Electrolyte Engineering to Construct Robust Interphase with High Ionic Conductivity for Wide Temperature Range Lithium Metal Batteries.

Abstract

Unstable interphase formed in conventional carbonate-based electrolytes significantly hinders the widespread application of lithium metal batteries (LMBs) with high-capacity nickel-rich layered oxides (e.g., LiNi0.8Co0.1Mn0.1O2, NCM811) over a wide temperature range. To balance ion transport kinetics and interfacial stability over wide temperature range, herein a bifunctional electrolyte (EAFP) tailoring the electrode/electrolyte interphase with 1,3-propanesultone as an additive was developed. The resulting cathode-electrolyte interphase with an inorganic inner layer and an organic outer layer possesses high mechanical stability and flexibility, alleviating stress accumulation and maintaining the structural integrity of the NCM811 cathode. Meanwhile, the inorganic-rich solid electrolyte interphase inhibits electrolyte side reactions and facilitates fast Li+ transport. As a result, the Li||Li cells exhibit stable performance in extensive temperatures with low overpotentials, especially achieving a long lifespan of 1000 h at 30 °C. Furthermore, the optimized EAFP is also suitable for LiFePO4 and LiCO2 cathodes (1000 cycles, retention: 67 %). The Li||NCM811 and graphite||NCM811 pouch cells with lean electrolyte (g/Ah grade) operate stably, verifying the broad electrode compatibility of EAFP. Notably, the Li||NCM811 cells can operate in wide climate range from -40 °C to 60 °C. This work establishes new guidelines for the regulation of interphase by electrolytes in all-weather LMBs.