High‐Energy Aqueous/Organic Hybrid Batteries Enabled by Cu²⁺ Redox Charge Carriers

Lithium||sulfur (Li||S) batteries are considered as one of the promising next‐generation batteries due to the high theoretical capacity and low cost of S cathodes, as well as the low redox potential of Li metal anodes (−3.04 V vs. standard hydrogen electrode). However, the S reduction reaction from S to Li 2 S leads to limited discharge voltage and capacity, largely hindering the energy density of Li||S batteries. Herein, high‐energy Li||S hybrid batteries were designed via an electrolyte decoupling strategy. In cathodes, S electrodes undergo the solid‐solid conversion reaction from S to Cu 2 S with four‐electron transfer in a Cu 2+ ‐based aqueous electrolyte. Such an energy storage mechanism contributes to enhanced electrochemical performance of S electrodes, including high discharge potential and capacity, superior rate performance and stable cycling behavior. As a result, the assembled Li||S hybrid batteries exhibit a high discharge voltage of 3.4 V and satisfactory capacity of 2.3 Ah g −1 , contributing to incredible energy density. This work provides an opportunity for the construction of high‐energy Li||S batteries.