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 induces a significant expansion of the interplanar spacing, followed by contraction at higher Zn concentrations owing to strong electrostatic interactions with the VO framework. Such competing expansion and contraction of interplanar spacing enhances the overall electrochemical properties. In addition, the pre-intercalated Zn facilitates the in situ formation of a Zn(OH)VO·2HO cathode-electrolyte interphase (CEI) layer, which not only suppresses vanadium dissolution but also regulates the desolvation of hydrated Zn, thus further enhancing the structural integrity and interfacial kinetics. Benefiting from these merits, the Zn pre-intercalated hydrate vanadium pentoxide (denoted as 2Zn-VOH) cathode delivers a high capacity of 395 mA h g at 0.1 A g, exhibits excellent cycling stability at both low and high current densities, and retains outstanding performance under low-temperature conditions (295 mAh g at 0.1 A g and - 10 °C, with 83.8 % capacity retention after 1000 cycles at 0.2 A g).