Systematic Modification of MoO3-Based Cathode by the Intercalation Engineering for High-Performance Aqueous Zinc-Ion Batteries

Aqueous Zn-ion batteries are attracting extensive attention, but their large-scale application is prevented by the poor electrochemical kinetics and terrible lifespan. Herein, a strategy of introducing the conductive poly(3,4-ethylenedioxythiophene) (PEDOT) into the interlayers of alpha-MoO3 is reported to systematically overcome the above shortcomings. Through data analyses of the cyclic coltammetry, electrochemical impedance spectroscopy, and galvanostatic intermittent titration technique, the electrochemical kinetics of the PEDOT-intercalated MoO3 (PEDOT-MoO3) is proved to be significantly improved. The first-principles calculations microscopically disclose that the changed energy band and the lowered binding energy between Zn2+ and host O2- boost electrochemical kinetics of PEDOT-MoO3. Meanwhile, its decreased hydrophilicity and the suppressed dissolution of molybdenum stabilizes the repeated cycling processes. Interestingly, it is found that excellent electrochemical kinetics of cathode electrode can restrain the growth of zinc dendrite on the Zn anode, prolonging the lifespan of aqueous Zn-ion batteries. As a result, the PEDOT-MoO3 exhibits the enhanced specific capacity (341.5 vs 146.7 mAh g(-1) at 0.1 A g(-1)), high rate capacity (178.2 vs 19.4 mAh g(-1) at 30 A g(-1)) and prolonged cycling stability (77.6% capacity retention over 500 cycles vs 2.3% capacity retention over 100 cycles at 30 A g(-1)) compared with pristine MoO3. Moreover, the PEDOT-MoO3 as cathode of quasi-solid-state ZIBs also delivers an impressive electrochemical performance.