Optimized chemical stability and electrochemical performance of LiFePO4 composite materials obtained by ZnO coating

An improved electrode performance is achieved in LiFepO(4) materials of different origin by a simple coating procedure. LiFePO4 samples were prepared by a conventional ceramic synthesis. Fe-57 Mossbauer data evidenced that heating above 750 degrees C with carbon should be avoided to limit the amount of iron phosphide impurities. The ceramic sample was compared to a commercial sample differing in particle size and porous system. ZnO precipitation of a ca. 2 nm films on the particles surface of both phosphate samples resulted in a protection vs electrolyte hydrolysis product that limits iron dissolution during lithium battery operation. As a consequence, capacity retention improves significantly at different rates. (C) 2008 The Electrochemical Society.