge with the following current. However, beyond the initial charge at the time of the first charge, 0.3 mA / cm
It may be charged at a current density of 2 or less.
【００２０】上記のような初回充電時の充電初期の正極
の単位面積当たりの電流密度は小さいほど正極の分極を
少なくするという点では適しているが、電流密度が小さ
くなりすぎると、充電時間が長くなり、生産性に問題を
生じる可能性があるので、この電流密度は上記のように
０．３ｍＡ／ｃｍ2 以下であって、０．０１ｍＡ／ｃｍ
2 以上が実用上適している。As described above, the smaller the current density per unit area of the positive electrode in the initial stage of charging at the time of the initial charge is suitable in that the polarization of the positive electrode is reduced, but if the current density is too small, the charging time is reduced. This current density is 0.3 mA / cm 2 or less, as described above, and 0.01 mA / cm 2
Two or more is practically suitable.
【００２１】[0021]
【実施例】つぎに、実施例を挙げて本発明をより具体的
に説明する。ただし、本発明はそれらの実施例のみに限
定されるものではない。Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.
【００２２】実施例１ バインダーであるポリフッ化ビニリデン２０ｇにＮ−メ
チル−２−ピロリドン２５０ｇを加え、６０℃に加熱し
てポリフッ化ビニリデンをＮ−メチル−２−ピロリドン
に溶解させ、バインダー溶液を調製した。このバインダ
ー溶液に正極活物質としてＬｉＮｉ0.7 Ｃｏ0.3 Ｏ2 を
４５０ｇ加え、かつ導電助剤としてカーボンブラック５
ｇとグラファイト２５ｇを加え、攪拌混合して正極合剤
ペーストを調製した。この正極合剤ペーストを集電体と
なる厚さ２０μｍのアルミニウム箔の両面に均一に塗布
し、乾燥して正極合剤層を形成し、ローラープレス機に
より圧縮成形した後、裁断して、平均厚み１５０μｍの
帯状正極を作製した。Example 1 250 g of N-methyl-2-pyrrolidone was added to 20 g of polyvinylidene fluoride as a binder, and the mixture was heated to 60 ° C. to dissolve the polyvinylidene fluoride in N-methyl-2-pyrrolidone to prepare a binder solution. did. LiNi 0 to the binder solution as a positive electrode active material. 7 Co 0. 3 O 2 was added 450 g, and carbon black 5 as a conductive auxiliary agent
g and 25 g of graphite were added and mixed with stirring to prepare a positive electrode mixture paste. This positive electrode mixture paste is uniformly applied to both sides of a 20 μm-thick aluminum foil serving as a current collector, dried to form a positive electrode mixture layer, compression-molded with a roller press, cut, and then cut. A belt-shaped positive electrode having a thickness of 150 μm was produced.
【００２３】また、上記と同様にバインダー溶液を調製
し、そのバインダー溶液に負極活物質として人造黒鉛を
１８０ｇ加え、攪拌混合して負極合剤ペーストを調製
し、その負極合剤ペーストを集電体となる厚さ１０μｍ
の銅箔の両面に均一に塗布し、乾燥して負極合剤層を形
成し、ローラープレス機により圧縮成形した後、裁断
し、平均厚みが１９０μｍで、負極合剤の密度が１．４
５ｇ／ｃｍ3 の帯状負極を作製した。Further, a binder solution is prepared in the same manner as above, 180 g of artificial graphite is added to the binder solution as a negative electrode active material, and the mixture is stirred and mixed to prepare a negative electrode mixture paste. Thickness 10μm
Is uniformly coated on both sides of the copper foil, dried to form a negative electrode mixture layer, compression molded by a roller press machine, and then cut to have an average thickness of 190 μm and a negative electrode mixture density of 1.4.
A band-shaped negative electrode of 5 g / cm 3 was produced.
【００２４】つぎに、上記帯状正極と帯状負極との間に
厚さ２５μｍの微孔性ポリエチレンフィルムからなるセ
パレータを配置し、渦巻状に巻回して渦巻状巻回構造の
電極体とした後、外形１８ｍｍの有底円筒状の電池缶内
に挿入し、正極および負極リード体の溶接を行った。Next, a separator made of a microporous polyethylene film having a thickness of 25 μm is disposed between the strip-shaped positive electrode and the strip-shaped negative electrode, and is spirally wound into an electrode body having a spirally wound structure. The battery was inserted into a cylindrical battery can having an outer shape of 18 mm and having a bottom, and the positive electrode and the negative electrode were welded.
