Room-Temperature-and-Pressure Vapor Deposition of Trace Amount of Pyrrole for Improving the Ageing Resistance and Electrochemical Performance of LiFePO₄/C

There are many reports on addressing the issues concerning low electronic and ionic conductivity of LiFePO4, but it is ignored by researchers that how to improve the ageing resistance and retain the electrochemical properties of LiFePO4 and carbon-coated LiFePO4 (LiFePO4/C) after long-term exposure to ambient atmosphere. In this report, an ambient-temperature-and-pressure vapor deposition approach is designed to improve the ageing resistance and electrochemical performance of LiFePO4/C upon exposure to ambient atmosphere. The mechanism of this approach is based on (1) a spontaneous process for evaporation of pyrrole; (2) a fine tuning of the pores in the carbon layer; and (3) restrained contact of LiFePO4 with H2O and electrolyte by in-situ formed oligomers of pyrrole with atomic-layer thickness. As a result, the surface-modified LiFePO4/C samples after exposure to ambient atmosphere for 4 months exhibit high ageing resistance and enhanced electrochemical performance as compared to the initial LiFePO4/C. (c) 2018 The Electrochemical Society.