JPH0963645A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JPH0963645A JPH0963645A JP7218787A JP21878795A JPH0963645A JP H0963645 A JPH0963645 A JP H0963645A JP 7218787 A JP7218787 A JP 7218787A JP 21878795 A JP21878795 A JP 21878795A JP H0963645 A JPH0963645 A JP H0963645A
- Authority
- JP
- Japan
- Prior art keywords
- solvent
- carbonate
- secondary battery
- lithium secondary
- volume ratio
- 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.)
- Pending
Links
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims description 19
- 229910052744 lithium Inorganic materials 0.000 title claims description 19
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 39
- 239000002904 solvent Substances 0.000 claims description 33
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 19
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 12
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 10
- 229910003002 lithium salt Inorganic materials 0.000 claims description 7
- 159000000002 lithium salts Chemical class 0.000 claims description 7
- 239000003792 electrolyte Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000007773 negative electrode material Substances 0.000 claims description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 4
- 239000003575 carbonaceous material Substances 0.000 claims description 4
- 229910001416 lithium ion Inorganic materials 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 239000007774 positive electrode material Substances 0.000 claims description 4
- 239000011255 nonaqueous electrolyte Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims 1
- 239000008151 electrolyte solution Substances 0.000 description 11
- 125000004432 carbon atom Chemical group C* 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 150000002148 esters Chemical class 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910013870 LiPF 6 Inorganic materials 0.000 description 3
- -1 ester carbonate Chemical class 0.000 description 3
- 239000012046 mixed solvent Substances 0.000 description 3
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 3
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 description 2
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 150000004651 carbonic acid esters Chemical class 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910020366 ClO 4 Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910012424 LiSO 3 Inorganic materials 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002482 conductive additive Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- CXHHBNMLPJOKQD-UHFFFAOYSA-M methyl carbonate Chemical compound COC([O-])=O CXHHBNMLPJOKQD-UHFFFAOYSA-M 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000007787 solid Substances 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
Landscapes
- Secondary Cells (AREA)
Abstract
(57)【要約】
【課題】 電解質の溶媒のイオン導電率が低く、リチウ
ム二次電池の高率放電特性を十分に高められない。
【解決手段】 電解質の溶媒として、炭酸エチレンと炭
酸ジメチルと酢酸エチルと炭酸ジエチルとの混合物を用
いる。そして、炭酸エチレンの溶媒に対する体積割合を
２０〜６０％とし、炭酸ジメチルの溶媒に対する体積割
合を２０〜６５％とし、酢酸エチルと炭酸ジエチルを併
せた混合液の溶媒に対する体積割合を１０〜３０％とす
る。(57) Abstract: The ionic conductivity of the solvent of the electrolyte is low, and the high rate discharge characteristics of the lithium secondary battery cannot be sufficiently enhanced. SOLUTION: A mixture of ethylene carbonate, dimethyl carbonate, ethyl acetate and diethyl carbonate is used as a solvent of the electrolyte. The volume ratio of ethylene carbonate to the solvent is 20 to 60%, the volume ratio of dimethyl carbonate to the solvent is 20 to 65%, and the volume ratio of the mixed solution of ethyl acetate and diethyl carbonate to the solvent is 10 to 30%. And
Description
【０００１】[0001]
【発明の属する技術分野】本発明はリチウム二次電池に
関するものである。TECHNICAL FIELD The present invention relates to a lithium secondary battery.
