Compact Si/C anodes fabricated by simultaneously regulating the size and oxidation degree of Si for Li-ion batteries. Issue 42 (9th October 2019)

• Record Type: Journal Article
• Authors: Zhao, Liang; He, Yan-Bing; Li, Chengfei; Jiang, Kelin; Wang, Peng; Ma, Jiabin; Xia, Heyi; Chen, Fangyuan; He, Yuanbiao; Chen, Zhen; You, Conghui; Kang, Feiyu
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 42(2019)
• Page Start: 24356
• Page End: 24365
• Publication Date: 2019-10-09
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9ta09255b
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : A compact Si/C anode with regulable size and oxidation extent of Si exhibits excellent performance in half and full Li-ion batteries. Abstract : The large volume expansion during lithiation and poor conductivity of Si as anodes of Li-ion batteries limit their practical applications. Herein, a compact graphite/Si/C (GSC) composite is designed in which the particle size and oxidation degree of Si can be regulated simultaneously by sand milling micro-Si particles. Optimal Si with a particle size of about 125 nm and an oxide layer (SiO x ) thickness of about 8 nm is obtained by controlling the sanding time, and is further uniformly coated on the surface of graphite. The synergistic effects of nanocrystallization and the SiO x layer of Si can minimize the volume expansion to achieve optimum electrochemical performance. A carbon coating is further applied on the outermost surface of graphite/Si particles to increase the conductivity, reduce the volume expansion, and stabilize the solid electrolyte interface (SEI) of nano-Si. The obtained GSC with a high tap density of 0.95 g cm −3 delivers an initial reversible capacity of 675 mA h g −1 and the capacity retention reaches 87.3% after 200 cycles at 1C. When the charging rate increases to 10C, the GSC still delivers a capacity of 528.0 mA h g −1 . Furthermore, a LiNi0.5 Co0.2 Mn0.3 O2 /GSC–graphite pouch cell with a capacity of 1869.3 mA h exhibits a high capacity retention of 90.1% even after 150 cycles under a high compaction density of 1.55 g cm −3 for GSC–graphite. The excellent performance demonstrates that the compact GSC composite is an attractive candidate for anode materials for next-generation Li-ion batteries.