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

Abstract

Electrolytes 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 (LiNi_0.8Co_0.1Mn_0.1O₂-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.