【０００２】[0002]
【従来の技術】リチウムイオンの吸蔵、放出が可能な炭
素材料を用いて負極材層を形成したリチウム二次電池
は、リチウムを用いて負極材層を形成したリチウム二次
電池に比べてデントライトの析出を抑制することができ
る。そのため、電池の短絡を防止して安全性を高められ
るという利点を有している。この種の電池としてリチウ
ム塩を溶媒に溶解させた非水電解液をセパレータに含浸
させたものを電解質層として用いたものがある。溶媒と
しては充放電効率、耐酸性に優れた環状炭酸エチレンの
一種である炭酸エチレン（ＥＣ）、炭酸プロピレン（Ｐ
Ｃ）等が注目されている。またリチウム塩としてはＬｉ
ＣｌＯ4 、ＬｉＢＦ4 、ＬｉＰＦ6 、ＬｉＳＯ3 ＣＦ3
等が用いられている。炭酸エチレンは誘電率が高くイオ
ン溶解度も大きいため、溶媒として炭酸エチレンを用い
るとイオン導電率の高い電解液を得られる。しかしなが
ら、炭酸エチレンは融点が３６．４℃と高く、常温では
固体であり、また粘性が高いので、炭酸エチレンを溶媒
として用いる場合には、炭酸ジメチル（ＤＭＣ）、炭酸
ジエチル（ＤＥＣ）、炭酸メチルエチル（ＭＥＣ）等の
鎖状の炭酸エステルを炭酸エチレンと混合して用いる。
このようにするとリチウム二次電池の使用温度範囲（−
２０℃〜６０℃）で炭酸エチレンを用いた溶媒を液体と
することができる。またこれらの混合溶媒に炭素数の多
いエステル［ＲＣＯＯＲ´（Ｒは炭素数３以上のアルキ
ル基、Ｒ´は炭素数１または２のアルキル基）］を更に
混合して、イオン導電率及び充放電効率を高めることが
提案されている。2. Description of the Related Art A lithium secondary battery in which a negative electrode material layer is formed using a carbon material capable of inserting and extracting lithium ions is a dendrite compared to a lithium secondary battery in which a negative electrode material layer is formed using lithium. Can be suppressed. Therefore, there is an advantage that the short circuit of the battery can be prevented and the safety can be improved. As a battery of this type, there is a battery in which a separator is impregnated with a non-aqueous electrolytic solution in which a lithium salt is dissolved in a solvent and which is used as an electrolyte layer. As the solvent, ethylene carbonate (EC), which is a kind of cyclic ethylene carbonate excellent in charge / discharge efficiency and acid resistance, and propylene carbonate (P
C) etc. are receiving attention. Also, as the lithium salt, Li
ClO 4 , LiBF 4 , LiPF 6 , LiSO 3 CF 3
Etc. are used. Since ethylene carbonate has a high dielectric constant and a high ionic solubility, an electrolytic solution having a high ionic conductivity can be obtained by using ethylene carbonate as a solvent. However, since ethylene carbonate has a high melting point of 36.4 ° C., is solid at room temperature, and has a high viscosity, when ethylene carbonate is used as a solvent, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl carbonate is used. A chain ester carbonate such as ethyl (MEC) is used as a mixture with ethylene carbonate.
In this way, the operating temperature range of the lithium secondary battery (-
The solvent using ethylene carbonate can be made liquid at 20 ° C. to 60 ° C.). Further, an ester having a large number of carbon atoms [RCOOR '(R is an alkyl group having 3 or more carbon atoms, R'is an alkyl group having 1 or 2 carbon atoms)] is further mixed with these mixed solvents to obtain ionic conductivity and charge / discharge. It has been proposed to increase efficiency.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、上記Ｒ
ＣＯＯＲ´の有機溶媒のＲの炭素数が大きくなると電解
液の誘電率が低下して、電解液の粘性率が増加する。そ
のため、炭素数の多いエステルを環状炭酸エステルと鎖
状炭酸エステルとの混合溶媒に加えると、鎖状炭酸エス
テルの有する低粘性が損なわれるため、溶媒のイオン導
電率が十分に向上しないという問題があった。また、炭
酸プロピレン（ＰＣ）及びγ−ブチロラクトン（γ−Ｂ
Ｌ）等を主成分とする混合溶媒においても同様の問題が
生じる。However, the above R
When the carbon number of R in the organic solvent of COOR 'becomes large, the dielectric constant of the electrolytic solution decreases and the viscosity of the electrolytic solution increases. Therefore, when an ester having a large number of carbon atoms is added to a mixed solvent of a cyclic carbonic acid ester and a chain carbonic acid ester, the low viscosity of the chain carbonic acid ester is impaired, so that the ionic conductivity of the solvent is not sufficiently improved. there were. In addition, propylene carbonate (PC) and γ-butyrolactone (γ-B
Similar problems occur in a mixed solvent containing L) or the like as a main component.
