LITHIUM SECONDARY BATTERY

• Main Authors: UNEMOTO ATSUSHI, KONISHI HIROAKI, NISHIMURA KATSUNORI, SEKI EIJI
• Format: Patent
• Language: English; Japanese
• Published: 06.02.2020
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

To provide a lithium secondary battery using an electrolyte system containing a solvent having low volatility such as a glyme-based solvent or an ion solution or the like, which optimizes a component of a negative electrode active material and an electrolyte, and expresses a high negative characteristic.SOLUTION: A lithium secondary battery 1 includes: a positive electrode 2 capable of absorbing and discharging a lithium ion; a negative electrode 3 containing a mixture of a carbon system material and a Si alloy as a negative electrode active material; and an electrolyte containing a solvent component including a lithium salt, a first addition agent, a second addition agent, and a glyme-based solvent or an ion liquid. The first addition agent is one or more kinds selected from a group of a fluoroethylene carbonate, a lithium-bis-oxalate-borate, and a tris pentafluorophenyl borane. The second addition agent is a vinylene carbonate. A content amount of the first addition agent in the electrolyte is 10 wt.% or more and is less than 30 wt.%. The content amount of the second agent in the electrolyte is 3 wt.% or more and is less than 20 wt.%.SELECTED DRAWING: Figure 1 【課題】グライム系溶媒やイオン液体等の揮発性が低い溶媒を含む電解液系を用いたリチウム二次電池において、負極活物質及び電解液の組成を最適化し、高い負極特性を発現させることを目的とする。【解決手段】本発明のリチウム二次電池１は、リチウムイオンを吸蔵及び放出可能な正極２と、負極活物質として炭素系材料及びＳｉ合金の混合物を含む負極３と、リチウム塩、第一添加剤、第二添加剤、並びにグライム系溶媒又はイオン液体を含む溶媒成分を含む電解液と、を有し、前記第一添加剤は、フルオロエチレンカーボネート、リチウムビスオキサレートボレート及びトリスペンタフルオロフェニルボランからなる群から選択される一種以上であり、前記第二添加剤は、ビニレンカーボネートであり、前記電解液における前記第一添加剤の含有量が、１０重量％以上３０重量％未満であり、前記電解液における前記第二添加剤の含有量が、３重量％以上２０重量％未満であることを特徴とする。【選択図】図１