【００２５】その後、電池缶内に１．４ＭＬｉＰＦ6 ／
ＥＣ＋ＭＥＣ（１：２）からなる電解液（すなわち、エ
チレンカーボネートとメチルエチルカーボネートの容積
比１：２の混合溶媒にＬｉＰＦ6 を１．４モル／リット
ル溶解させてなる電解液）を４．０ｃｃ注入した。つい
で、上記電池缶の開口部を常法に従って封口し、図１に
示す構造の筒形リチウムイオン二次電池を作製した。Thereafter, 1.4 M LiPF 6 /
4.0 cc of an electrolyte solution composed of EC + MEC (1: 2) (that is, an electrolyte solution obtained by dissolving 1.4 mol / l of LiPF 6 in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 1: 2) was injected. did. Next, the opening of the battery can was sealed according to a conventional method to produce a cylindrical lithium ion secondary battery having the structure shown in FIG.
【００２６】ここで、図１に示す電池について説明する
と、１は上記の正極で、２は負極である。ただし、図１
では、繁雑化を避けるため、正極１や負極２の作製にあ
たって使用した集電体としての金属箔などは図示してい
ない。そして、これらの正極１と負極２はセパレータ３
を介して渦巻状に巻回され、渦巻状巻回構造の電極体と
して上記の電解液４と共に電池缶５内に収容されてい
る。Here, the battery shown in FIG. 1 will be described. 1 is the above-mentioned positive electrode, and 2 is the negative electrode. However, FIG.
Here, in order to avoid complication, a metal foil or the like as a current collector used in manufacturing the positive electrode 1 and the negative electrode 2 is not illustrated. The positive electrode 1 and the negative electrode 2 are connected to a separator 3
, And is housed in a battery can 5 together with the electrolytic solution 4 as an electrode body having a spirally wound structure.
【００２７】電池缶５はステンレス鋼製で、負極端子を
兼ねており、電池缶５の底部には上記渦巻状巻回構造の
電極体の挿入に先立って、ポリプロピレンからなる絶縁
体６が配置されている。封口板７はアルミニウム製で、
円板状をしていて、中央部に薄肉部７ａを設け、かつ上
記薄肉部７ａの周囲に電池内圧を防爆弁９に作用させる
ための圧力導入口７ｂとしての孔が設けられている。そ
して、この薄肉部７ａの上面に防爆弁９の突出部９ａが
溶接され、溶接部分１１を構成している。なお、上記の
封口板７に設けた薄肉部７ａや防爆弁９の突出部９ａな
どは、図面上での理解がしやすいように、切断面のみを
図示しており、切断面後方の輪郭線は図示を省略してい
る。また、封口板７の薄肉部７ａと防爆弁９の突出部９
ａとの溶接部分１１も、図面上での理解が容易なよう
に、実際よりは誇張した状態に図示している。The battery can 5 is made of stainless steel and also serves as a negative electrode terminal. An insulator 6 made of polypropylene is arranged at the bottom of the battery can 5 before inserting the spirally wound electrode body. ing. The sealing plate 7 is made of aluminum,
It has a disk shape, is provided with a thin portion 7a at the center, and a hole is provided around the thin portion 7a as a pressure introduction port 7b for applying an internal pressure of the battery to the explosion-proof valve 9. The projection 9a of the explosion-proof valve 9 is welded to the upper surface of the thin portion 7a to form a welded portion 11. In addition, the thin portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are illustrated only in a cut plane so as to be easily understood in the drawings, and a contour line behind the cut plane is shown. Is not shown. Further, the thin portion 7a of the sealing plate 7 and the projection 9 of the explosion-proof valve 9 are provided.
The welded portion 11 with "a" is illustrated in an exaggerated state rather than the actual one so that the drawing can be easily understood.
