Supercapacitive study for electrode materials around the framework-collapse point of a Ni-based coordination polymer

A coordination polymer precursor, namely Ni-TATB, has been synthesized from 4,4 ',4 ''-s-triazine-2,4,6-triyl-tribenzoate (H(3)TATB) as a tripodal ligand and nickel acetate providing nickel metal nodes. According to the thermogravimetric curve, Ni-TATB is calcined at four temperatures of 300 degrees C, 365 degrees C, 375 degrees C and 400 degrees C around the collapse point (370 degrees C), and the corresponding products are obtained, namely, Ni-TATB-300, Ni-TATB-365, Ni-TATB-375 and Ni-TATB-400, respectively. The characterization results show that below 370 degrees C, with the increase of the calcination temperature, the Ni-TATB skeleton structure will be retained, and more Ni(ii) species are exposed on the surface, resulting in the improvement of the electrochemical performance. However, the calcination temperature selected above 370 degrees C will destroy the framework structure of MOFs and reduce Ni(ii) to Ni(0), resulting in a significant decrease in the performance. Electrochemical performance tests show that the Ni-TATB-365 electrode exhibits a maximum specific capacity of 294.5 C g(-1) at a current density of 1.0 A g(-1), superior to the other electrodes, suggesting that high-temperature activation while maintaining the framework architecture of the coordination polymer can effectively enhance the final performance. Additionally, the asymmetric supercapacitors, which consist of activated carbon (AC) and a Ni-TATB-365 device, Ni-TATB-365//AC, deliver a higher energy density of 24.44 W h kg(-1), superior cycling stability and practical applications in powering LEDs.