Stress-release design for high-capacity and long-time lifespan aqueous zinc-ion batteries

Mn-based cathodes are promising candidates for aqueous zinc-ion batteries (ZIBs) owing to the merits of low toxicity, high energy density, and safety. However, due to the strong electrostatic resistance of Zn²⁺, ZIBs usually suffer from huge mechanical stress during cycling and result in serious volume fluctuation and structural instability. Correspondingly, it is still significant to explore an effective stress-release strategy for achieving a long-time cycle lifespan with high available capacity. Herein, we report an urchin-like hierarchical porous Mn₂O₃ yolk-shell microspheres (HP–Mn₂O₃-YSMSs). As a proof of concept, the designed hierarchical porous yolk-shell architecture effectively releases the internal stresses from both radial and tangential directions via the internal void space and porous shell. Specifically, the HP-Mn₂O₃-YSMSs manifest high reversible capacity (311 mAh/g at 0.1 A/g) and long cycle life (81.3% retention at 2.0 A/g after 4000 cycles). This effective stress-release design opens a new direction for the development of the structural stable electrodes for practical energy applications.