Organic-inorganic hybrids cathode with Hydrogen Bonding Network for highly efficient zinc-ion batteries

Abstract

Organic-inorganic hybridization has been explored to improve the electrochemical performance of electrodes for aqueous zinc-ion batteries. In this work, 4,4′-diamino-2,2′-bipyridine (DB) and 2,6-diaminoanthraquinone (DAAQ) intercalated vanadium pentoxide (HVO-DB and HVO-DAAQ) are prepared by pre-intercalation techniques. The incorporation of DAAQ and DB play a pivotal role in not merely enhancing the interlayer spacing of VO_x slabs substantially, which consequently elevates the efficiency of ion diffusion processes, but also in reinforcing the overall structural stability through promoting the establishment of a robust hydrogen bond network. Moreover, the abundant CO redox-active sites present in DAAQ actively coordinate with Zn²⁺ during the insertion process, leading to a notable enhancement in specific capacity. HVO-DAAQ demonstrates an exceptional specific capacity of 395 mA h g⁻¹ when charged at 0.1 A g⁻¹, coupled with remarkable cycling stability, retaining 87.8 % of its capacity even after enduring 2000 cycles at a high rate of 5 A g⁻¹, and superior rate performance. Ex-situ characterization reveals the exceptional reversibility of Zn²⁺ insertion, alongside the remarkable capacity of hydrogen bond networks to undergo disruption and subsequent reconstruction, showcasing a dynamic and resilient structural adaptability. Furthermore, this work provides insights into the synergistic energy storage mechanism in the organic-inorganic hybrids cathode for aqueous zinc-ion batteries.