【００２８】端子板８は、圧延鋼製で表面にニッケルメ
ッキが施され、周縁部が鍔状になった帽子状をしてお
り、この端子板８にはガス排出孔８ａが設けられてい
る。防爆弁９は、アルミニウム製で、円板状をしてお
り、その中央部には発電要素側（図１では、下側）に先
端部を有する突出部９ａが設けられ、かつ薄肉部９ｂが
設けられ、上記突出部９ａの下面が、前記したように、
封口板７の薄肉部７ａの上面に溶接され、溶接部分１１
を構成している。絶縁パッキング１０は、ポリプロピレ
ン製で、環状をしており、封口板７の周縁部の上部に配
置され、その上部に防爆弁９が配置していて、封口板７
と防爆弁９とを絶縁するとともに、両者の間から電解液
が漏れないように両者の間隙を封止している。環状ガス
ケット１２はポリプロピレン製で、リード体１３はアル
ミニウム製で、前記封口板７と正極１とを接続し、渦巻
状巻回構造の電極体の上部には絶縁体１４が配置され、
負極２と電池缶５の底部とはニッケル製のリード体１５
で接続されている。The terminal plate 8 is made of rolled steel, has a nickel-plated surface, and has a hat-like shape with a brim-shaped peripheral portion. The terminal plate 8 is provided with a gas discharge hole 8a. . The explosion-proof valve 9 is made of aluminum and has a disk shape. A projection 9a having a tip portion is provided at a center portion of the explosion-proof valve on the power generation element side (the lower side in FIG. 1), and a thin portion 9b is provided. Provided, and the lower surface of the protruding portion 9a is, as described above,
The welding portion 11 is welded to the upper surface of the thin portion 7a of the sealing plate 7.
Is composed. The insulating packing 10 is made of polypropylene and has an annular shape. The insulating packing 10 is disposed above the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is disposed thereon.
And the explosion-proof valve 9 and the gap between the two is sealed so that the electrolyte does not leak from between the two. The annular gasket 12 is made of polypropylene, the lead body 13 is made of aluminum, connects the sealing plate 7 and the positive electrode 1, and an insulator 14 is disposed above the spirally wound electrode body,
The negative electrode 2 and the bottom of the battery can 5 are connected to a lead 15 made of nickel.
Connected by
【００２９】上記のようにして組み立てられた電池にお
いては、封口板７の薄肉部７ａと防爆弁９の突出部９ａ
とが溶接部分１１で接触し、防爆弁９の周縁部と端子板
８の周縁部とが接触し、正極１と封口板７とは正極側の
リード体１３で接続されているので、正極１と端子板８
とはリード体１３、封口板７、防爆弁９およびそれらの
溶接部分１１によって電気的接続が得られ、電路として
正常に機能する。In the battery assembled as described above, the thin portion 7a of the sealing plate 7 and the projection 9a of the explosion-proof valve 9 are provided.
Contact at the welded portion 11, the peripheral portion of the explosion-proof valve 9 and the peripheral portion of the terminal plate 8 come into contact, and the positive electrode 1 and the sealing plate 7 are connected by the lead 13 on the positive electrode side. And terminal plate 8
The electrical connection is obtained by the lead body 13, the sealing plate 7, the explosion-proof valve 9 and the welded portion 11 thereof, and the lead body normally functions as an electric circuit.
【００３０】そして、電池に異常事態が起こり、電池内
部にガスが発生して電池の内圧が上昇した場合には、そ
の内圧上昇により、防爆弁９の中央部が内圧方向（図１
では、上側の方向）に変形し、それに伴って溶接部分１
１で一体化されている薄肉部７ａに剪断力が働いて、該
薄肉部７ａが破断するか、または防爆弁９の突出部９ａ
と封口板７の薄肉部７ａとの溶接部分１１が剥離し、そ
れによって、正極１と端子板８との電気的接続が消失し
て、電流が遮断されるようになる。その結果、電池反応
が進行しなくなるので、過充電時や短絡時でも、充電電
流や短絡電流による電池の温度上昇や内圧上昇がそれ以
上進行しなくなって、電池の発火や破裂を防止できるよ
うに設計されている。When an abnormal situation occurs in the battery and gas is generated inside the battery and the internal pressure of the battery rises, the internal pressure rises and the central part of the explosion-proof valve 9 moves in the direction of the internal pressure (FIG. 1).
Then, it is deformed in the upper direction)
The shearing force acts on the thin portion 7a integrated at 1 and the thin portion 7a is broken or the projection 9a of the explosion-proof valve 9 is formed.
And the thin portion 7a of the sealing plate 7 is peeled off, whereby the electrical connection between the positive electrode 1 and the terminal plate 8 is lost and the current is cut off. As a result, the battery reaction does not proceed, so that even during overcharge or short circuit, the battery temperature rise and internal pressure rise due to the charging current and short circuit current do not progress further, so that ignition and rupture of the battery can be prevented. Designed.
