NiCo LDH deposited on novel LIG-derived substrates with controllable morphology for high-performance symmetric supercapacitors

Abstract

The design of self-supporting materials with controllable morphology for hydrothermal substrates provides a crucial approach to fabricating electrodes with outstanding electrochemical performance. We have developed a two-stage laser scribing method for preparing iron laser-induced graphene (dFe-LIG), which is derived from a one-stage LIG (sFe-LIG). The repeated laser scribing on polyethersulfone (PES) films can improve orderliness and densification in the LIG framework. Nickel‑cobalt layered double hydroxide (NiCo-LDH) are deposited onto dFe-LIG more easily than sFe-LIG or LIG via the hydrothermal reaction, and the products are labeled as NC@dFe-LIG. A super high areal specific capacitance of NC@dFe-LIG-P12 (P12 denotes a repeated laser power is 12 W) is up to 3616 mF cm⁻² at 2 mA cm⁻², which is 130 times that of NC@sFe-LIG-P10 (only one laser power is 10 W) and 260 times of NC@LIG-P6 (only one laser power is 6 W), indicating that the superior morphology of electrode materials enhances the diffusion of electrolyte ions. SC devices have been built using two same NC@dFe-LIG electrodes for simultaneously working on the positive and negative electrodes, which have exhibited a high areal specific capacitance of 245 mF cm⁻². These outstanding electrochemical properties position dFe-LIG as a highly promising candidate for use as a substrate in synthesizing advanced electrode materials.