Effect of cathode binder on capacity retention and cycle life in transition metal phosphate of a rechargeable lithium battery

Abstract

With an objective of understanding the differences in the capacity retention behavior and cycle life of cathode consisting transition metal phosphate, Cr 0.5Nb 1.5(PO 4) 3, active material and the binder polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), the role of these binders have been analyzed. An electrochemical analysis of the active material mixed with the binders PVDF or PTFE reveals that the PTFE cell experiences an additional discharge capacity of 93 mA h g −1 during the discharge cycle compared to the PVDF cell. The results of X-ray photoelectron spectroscopy studies of the PTFE mixed cathode reveals nearly the same intensity of F (1s) spectra for before and after discharge cycles suggests that the fluorine atom is not decomposed but permits high utilization of the reactant to be achieved in the cathode during discharge/charge cycles. A remarkable improvement in cell performance in terms of capacity and cycle life for PTFE suggests that the binder PTFE should be an attractive candidate in lithium batteries than that of PVDF.