Improving electrochemical performances of LiFePO4/C cathode material via a novel three-layer electrode
(1. Faculty of Metallurgical and Energy Engineering,
Kunming University of Science and Technology, Kunming 650093, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Kunming University of Science and Technology, Kunming 650093, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Abstract: As an improvement on the conventional two-layer electrode (active material layer|current collector), a novel sandwich-like three-layer electrode (conductive layer|active material layer|current collector) for cathode material LiFePO4/C was introduced in order to improve its electrochemical performance. LiFePO4/C in the three-layer electrode exhibited superior rate capability in comparison with that in the two-layer electrode in accordance with charge-discharge examination. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that Fe3+/Fe2+ redox couple for LiFePO4 in the three-layer electrode displayed faster kinetics, better reversibility and much lower charge transfer resistance than that in the two-layer electrode in electrochemical process. For three-layer electrode, the holes in the surface of active material layer were filled by smaller acetylene black grains, which formed electrical connections and provided more pathways to electron transport to/from LiFePO4/C particles exposed to the bulk electrolyte.
Key words: lithium ion cells; LiFePO4; cathode electrode configuration; three-layer electrode; electrochemical performances