In situ formation of LiF decoration on a Li-rich material for long-cycle life and superb low-temperature performance

Abstract

The electrochemical properties of layered Li-rich oxide Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ (LLO) can be enhanced by coating various materials. This paper demonstrates, for the first time, that an in situ formation of an ultrathin and uniform LiF coating layer on LLO is realized via the decomposition of LiPF₆, which can effectively protect the surface of the LLO electrode, resulting in much enhanced structural stability and faster lithium ion diffusion kinetics. Such LiF coated LLO shows markedly improved cycle life, rate capability, low-temperature performance and suppressed voltage decay. It exhibits a capacity retention of 93% beyond 1000 cycles at 10C, a capacity of 112 mA h g⁻¹ at −30 °C and a negligible voltage decay of 0.0023 V per cycle, displaying great application prospects in such energy storage materials.