Introducing Ce into the interface of NiCo LDH@PBAs to build multi core–shell electrode with superior stability of supercapacitor

Abstract

Core-shell electrodes have been used in many fields, however, the poor conductivity caused by the weak interfacial interaction limits the practical application of the composites. Herein, a novel multi core–shell material (NiCo-Ce@PBAs) used as electrode in supercapacitor is prepared using Ce as bridge to connect the core (NiCo LDH) and shell (NiCo PBAs). Benefiting from the gradient orbital coupling of 2p-4f-π derived from O-Ce-C≡N unit sites in NiCo-Ce@PBAs, the composite shows enhanced covalency and determines to delocalize the electronic expansion in the interaction. Besides, the redox pair of Ce3+-Ce4+ also makes great contribution to expedite the charge transfer as well as enhancing the binding energies of metals in core and shell. Overall, the optimized core–shell electrodes show excellent electrochemical performance with high area-specific capacitance of 1847 F g−1 at 1 A g−1, which is much higher than that of LDH-based electrodes ever reported. In addition, the electrode is found better cyclic performance than the others (95.7 % even after 10,000 cycles), which is due to the fact that the special 4f empty orbits can store partial electrons, thus decreasing the polarization phenomenon. It also shows great practical application when using commercial activated carbon as cathode. This work illustrates a new strategy to construct core–shell electrodes with strong interfacial interaction as well as revealing the important role of orbital theory in the design of multi core–shell electrodes.