<p>Aqueous zinc-ion batteries (AZIBs) have attracted significant interest due to their high specific capacity, low cost, and environmental compatibility. However, their widespread application is hindered by limited cycle stability and poor rate capability. Enhancing the electrochemical performance of cathode materials remains a critical and sustainable strategy to overcome these challenges. This study investigates the influence of hydrothermal reaction time on the structural, morphological, and electrochemical properties of α-MnO₂ cathodes for AZIBs. The α-MnO₂ synthesized under optimized conditions, specifically, a 6-h hydrothermal reaction at 140&#xa0;°C (MnO₂-6&#xa0;h), exhibited a pure single-phase structure, expanded tunnel dimensions, high specific surface area, and enlarged pore volume, resulting in markedly improved electrochemical performance relative to samples prepared with shorter or longer reaction times. These findings provide a foundational understanding crucial for the subsequent development of strategies aimed at enhancing cycle life and rate capability of α-MnO₂-based cathodes in AZIB systems.</p>