Preparation and Performance Study of Intelligent Self-heating Electrode Materials for Low Temperature Li-Ion Batteries Based on PTC Effect

An internal resistance heating method was proposed to control the operating temperature of Li-ion batteries to address rapid performance degradation under low temperature conditions. Main research content: (a) Preparation and process optimization of PTC (positive temperature coefficient) effects materials: Using micrometer nickel powder as the conductive material and polypropylene/polyvinylidene fluoride (PP/PVDF) as the polymer matrix. The polymer matrix was mixed with the conductive material using high-temperature melting method. The PTC materials with a transition temperature below 40°C were prepared through controlling the preparation process repeatedly and meticulously, and the optimal preparation process was determined. (b) Performance testing and analysis of PTC materials: The thermal analysis, volume change analysis, structure and micro-structure analysis were conducted through resistivity temperature curve, tensile performance, SEM and thermal expansion testing, respectively. The influence of conductive material content, heat treatment temperature, heat treatment time on the performance of PTC materials was systematically studied. (c) “Self heating Battery” assembly and performance study: A self heating Li-ion battery was assembled and its electrochemical performance was tested systematically. The results showed that the low-temperature discharge performance of the battery was significantly improved. This work can help improve the low-temperature performance of Li-ion batteries and expand its application areas.