Cu(NO3)2 as efficient electrolyte additive for 4 V class Li metal batteries with ultrahigh stability

Abstract Li-metal batteries (LMBs) have attracted increasing attention because of the high energy density and low reduction potential of lithium metal. However, lithium dendrites generated by the uneven Li deposition during cycling seriously threaten the safety of the battery and limit its commercial application. Herein, we propose a novel and facile strategy by adding Cu(NO3)2 additive in carbonate electrolyte, which effectively inhibits the growth of lithium dendrites and prolongs the lifespan of LMBs based on LiMn2O4 as 4 V class cathode. Due to the contribution of Cu(NO3)2, the solid electrolyte interphase (SEI) is rapidly and stably formed attaching on lithium metal without evident lithium dendrites. Moreover, Cu ions can also participate in the formation of cathode electrolyte interphase (CEI), effectively suppressing the decomposition of electrolyte and dissolution of Mn in LiMn2O4. The Li|LiMn2O4 cell with additive maintains the capacity retention of 87.26% and an average coulombic efficiency of 99.40% when approching 1000 cycles at ~1.2 mA cm−2. Our findings shed light on understanding the role of transiton metal nitrate additive for stabilizing LMBs with long lifespan.