【０００４】本発明の目的は、電解質の溶媒のイオン導
電率が高く、高率放電特性の高いリチウム二次電池を提
供することにある。An object of the present invention is to provide a lithium secondary battery in which the ionic conductivity of the solvent of the electrolyte is high and the high rate discharge characteristics are high.
【０００５】[0005]
【課題を解決するための手段】本発明は、リチウムイオ
ンの吸蔵、放出が可能な炭素材料からなる負極材層とリ
チウム含有酸化物からなる正極材層とが非水電解液を含
有する電解質層を介して積層され、非水電解液がリチウ
ム塩が溶媒に溶解されたものからなるリチウム二次電池
を対象にする。The present invention is directed to an electrolyte layer in which a negative electrode material layer made of a carbon material capable of inserting and extracting lithium ions and a positive electrode material layer made of a lithium-containing oxide contain a non-aqueous electrolytic solution. It is intended for a lithium secondary battery in which a non-aqueous electrolyte is laminated via a lithium salt and a lithium salt is dissolved in a solvent.
【０００６】本発明では、溶媒として、炭酸エチレンと
炭酸ジメチルと酢酸エチルと炭酸ジエチルの混合物を用
い、炭酸エチレンの溶媒に対する体積割合を２０〜６０
％とし、炭酸ジメチルの溶媒に対する体積割合を２０〜
６５％とし、酢酸エチルと炭酸ジエチルとを併せた混合
液の溶媒に対する体積割合を１０〜３０％とする。In the present invention, a mixture of ethylene carbonate, dimethyl carbonate, ethyl acetate and diethyl carbonate is used as a solvent, and the volume ratio of ethylene carbonate to the solvent is 20 to 60.
%, And the volume ratio of dimethyl carbonate to the solvent is 20 to
The volume ratio of the mixed solution of ethyl acetate and diethyl carbonate to the solvent is 10 to 30%.
【０００７】[0007]
【発明の実施の形態】図１は、試験に用いた実施例及び
比較例の円筒形リチウム二次電池の断面図である。本図
に示すように各電池は、負極１と正極２とがセパレータ
３を介して積層させるように巻回された極板群４が電池
ケース５内に収納されて構成されている。各電池は次の
ようにして作った。まず、日本黒鉛株式会社でＪＳＰの
製品名で製造された人造黒鉛粉末と、ポリフッ化ビニリ
デンからなるバインダとを重量比９０：１０で秤量した
ものに、Ｎ−メチルピロリドン（ＮＭＰ）を加えて湿式
混合した。これを銅箔からなる負極集電体に両面塗布
し、１２０℃で３０分乾燥して負極１を作った。次に、
ＬｉＣｏＯ2 からなる正極活物質と黒鉛粉末からなる導
電助剤とポリフッ化ビニリデンからなるバインダとを重
量比８５：１０：５で秤量したものに、Ｎ−メチルピロ
リドン（ＮＭＰ）を加えて湿式混合した。これをアルミ
箔からなる正極集電体に両面塗布し、１２０℃で３０分
乾燥して正極２を作った。1 is a cross-sectional view of cylindrical lithium secondary batteries of Examples and Comparative Examples used in a test. As shown in the figure, each battery is configured such that an electrode plate group 4 in which a negative electrode 1 and a positive electrode 2 are wound so as to be laminated via a separator 3 is housed in a battery case 5. Each battery was made as follows. First, an artificial graphite powder manufactured by Nippon Graphite Co., Ltd. under the product name of JSP and a binder made of polyvinylidene fluoride were weighed at a weight ratio of 90:10, and N-methylpyrrolidone (NMP) was added to the wet mixture. Mixed. This was applied on both surfaces of a negative electrode current collector made of copper foil and dried at 120 ° C. for 30 minutes to prepare negative electrode 1. next,
N-methylpyrrolidone (NMP) was added to a mixture of a positive electrode active material made of LiCoO 2, a conductive additive made of graphite powder and a binder made of polyvinylidene fluoride at a weight ratio of 85: 10: 5, and wet-mixed. . Both sides were applied to a positive electrode current collector made of aluminum foil and dried at 120 ° C. for 30 minutes to prepare a positive electrode 2.
