LI Zhengwei 1, WU Qiang 1, ZHOU Jianhua 1, QIN Haiqing 2, MIAO Lei 1, LIU Wenping 2, 3, LEI Xiaoxu 2, 3, ZHANG Zhenjun 2, 3, LU Anjun 2, 3, MO Zuxue 2, 3
(1. Guangxi Key Laboratory of Conformational Relationships for Electronic Information Materials, School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, Guangxi, China; 2. Guangxi Key Laboratory of Superhard Material, China Nonferrous Metal (Guilin) Geology and Mining Co., Ltd., Guilin 541004, Guangxi, China; 3. Guangxi Technology Innovation Center for Special Mineral Material, China Nonferrous Metal (Guilin) Geology and Mining Co., Ltd., Guilin 541004, Guangxi, China)
Abstract: Silicon anode material becomes one of the ideal materials for high energy density lithium-ion battery, due to its low cost, high specific capacity and reliable safety. However, severe volume expansion during lithium embedding, poor material conductivity and poor cycling stability limit the commercial application of silicon anode material. Therefor, agar-derived carbon/NH4F@nanosilicon composites (Si@FNC) were prepared by using a one-pot sol-gel method with agar and NH4F to realize carbon coating and doping modification. Structure, morphology and electrochemical properties of the Si@FNC composites were studied. Cyclic stability and electrical conductivity of the Si@FNC composites were significantly improved after NH4F modification. When the mass ratio of NH4F to Si was 1:5, the first discharge specific capacity was 2001.0 mAh·g−1 at a current density of 500 mA·g−1, while the residual capacity was still maintained at 836.7 mAh·g−1 after 200 cycles. The results could be used as a reference for further exploration of high-capacity silicon-carbon anode materials.
Key words: lithium-ion battery; silicon-carbon anode material; nanosilicon; NH4F doping modification