Colloidal Electrolyte Enables Bulk-to-Interface Stabilization for Aqueous Manganese Metal Batteries

Abstract

Abstract Aqueous Mn metal batteries combine the potential for high safety and energy density, yet are limited by high water activity, sluggish Mn2+ desolvation, and severe interfacial parasitic reactions, which cannot be resolved by isolated strategies. Here we develop an ether-oxygen-rich colloidal electrolyte (EORC) whose nanoscale units couple bulk solvation regulation with interfacial stabilization. EORC disrupts the water hydrogen-bond network, partially replaces Mn2+ solvated waters, and enriches ether-oxygen species to reconstruct the electrical double layer. This continuous bulk-to-interface regulation reduces free water activity, lowers desolvation and nucleation barriers, promotes uniform Mn deposition, and suppresses interfacial parasitic reactions, e.g., corrosion and byproducts accumulation. Consequently, Mn∥Mn symmetric cells operate stably for over 3000 h and Mn∥AgVO full cells achieve over 11000 cycles with 93% capacity retention, along with enhanced low-temperature and pouch cell performance. This work offers a transformative strategy that bridges bulk electrolyte chemistry and interfacial electrochemistry for stable aqueous Mn anodes.