Enriching Oxygen Vacancy in Co₃O₄ by Solution Combustion Synthesis for Enhanced Supercapacitive Property

Abstract

Transition-metal oxides show great promise as electrode materials for supercapacitors due to their ease of synthesis, affordability, adequate redox stability, and high theoretical capacity. However, their inherent poor electrical conductivity and sluggish reaction kinetics typically lead to low specific capacity, reduced energy and power density, and sluggish rate capability in energy storage devices. In this study, we have re-engineered common Co3O4 using a controlled solution combustion method to enhance oxygen vacancy within the oxide materials. We compared this approach with other calcination-based preparation techniques. Notably, the solution combustion-derived Co3O4 (SCS) exhibited the most significant oxygen vacancy along with higher surface area and smaller crystallite size compared to calcination-derived Co3O4 (CLS) and Co3O4 (ZIF). The Co3O4 (SCS)-modified electrode demonstrated a remarkable specific capacitance of 688.3 F/g at a current density of 1 A/g in a three-electrode electrochemical systemnearly four times of Co3O4 (ZIF) (173.3 F/g). Furthermore, the solid-state asymmetric supercapacitor constructed with Co3O4 (SCS) [Co3O4 (SCS) @ITO//ITO] exhibited a specific capacitance of 232 F/g at a 1 A/g current density, along with high energy densities across a wide range of power densities (e.g., 93.12 Wh/kg at 848.2 W/kg and 79.07 Wh/kg at 4248.55 W/kg), surpassing the performance of most reported hybrid supercapacitors. As a proof-of-concept, we further improved the oxygen vacancy in Co3O4 (SCS) through H2 treatment, resulting in reduced Co3O4 (SCS-R) with an enhanced specific capacitance of 278 F/g, an energy density of 111.58 Wh/kg, and a power density of 869.45 W/kg at a 1 A/g current density. This modified material also demonstrated exceptional capacitive efficiency (90%) and Coulombic efficiency (90.2%) retention even after 6000 cycles. Ultimately, this report introduces a straightforward solution combustion synthesis strategy for generating oxygen vacancies in metal oxides, holding significant promise for enhancing their energy storage properties.

Electrochemical energy storage in an organic supercapacitor via a non-electrochemical proton charge assembly

“…The conventional wisdom that multiple redox transitions within the electrode have a direct link with the attainable energy density is affirmed by classical demonstrations of charge storage in electrode materials such as RuO 2 , NiO, Co 3 O 4 , MnO 2 , and conducting polymers, and they all exhibited a very high charge storage capability in their available potential window. [24][25][26][27][28] We show that in the process of developing high-energy supercapacitors, redox activity is not quintessential, at least in the domain of molecular systems. Even functionality without any capability for faradaic redox transitions can indeed enrich their energy storage capability.…”

“…The conventional wisdom that multiple redox transitions within the electrode have a direct link with the attainable energy density is affirmed by classical demonstrations of charge storage in electrode materials such as RuO 2 , NiO, Co 3 O 4 , MnO 2 , and conducting polymers, and they all exhibited a very high charge storage capability in their available potential window. 24–28…”

Hierarchically Uniform 2D Porous Sheet-like NiO/NiCo2O4: A High-Performance Positrode Material for All-Solid-State Hybrid Pseudocapacitors with Superior Ragone and Cyclic Efficiencies

“…Due to the rapid exhaustion of fossil fuels and their adverse impact on the global environment, there is an immense need to develop innovative energy resources and novel procedures associated with energy conversion and storage systems . Among several such perceptive systems, supercapacitors with all-solid-state architecture are considered exceptionally important due to their ultimate power delivery output, extended durability, high operational safety, and easy transportability. , Consequently, supercapacitors have progressed as the most contemporary energy storage systems, which are being rationalized to support technological revolutions . The supercapacitors face the limitation of low charge storage and Ragone efficiency due to the limited number of accessible active sites and high charge transfer resistance of the electrode materials, and considerable diffusion resistance of electroactive ions, during the charge storage process in the devices.…”