Regulating the electrolyte solvation structure by weakening the solvating power of solvents for stable lithium metal batteries

Rational electrolyte design is essential for stabilizing high-energy-density lithium (Li) metal batteries but is plagued by poor understanding on the effect of electrolyte component properties on solvation structure and interfacial chemistry. Herein, regulating the solvation structure in localized high-concentration electrolytes (LHCE) by weakening the solvating power of solvents is proposed for high-performance LHCE. 1,3-dimethoxypropane (DMP) solvent has relatively weak solvating power but maintains the high solubility of Li salts, thus impelling the formation of nanometric aggregates where an anion coordinates to more than two Li-ions (referred to AGG-n) in LHCE. The decomposition of AGG-n increases the LiF content in solid electrolyte interphase (SEI), further enabling uniform Li deposition. The cycle life of Li metal batteries with DMP-based LHCE is 2.1 times (386 cycles) as that of advanced ether-based LHCE under demanding conditions. Furthermore, a Li metal pouch cell of 462 Wh kg(-1) undergoes 58 cycles with the DMP-based LHCE pioneeringly. This work inspires ingenious solvating power regulation to design high-performance electrolytes for practical Li metal batteries.

Automated summary

Rational electrolyte design is proposed by regulating the solvation structure in localized high-concentration electrolytes (LHCE) through weakening the solvating power of solvents. The use of 1,3-dimethoxypropane (DMP) solvent leads to the formation of nanometric aggregates (AGG-n) where an anion coordinates to more than two Li-ions in LHCE. The Li metal batteries with DMP-based LHCE demonstrate significantly improved cycle life and high energy density compared to advanced ether-based LHCE under demanding conditions.