Biomineralized zircon-coated PVDF nanofiber separator for enhancing thermo- and electro-chemical properties of lithium ion batteries

As one of the components of the lithium ion batteries (LIBs), the separator plays a vital part in the safety and electrochemical performance. In this work, a ZrO 2 -ceramic-coated polyvinylidene fluoride (PVDF) nanofibrous separator for LIBs was successfully prepared by electrospinning, subsequent dopamine hydrophilic modification and biomimetic mineralization process. These preparation processes were environmentally friendly and simple. The ZrO 2 -ceramic coating endows the separator with outstanding electrolyte wettability and thermal stability. To be specific, the separator exhibits higher ionic conductivity (2.261 mS cm −1 ), high porosity (85.1%) and favorable electrolyte wettability (352%), and lower interfacial impedance (220 Ω). Compared with commercial polyolefin separator and PVDF nanofibrous separator, the ZrO 2 -ceramic-coated PVDF nanofibrous separator exhibits excellent rate performance and well cyclic stability. Most importantly the ZrO 2 –PDA/PEI–PVDF separator can still maintain a complete structure even at a high temperature of 300 °C. Compared with commercial separators, it greatly improves the safety of lithium ion batteries at high temperature. Therefore, this separator has far-reaching prospects for improving lithium ion safety and cycle stability.