【０００８】次に負極１と正極２とを２００℃で４時間
真空乾燥した。そして、ドライ雰囲気中で正極２、セパ
レータ３、負極１、セパレータ３…の順で、負極板１と
正極２とがセパレータ３を介して積層させるように巻回
して極板群４を作った。なおセパレータ３としては、ポ
リプロピレン製の微孔性フィルムを用いた。次に極板群
４を電池ケース５内に収納してから、正極２を電池ケー
ス５の蓋部に形成された正極端子６に超音波溶接により
接続し、負極１を電池ケース５に超音波溶接により接続
した。次に炭酸エチレン（ＥＣ）と炭酸ジメチル（ＤＭ
Ｃ）と酢酸エチル（ＥＡ）と炭酸ジエチル（ＤＥＣ）と
が下記表１に示される体積割合になるようにそれぞれア
ルゴン雰囲気中で混合して溶媒を作り、これらの溶媒中
に１ＭのＬｉＰＦ6 からなるリチウム塩をそれぞれ溶解
して電解液を作った。次に、各電解液をセパレータ３に
３mlを含浸させて、公称容量４００mAh のリチウム二次
電池をそれぞれ完成した。表１には各電池を１Ａで終止
電圧３Ｖまで高率放電したときの容量も併せて示した。Next, the negative electrode 1 and the positive electrode 2 were vacuum dried at 200 ° C. for 4 hours. Then, in a dry atmosphere, the positive electrode 2, the separator 3, the negative electrode 1, the separator 3, ... Are wound in this order so that the negative electrode plate 1 and the positive electrode 2 are laminated with the separator 3 interposed therebetween to form an electrode plate group 4. A microporous film made of polypropylene was used as the separator 3. Next, after the electrode plate group 4 is housed in the battery case 5, the positive electrode 2 is connected to the positive electrode terminal 6 formed on the lid of the battery case 5 by ultrasonic welding, and the negative electrode 1 is ultrasonically connected to the battery case 5. Connected by welding. Next, ethylene carbonate (EC) and dimethyl carbonate (DM
C), ethyl acetate (EA), and diethyl carbonate (DEC) were mixed in an argon atmosphere so as to have the volume ratios shown in Table 1 below to make a solvent, and 1 M LiPF 6 was added to these solvents. Each of the following lithium salts was dissolved to form an electrolytic solution. Next, 3 ml of each electrolytic solution was impregnated into the separator 3 to complete a lithium secondary battery having a nominal capacity of 400 mAh. Table 1 also shows the capacity when each battery was discharged at a high rate up to a final voltage of 3 V at 1 A.
【０００９】[0009]
【表１】 本表より、本実施例の各電池は、比較例の各電池に比べ
て高い容量を得られるのが分る。[Table 1] From this table, it can be seen that each battery of this example can obtain a higher capacity than each battery of the comparative example.
【００１０】次に実施例１及び比較例３の電池を制限電
流１００mAで４．１５Ｖの定電圧充電を５時間行った後
に、１Ａの電流で終止電圧３Ｖまで高率放電を行った。
図２はその測定結果を示している。本図より、実施例１
の電池は、比較例３の電池に比べて作動電圧が高く、エ
ネルギー密度が高いのが分る。表１及び図２において、
本実施例の電池の性能が向上している理由は、電解液の
イオン導電率が高くなり、過電圧が低下したためであ
る。これらの試験を繰り返して行って得られた溶媒の良
好な混合割合の範囲を図３に示す。本図より炭酸エチレ
ンの溶媒に対する体積割合を２０〜６０％とし、炭酸ジ
メチルの溶媒に対する体積割合を２０〜６５％とし、酢
酸エチルと炭酸ジエチルとを併せた混合液の溶媒に対す
る体積割合を１０〜３０％とすれば良いのが分る。な
お、酢酸エチルの溶媒に対する体積割合の下限は、電解
液が−２０℃で凝固しない添加量とした。Next, the batteries of Example 1 and Comparative Example 3 were charged at a constant voltage of 100 mA at a constant voltage of 4.15 V for 5 hours, and then discharged at a high rate to a final voltage of 3 V at a current of 1 A.
