Improvement of High Voltage Cyclic Performance by Novel Binder for High Energy Lithium Ion Battery Application

摘要

In this study, we report the effect of PVdF for cycle fading at high cut-off voltage and structural change of active material after the cycle test. From cyclic voltammograms of PVdF on the LiCoO_2 thin film, redox currents gradually decreased and redox voltage shifted. The chemical composition of electrolyte was determined by gas chromatography (GC) analysis after the cycle test. It was found that a decomposition product of solvent in electrolyte increased after the cycle test. The amount of dissolved Co was increased after cycle test as determined by ICP measurement of the anode electrode. The degradation at the surface of LiCoO_2 was observed by TEM spectroscopy. The structure of PVdF binder in the electrode before/after cycle was investigated using solid-state 19F MAS nuclear magnetic resonance (NMR).