Evaluating\nthe Intrinsic Zinc Storage Capacity of\nCation-Preintercalated Cathode with Electrochemically Active Surface\nArea

The guest cation preintercalation strategy has been widely\nadopted\nto improve the performance of zinc–vanadium batteries. However,\nexisting studies always ignore the deintercalation of guest cations.\nThis work focuses on the severe and universal deintercalation phenomenon\nand confirms the unaltered capacity after deintercalation, indicating\nthat the capacity improvement mechanism cannot be attributed to the\nrole of guest cations. Therefore, after excluding all of the previously\nresearched factors for capacity improvement, the decisive factor is\nidentified as the morphology (surface area). Based on the electrochemically\nactive surface area (ECSA), a quantitative relationship with intrinsic\ncapacity is established for the first time. This guides us to enhance\nbattery capacity via enhancing ECSA through liquid-phase ultrasonic\ncrushing to achieve the highest capacity of cation-preintercalated\nV<sub>2</sub>O<sub>5</sub>·<i>n</i>H<sub>2</sub>O (333.7\nmAh g<sup>–1</sup> at 10 A g<sup>–1</sup>). We believe\nthat the enhanced ECSA is a plausible explanation for the improved\nperformance of hydrated vanadium oxides.