Tuning the Electronic and Electrochemical Properties of 3D Porous Laser‐Induced Graphene by Electrochemically Induced Deposition of Polyoxovanadate Nanoclusters for Flexible Supercapacitors

Abstract The advancement of microelectronic devices mandates the development of flexible energy storage systems to enable the fabrication of miniaturized and wearable electronics. Herein, a sustainable approach is demonstrated for tuning the electronic and electrochemical properties of hierarchically porous laser‐induced graphene (LIG) substrates. The methodology entails the electrochemical deposition of polyoxovanadate nanoclusters (K 5 (CH 3 CN) 3 V 12 O 32 Cl (= K 5 V 12) onto the highly porous LIG matrix. The comprehensive characterization is integrated through micro‐Raman spectroscopy and in‐depth X‐ray photoelectron spectroscopy to elucidate the deposition mechanism and electronic properties of the fabricated electrode. The results indicate a significant correlation between the orientation of the deposited clusters and the non‐crystalline regions of the LIG structure. Additionally, the cluster deposition results in a reduction of grain boundary defects in the nano‐graphite lattice of LIG. The optimized electrode exhibits enhanced areal capacitance (C A) of 125 mF cm −2 at a current density of 0. 1 mA cm −2, representing a fivefold improvement compared to the undoped LIG substrate. Furthermore, as a proof of concept, a flexible solid‐state symmetrical supercapacitor device, fabricated with a PVA‐H 2 SO 4 gel electrolyte, demonstrates an areal capacitance of 24. 92 mF cm −2 at current density of 0. 1 mA cm −2 and exhibits exceptional cycling stability, enduring up to 5000 consecutive galvanostatic charge‐discharge cycles.