Electrospun PAN membranes toughened and strengthened by TPU/SHNT for high-performance lithium-ion batteries

Abstract

Membrane separators should have robust characteristics to ensure that batteries have a high discharge capacity and could shun the probability of thermal runaway. In this study, thermoplastic polyurethane (TPU) and inorganic surface-modified halloysite nanotube (SHNT) are considered to improve the toughness and strength of electrospun polyacrylonitrile (PAN) fibers. This is because TPU is elastic, while SHNT has a high aspect ratio and a special hollow structure. The obtained PAN/TPU/SHNT membrane exhibits improvement in its overall performance. It exhibits excellent thermal stability, increased flexibility, and high ionic conductivity. More importanly, the tensile strength of membranes increases to 28.5 MPa and observed a significant vibration amplitude, which is signifying better flexibility and elasticity. With PAN/TPU/SHNT-3 as a battery separator, the lithium-ion battery delivers a capacity of 108.41 mAh/g and a retention of 98.30 % at 2C for 100 cycles. These data on capacity and retention are higher than those of Celgard 2400. Incorporating SHNT to improve the fiber strength and TPU for its elasticity into electrospun PAN membrane separators should prove effective in enhancing not only the electrochemical performance but also the safety of batteries.