Phosphorous-doped bimetallic sulfides embedded in heteroatom-doped carbon nanoarrays for flexible all-solid-state supercapacitors

Flexible supercapacitors (SCs) have become a popular research topic due to their extra-long service life, foldability, and wearability. Nevertheless, their low energy density restricts their applications. Here, we synthesized phosphorus-doped bimetallic sulfides embedded in heteroatom-doped (N, S, and P) carbon shells (P-ZCS/HC) using a simple approach to create high-performance flexible electrodes. The three-dimensional architecture made by interlaced nanosheets was preserved, and raised nanoparticles appeared on the rough surface during the annealing operation, increasing the specific surface area and potential exposure to the electrolyte. It is noteworthy that the optimal P-ZCS/HC electrode possessed a remarkable capacity of 1080 C g−1 at 1 A g−1 along with superb cycling stability. These extraordinary properties were primarily caused by plentiful redox reactions, enhanced conductivity, and synergic effects of the P-doped metal sulfides and heteroatom-doped carbon shells. Density functional theory simulations confirmed the good function of the P-doped electrodes and their ability to boost conductivity, improve reactive dynamics, and promote OH− adsorption. Notably, the assembled all-solid-state hybrid SC exhibited a maximum energy density of 62.9 W h kg−1 and a power density of 16 kW kg−1, while being able to maintain 92.0% of its initial capacity after 10,000 cycles. This systematic report provides new insight into the design and synthesis of electrodes with complex components and outstanding structures for the flexible energy field.