Rapid advancement in technology has led to the development of micro/nanodevices that has escalated the need for safe and facile energy storage and conversion devices. Supercapacitors have been particularly researched for this purpose owing to their excellent high-power density, long life, discharge speed, and low-cost properties. Compared with batteries, supercapacitors have low energy density that has limited their applications in many fields, however. For this reason, numerous strategies have been proposed to boost their energy density. Among them, Prussian blue analogues have been identified as a promising solution. Existing literature on Prussian blue analogues has mainly assessed their structures and properties, and as expected, they exhibit excellent specific capacitance and cycling stability that are desirable for developing high-performance energy storage devices.
Generally, graphitic-phase C3N4 (g- C3N4) is a well-crystallized polymer with fast charge rate and perpendicular electron transport properties, alongside other properties, making it a potential candidate material for electrochemical devices. Yangming Shi (Master Student), Dr. Pinghua Chen, Jiezeng Chen (Master Student), Dr. Dezhi Chen, Dr. Professor Hongying Shu, Professor Hualin Jiang, and Professor Xubiao Luo from Nanchang Hangkong University proposed an all-solid-state as-prepared supercapacitor as an alternative method of developing effective energy storage devices. Their research work is currently published in the Chemical Engineering Journal.
In their approach, the authors first synthesized the novel PBA Rb-Ni hexacyanoferrate (Rb-NiHCF) with a specific structure of a hollow mesoporous nano-box and incorporated it with an organic semiconductor g-C3N4 to form a hybrid H RbNiHCF/g-C3N4. Next, the resulting hybrid H RbNiHCF/g-C3N4 was coupled with active carbon to produce a supercapacitor with high energy density properties. They finally evaluated the applicability of the resulting supercapacitor by using it to light an LED indicator.
The authors reported that the synthesized mesoporous hollow Prussian blue analogues (PBA) nano-box/g-C3N4 hybrid exhibited excellent electrochemical performance and outstanding cycling stability. For instance, a specific capacity of 201.6 m Ahg-1 higher than that of PB/PBA based electrodes was reported. This was attributed to the effects of g-C3N4 that functioned to uniformly distribute the PBA resulting in an improved conductivity and storage capacity. Similarly, the asymmetric supercapacitor exhibited a high energy density of 46.9 Wh kg-1 at a power density of 808.2 W kg-1, which is notably closer to those of commercially available Ni/MH batteries. Moreover, the authors successfully used the device to lit a LED indicator, which worked for more than 3 minutes, thus confirming the feasibility of the electrode.
In summary, the study successfully developed, for the first time, an all-solid-state asymmetric supercapacitor electrode using a hollow Prussian blue analogue/g-C3N4 nanobox. Results showed that the resulting electrode exhibited excellent electrochemical performance with high cycling stability, high current density, high energy density, and high-power density that compared well with those of commercially available batteries. Therefore, the results would increase the use of the device as a safe and high-performance anode material for supercapacitors in numerous practical applications said Professor Hualin Jiang in a statement to Advances in Engineering.
Shi, Y., Chen, P., Chen, J., Chen, D., Shu, H., Jiang, H., & Luo, X. (2020). Hollow Prussian blue analogue/g-C3N4 nanobox for all-solid-state asymmetric supercapacitor. Chemical Engineering Journal, 404, 126284.