Uncovering Synergistic Effects of Electrode/Electrolyte Toward Concerted Cathodic Structure Stabilization for Superior‐Performance Aqueous Zn‐δ‐MnO₂ Battery

Rechargeable aqueous Zn‐δ‐MnO 2 batteries, featuring high safety, high theoretical capacity, and low cost, have emerged as promising candidates for grid‐scale energy storage systems. Nevertheless, the severe cathodic structural degradation greatly hinders its further commercial application. Herein, a facile coupling engineering strategy, employing the Ti 3 C 2 T x MXene skeleton coupled with electrolyte additive K 2 SO 4 to reinforce the structural stability of the δ‐MnO 2 cathode is proposed. Notably, the designed K‐birnessite δ‐MnO 2 /Ti 3 C 2 T x composite cathode (KMO/Ti 3 C 2 ) coupled with K 2 SO 4 electrolyte additive exhibits unique electrode/electrolyte synergistic effects on inhibiting the cathodic structural collapse and promoting the Mn 2+ electrodeposition. Meanwhile, the plating/stripping reversibility of the Zn anode is considerably improved by manipulating the formation of zinc dendrites. Consequently, the Zn//KMO/Ti 3 C 2 battery achieves the remarkable specific capacity of 502.2 mAh g −1 at 0.3 A g −1 and 371.1 mAh g −1 at 2.0 A g −1 . Furthermore, after 9500 cycles at a high current density of 10 A g −1 , the capacity retention reaches 93.3%. Besides, the dendrite‐free Zn anode delivers excellent cycling stability (over 4800 h at 0.2 mA cm −2 ) and high coulombic efficiency (99.9% after 2300 cycles). The synergistic effect of electrode/electrolyte provides distinctive insights into the structural stabilization of the manganese‐based cathode to improve the overall performance of batteries.