Carbon nanofibers coated with phosphorized CoNi-layered double hydroxide//nitrogen-doped covalent organic framework flexible asymmetric supercapacitors

As worldwide demand for high-performance energy storage rises, supercapacitors have become increasingly prominent due to their superior power capabilities and extended operational lifespan. In this study, CoNi-layered double hydroxide (CoNi-LDH) was deposited onto electrospun carbon nanofibers (CNFs) via a simple hydrothermal method, then by phosphorization to fabricate CoNiP nanostructured arrays to serve as the positive electrode material for an asymmetric supercapacitor. Meanwhile, a covalent organic framework (COF) was synthesized via a solvothermal method, carbonized under a nitrogen atmosphere, and coated onto carbon cloth as the negative electrode material (N-COF). Specifically, CNF/CoNiP-500 achieved a specific capacitance of 675.94 F g −1 at 0.5 A g −1 , while N-COF reached 267.53 F g −1 . The flexible asymmetric supercapacitor based on CNF/CoNiP//N-COF demonstrates outstanding electrochemical behavior: it achieves a specific capacitance of 248.08 F g −1 at 1 A g −1 within a 1.5 V window. The full device provides an energy density of 81.21 Wh kg −1 at a power density of 1499.62 W kg −1 and maintains 90.56 % of its initial capacitance after 10,000 cycles. Phosphorization and nitrogen doping significantly enhanced electrode conductivity and pseudocapacitive performance, providing technological support for the development of next-generation high-performance flexible supercapacitors.