Environmentally Benign and Long Cycling Mn-Ion Full Batteries Enabled by Hydrated Eutectic Electrolytes and...

Aqueous rechargeable manganese (Mn)-ion batteries have recently emerged as a promising candidate for multivalent ion rechargeable batteries. However, challenges remain, particularly in expanding the electrolyte's voltage window and identifying compatible anode materials. Herein, we introduce a Mn-ion full battery comprising a nickel hexacyanoferrate (NiHCF) cathode, a perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) anode, and a novel hydrated eutectic electrolyte formulated from Mn(ClO₄)₂·6H₂O and acetamide. This electrolyte composition, optimized for molar ratio, provides a stable solvation structure that suppresses water reactivity and supports high ionic conductivity, as confirmed by spectroscopic and molecular dynamics analyses. The PTCDI anode facilitates highly reversible Mn²⁺ storage via a unique enolization redox reaction, delivering exceptional rate capability and cycling stability. As a result, the NiHCF||PTCDI full battery achieves a 1.2 V plateau, excellent rate performance (up to 5.0 A g^-1), and long cycling life with 95.6% capacity retention over 1200 cycles at 1.0 A g^-1. This study proposes a feasible strategy for the construction of environment-friendly, long-life and low-cost aqueous Mn-ion full batteries, offering a sustainable and high-performance solution for future energy storage applications.