Regulating dissolution chemistry of nitrates in carbonate electrolyte for high-stable lithium metal batteries

Abstract

Lithium metal batteries (LMBs) have received increasing attention due to the high energy density. However, the practical application of LMBs is limited due to the incompatibility of ester electrolytes. Transition metal (TM) nitrates have been reported as effective additives in ester electrolyte to improve the stability of lithium anode. Unfortunately, the nitrates are restricted to use due to their poor solubility. We find that the nitrates containing crystal water have high solubility in ester electrolytes. Considering that most TM nitrates contain crystal water and the crystal water can be used as a perfect solubilizer of nitrates, thus, the method is of universality and facile without introducing any solubilizing agent. Herein, In(NO3)3·6H2O is chosen as one typical case with increased solubility up to 0.2 M compared with In(NO3)3 which hardly dissolves in ester electrolyte. The additive promotes the rapid and stable formation of the solid electrolyte interface (SEI), which effectively inhibits the lithium dendrites formation. Moreover, the induced cathode electrolyte interface (CEI) maintains the structural stability of LiNi0.8Co0.1Mn0.1O2 (NCM811). As a result, the electrochemical performance of Li|NCM811 cell is obviously improved. Our study provides a new idea for dissolving nitrates in ester electrolytes and discloses the synergistic function of TM-ions.