FIG. 2 shows the measurement results. From this figure, Example 1
It can be seen that the battery No. 2 has a higher operating voltage and a higher energy density than the battery of Comparative Example 3. In Table 1 and FIG.
The reason why the performance of the battery of this example is improved is that the ionic conductivity of the electrolytic solution is increased and the overvoltage is decreased. The range of the good mixing ratio of the solvent obtained by repeating these tests is shown in FIG. From this figure, the volume ratio of ethylene carbonate to the solvent is set to 20 to 60%, the volume ratio of dimethyl carbonate to the solvent is set to 20 to 65%, and the volume ratio of the mixed solution of ethyl acetate and diethyl carbonate to the solvent is set to 10 to 10. You can see that it should be 30%. The lower limit of the volume ratio of ethyl acetate to the solvent was the addition amount at which the electrolytic solution did not solidify at -20 ° C.
【００１１】以下、明細書に記載した発明についてその
構成を示す。The structure of the invention described in the specification will be shown below.
【００１２】（１） リチウムイオンの吸蔵、放出が可
能な炭素材料からなる負極材層とＬｉＣｏＯ2 からなる
正極材層とが非水電解液を含有する電解質層を介して積
層され、前記非水電解液は、ＬｉＰＦ6 からなるリチウ
ム塩が溶媒に溶解されてなるリチウム二次電池におい
て、前記溶媒として、炭酸エチレンと炭酸ジメチルと酢
酸エチルと炭酸ジエチルとの混合物を用い、前記炭酸エ
チレンの前記溶媒に対する体積割合が２０〜６０％であ
り、前記炭酸ジメチルの前記溶媒に対する体積割合が２
０〜６５％であり、前記酢酸エチルと前記炭酸ジエチル
とを併せた混合液の前記溶媒に対する体積割合が１０〜
３０％であることを特徴とするリチウム二次電池。(1) A negative electrode material layer made of a carbon material capable of occluding and releasing lithium ions and a positive electrode material layer made of LiCoO 2 are laminated with an electrolyte layer containing a nonaqueous electrolytic solution interposed therebetween, The electrolytic solution is a lithium secondary battery in which a lithium salt made of LiPF 6 is dissolved in a solvent, and a mixture of ethylene carbonate, dimethyl carbonate, ethyl acetate and diethyl carbonate is used as the solvent, and the solvent of the ethylene carbonate is used. Is 20 to 60%, and the volume ratio of the dimethyl carbonate to the solvent is 2%.
0 to 65%, and the volume ratio of the mixed solution of the ethyl acetate and the diethyl carbonate to the solvent is 10 to
A lithium secondary battery characterized by being 30%.
【００１３】[0013]
【発明の効果】酢酸エチルは、低粘性を有している上に
凝固点が低いので、炭素数の多いエステルの代りに酢酸
エチル（炭素数の少ないエステル）を溶媒に加えると、
溶媒のイオン導電率が向上する。特に低温におけるイオ
ン導電率が向上する。そこで、本発明の体積割合で、炭
酸エチレンと炭酸ジメチルと酢酸エチルと炭酸ジエチル
とを混合した溶媒を用いると、リチウム二次電池の高率
放電特性が向上する。特に低温における高率放電特性が
向上する。EFFECT OF THE INVENTION Since ethyl acetate has a low viscosity and a low freezing point, if ethyl acetate (ester with a small number of carbon atoms) is added to the solvent instead of ester with a large number of carbon atoms,
The ionic conductivity of the solvent is improved. In particular, the ionic conductivity is improved at low temperatures. Therefore, when a solvent obtained by mixing ethylene carbonate, dimethyl carbonate, ethyl acetate and diethyl carbonate in the volume ratio of the present invention is used, the high rate discharge characteristics of the lithium secondary battery are improved. In particular, the high rate discharge characteristics at low temperatures are improved.
【図１】 試験に用いたリチウム二次電池の断面図であ
る。FIG. 1 is a cross-sectional view of a lithium secondary battery used in a test.
