Two Birds with One Stone: Boosting Zinc-Ion Insertion/Extraction Kinetics and Suppressing Vanadium Dissolution of VO via La Incorporation Enable Advanced Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) with cost-effective and safe features are highly competitive in grid energy storage applications, but plagued by the sluggish Zn diffusion kinetics and poor cyclability of cathodes. Herein, a one-stone-two-birds strategy of La incorporation (La-VO) is developed to motivate Zn insertion/extraction kinetics and stabilize vanadium species for VO. Theoretical and experimental studies reveal the incorporated La ions in VO can not only serve as pillars to expand the interlayer distance (11.77 Å) and lower the Zn migration energy barrier (0.82 eV) but also offer intermediated level and narrower band gap (0.54 eV), thus accelerating the electron/ion diffusion kinetics. Importantly, the steadily doped La ions effectively stabilize the V-O bonds by shortening the bond length, thereby inhibiting vanadium species dissolution. Therefore, the resulting La-VO-ZIBs deliver an exceptional rate capacity of 405 mA h g (0.1 A g), long-term stability with 93.8% retention after 5000 cycles (10 A g), and extraordinary energy density of 289.3 W h kg, outperforming various metal-ions-doped VO cathodes. Moreover, the La-VO pouch cell presents excellent electrochemical performance and impressive flexibility and integration ability. The strategies of incorporating rare-earth-metal ions provide guidance to other well-established aqueous ZIBs cathodes and other advanced electrochemical devices.