Mitigating self-discharge in supercapacitors through strategic mesoporous structural modification of NiCo layered double hydroxides

Abstract

Nickel - Cobalt layered double hydroxide (NiCo LDH) based supercapacitors suffer from severe self-discharge due to their uneven charge distribution, which affects the application of supercapacitors (SCs) in real life. In this paper, three-dimensional self-supported mesoporous NiCo layered double hydroxide mesoporous on nickel foam (NF) (NiCo LDHMs/NF) was prepared by H2O2 etching. The self-discharge phenomenon of supercapacitors assembled using the reaction-derived NiCo LDHMs/NF as the positive electrode and activated carbon as the negative electrode is significantly suppressed. Comparing with the original NiCo LDH devices, the successful construction of mesoporous structures in NiCo LDH resulted in slower open-circuit voltage (OCV) decay (0.93 V vs. 0.59 V in the range of open-circuit voltage of 1.8 V for the same time of 7200 S), and lower leakage current (0.09 mA vs. 0.18 mA at 1.8 V). Due to the formation of mesoporous structure, the charged ions adsorbed on the electrode have more storage sites. Which reduces the movement or loss of charged ions to inhibit the charge redistribution, so it has a high specific capacitance and the self-discharge phenomenon has been greatly reduced.