Phase change nanocapsules filled separator for wide-temperature-range performance enhancement of Li-ion battery

Abstract

The rapid development of electrical vehicle urgently requires high-performance Li-ion battery that can operate over a wide temperature range. Herein, disodium hydrogen phosphate dodecahydrate encapsulated with silica were embedded to polyvinylidene fluoride as DHPD@SiO₂/PVDF (DSP) membrane. The DSP based cell exhibited superior average discharge capacity (132 mAhg⁻¹) and coulombic efficiency (96%) under room temperature as the silica shell in nanocapsules could enhance electrolyte affinity, separator porosity and mechanical strength to reduce interfacial resistance and increase Li-ion conductivity. Furthermore, the DSP membrane is leakage-proof with a comparable latent heat due to the synergistic effect between porous silica and hydrophobic PVDF. When battery discharged in cold environment, heat release from hydrate salt solidification could mitigate the damage to alleviate discharge capacity degradation by 57.7%. The present design of separator that integrating electrochemical properties promotion and low-temperature thermal management provides a novel and efficient strategy to enhance wide-temperature-range performance of battery.