A biodegradable nano-composite membrane for high-safety and durable lithium-ion batteries

Abstract

As a key component of lithium-ion batteries (LIBs), separator plays a crucial role in the performance and safety of LIBs. In this paper, a cellulose-based porous membrane modified by nano CaCO₃ is prepared conveniently by electrospinning. The membrane exhibits rich fibrous porous networks and uniform distribution of nanoparticles. Strengthened by CaCO₃, the tensile strength of the cellulose porous membrane elevates from 4.7 ± 0.4 MPa to 7.7 ± 0.7 MPa. Besides, the modified membranes possess improved thermal stability and can maintain their original size after treatment at 150°C and 180°C. Also, the electrolyte uptake of cellulose/CaCO₃ membrane is 73% higher than that of the pure cellulose membrane. Thus, the ionic conductivity of membrane achieves 1.08 mS cm⁻¹ and the electrochemical window is about 4.8 V, which meets the practical requirements of LIBs. Significantly, with LiFePO₄/Li battery this membrane can run for 230 cycles with a capacity retention of 97.4% and a discharge capacity of 149.0 mAh g⁻¹, demonstrating the huge potential for high safety and next-generation LIBs.