Metal-organic-framework-derived multi-heteroatom doped Cu1.8Se/C composites for high-performance Na-ion hybrid capacitor

Abstract A series of smulti-heteroatom doped Cu1.8Se/C composites are synthesized through a one-step direct selenization of Cu-based MOF containing hexa(4-carboxyl-phenoxy)-cyclotriphosphazene (HCTP-COOH) ligand. The MOF-derived Cu1.8Se/C composites with nanosheet structures are characterized to be Cu1.8Se nanoparticles embedded in carbon matrix doped with N, P and O atoms. The superior sodium-storage performance of Cu1.8Se/C-450 composite is proven to be resulted from the high specific surface area, the unique structure and the multi-heteroatom doping. The Na-ion half-cells from Cu1.8Se/C-450 electrodes exhibit a maximum capacity of 372.9 mA h g−1 at 50 mA g−1, an satisfactory rate capacity (133.3 mA h g−1 at 5 A g−1) and modest cycling stability. A sodium-ion hybrid capacitor (SHIC) device Cu1.8Se/C-450//AC assembled with Cu1.8Se/C-450 and AC shows desirable energy-storage properties. It delivers a maximum energy density of 65.8 W h kg−1 at 81.4 kW kg−1, and a capacity retention of 75.3% with 3000 testing cycles at 2 A g−1 with the operation voltage window of 0–4.0 V. The prospects of stated materials synthesis strategy and application of the as-prepared material Cu1.8Se/C-450 in SHIC device are presented.