Turning indium oxide into high-performing electrode materials via cation substitution strategy: Preserving single crystalline cubic structure of 2D nanoflakes towards energy storage devices

Enhancement in electrochemical performance of electrode materials has been the recent focus for material development of electrochemical energy storage devices. For the first time, we turn a post transition metal oxide, indium oxide (In₂O₃), into a high capacity, excellent stability and rate capability electrode by introducing suitable cations. Various electrode materials M-In₂O₃ (where M is Co, Fe, Mg, Mn, Ni, and Zn) have been prepared by simple and inexpensive cation substitution route. Among all, the optimal promoter Co–In₂O₃ electrode deliver higher specific capacity (4.8 times) and rate capability (1.3 times) than bare In₂O₃. The capacitive contribution and diffusion contribution reactions have been studied for all the electrodes. The capacitive distribution has been increased by Mg and Zn substitution and the diffusion contribution has been enhanced with Co, Fe, Mn, and Ni substitution. Furthermore, structural and electronic properties of In₂O₃ substituted with the cations have been studied through first principles density functional theory calculations. Moreover, seven asymmetric supercapacitor devices have been assembled by using In₂O₃ and M-In₂O₃ as the positive and the reduced graphene oxide as the negative electrode materials. The wrist watch, stop watch, and LEDs have been successfully operated, illustrate the prospective of electrode materials towards practical applications.