A bifunctional electrolyte for activating Mg–Li hybrid batteries

Abstract

Great progress has been made by regulating functional electrolytes for Mg metal batteries to achieve high capacity and stability. However, the electrolytes enabled by functional additives need to overcome the ever-existing contradiction between increasing additives in the electrolytes and the cell energy densities, which is much more meaningful for practical applications calling for high energy densities of full-cells. Herein, we reported a dual-salt electrolyte, composed of Mg and Li salts, which functions as a bifunctional electrolyte to simultaneously optimize the cathode and anode in Mg batteries. The electrolyte resulted in a unique Mg²⁺/Li⁺ co-insertion organic cathode, enabling a Mg–Li hybrid storage battery of ∼23 W h kg⁻¹ with an ultra-long lifetime of more than 3000 cycles. This work may provide new insights into multiple-ion storage in organic electrodes for advanced batteries, considering the great potential of organic structural design.