Exploring Nb-NMC811||Si Lithium-Ion Batteries for Low-Temperature Conditions

Abstract Ni-rich NMC‖Si systems are considered one of the most promising candidates for high-energy-density lithium-ion batteries (LIBs) due to their high theoretical capacity and suitable operating voltage. Multiple strategies have been extensively explored to enhance the electrochemical performance of both high Ni NMC cathodes and Si anodes. Nevertheless, their performance at low temperatures remains a critical bottleneck, as sluggish kinetics processes and the failure of solid electrolyte interface (SEI) film lead to pronounced polarization and accelerated degradation, highlighting the necessity of improving their low-temperature electrochemical behavior. The electrolyte, which bridges the cathode and anode and governs the formation of electrode–electrolyte interfaces, is of critical importance under low-temperature conditions. In this paper, carbonate electrolyte (E1: 88 wt% 1.2 M LiPF6 in EC/EMC 3/7(w/w) + 10 wt% FEC + 2 wt% VC) and ether-based electrolyte (M47: LiFSI-1.2DME-3TTE) were applied to Nb-NMC811||Si system and long cycling was evaluated at 0 oC. Ether-based electrolyte exhibits outstanding electrochemical cycling at 0 oC, delivering a capacity retention of 80% (M47) vs. 11% (E1) after 580 cycles at C/2 rate. The studies on fading mechanisms of Nb-NMC811||Si system have demonstrated that M47 could significantly reduce surface charge transfer resistance and improve the stability of the morphology.