Control competing expansion and contraction of interplanar spacing in layer structured cathode for stable and low-temperature zinc batteries

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 ).