Deciphering Mn²⁺ Solvation and Interfacial Chemistry for Rechargeable Nonaqueous Mn-Metal Batteries

Manganese emerges as a compelling metal anode for multivalent ion batteries given its favorable redox potential (-1.18 V vs standard hydrogen electrode), high theoretical specific capacity (976 mAh g^-1), and large abundance. However, its practical deployment is hindered by kinetic challenges, including strong Mn²⁺ solvation effects, electron repulsion from the half-filled 3d orbital, and surface passivation of oxide layer, which collectively contribute to excessive overpotential during the Mn plating/stripping process. To address these challenges, herein, we propose a synergistic strategy integrating Mn²⁺ solvation regulation using 2-methoxyethylamine (MOEA) and electrode interfacial engineering with indium nitride (InN). Spectroscopic and theoretical analyses reveal that MOEA-regulated Mn²⁺ solvation sheath reduces the energy barrier associated with charge transfer, while InN-coated Mn anode leverages abundant nucleation sites to facilitate Mn deposition. These concerted effects enable remarkable plating/stripping stability of Mn||Mn symmetric cells over 3400 h under 0.2 mA cm^-2 and 0.2 mAh cm^-2. Full cells pairing Mn anodes with pyrene-4,5,9,10-tetraone (PTO) cathodes further validate the strategy's efficacy, delivering a specific capacity of 144 mAh g^-1 at 100 mA g^-1 and a stable cycling for 400 cycles. This work provides fundamental insights into Mn²⁺ solvation and interfacial chemistry for rechargeable Mn-metal batteries.