In situ preparation of LiFePO4/C with unique copolymer carbon resource for superior performance lithium-ion batteries

Olivine-type LiFePO4, taking advantage of structure stability and environmental friendliness, points out a new direction towards development of Li-ion batteries applying in the plug-in hybrid vehicles. However, the inferior electronic conductivity (-10(-9) S cm(-1) at 298 K) and lower lithium ion diffusion coefficient (similar to 10(15) cm(2) S-1 at 298 K) still hinder the farther application in power battery. To overcome the defects, LiFePO4/C composite with special copolymer carbon resource (polyacrylonitrile block polymethyl methacrylate) is synthesized successfully by in situ carbothermal reduction method. From BET, SEM and TEM, the sample obtained is coated by thin and homogeneous porous carbon layers, which may be induced by the copolymer carbon resource. The porous layers give opportunity to faster diffusion of Li ion and closely contact between active substance and electrolyte, providing the high active sites. Unquestionably, the modified LiFePO4/C demonstrates such outstanding properties as high initial discharge capacity (165.3 mA h g(-1) at 0.2 degrees C), superior rate capability (78.9 mA h g(-1) at 30C), and excellent cycling performance with 98% cycle retention after 100 cycles at 0.2 degrees C. The well-designed LiFePO4/C cathode material becomes an increasingly eye-catching candidate applicable to the fields of rechargeable lithium ion batteries. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The research indicates that the LiFePO4/C composite material prepared using special copolymer carbon resource demonstrates excellent performance, including high discharge capacity, superior rate capability, and excellent cycling stability. The porous carbon layers allow for faster lithium ion diffusion and higher active sites, leading to outstanding battery performance.