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 m Acm(-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 jLiNi(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.