Anchored Weakly‐Solvated Electrolytes for High‐Voltage and Low‐Temperature Lithium‐ion Batteries

Abstract

AbstractElectrolytes endowed with high oxidation/reduction interfacial stability, fast Li‐ion desolvation process and decent ionic conductivity over wide temperature region are known critical for low temperature and fast‐charging performance of energy‐dense batteries, yet these characteristics are rarely satisfied simultaneously. Here, we report anchored weakly‐solvated electrolytes (AWSEs), that are designed by extending the chain length of polyoxymethylene ether electrolyte solvent, can achieve the above merits at moderate salt concentrations. The −O−CH2−O− segment in solvent enables the weak four‐membered ring Li+ coordination structure and the increased number of segments can anchor the solvent by Li+ without largely sacrificing the ionic dissociation ability. Therefore, the single salt/single solvent AWSEs enable solvent co‐intercalation‐free behavior towards graphite (Gr) anode and high oxidation stability towards high‐nickel cathode (LiNi0.8Co0.1Mn0.1O2‐NCM811), as well as the formation of inorganic rich electrode/electrolyte interphase on both of them due to the anion‐rich solvation shells. The capacity retention of Gr||NCM811 Ah‐class pouch cell can reach 70.85 % for 1000 cycles at room‐temperature and 75.86 % for 400 cycles at −20 °C. This work points out a promising path toward the molecular design of electrolyte solvents for high‐energy/power battery systems that are adaptive for extreme conditions.