Dual-Carbon Network for the Effective Transport of Charged Species in a LiFePO4 Cathode for Lithium-Ion Batteries

摘要

Cost and safety considerations have driven up the interest in LiFePO4 as a lithium-ion battery cathode material. Carbon nanopainting is currently the most common approach to increase the power density of LiFePO4, but more can be done to improve the application performance further. In this study the rate performance of LiFePO4 was increased by using a conductive dual-carbon network that can extract and conduct electrons from the Li+ storage host more effectively than common pyrolyzed carbon. The dual-carbon network consists of a connected network of graphene sheets and a nanoscale continuous coating of pyrolyzed conductive carbon on the surface of the aggregated LiFePO4 nanocrystals. Such a construction supports fast electron transport between the aggregated LiFePO4 nanocrystals as well as within them. Consequently the LiFePO4/C composite fabricated as such delivered very high rate performances even at very high discharge rates (104 mAhg(-1) at 50 C where 1 C= 170 mAg(-1)).