Ternary Ni/Mn/Cu cations pre-intercalation to realize high-rate vanadium pentoxide hydrate cathode for aqueous zinc-ion batteries

Layered V 2 O 5 ·H 2 O (vanadium pentoxide hydrate) is a highly promising cathode material for aqueous zinc-ion batteries owing to its large interlayer space, variable V valence states, and unique interlayer H 2 O. However, the low electronic conductivity and easily exfoliated lattice layers lead to its poor charge transport kinetics and lattice stability. In this regard, we develop a ternary transition metal ions pre-intercalation strategy, where ternary Ni/Mn/Cu cations are successfully pre-intercalated into V 2 O 5 ·H 2 O by one-step hydrothermal method. It is revealed that Mn cation activates the additional Mn 4+ /Mn 3+ redox reaction, and ternary Ni/Mn/Cu cations cause the strong ion column effect, induce the highest p-band center of O, and improve the electrical conductivity, thus simultaneously enhancing the lattice stability and charge transport kinetics. As a result, the energy density of 391 Wh kg −1 at 0.1 A g −1 and the high-rate capability with a capacity of 240 mAh g −1 at 3 A g −1 after 600 cycles are achieved. Besides, the electrochemical reaction mechanism is revealed to be H + intercalation at high potentials, and followed Zn 2+ intercalation at low potentials, and Zn 2+ intercalation contributes most of the capacity (> 65%) and H + intercalation promotes the optimization of electrochemical performance. Graphical abstract