Constructing C–O–Mn Interface via Graphene Nanoribbons to Enable a Breakthrough in Low-Valent Manganese Oxide Aqueous Zinc-Ion Battery Cathodes

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 MnxOy (including MnO₂, Mn-deficient MnxO, and MnOOH). The resulting MnxOy 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 MnxOy; on the other hand, it stabilizes the oxygen framework through the C-O-Mn bonding network, efficiently suppressing the vacancy-induced structural collapse of MnxOy. 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.