Degradable cellulose acetate/poly-l-lactic acid/halloysite nanotube composite nanofiber membranes with outstanding performance for gel polymer electrolytes

Abstract

The biodegraded cellulose acetate (CA)/poly-L-lactic acid (PLLA)/Halloysite nanotube composite nanofiber membranes were fabricated for the preparation of gel polymer electrolytes (GPEs) used in lithium-ion batteries. The microstructure, crystallization behaviour and thermal stability of nanofiber membranes were analysed. The testing results showed that the crystallization behaviour of the polymeric materials was significantly inhibited, and that the thermal stability of the polymer nanofiber membranes was improved due to the addition of the halloysite nanotubes (HNTs). The composite GPEs based on the CA/PLLA/HNT nanofiber membranes presented a satisfactory electrochemical performance, including high ionic conductivities, proper lithium-ion transference numbers, and good electrochemical stability. An ionic conductivity of 1.52 × 10⁻³ S cm⁻¹ was obtained from the above mentioned GPEs, which is far greater than the existing bio-based GPEs. Moreover, the initial discharge capacities, cycle performance and rate performance of the Li/GPE/LiCoO₂ cells involved with the CA/PLLA/HNT nanofiber membranes was superior to those of the commercial Celgard® 2500. Therefore, through the proper collocation of biodegradable polymer materials and functional nanoparticles, the resulting composite GPEs exhibited the recommendable integrated performance. The CA/PLLA/HNT composite nanofiber membranes can be used as novel green skeleton materials in GPEs for high performance lithium-ion batteries, which provide a perfect combination of high performance and environmental protection.