Preparation of NiCo2S4@Nd2O3 composite electrode materials and investigation of their electrochemical performance in supercapacitor devices
摘要
In this study, a NiCo2S4@Nd2O3 core–shell structured positive electrode was constructed via a two-step strategy. First, NiCo2S4 nanorod cores were synthesized through a hydrothermal–sulfidation process, followed by the in situ coating of Nd2O3 nanosheet shells using a sol–gel method. The CNT negative electrode was fabricated by loading carbon nanotubes onto a carbon paper substrate via vacuum filtration. Multiscale characterizations confirm the formation of a tightly integrated heterogeneous interface between the NiCo2S4 nanorod core and the Nd2O3 nanosheet shell, which effectively mitigates the volume expansion of NiCo2S4 and accelerates charge transport. Electrochemical measurements reveal that the NiCo2S4@Nd2O3 core–shell electrode delivers a high specific capacitance of 2351 F g− 1 at 1 A g− 1, with a capacitance retention of 77.4% at 20 A g− 1, significantly outperforming pristine NiCo2S4 or Nd2O3 electrodes. An asymmetric supercapacitor assembled using the NiCo2S4@Nd2O3 positive electrode and the CNT negative electrode exhibits outstanding overall performance within a wide voltage window of 0–1.6 V. It achieves a specific capacitance of 242 F g− 1 at 1 A g− 1 and retains approximately 93% of its initial capacitance after 6000 charge–discharge cycles. Moreover, the device delivers an energy density of 86.4 Wh kg− 1 at a power density of 800 W kg− 1, and still maintains 62.4 Wh kg− 1 when the power density increases to 12 000 W kg− 1. The core–shell structural design strategy proposed in this work provides an effective pathway for the development of high-performance supercapacitors and holds significant promise for applications in flexible energy storage systems.