NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Authors: HASHIMOTO HIROSHI, AOKI URUMI, OMOMO YOSHITOMO
• Format: Patent
• Language: English; Japanese
• Published: 23.07.2015
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which can exhibit superior charge and discharge cycle characteristics even in the case that an upper limit voltage at charging thereof is increased.SOLUTION: A nonaqueous electrolyte secondary battery comprises: a positive electrode having a positive electrode mixture layer including a positive electrode active material, a conductive assistant and a binder; and a negative electrode having a negative electrode mixture layer including a negative electrode active material and a binder. The positive electrode mixture layer includes, as the positive electrode active material, a lithium-containing metal oxide including at least Co and a particular amount of at least one element Mselected from a group consisting of Al and Mg, the content of the conductive assistant being over 0.5 to 2.0 mass%. The negative electrode mixture layer includes, as the negative electrode active material, graphite A having an average particle diameter of over 15 to 25 μm, and graphite B having an average particle diameter of 8 to 15 μm and consisting of graphite particles coated with amorphous carbon. 【課題】 充電時の上限電圧を高めても、優れた充放電サイクル特性を発揮し得る非水電解質二次電池を提供する。【解決手段】 正極活物質、導電助剤およびバインダを含有する正極合剤層を有する正極と、負極活物質およびバインダを含有する負極合剤層を有する負極とを備えており、前記正極合剤層は、正極活物質として、Ｃｏと、特定量のＡｌおよびＭｇよりなる群から選択される少なくとも１種の元素Ｍ１とを、少なくとも含むリチウム含有金属酸化物を含有し、かつ導電助剤の含有量が０．５質量％を超え２．０質量％以下であり、前記負極合剤層は、負極活物質として、平均粒子径が１５μｍを超え２５μｍ以下の黒鉛Ａと、平均粒子径が８μｍ以上１５μｍ以下であり、かつ黒鉛粒子の表面が非晶質炭素で被覆されている黒鉛Ｂとを含有していることを特徴とする非水電解質二次電池により、前記課題を解決する。【選択図】 なし