Design of missing linker defects and tuning Ni-dopants engineering for Co-MOFs to boost rate capability and capacity in supercapacitor

Metal-organic frameworks (MOFs) have emerged as promising supercapacitor electrode materials due to their structural tunability and high density of electroactive sites. However, intrinsically low electrical conductivity fundamentally constrains their electrochemical performance. To overcome this limitation, we implement a defect engineering strategy, constructing missing-linker defects and Ni dopants within 2D CoNi-BTC/IPA nanosheets via one-pot solvothermal synthesis. This synergistic strategy simultaneously modulates the electronic structure of MOFs while generating supplementary electroactive sites, thereby enhancing charge transfer kinetics and specific capacity—collectively enabling exceptional electrochemical performance. The optimized architecture achieves a high specific capacity of 1220.4 F g⁻¹ at a current density of 0.5 A g⁻¹, representing a five-fold improvement compared to Co-BTC (226.9 F g⁻¹ at 0.5 A g⁻¹). Even with an increase in current density from 0.5 to 10 A g⁻¹, it retains an excellent capacity retention rate of 96.8 %. The CoNi-BTC/IPA//AC hybrid supercapacitor device showcases a power density of 687.7 W kg⁻¹ alongside an energy density of 50.4 Wh kg⁻¹. Furthermore, it maintains 80 % capacity retention after undergoing 8000 cycles of charging and discharging.