Interlayer-Engineered 1T-MoSe₂ Enabling Reversible Mn²⁺/H⁺ Hybrid Storage for Aqueous Manganese Batteries

Aqueous manganese batteries are emerging as safe, low-cost options for large-scale energy storage but are limited by sluggish Mn²⁺ diffusion and poor reversibility. Here, we report an interlayer-engineered 1T-phase MoSe₂ cathode enabling fast, reversible hybrid storage of Mn²⁺ and H⁺ ions. Controlled chemical exfoliation induces a metallic phase transition and expands the interlayer spacing, creating a favorable environment for multivalent ion transport. The exfoliated MoSe₂ delivers 153.4 mAh g^-1 at 0.1 A g^-1 and retains 92.5% capacity after 1800 cycles. Kinetic analysis shows a reduced ion migration barrier compared with bulk MoSe₂, highlighting the role of phase engineering and interlayer expansion. Spectroscopic and electrochemical analyses reveal a reversible Mn²⁺/H⁺ co-intercalation mechanism. A full cell paired with a Mn metal anode delivers 165.3 mAh g^-1 and retains 89.9% of its capacity after 2000 cycles, demonstrating the practical feasibility of a rechargeable aqueous Mn-metal battery. This work establishes phase-engineered layered dichalcogenides as a platform for aqueous multivalent batteries and provides design principles to overcome kinetic limitations.