Solid‐State Lithium Conductors for Lithium Metal Batteries Based on Electrospun Nanofiber/Plastic Crystal Composites

Organic ionic plastic crystals (OIPCs) are a class of solid‐state electrolytes with good thermal stability, non‐flammability, non‐volatility, and good electrochemical stability. When prepared in a composite with electrospun polyvinylidene fluoride (PVdF) nanofibers, a 1:1 mixture of the OIPC N ‐ethyl‐ N ‐methylpyrrolidinium bis(fluorosulfonyl)imide ([C 2 mpyr][FSI]) and lithium bis(fluorosulfonyl)imide (LiFSI) produced a free‐standing, robust solid‐state electrolyte. These high‐concentration Li‐containing electrolyte membranes had a transference number of 0.37(±0.02) and supported stable lithium symmetric‐cell cycling at a current density of 0.13 mA cm −2 . The effect of incorporating PVdF in the Li‐containing plastic crystal was investigated for different ratios of PVdF and [Li][FSI]/[C 2 mpyr][FSI]. In addition, Li|LiNi 1/3 Co 1/3 Mn 1/3 O 2 cells were prepared and cycled at ambient temperature and displayed a good rate performance and stability.