Regulation of Molecular Microheterogeneity in Electrolytes Enables Ampere-Hour-Level Aqueous LiMnO||LiTiO Pouch Cells.

Aqueous batteries are attractive due to their high safety and fast reaction kinetics, but the narrow electrochemical stability window of HO limits their applications. It is a big challenge to broaden the electrochemical operation window of aqueous electrolytes while retaining fast reaction kinetics. Here, a new organic aqueous mixture electrolyte of manipulatable (3D) molecular microheterogeneity with HO-rich and HO-poor domains is demonstrated. HO-poor domains molecularly surround the reformed microclusters of HO molecules through interfacial H-bonds, which thus not only inhibit the long-range transfer of HO but also allow fast and consecutive Li transport. This new design enables low-voltage anodes reversibly cycling with aqueous-based electrolytes and high ionic conductivity of 4.5 mS cm. LiMnO||LiTiO full cells demonstrate excellent cycling stability over 1000 cycles under various C rates and a low temperature of -20 °C. 1 Ah pouch cell delivers a high energy density of 79.3 Wh kg and high Coulombic efficiency of 99.4% at 1 C over 200 cycles. This work provides new insights into the design of electrolytes based on the molecular microheterogeneity for rechargeable batteries.