A Positive-Temperature-Coefficient Layer Based on Ni-Mixed Poly (Vinylidene Fluoride) Composites for LiFePO4 Electrode

This paper discusses a positive-temperature-coefficient (PTC) electrode prepared by coating a layer of Ni particle-mixed poly (vinylidene fluoride) (PVDF) composites between the active LiFePO4 layer and current collector. The performance of the LiFePO4 electrode with PTC layer is compared with the electrode without PTC layer. Experimental results from electrical resistivity, capacity, and electrochemical impedance spectrometry at different temperature demonstrate that the PTC layer shows an enormous increase of the resistance and blocks fully off electrochemical behaviors at 90 °C. These results express that the PTC layer can be used for preventing thermal runaway during the abnormal overheat. Furthermore, the rate and cycle performance at ambient temperature indicate that the PTC layer can provide favorable interface and lower electrode polarization.