Surface fluorinated graphite suppressing the lithium dendrite formation for fast chargeable lithium ion batteries

Abstract

Developing lithium-ion batteries with high power and fast charging features has been highlighted as an essential research area to address growing energy demands for portable electronics and long-range electric vehicles. The commercial graphite anode has been recognized as a competent material owing to its benefits, including a long cycle life, high columbic efficiency, and low volume expansion. However, the intrinsic features of their intercalation kinetics render them highly susceptible to lithium deposition, resulting in poor cycle stability at fast charging conditions. In this study, we propose a simple thermal fluorine treatment of flake-type graphite to produce fluorine-doped-flake graphite. We observed the fluorine treatment improves the Li+ ion intercalation kinetics and reduces the lithium deposition and dendrite growth upon fast charging conditions. As a result, enhanced lithiation behavior was observed, with a high specific capacity of 348.3 mAh g-1 and a good rate capability of 66 % at 2C-rate in half-cell conditions. Furthermore, a full cell demonstrated outstanding cycle stability with 83.5 % capacity retention at 2C even after 950 cycles. Our findings emphasize that fluorine doping in graphite could be a straightforward and practical approach to mitigate Li deposition issues and enhance the fast charge kinetics of graphite-based commercial Li-ion batteries.