Photo-assisted asymmetric supercapacitors based on dual photoelectrodes for enhanced photoelectric energy storage

Photo-rechargeable energy storage devices pave a new way for directly utilizing solar energy, and therefore, the design and assembly of photo-assisted supercapacitors in order to realize the efficient storage of solar energy become increasingly important. In this study, a novel photo-assisted asymmetric supercapacitor (ASC) with dual photoelectrodes was specifically assembled. We rationally designed nanoflower-like ZnCo2O4 (ZCO NF) as the positive electrode, which can deliver a larger specific capacitance (563 F g(-1) at 1 A g(-1)) under light illumination than that under dark conditions (456 F g(-1) at 1 A g(-1)). Simultaneously, hollow sphere-structured CuCo2S4 (CCS HS) was prepared as the negative electrode. It exhibits a specific capacity of 305 F g(-1) with light, which is approximately two folds higher than that without light. More importantly, the energy density of the assembled light-sensitive ZCO NF//CCS HS ASC can reach 60.9 W h kg(-1) at 700 W kg(-1) with light, whereas it is only 46.5 W h kg(-1) at 700 W kg(-1) without light. In addition, density functional theory (DFT) approach was used to study the charge-transfer mechanism of the photo-assisted ASC with dual photoelectrodes. Thus, this study may open up a new avenue for the design of light-sensitive devices for effective solar energy storage.

Automated summary

Photo-rechargeable energy storage devices offer a new way to use solar energy, making the design and assembly of photo-assisted supercapacitors crucial for efficient solar energy storage. In this study, a novel asymmetric supercapacitor with dual photoelectrodes was assembled, using ZnCo2O4 and CuCo2S4 as positive and negative electrodes respectively, achieving higher specific capacitance and energy density under light illumination. The charge-transfer mechanism of the photo-assisted supercapacitor was also studied using density functional theory. This study opens up a new avenue for the design of light-sensitive devices for effective solar energy storage.