Eliminating Local Electrolyte Failure Induced by Asynchronous Reaction for High‐Loading and Long‐Lifespan All‐Solid‐State Batteries

The design of practical cathodes with high areal capacity in polymer‐based all‐solid‐state batteries remains challenged by the absence of an effective guiding principle that prolongs battery life‐span. Unlike liquid batteries, the notorious interface incompatibility between cathodes and electrolytes limited the cycling life of the all‐solid‐state batteries. Herein, this study proposes a dynamically stable cathode design with a fully covered surface, effectively mitigating interface failure and enabling the cyclic time of batteries with a cathode loading of 12.7 mg cm‒2 over 10 000 h. This study unveils the importance of local state of charge in affecting the interfacial properties of particles through local oxidative‐stability of electrolytes on the interface. This study shows that the phenomena can be strongly influenced by the porosity of the cathode through the perspective of discreteness of ion transport. These insights and approach provide a broader promise for solid batteries for long lifetime. Simultaneously achieving high‐energy cathode and long cycle life is still challenged by the interfacial stability under high‐voltage and high loadings. Here, this study reveals the role of cathode structure on electrochemical stability of electrolytes. This diagnosis inspires a universal and practical electrode fabrication method, enabling all‐solid‐state batteries with high loading to exhibit extremely long cyclic time at high cut‐off voltages.