【００３１】なお、上記防爆弁９には薄肉部９ｂが設け
られており、例えば、充電が極度に進行にして電解液や
活物質などの発電要素が分解し、大量のガスが発生した
場合は、防爆弁９が変形して、防爆弁９の突出部９ａと
封口板７の薄肉部７ａとの溶接部分１１が剥離した後、
この防爆弁９に設けた薄肉部９ｂが開裂してガスを端子
板８のガス排出孔８ａから電池外部に排出させて電池の
破裂を防止することができるように設計されている。The explosion-proof valve 9 is provided with a thin portion 9b. For example, when charging proceeds extremely and power generation elements such as an electrolyte and an active material are decomposed and a large amount of gas is generated. After the explosion-proof valve 9 is deformed and the welding portion 11 between the projection 9a of the explosion-proof valve 9 and the thin portion 7a of the sealing plate 7 is peeled off,
The thin portion 9b provided on the explosion-proof valve 9 is designed to be opened so that gas is discharged from the gas discharge holes 8a of the terminal plate 8 to the outside of the battery to prevent the battery from being ruptured.
【００３２】上記のように作製したリチウムイオン二次
電池を、２０℃で正極の単位面積当たり０．２ｍＡ／ｃ
ｍ2 の電流密度で１．５時間充電し、その後、０．２
Ｃ、４．１Ｖの定電流定電圧方式で１０時間充電を行
い、充電後、１Ｃで２．７５Ｖまで放電した。The lithium ion secondary battery prepared as described above was subjected to a heating at 20 ° C. of 0.2 mA / c per unit area of the positive electrode.
Charge for 1.5 hours at a current density of m 2 , then 0.2
C. The battery was charged for 10 hours using a constant current and constant voltage method of 4.1 V, and after charging, the battery was discharged to 2.75 V at 1 C.
【００３３】実施例２ 負極合剤の密度を１．５３ｇ／ｃｍ3 にして負極を作製
した以外は、実施例１と同様に電池を作製した後、２０
℃で正極の単位面積当たり０．３ｍＡ／ｃｍ2の電流密
度で１時間充電し、その後、０．５Ｃ、４．１Ｖの定電
流定点圧方式で５時間充電を行い、充電後、１Ｃで２．
７５Ｖまで放電した。Example 2 A battery was prepared in the same manner as in Example 1 except that the density of the negative electrode mixture was 1.53 g / cm 3 to prepare a negative electrode.
At 1 ° C. for 1 hour at a current density of 0.3 mA / cm 2 per unit area of the positive electrode, and then for 5 hours at a constant current and constant point pressure of 0.5 C and 4.1 V. .
Discharged to 75V.
【００３４】実施例３ 実施例１と同様に電池を作製した後、２０℃で正極の単
位面積当たり０．５ｍＡ／ｃｍ2 の電流密度で１時間充
電し、その後、０．２Ｃ、４．１Ｖの定電流定点圧方式
で８時間充電を行い、充電後、１Ｃで２．７５Ｖまで放
電した。Example 3 After a battery was prepared in the same manner as in Example 1, the battery was charged at 20 ° C. for 1 hour at a current density of 0.5 mA / cm 2 per unit area of the positive electrode, and then charged at 0.2 C and 4.1 V. The battery was charged for 8 hours using the constant current and constant point pressure method described above, and then discharged to 2.75 V at 1 C.
【００３５】実施例４ 負極合剤の密度を１．６０ｇ／ｃｍ3 にして負極を作製
した以外は、実施例１と同様に電池を作製した後、２０
℃で正極の単位面積当たり０．３ｍＡ／ｃｍ2の電流密
度で１．５時間充電し（充電量は電池容量の約１／
９）、その後、０．２Ｃ、４．１Ｖの定電流定電圧方式
で１０時間充電を行い、１Ｃで２．７５Ｖまで放電し
た。Example 4 A battery was prepared in the same manner as in Example 1 except that the density of the negative electrode mixture was 1.60 g / cm 3 , and then a battery was prepared.
At 1.5 ° C. at a current density of 0.3 mA / cm 2 per unit area of the positive electrode (charged amount is about 1 /
9) Then, the battery was charged for 10 hours using a constant current and constant voltage method of 0.2 C and 4.1 V, and then discharged at 1. C to 2.75 V.
