Ag nanoparticles promoted LiFePO4F nanospheres cathode with superior cycling stability for lithium-ion batteries

Abstract

Tavorite-like structure LiFePO4F has been recently studied as potential alternative cathode materials for lithium-ion batteries due to its outstanding structural stability, abundant resources and remarkable safety. However, its poor electronic conductivity and lithium-ion diffusion coefficient leads to the unsatisfactory cycling stability and rate capabilities of LiFePO4F. Herein, Ag decorated LiFePO4F nanospheres have been synthesized for the first time via a precipitation method with in-situ reduction of Ag+, simultaneously improving electronic conductivity and lithium-ion diffusion coefficient. The Ag nanoparticles with size of ∼10 nm are in-situ grown on the surface of LiFePO4F nanospheres with impressive electrochemical performance. It delivers a high discharge capacity of 148.7 mAh g−1 (very close to the theoretical capacity of 152 mAh g−1) at 0.1 C. It is worth mentioning that the Ag-decorated LiFePO4F nanospheres reveal superior cycling stability. The initial discharge capacities of Ag-decorated LiFePO4F reaches up to 120.3 mAh·g−1 at 0.5 C, and the capacity retention is as high as 96.1% after 300 cycles, which is remarkable higher than that of pure LiFePO4F nanospheres with initial discharge capacity of 110.2 mAh·g−1 and capacity retention of 83.1% after 300 cycles. Furthermore, the Ag-decorated LiFePO4F displays the average discharge potential loss of only 0.7% which is lower than pure LiFePO4F of 4.7% after 300 cycles, and the corresponding specific energy retention ratio of 95.5% which is higher than that of 80.1%.