LiFePO4-covered silicon composite cathode with additional Li storage for lithium-ion batteries

Abstract

We prepared a composite of LiFePO4 (LFP)-covered silicon particles, C-LFP-Si, via a facile solvothermal process followed by calcination. LFP particles are grown on Si particles and contact closely with them due to the abundant oxygenic groups on the surface of Si. As a result, the Si particles are fully surrounded by LFP, producing a large amount of LFP-Si interfaces. The Si–O oxygenic groups at the interfaces serve as additional Li storage sites, thus resulting in extra capacity. When employed as a cathode for Li-ion batteries (LIBs), the composite possesses a very high reversible specific capacity of 186 mAh g−1 at the rate of 0.1 C, and a high capacity retention rate of 95% after 400 cycles at 1 C. Additionally, the composite also possesses a high specific energy of 618.8 Wh kg−1, much higher than the commercial LFP, and the full cell based on the C-LFP-Si composite cathode can bring a high-mass energy density of 273.1 Wh kg−1. Equally importantly, the fabrication of this structured composite of LFP and Si with large capacity is facile, together with the inherited stability feature, eco-friendliness, and low cost, making it promising in future practical large-scale producing applications.