Atomic‐Level Regulation of Gibbs Free Energy for Thermodynamically Suppressing Vanadium Dissolution in V <sub>6</sub> O <sub>13</sub> Cathode Toward Stable Zinc Storage
Can Huang, Geng Zhang, T. Liu, T. Liu, Jie Yang, Shuang Hou, Qiang Deng, T. T. Liu, T. T. Liu, Lingzhi zhao
Abstract
ABSTRACT Vanadium oxides have been considered as ideal cathode materials for aqueous zinc‐ion batteries (AZIBs) due to their multivalent characteristics and open framework. Nevertheless, spontaneous vanadium dissolution and inherent low electronic conductivity of vanadium oxides result in severe capacity degradation during prolonged cycling. Herein, we propose a strategy of atomic‐level N refilling oxygen vacancy (V o ) to thermodynamically enhance the intrinsic structural strength of the V 6 O 13 cathode (V 6 O 13 ‐V o ‐N) through regulation of Gibbs free energy (ΔG = ΔH − TΔS). Theoretical calculations indicate that refilled N atoms strengthen V─O bonds by improving orbital hybridization between V 3d and O 2p and reduce the lattice formation energy, endowing V 6 O 13 ‐V o ‐N with enhanced intrinsic structural strength, which contributes to an increased enthalpy change (ΔH). Moreover, N refilling can maintain structural integrity and stabilize oxygen vacancies during dynamic cycling, ultimately leading to a reduced entropy change (ΔS). Consequently, the directional regulation of ΔH and ΔS leads to an elevated ΔG value, establishing a thermodynamic barrier to inhibit spontaneous vanadium dissolution. Additionally, N refilling boosts the intrinsic electronic conductivity of V 6 O 13 ‐V o ‐N, thereby significantly accelerating Zn 2+ storage kinetics. As expected, the V 6 O 13 ‐V o ‐N cathode delivers high specific capacity and excellent long‐cycling stability (90.3% retention after 10 000 cycles at 10 A g −1 ).