【００３６】比較例１ 負極合剤の密度を１．６０ｇ／ｃｍ3 にして負極を作製
した以外は、実施例１と同様に電池を作製した後、２０
℃で正極の単位面積当たり０．５ｍＡ／ｃｍ2の電流密
度で１時間充電し、その後、０．２Ｃ、４．１Ｖの定電
流定電圧方式で８時間充電を行い、充電後、１Ｃで２．
７５Ｖまで放電した。Comparative Example 1 A battery was prepared in the same manner as in Example 1 except that the density of the negative electrode mixture was 1.60 g / cm 3 to prepare a negative electrode.
At 1 ° C. for 1 hour at a current density of 0.5 mA / cm 2 per unit area of the positive electrode, and then for 8 hours at a constant current and constant voltage of 0.2 C and 4.1 V. .
Discharged to 75V.
【００３７】比較例２ 負極合剤密度を１．６０ｇ／ｃｍ3 にして負極を作製し
た以外は、実施例１と同様に電池を作製した後、２０℃
で正極の単位面積当たり１．０ｍＡ／ｃｍ2 の電流密度
で１時間充電し、その後、０．２Ｃ、４．１Ｖの定電流
定電圧方式で８時間充電を行い、充電後、１Ｃで２．７
５Ｖまで放電した。COMPARATIVE EXAMPLE 2 A battery was prepared in the same manner as in Example 1 except that the negative electrode mixture density was 1.60 g / cm 3 , and then a battery was prepared at 20 ° C.
The battery was charged at a current density of 1.0 mA / cm 2 per unit area of the positive electrode for 1 hour, and then charged at a constant current and constant voltage of 0.2 C and 4.1 V for 8 hours. 7
Discharged to 5V.
【００３８】上記実施例１〜４および比較例１〜２のリ
チウムイオン二次電池について、下記の条件で、負極の
表面への金属リチウムの析出、サイクル特性および電池
の安全性確認試験を行った。この安全性確認試験は、通
常の製品では遭遇しないような苛酷な条件下で破壊試
験、つまり、通常の製品では行わないような安全性に欠
ける状態に電池を作製し、かつ強制的に短絡を発生させ
る破壊試験を試験的に行って短絡させた場合の安全性を
評価するものであり、これらの評価方法や試験方法は下
記の通りである。The lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to tests for confirming the deposition of metallic lithium on the surface of the negative electrode, cycle characteristics and battery safety under the following conditions. . This safety confirmation test is a destructive test under severe conditions that are not encountered with ordinary products, that is, a battery is manufactured in a state of lack of safety that is not performed with ordinary products, and a short circuit is forcibly performed. The destructive test to be performed is performed as a test to evaluate the safety in the case of short-circuit, and the evaluation method and test method are as follows.
【００３９】〈負極の表面へのリチウム析出〉上記実施
例１〜４および比較例１〜２のリチウムイオン二次電池
を２０℃で４．２Ｖまで充電した後、電池を分解し、負
極の表面への金属リチウムの析出を目視により観察す
る。<Lithium Deposition on the Surface of the Negative Electrode> The lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were charged to 4.2 V at 20 ° C. The precipitation of metallic lithium on the surface is visually observed.
【００４０】〈サイクル特性〉上記実施例１〜４および
比較例１〜２のリチウムイオン二次電池を２０℃で４．
２Ｖ〜２．７５Ｖの範囲で充放電させ、その５００サイ
クル目の放電容量の１サイクル目の放電容量に対する比
〔（５００サイクル目の放電容量）／（１サイクル目の
放電容量）×１００％〕を５００サイクル時の容量保持
率（％）としてサイクル特性を評価する。<Cycle Characteristics> The lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were used at 20 ° C.
Charge / discharge in the range of 2 V to 2.75 V, and the ratio of the discharge capacity at the 500th cycle to the discharge capacity at the first cycle [(discharge capacity at the 500th cycle) / (discharge capacity at the first cycle) × 100%] Is evaluated as the capacity retention rate (%) at the time of 500 cycles to evaluate the cycle characteristics.