【図２】 試験に用いたリチウム二次電池の高率放電特
性を示す図である。FIG. 2 is a diagram showing a high rate discharge characteristic of a lithium secondary battery used in a test.
【図３】 溶媒の良好な混合割合の範囲を示す図であるFIG. 3 is a diagram showing a range of a good mixing ratio of a solvent.
Claims (1)
素材料からなる負極材層とリチウム含有酸化物からなる
正極材層とが非水電解液を含有する電解質層を介して積
層され、 前記非水電解液がリチウム塩が溶媒に溶解されたものか
らなるリチウム二次電池において、 前記溶媒として、炭酸エチレンと炭酸ジメチルと酢酸エ
チルと炭酸ジエチルとの混合物を用い、 前記炭酸エチレンの前記溶媒に対する体積割合が２０〜
６０％であり、前記炭酸ジメチルの前記溶媒に対する体
積割合が２０〜６５％であり、前記酢酸エチルと前記炭
酸ジエチルとを併せた混合液の前記溶媒に対する体積割
合が１０〜３０％であることを特徴とするリチウム二次
電池。1. A negative electrode material layer made of a carbon material capable of inserting and extracting lithium ions and a positive electrode material layer made of a lithium-containing oxide are laminated via an electrolyte layer containing a non-aqueous electrolyte solution, In a lithium secondary battery in which a water electrolyte is a lithium salt dissolved in a solvent, a mixture of ethylene carbonate, dimethyl carbonate, ethyl acetate, and diethyl carbonate is used as the solvent, and the volume of the ethylene carbonate with respect to the solvent is Ratio is 20 ~
60%, the volume ratio of the dimethyl carbonate to the solvent is 20 to 65%, and the volume ratio of the mixed solution of the ethyl acetate and the diethyl carbonate to the solvent is 10 to 30%. Characteristic lithium secondary battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7218787A JPH0963645A (en) | 1995-08-28 | 1995-08-28 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7218787A JPH0963645A (en) | 1995-08-28 | 1995-08-28 | Lithium secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0963645A true JPH0963645A (en) | 1997-03-07 |
Family
ID=16725375
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7218787A Pending JPH0963645A (en) | 1995-08-28 | 1995-08-28 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0963645A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0980108A1 (en) * | 1998-08-13 | 2000-02-16 | Wilson Greatbatch Limited | Nonaqueous organic electrolytes for low temperature discharge of rechargeable electrochemical cells |
| US6492064B1 (en) * | 1998-06-04 | 2002-12-10 | California Institute Of Technology | Organic solvents, electrolytes, and lithium ion cells with good low temperature performance |
| US6541162B1 (en) * | 1998-12-18 | 2003-04-01 | Samsung Sdi Co., Ltd. | Electrolyte for rechargeable lithium battery and rechargeable lithium battery comprising the same |
| KR20040036817A (en) * | 2002-10-25 | 2004-05-03 | 한국전기연구원 | Lithium secondary battery |
| US6746804B2 (en) | 1998-05-13 | 2004-06-08 | Wilson Greatbatch Technologies, Inc. | Nonaqueous organic electrolytes for low temperature discharge of rechargeable electrochemical cells |
-
1995
- 1995-08-28 JP JP7218787A patent/JPH0963645A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6746804B2 (en) | 1998-05-13 | 2004-06-08 | Wilson Greatbatch Technologies, Inc. | Nonaqueous organic electrolytes for low temperature discharge of rechargeable electrochemical cells |
| US6492064B1 (en) * | 1998-06-04 | 2002-12-10 | California Institute Of Technology | Organic solvents, electrolytes, and lithium ion cells with good low temperature performance |
| EP0980108A1 (en) * | 1998-08-13 | 2000-02-16 | Wilson Greatbatch Limited | Nonaqueous organic electrolytes for low temperature discharge of rechargeable electrochemical cells |
| US6541162B1 (en) * | 1998-12-18 | 2003-04-01 | Samsung Sdi Co., Ltd. | Electrolyte for rechargeable lithium battery and rechargeable lithium battery comprising the same |
| KR20040036817A (en) * | 2002-10-25 | 2004-05-03 | 한국전기연구원 | Lithium secondary battery |
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