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

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 (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 degrees 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. An electrolyte design approach with fluorine-free solvent, namely anchored weakly solvated electrolytes, which are prepared by prolonging the chain length of polyoxymethylene ether, can achieve high oxidation/reduction interface stability, rapid lithium-ion de-solvation process and appropriate ionic conductivity in a wide temperature range at moderate salt concentration. image