Interfacial superionic conductor towards solidified lithium-ion batteries with superb rate performance and long cycle life

The poor interface contact between the electrode and solid electrolyte is a major obstacle damaging the cycle performance and stability of solid-state lithium-ion batteries. Adding inorganic or organic layer as the buffers on the electrode/electrolyte interface can improve the physical contact, but still hardly achieve high rate capability due to the slow ion-diffusion kinetics on the interface. Here, we design an organic interfacial superionic conductor (ISC) with high ion-conductivity based on polyether polyols (PPG) through polar functional-group modification to enhance the ion-diffusion kinetics on the polyurethane-based electrolyte/cathode interface and construct ion-conductive framework in LFP cathode, which was verified by cryogenic electron microscopy (Cryo-EM) and surface enhanced Raman spectroscopy (SERS). Consequently, the assembled LFP cathode demonstrated a high specific capacity of ∼95.7 mAh/g with retention of ∼92% after 1000 cycles at 10 C.