【００４１】〈安全性確認試験〉上記実施例１〜４およ
び比較例１〜２のリチウムイオン二次電池を、異常事態
発生時の電流遮断機構などの安全機構を持たない状態に
作製し、強制的な釘刺し試験を行って安全性を確認す
る。すなわち、通常の製品では電池に異常事態が発生し
た場合には、図１に示すような電流を遮断して電池の発
火や破裂を防止する安全機構が設けられているが、この
安全機構を設けることなく電池をそれぞれ５０個ずつ作
製し、それらの電池を２０℃で４．２Ｖまで充電した
後、電池の側面から横方向に１／２の深さまで直径３ｍ
ｍの釘を１２０ｍｍ／ｓｅｃの速度で突き刺し、強制的
に短絡を発生させて、発煙および発火の有無を観察す
る。<Safety Confirmation Test> The lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were manufactured without a safety mechanism such as a current cutoff mechanism in the event of an abnormal situation, and forced to operate. Confirm safety by conducting a typical nail penetration test. That is, a normal product is provided with a safety mechanism for interrupting the current as shown in FIG. 1 to prevent the battery from being ignited or exploded when an abnormal situation occurs in the battery. Each of the batteries was prepared without charge and charged to 4.2 V at 20 ° C., and then 3 m in diameter from the side of the battery to a depth of １ ／ in the lateral direction.
A nail of m is pierced at a speed of 120 mm / sec, a short circuit is forcibly generated, and the occurrence of smoke and ignition is observed.
【００４２】上記実施例１〜４および比較例１〜２のリ
チウムイオン二次電池について、上記特性を測定した結
果を表１に示す。Table 1 shows the results of measuring the above characteristics of the lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 and 2.
【００４３】[0043]
【表１】 [Table 1]
【００４４】表１に示す結果から明らかなように、実施
例１〜４は、サイクル特性が優れ、かつ安全性が優れて
いた。すなわち、実施例１〜３の電池では負極合剤の密
度を１．５５ｇ／ｃｍ3 以下にし、実施例４の電池では
初回充電を充電初期の正極の単位面積当たりの電流密度
を０．３ｍＡ／ｃｍ2 以下で行ったことにより、サイク
ル特性が優れ、かつ苛酷な条件下での安全性確認試験で
も発火が生じることなく、安全性が優れていた。As is clear from the results shown in Table 1, Examples 1 to 4 were excellent in cycle characteristics and excellent in safety. That is, in the batteries of Examples 1 to 3, the density of the negative electrode mixture was 1.55 g / cm 3 or less, and in the battery of Example 4, the initial charge was 0.3 mA / current density per unit area of the positive electrode in the initial stage of charge. When the test was carried out at a density of not more than 2 cm 2 , the cycle characteristics were excellent, and safety was excellent without ignition even in a safety confirmation test under severe conditions.
【００４５】これに対して、比較例１では、負極合剤の
密度が１．６０ｇ／ｃｍ3 と高く、また充電時の電流密
度も０．５ｍＡ／ｃｍ2 と高かったため、サイクル特性
が低下し、かつ発煙確率が増加し、比較例２では、充電
時の電流密度が１．０ｍＡ／ｃｍ2 とさらに高くなった
ため、サイクル特性の低下がさらに大きくなるととも
に、発火の生じるものがあり、安全性に欠けていた。な
お、実施例３は、比較例１と同様に０．５ｍＡ／ｃｍ2
の電流密度で充電を行っているが、それにもかかわら
ず、サイクル特性が優れ、かつ安全性が優れていた。ま
た、実施例４も、比較例２と同様に負極合剤の密度を
１．６０ｇ／ｃｍ3 にしているにもかかわらず、サイク
ル特性が優れ、かつ安全性が優れていた。On the other hand, in Comparative Example 1, the density of the negative electrode mixture was as high as 1.60 g / cm 3, and the current density during charging was as high as 0.5 mA / cm 2. In addition, in Comparative Example 2, the current density at the time of charging was further increased to 1.0 mA / cm 2 , so that the deterioration of the cycle characteristics was further increased, and there was a case where ignition occurred, resulting in safety. Was lacking. In addition, Example 3 was 0.5 mA / cm 2 similarly to Comparative Example 1.
Although the battery was charged at a current density of not more than 1, the cycle characteristics were excellent and the safety was excellent. Also in Example 4, the cycle characteristics were excellent and the safety was excellent even though the density of the negative electrode mixture was 1.60 g / cm 3 as in Comparative Example 2.
