Bismuth phosphate: A novel cathode material based on conversion reaction for lithium-ion batteries

摘要

Here, we provide a new scientific insight in the field of lithium-ion batteries, in which BiPO_4 is initially reported as a cathode material based on conversion reaction. BiPO_4 exists in three polymorphic phases, which have been synthesized using a room-temperature liquid precipitation route followed by heating treatment. The effects of phase transformation on electrochemical performances of BiPO_4 have been investigated. Herein the hexagonal BiPO_4 exhibits the best reversibility, rate capability and cycling stability. A conversion reaction has also been proved to occur in BiPO_4 with reduction of BiPO_4 into a metallic Bi~0 phase and a Li_3PO_4 phase upon lithiation, and the reformation of BiPO_4 phase during next charge process. Its theoretical specific capacity and theoretical output voltage are 264.5 mA h g~(-1) and ~3.14 V, respectively. Especially, its theoretical volumetric energy density is as high as 5253.1 Wh L~(-1), close to twice higher than LiCoO_2. Therefore, it is still worthy of further study for lithium-ion batteries.