A Safer High‐Energy Lithium‐Ion Capacitor Using Fast‐Charging and Stableω‐Li3V2O5Anode

Abstract Lithium‐ion capacitors (LICs) are flourishing toward high energy density and high safety, which depend significantly on the performance of the intercalation‐type anodes used in LICs. However, commercially available graphite and Li 4 Ti 5 O 12 anodes in LICs suffer from inferior electrochemical performance and safety risks due to limited rate capability, energy density, thermal decomposition, and gassing issues. Here a safer high‐energy LIC based on a fast‐charging ω ‐Li 3 V 2 O 5 ( ω ‐LVO) anode with a stable bulk/interface structure is reported. The electrochemical performance, thermal safety, and gassing behavior of the ω ‐LVO‐based LIC device are investigated, followed by the exploration of the stability of the ω ‐LVO anode. The ω ‐LVO anode exhibits fast lithium‐ion transport kinetics at room/elevated temperatures. Paired with an active carbon (AC) cathode, the AC|| ω ‐LVO LIC with high energy density and long‐term endurability is achieved. The accelerating rate calorimetry, in situ gas assessment, and ultrasonic scanning imaging technologies further verify the high safety of the as‐fabricated LIC device. Theoretical and experimental results unveil that the high safety originates from the high structure/interface stability of the ω ‐LVO anode. This work provides important insights into electrochemical/thermochemical behaviors of ω ‐LVO‐based anodes within LICs and offers new opportunities to develop safer high‐energy LIC devices.