Constructing C-O-Mn Interface via Graphene Nanoribbons to Enable a Breakthrough in Low-Valent Manganese Oxide Aqueous...

To tackle the constraint of insufficient cathode diversity in conventional aqueous zinc-ion batteries (AZIBs), this study fabricates a C-O-Mn interface via the self-assembly of graphene nanoribbons (GNRs) with MnO, which drives the transformation of rock-salt MnO into polymorphic Mn_xO_y (including MnO₂, Mn-deficient Mn_xO, and MnOOH). The resulting Mn_xO_y features excellent Zn²⁺ affinity and structural stability, rendering it a promising cathode material for AZIBs. The alternating magnetic order of high-spin Mn²⁺ in antiferromagnetic MnO facilitates the formation of a C-O-Mn coupling network with the edges of GNRs, while electrochemical induction further triggers atomic-scale interface reconstruction. This reconstructed C-O-Mn interface exerts a dual function in the material system: on one hand, it promotes the generation of manganese vacancies, thereby driving the structural evolution of MnO into Zn²⁺-affine Mn_xO_y; on the other hand, it stabilizes the oxygen framework through the C-O-Mn bonding network, efficiently suppressing the vacancy-induced structural collapse of Mn_xO_y. Such a synergistic effect enhances the Zn²⁺ diffusion coefficient and reduces the charge transfer resistance simultaneously. The as-prepared cathode exhibits remarkable electrochemical performance, delivering an ultrahigh specific discharge capacity of 620 mAh g^-1 at 0.1 A g^-1 and maintaining a reversible capacity of 175 mAh g^-1 even at 10 A g^-1. Furthermore, it achieves outstanding cycling stability with nearly 100% capacity retention over 1100 cycles.