Enhancing electrochemical energy storage in Zinc hybrid capacitors using 3D-printed GO/AC electrodes with Oxygen functional groups

Abstract

Zinc-ion hybrid capacitors (ZIHCs), promising for energy storage, encounter challenges such as mismatched positive and negative electrode capacities. Addressing this, increasing the thickness of positive electrode proves effective. However, traditional thick electrodes show an extended ion diffusion paths, which slows reactions and decreasing charge-discharge efficiency. Innovations in electrode structures have been achieved through 3D printing technology with an "embedded" composite material of activated carbon and graphene oxide, creating grids with varying layers to explore the relationship between layer number and capacitor performance. Density Functional Theory (DFT) simulations confirm the crucial role of oxygen functional groups on graphene oxide in enhancing storage capacity, with these findings supported by excellent electrochemical performance in tests. Precise control of electrode structures through 3D printing optimizes ion transport pathways, achieving a high specific capacity of 0.92 mAh cm−2 at a current density of 10 mA cm−2, maintaining 86.4 % cycle stability after 8,000 cycles. These results underscore the potential of 3 D printing to advance electrode design and suggest new directions for research.