High-performance zinc-ion storage enabled by layer-structured hydrated ruthenium oxide cathode

Abstract

Transition metal oxides (TMOs) are typical host materials for Zn²⁺ storage in aqueous zinc-based energy storage systems, whereas the strong electrostatic interaction between Zn²⁺ and TMO hosts causes severe lattice distortion and structural instability of the TMOs, leading to poor Zn²⁺-storage performance. Herein, we report advanced TMO materials featured by weak lattice distortion and low-barrier ion-transport channels to realize high-performance Zn²⁺ storage. Hydrated ruthenium oxide materials are synthesized, whose [RuO₆] octahedra present weak intrinsic Jahn-Teller distortion with very slight compression/elongation of RuO bonds during Zn²⁺ storage, and meanwhile, the interlayer water molecules not only dampen the charge transfer between inserted Zn²⁺ and the lattice oxygen to weaken the electrostatic interaction between them but also induce Zn²⁺ moving through low-energy-barrier integral rotation of octahedral [Zn(H₂O)₆]²⁺ cluster to decrease Zn²⁺ diffusion resistance in the nanochannels of the cathode material, synergistically enabling high-performance Zn²⁺ 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.