Hybrid‐Electrolytes System Established by Dual Super‐lyophobic Membrane Enabling High‐Voltage Aqueous Lithium Metal Batteries

Abstract Aqueous electrolytes and related aqueous rechargeable batteries own unique advantage on safety and environmental friendliness, but coupling high energy density Li‐metal batteries with aqueous electrolyte still represent challenging and not yet reported. Here, this work makes a breakthrough in “high‐voltage aqueous Li‐metal batteries” (HVALMBs) by adopting a brilliant hybrid‐electrolytes strategy. Concentrated ternary‐salts ether‐based electrolyte (CTE) acts as the anolyte to ensure the stability and reversibility of Li‐metal plating/stripping. Eco‐friendly water‐in‐salt (WiS) electrolyte acts as catholyte to support the healthy operation of high‐voltage cathodes. Most importantly, the aqueous catholyte and non‐aqueous anolyte are isolated in each independent chamber without any crosstalk. Aqueous catholyte permeation toward Li anode can be completely prohibited without proton‐induced corrosion, which is enabled by the introduction of under‐liquid dual super‐lyophobic membrane‐based separator, which can realize the segregation of the most effective immiscible electrolytes with a surface tension difference as small as 6 mJ m −2 . As a result, the aqueous electrolyte can be successfully coupled with Li‐metal anode and achieve the fabrication of HVALMBs (hybrid‐electrolytes system), which presents long‐term cycle stability with a capacity retention of 81.0% after 300 cycles (LiNi 0.8 Mn 0.1 Co 0.1 O 2 || Li (limited) cell) and high energy density (682 Wh kg −1 ).