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