Electrochemical performance and kinetics of lifepo4/C cathode in a low-temperature electrolyte

Abstract

The electrochemical performance of LiFePO4/C cathode in a carbonate-based electrolyte (1.0M LiPF6 / EC-DMC-PC-FEC) was tested in coin type cells at low temperatures. The discharge capacities of the LiFePO4/C cathode were about 161.6mAh/g (20oC), 141.4mAh/g (-10oC) and 112.9mAh/g (-20oC) at 0.1C charge-discharge rate. The electrode kinetics of LiFePO4/C cathode was determined at different temperatures using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The analyses demonstrate that the sluggish of charge-transfer reaction on the LiFePO4/C-electrolyte interface and the dramatic decrease in lithium ion diffusivity in the bulk LiFePO4/C material were the key performance limiting factors at low temperature. © 2010 WEVA.