Long-life high-voltage all-solid-state batteries enabled by bismuth (III)triflate mediated polymer electrolytes

The interfacial instability of the poly(ethylene oxide) (PEO)-based electrolytes hinders the long-term cycling of the high voltage LiNi0.8Co0.1Mn0.1O2/Li all-solid-state batteries (ASSBs) and further application. In this work, we have demonstrated an effective additive bismuth (III) triflate (BiOTF) benefiting to the exceptional performance of the PEO-based electrolytes. Attributed to the intensive mediation of the BiOTF to the polymer matrix and anions, the coordination of the Li+-EO has been weaken and the bondage of anion has been improved, resulting to the improvement of the Li+ conductivity and the electrochemical stability. The reduced Bi 'seeds' on the surface of the lithium anode could effectively alloy with lithium to suppress the lithium dendrite growth. Importantly, the BiOTF mediates the formation of LiF in the both interfaces, which contributes to the interfacial stability (especially at high voltage) and protection of the electrodes, enabling the long-term cycling of the ASSBs under high voltage. Therefore, the Li/Li symmetric cell can undergo long-term lithium plating/stripping for over 2800 h. And the steady cycling of 4.4 V NMC811/Li ASSB with the optimized electrolyte for 800 times can be achieved, with an impress capacity retention of 72.4 %.