Rational design of hierarchically-solvating electrolytes enabling highly stable lithium metal batteries with high-nickel cathodes

Abstract

The practical implementation of lithium-metal anodes in high-energy-density batteries with high-nickel cathodes requires the electrolytes that prevent dendrite growth, enable high rate performance, and provide adequate cathodic stability. Traditional electrolytes, however, struggle to fulfill these requirements, and a universal electrolyte design rule remains lacking. Herein, we introduce a hybrid strongly-weakly-solvating solvent (HSWSS) rule, based on Raman shifts and dielectric constants of solvents, to rationally design a multi-component hierarchically-solvating electrolyte (HSE) with a wide electrochemical window (>4.45 V), decent ionic conductivity (4.28 mS cm−1), and dendrite suppression ability. By introducing strongly-solvating cosolvent and appropriate Li salts into weakly solvating solvent, the HSE enable the Li||LiNi0.8Co0.1Mn0.1O2 cell (1.8 mAh cm−2, with 3 times excess ultrathin Li metal) to exhibit a high capacity retention of 74.3 % after 150 cycles at 1 C with a remarkable high Coulombic efficiency of 99.60 %. HSEs can also be conveniently prepared using commercially available solvents and salts, making them practical and cost effective for large-scale lithium-metal battery manufacturing. As a result, this rational design offers a new direction for the development of advanced electrolytes in high-energy-density lithium-metal batteries.