A variational method guided confining tip discharge for MOF-derived supercapacitors

Nanosized electrode materials have received wide attention in electrochemistry since their large specific surface areas are the precondition for the excellent performance of electrochemistry, such as supercapacitors, Li-ion batteries, Na-ion batteries, electrocatalysis, photoelectrocatalysis, electrolysis and electrodeposition. However it also leads to the high value of curvature of nanomaterials, causing the unavoidable and non-ignorable leakage currents, and therefore the activity degradation. Here, guided by the variational method, we first theoretically predict that, with giving a certain value of curvature, the paraboloid structure possesses the maximal surface area to greatly reduce the tip-charge, thus guaranteeing the electrochemical performance. Consequently, with using supercapacitors as the model application, this unusual morphological structure was successfully constructed in the metal-organic frameworks (MOFs)-derived [email protected] nanowire arrays ([email protected] NWRs), which largely ensures the [email protected] NWRs || AC device exhibits an ultralow leakage current of 10.28 μA. The low curvature structure of [email protected] NWRs also significantly improves the electrochemical performance of supercapacitors with a large specific capacitance of 1483 C g−1 at 1 A g−1 and a high cyclic stability of 80% capacity maintained over 5000 cycles at 5 A g−1. The finding in this work highlights the great potential of the reasonable material design approach for advanced energy applications.