Harnessing Electron Delocalization for Enhanced Capacity and Stability in Heterostructured Cathode for All‐Solid‐State Thin‐Film Battery

Abstract Due to the maturation of Internet of Things (IoT) technology, all‐solid‐state thin‐film batteries (ATFBs) have become an optimal power source for microelectronic devices by virtue of their exceptional compatibility and ease of integration. Nevertheless, ATFBs face challenges related to the electron and ion transport properties of electrode materials, resulting in a limited specific capacity and comprehensive performance that often falls short of practical application requirements. Herein, a strategy of constructing V 2 O 5 ‐Cu 2 V 2 O 7 heterostructures is proposed with an electron delocalization interface via introducing copper heteroatom, which effectively improves the lithium storage capacity. Meanwhile, the construction of the built‐in electric field and the electron delocalization effect enhance the electron and ion transport kinetics. Consequently, the initial discharge specific capacity of the heterostructured thin‐film cathode is up to 76.4 µAh cm −2 µm −1 and exhibited ultra‐high cycling stability over 4000 cycles in liquid half cells. Finally, benefiting from this high capacity and stable heterostructured cathode, a highly durable and flexible ATFB is further demonstrated. This work provides new ideas to further improve the energy density and cycling stability of thin‐film cathodes and is expected to extend the potential applications in microelectronics.