Boron-Doped Trimetallic Cu-Ni-Co Oxide Nanoneedles for Supercapacitor Application
Iftikhar Hussain, Terry Mak, Kaili Zhang
Abstract
Doping has been one of the efficient ways in incorporating potential elements to further increase electrode efficiencies. The introduction of boron as a dopant reinforces transition metal to oxide bonding and makes it stable during the cycling process. Herein, we prepared Cu-Ni-Co oxide (CNCO) with agglomerated nanoneedle-like structures in the first step and then structurally doped it with boron (CNCO-D-SD) in the second step. The agglomerated nanoneedle-like structures with merged tips were retained with boron doping, but stability was decreased. Then, we evaluated the incorporation of boron in one step, and, interestingly, it resulted to self-organized, boron-doped Cu-Ni-Co oxide (CNCO-D-SO) one-dimensional (1D) vertically aligned nanoneedle-like structures. Herein, boric acid acted as a dopant as well as a structural-directing agent. The CNCO-D-SO exhibited superior overall electrochemical performance to the CNCO and CNCO-D-SD. Interestingly, the as-assembled hybrid supercapacitor (HSC) device made from CNCO-D-SO//rGO showed outstanding stability (87% after 8,000 cycles) compared to CNCO-D-SD//rGO (46% after 5,000 cycles) and bare CNCO//rGO (53% after 5,000 cycles). This study demonstrates that doping can improve the stability and/or capacity of Cu-Ni-Co oxide, but the nature of the active materials is also equally important for achieving satisfactory performance. Furthermore, this study suggests a more efficient as well as time-, energy-, and cost-saving preparation of structured electrodes. Overall, the outcomes showed that the as-assembled CNCO-D-SO//rGO HSC device had higher storage capacity, better stability and conductivity, and scalable time-saving fabrication, suggesting that it has great potential in next-generation energy storage applications.