Construction of chemical self-charging zinc ion batteries based on defect coupled nitrogen modulation of zinc manganite vertical graphene arrays

Abstract

Self-charging power systems, which can simultaneously achieve energy harvesting and storage, play a significant role in the field of energy technology. Nevertheless, the traditional integrated systems are not only severely restricted by the energy availability, but also have a complex architecture. Herein, a novel chemical self-charging aqueous zinc ion battery (CSCAZIB) with a two-electrode structure is reported. In such a self-powered system, the discharged cathode and oxygen in air will undergo spontaneous redox reactions and self-charging. A defect coupled nitrogen modulated zinc manganite vertical graphene array (N-ZnMn₂O_4−x/VG) is designed as the cathode for CSCAZIBs. Benefiting from the high surface area, rich active sites, fast electron/ion diffusion, and strong structural stability, the assembled device not only shows a large specific capacity (222 mA h g⁻¹ at 0.1 A g⁻¹) and good rate capability (61.58% retention from 0.1 to 3 A g⁻¹) along with admirable cycle life (92.6% retention after 3000 cycles at 1.0 A g⁻¹), but also delivers excellent energy density (278 W h kg⁻¹) and remarkable power density (3.62 kW kg⁻¹). The as-assembled CSCAZIBs could be self-charged to 1.5 V after oxidation in an ambient environment for 30 h, and present a decent specific capacity of up to 176.8 mA h g⁻¹ at 0.2 A g⁻¹. Significantly, even in chemical or/and galvanostatic charging hybrid modes, the CSCAZIBs can still work normally. This work expands a promising prospect for rechargeable aqueous metal ion batteries, and simultaneously realizes energy harvesting, conversion and storage.