The plastic crystal composite polyacrylate polymer electrolyte with a semi-interpenetrating network structure for all-solid-state LIBs

Abstract

In order to overcome the tradeoff between the mechanical and electrochemical properties of polymer electrolytes, a novel semi-interpenetrating network structure is proposed. It can effectively solve the problems of low conductivity, poor interface stability, and weak mechanical strength of polymer electrolytes. Specifically, we use a plastic crystal composite polyacrylate polymer electrolyte doped with PVDF-HFP and after in situ UV curing, the polymer matrix with a semi-interpenetrating structure is formed by linear PVDF-HFP and cross-linked polyacrylate network structure (S-PCCE). A significant feature of the semi-interpenetrating network structure is the fine integration of the cross-linked polymer network and the linear polymer, resulting in synergistic effects that can improve the flexibility, mechanical strength, and ionic conductivity of the plastic-crystal composite polymer electrolyte. The ionic conductivity can reach 1.45 × 10⁻³ S cm⁻¹ at room temperature and 4.8 × 10⁻³ S cm⁻¹ at 60 °C, which is conducive to high battery performance. The LiFePO₄/S-PCCE/Li battery has an initial discharge specific capacity of 156 mA h g⁻¹ and a maximum discharge specific capacity of 163 mA h g⁻¹ at 0.2C. After 50 cycles, the battery can still maintain a high discharge specific capacity of 155 mA h g⁻¹ and a Coulomb efficiency of 99.4%. At the same time, the thermogravimetric curve shows that the electrolyte has good adaptability to high temperatures. Therefore, polymer electrolytes with a semi-interpenetrating network structure have good application prospects.