500-mW cm⁻² underwater Zn-H₂O₂ batteries with ultrafine edge-enriched electrocatalysts

Aqueous metal-H₂O₂ cells are emerging as power batteries because of their large theoretical energy densities and multiple application scenarios, especially in underwater environments. However, the peak power densities are less than 300 mW cm⁻² for most reported metal-H₂O₂ cells based on Mg/Al or their alloys due to the self-corrosion. Herein, we reported a Zn-H₂O₂ cell with ultrafine bean-pod-like ZnCo/N-doped electrocatalysts that were synthesized via multifunctional single-cell-chain biomass. The electrocatalyst provides abundant active sites on the crinkly interface and offers a shortened pathway for electron/ion transfer due to the desired root-like carbon nanotube (CNT) arrays. Therefore, the optimized electrocatalyst exhibited outstanding oxygen reduction reaction (ORR) activity, with high E_1/2 (0.90 V) and E_onset (1.01 V) values. More importantly, Zn-H₂O₂ batteries achieve a record-breaking peak-power density of 510 mW cm⁻² and a high specific energy density of 953 Wh kg⁻¹.