Transition metal oxides (TMOs) are typical host materials for Zn 2+ storage in aqueous zinc-based energy storage systems, whereas the strong electrostatic interaction between Zn 2+ and TMO hosts causes severe lattice distortion and structural instability of the TMOs, leading to poor Zn 2+ -storage performance. Herein, we report advanced TMO materials featured by weak lattice distortion and low-barrier ion-transport channels to realize high-performance Zn 2+ storage. Hydrated ruthenium oxide materials are synthesized, whose [RuO 6 ] octahedra present weak intrinsic Jahn-Teller distortion with very slight compression/elongation of Ru O bonds during Zn 2+ storage, and meanwhile, the interlayer water molecules not only dampen the charge transfer between inserted Zn 2+ and the lattice oxygen to weaken the electrostatic interaction between them but also induce Zn 2+ moving through low-energy-barrier integral rotation of octahedral [Zn(H 2 O) 6 ] 2+ cluster to decrease Zn 2+ diffusion resistance in the nanochannels of the cathode material, synergistically enabling high-performance Zn 2+ storage. The cathode materials present a large capacity of 259 mAh/g, good rate performance and an exceptional cycling stability with an average capacity decay rate of only 0.00266 % per cycle over 10,000 cycles, remarkably superior to current TMO cathode materials. This work provides new inspiration for the design of TMO materials for high-performance zinc-based electrochemical energy storage.
Pre-intercalation has emerged as a highly effective strategy to enhance structural integrity and ion transport kinetics in cathodes for aqueous Zn-ion batteries. Here, we report a zinc-ion pre-intercalated hydrate vanadium oxide cathode, in which the initial insertion of Zn 2+ induces a significant expansion of the interplanar spacing, followed by contraction at higher Zn 2+ concentrations owing to strong electrostatic interactions with the V O framework. Such competing expansion and contraction of interplanar spacing enhances the overall electrochemical properties. In addition, the pre-intercalated Zn 2+ facilitates the in situ formation of a Zn 3 (OH) 2 V 2 O 7 ·2H 2 O cathode-electrolyte interphase (CEI) layer, which not only suppresses vanadium dissolution but also regulates the desolvation of hydrated Zn 2+ , thus further enhancing the structural integrity and interfacial kinetics. Benefiting from these merits, the Zn 2+ pre-intercalated hydrate vanadium pentoxide (denoted as 2Zn-VOH) cathode delivers a high capacity of 395 mA h g −1 at 0.1 A g −1 , exhibits excellent cycling stability at both low and high current densities, and retains outstanding performance under low-temperature conditions (295 mAh g −1 at 0.1 A g −1 and − 10 °C, with 83.8 % capacity retention after 1000 cycles at 0.2 A g −1 ).
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