Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO₄/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

Yang Liu; Jieyu Zhang; Ying Li; Yemin Hu; Wenxian Li; Mingyuan Zhu; Pengfei Hu; Shulei Chou; Guoxiu Wang

doi:10.3390/nano7110368

Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO₄/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

Nanomaterials (Basel). 2017 Nov 3;7(11):368. doi: 10.3390/nano7110368.

Authors

Yang Liu¹, Jieyu Zhang^{2

3}, Ying Li⁴, Yemin Hu⁵, Wenxian Li⁶, Mingyuan Zhu⁷, Pengfei Hu⁸, Shulei Chou⁹, Guoxiu Wang¹⁰

Affiliations

¹ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. yangliu8651@shu.edu.cn.
² Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. zjy6162@staff.shu.edu.cn.
³ Shanghai Key Laboratory of Modern Metallurgy & Materials Processing, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. zjy6162@staff.shu.edu.cn.
⁴ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. liying62@shu.edu.cn.
⁵ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. huyemin@shu.edu.cn.
⁶ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. shuliwx@shu.edu.cn.
⁷ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. zmy@shu.edu.cn.
⁸ Laboratory for Microstructures, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China. hpf-hqx@shu.edu.cn.
⁹ Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia. shulei@uow.edu.au.
¹⁰ Department of Chemistry and Forensic Science, University of Technology Sydney, Sydney, NSW 2007, Australia. Guoxiu.Wang@uts.edu.au.

Abstract

To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO₄/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO₄/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO₄/C composite exhibits superior discharge capacity (163 mAh g^-1 at 0.1 C), good high-rate discharge capacity (118 mAh g^-1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

Keywords: lithium ion battery; lithium iron phosphate; micro hollow sphere; solvothermal method.