Sacrificial template synthesis of hollow-structured NiCoP microcubes as novel electrode materials for asymmetric supercapacitors

Abstract

Transition bimetallic phosphides with optimal composition and morphology are efficient electrocapacitive materials for asymmetric supercapacitors (ASCs). Herein, a unique bimetallic phosphide, NiCoP, with a hollow microcube structure, was synthesized by a sacrificial template method followed by phosphorization calcination. Impressively, the resulting nanosheet-based NiCoP hollow microcube (NiCoP-HMC) electrode exhibits a remarkable specific capacity of 1088.9 C g⁻¹ at 1 A g⁻¹ and superior cycling performance (the capacity remains 90.2% after cycling for 10 000 cycles at 6 A g⁻¹), owing to its unique morphology, the superiority of bimetallic phosphides, and its battery type feature. Furthermore, an ASC was fabricated by using the obtained NiCoP-HMCs as the positive electrode and using active carbon (AC) as the negative electrode. The assembled ASC device delivers a high specific energy of 78.2 W h kg⁻¹ at a specific power of 799.9 W kg⁻¹ and has 84.8% capacity retention over 10 000 cycles at 8 A g⁻¹, demonstrating its great potential for applications in the field of high-capacity supercapacitors. These results illustrate NiCoP-HMCs as promising positive electrode materials for supercapacitors.