Structural design of Prussian blue analogue derived CoSe2/FeSe2@C composites for high-performance all-solid-state flexible asymmetrical supercapacitors

Abstract

Designing and manufacturing novel energy storage device electrode materials, particularly for supercapacitors, are of critical importance. Here, structure-adjustable porous bimetallic selenides (CoSe2/FeSe2) and carbon composites (CoSe2/FeSe2@C), derived from Co/Fe-Prussian Blue analogs, were successfully designed and fabricated as a high-performance positive electrode material. The results demonstrated the size and structure are crucial for electrochemical performance. Specially, the CoSe2/FeSe2@C-2 composite exhibits exceptional performance, with a specific capacitance of 1010 F g−1 at 0.5 A g−1 and prolonged lifespan (maintains 95.5% of its initial capacity after 15,000 cycles at 5 A g−1). The all-solid-state flexible asymmetrical supercapacitors (CoSe2/FeSe2@C-2//AC) were assembled with the positive electrode of CoSe2/FeSe2@C-2, which delivered a high energy density (13.13 Wh kg−1), and exceptional cycling stability (91.17% of the initial capacity after 7000 cycles at 2 A g−1). This work opens up an avenue to synthesize bimetallic selenides with different sizes and structures rationally and environmentally.