【００４６】[0046]
【発明の効果】以上説明したように、本発明では、負極
活物質に炭素系材料を含み、容量密度が４００Ｗｈ／ｌ
以上の高容量のリチウムイオン二次電池において、サイ
クル特性が優れ、かつ安全性が優れたリチウムイオン二
次電池を提供することができた。As described above, according to the present invention, the negative electrode active material contains a carbon-based material and has a capacity density of 400 Wh / l.
In the high-capacity lithium ion secondary battery described above, a lithium ion secondary battery having excellent cycle characteristics and excellent safety could be provided.
【図１】本発明のリチウムイオン二次電池の一例を模式
的に示す断面図である。FIG. 1 is a cross-sectional view schematically showing one example of a lithium ion secondary battery of the present invention.
１ 正極 ２ 負極 ３ セパレータ ４ 電解液 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Electrolyte
Claims (2)
度が４００Ｗｈ／ｌ以上のリチウムイオン二次電池にお
いて、負極合剤の密度を１．５５ｇ／ｃｍ3以下にした
ことを特徴とするリチウムイオン二次電池。1. A lithium ion secondary battery containing a carbon-based material as a negative electrode active material and having a capacity density of 400 Wh / l or more, wherein the density of the negative electrode mixture is 1.55 g / cm 3 or less. Lithium ion secondary battery.
度が４００Ｗｈ／ｌ以上のリチウムイオン二次電池の初
回充電に当たり、充電初期の正極の単位面積当たりの電
流密度を０．３ｍＡ／ｃｍ2 以下にして初回充電するこ
とを特徴とするリチウムイオン二次電池の初回充電方
法。2. The current density per unit area of the positive electrode in the initial stage of charging is 0.3 mA / cm 2 at the time of initial charging of a lithium ion secondary battery containing a carbon-based material in the negative electrode active material and having a capacity density of 400 Wh / l or more. An initial charging method for a lithium ion secondary battery, wherein the initial charging is performed by setting the battery to 2 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10102437A JPH11297310A (en) | 1998-04-14 | 1998-04-14 | Lithium ion secondary battery, and first time charging method therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10102437A JPH11297310A (en) | 1998-04-14 | 1998-04-14 | Lithium ion secondary battery, and first time charging method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11297310A true JPH11297310A (en) | 1999-10-29 |
Family
ID=14327452
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10102437A Withdrawn JPH11297310A (en) | 1998-04-14 | 1998-04-14 | Lithium ion secondary battery, and first time charging method therefor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11297310A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002013294A1 (en) * | 2000-08-04 | 2002-02-14 | Matsushita Electric Industrial Co., Ltd. | Negative electrode for nonaqueous-electrolyte secondary battery and battery employing the same |
| KR100782868B1 (en) * | 2000-05-16 | 2007-12-06 | 소니 가부시끼 가이샤 | Charging method for charging nonaqueous electrolyte secondary battery |
| WO2021172175A1 (en) * | 2020-02-28 | 2021-09-02 | パナソニックＩｐマネジメント株式会社 | Charge and discharge method for nonaqueous electrolyte secondary battery, and charge and discharge system for nonaqueous electrolyte secondary battery |
-
1998
- 1998-04-14 JP JP10102437A patent/JPH11297310A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100782868B1 (en) * | 2000-05-16 | 2007-12-06 | 소니 가부시끼 가이샤 | Charging method for charging nonaqueous electrolyte secondary battery |
| WO2002013294A1 (en) * | 2000-08-04 | 2002-02-14 | Matsushita Electric Industrial Co., Ltd. | Negative electrode for nonaqueous-electrolyte secondary battery and battery employing the same |
| US6846593B2 (en) | 2000-08-04 | 2005-01-25 | Matsushita Electric Industrial Co., Ltd. | Negative electrode for non-aqueous electrolyte secondary battery and battery employing the same |
| WO2021172175A1 (en) * | 2020-02-28 | 2021-09-02 | パナソニックＩｐマネジメント株式会社 | Charge and discharge method for nonaqueous electrolyte secondary battery, and charge and discharge system for nonaqueous electrolyte secondary battery |
| EP4113665A4 (en) * | 2020-02-28 | 2023-09-20 | Panasonic Intellectual Property Management Co., Ltd. | Charge and discharge method for nonaqueous electrolyte secondary battery, and charge and discharge system for nonaqueous electrolyte secondary battery |
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