title: Fluorination Induced the Surface Segregation of High Voltage Spinel on Lithium-Rich Layered Cathodes for Enhanced Rate Capability in Lithium Ion Batteries.
abstract: This study is aimed to explore the effect of fluoride doping and the associated structural transformation on lithium-rich layered cathode materials. The polymeric fluoride source is first adopted for synthesizing lithium intercalated oxide through a newly developed organic precipitation process. A heterostructured spinel/layered composite cathode material is obtained after appreciable fluorination and a superior rate capability is successfully achieved. The fluoride dopant amount and the surface spinel phase are evidenced and systematically examined by various structural spectroscopy and electrochemical analysis. It appears the reversible Ni(2+/4+) redox couple at high voltage regime around 4.8 V because of the formation of spinel LiNi1/2Mn3/2O4 phase. The mechanism of "layer to spinel" phase transformation is discussed in detail.
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University , Hsinchu, 30013 Taiwan.
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Jin
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University , Hsinchu, 30013 Taiwan.
authors.forename: Jenq-Gong
authors.initials: JG
authors.lastname: Duh
keywords: composite cathode material; fluorination; high rate capability; high voltage spinel; lithium ion battery; phase transformation