Regulating core-shell interfacial interaction by oxygen bridging for enhancing electrochemical performance

Abstract

It is crucial to design core-shell materials with interfacial interaction, which enhances their electrical conductivity, structural stability, and facilitates efficient charge transfer at the interface. In this study, two core-shell electrodes NC-O-PBA (NC: nickel cobalt layered double hydroxides, O-bridged core-shell materials) and LCCH@Ni(OH)2@PBA (LCCH: linear cobalt carbonate hydroxides, PBA: prussian blue analogs) were fabricated via interfacial contrast strategy to investigate the optimization function of oxygen at core-shell interface. Results show that as-prepared NC-O-PBA with high oxygen content creates an ideal condition for the formation of oxygen bridging. Moreover, the NC-O-PBA promotes a strong bond cooperation between core (NiCo-LDH) and shell (NiCo PBAs). The unit in PBAs can partly coordinate with the oxygen (from hydroxyl groups and interlayer ions in LDH), thus forming a strong interfacial coordination bonding between LDH and PBAs (Ni/Co(LDH)-O-CN(PBAs) or Ni/Co(LDH)-O-Ni/Co(PBAs)). Subsequently, NC-O-PBA electrode presents a high capacity of 1040.6 F g−1 at 1 A g−1 and a retention rate of 87.5% at 1500 cycles of 3 A g−1, much higher than LCCH@Ni(OH)2@PBA (462.4 F g−1 and 41.26%). Finally, in-situ Raman results demonstrated the enhanced Faraday redox reaction of NC-O-PBA. This interfacial contrast strategy and oxygen-bridged approach provide a novel idea for the development of high-performance core-shell electrode materials and facilitate deeper insights into mechanism.