Synergistic Corrosion Engineering on Metallic Manganese Toward High‐Performance Electrochemical Energy Storage

Abstract MnO/rGO with enhanced electrochemical kinetic properties is widely investigated as electrode for high‐performance electrochemical energy storage (EES) devices. However, the synthesis of MnO/rGO via traditional methods suffers from low atomic utilization and complex techniques that are undesirable for practical implementation. Different from existing fabrication strategies, here using metallic manganese as Mn source, a novel, eco‐friendly, and corrosion engineering‐based approach to address the above issues is demonstrated. It is thermodynamically feasible as supported by the E‐pH analysis and for the first time, a significant synergetic effect is observed between NH₄⁺ and GO in strengthening the metallic Mn corrosion reaction. Particularly, in the “ammonia circulation” process, the NH₃ molecule, derived from NH₄⁺, acts as a “carrier” for Mn²⁺ to facilitate its transfer by forming [Mn(NH₃)₂]²⁺, which effectively prevents “in situ corrosion”. The phase and structure evolution during the reaction are clarified, and the synergistic corrosion mechanism is also proposed. Benefiting from the efficient lithium‐ion evolution kinetics, Mn─O─C bond formed between MnO and rGO and outstanding structural integrity, the resultant MnO/rGO demonstrates exceptional EES performances in both lithium‐ion batteries and lithium‐ion capacitors. This finding will offer potential for mild, cost‐effective, and environmentally friendly fabrication of other graphene‐based metal oxide electrodes using corrosion engineering.