CoFe-PBA templated PDA derived C coated (Co,Fe)O nanoparticles encapsulated with in the porous hollow nanocages as anodes for long-lasting and high-rate lithium-ion batteries and hybrid supercapacitors

Polydopamine (PDA) derived C coated (Co,Fe)O nanoparticles (NPs), templated from CoFe-PBA, have been engineered as high-efficiency anodes for lithium-ion batteries (LIBs) and supercapacitors (SCs) using a coprecipitation method combined with nanoscale Kirkendall diffusion. These NPs are encapsulated within porous hollow nanocages (HNCs), demonstrating exceptional cycling performance. The preparation process involves co-precipitation followed by coating with PDA at different concentrations and subsequent application of the Kirkendall diffusion mechanism, resulting in the formation of (Co,Fe)O@C, (Co,Fe)O@PDA-C-50, and (Co, Fe)O@PDA-C-100 HNCs. This method capitalizes on the synergistic effect of C coating, creating conductive, porous heterostructures that promote fast ion transport, effective electrolyte percolation, and efficient management of volume fluctuations. When employed as anodes for LIBs, the (Co,Fe)O@PDA-C-100 HNCs exhibit outstanding structural durability and high-rate performance, maintaining stability at 0.5 and 1.0 A/g over 300 cycles, with a remarkable rate capability of 283.5mAh/g at 10 A/g. In SCs, the (Co,Fe)O@PDA-C-100 HNCs achieve a capacitance of 1510mAh/g at 1.0 A/g and retain 98 % of their capacity after 15,000 GCD cycles at 2 A/ g in a three-electrode configuration. In hybrid supercapacitor (HSCs) device like (Co,Fe)O@PDA-C-100@NF// RGO@NF, the system delivers the energy density of 30 Wh kg- 1 and a power density of 1059 W kg- 1, with 97 % capacitance retention after 20,000 cycles at 2 A/g. These findings underscore the structural superiority of (Co,Fe) O@PDA-C-100 HNCs.