There has been growing interest in using transition metal dichalcogenides (TMDs) in various technologies due to their unique mechanical, optical, and electronic properties, including supercapacitor technology.
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Specifically, molybdenum disulfide (MoS2) has shown potential as a high-performance electrode material for supercapacitors. This article explores the use of TMDs in supercapacitors, their current commercial and research landscape, the use of MoS2 in supercapacitor technologies and the future of this technology.
Transition Metal Dichalcogenides (TMDs)
Transition metal dichalcogenides (TMDs) are only a few atoms thick two-dimensional (2D) nanomaterials composed of a transition metal like niobium, tungsten, molybdenum, and a chalcogen like tellurium, selenium, and sulfur.
The 2D nanostructures of TMDs give them unique mechanical properties, strong light-matter interactions and high electron mobility. One of the key properties of TMDs is direct bandgap which means that they can efficiently absorb and emit light, making them promising candidates for optoelectronics applications such as photovoltaics and light-emitting diodes.
Supercapacitors differ from conventional capacitors due to their high energy density, high power, longer life cycle and fast-charge–discharge rates. The current commercial landscape for supercapacitors is dominated by technologies like electrochemical double-layer capacitors (EDLC), which store electrical energy by binding charges at the electrode-electrolyte interface to create a double layer of charges, and a pseudocapacitor, which stores electrical energy via faradaic reactions.
Hybrid Energy Storage Systems
A study published in 2022 offered material-based solutions for electrical energy storage to meet the demands of the Indian market. The researchers explored for supercapacitor-electrode materials to meet the Indian market's minimum energy density requirement of 4.06 ± 0.05 Wh kg−1 and found that metal oxide-carbon hybrid materials based hybrid energy storage systems can enable clean, environment-friendly and cost-effective solutions for renewable energy resources.
Using MoS2 in Supercapacitor Technologies
MoS2 has several properties that make it attractive as an electrode material for supercapacitors. It includes a high specific surface area for charge storage, a high electronic conductivity allowing fast charge and discharge rates and high mechanical strength making it resistant to degradation during cycling.
Due to its distinct electrical characteristics and direct bandgap, molybdenum sulfide (MoS2) is an active material used to construct two-dimensional supercapacitors devices. In MoS2 nanostructures, the exposed active edge sites and sizable area-specific surfaces are very intriguing material features.
Recent Research on MoS2-based Supercapacitors
A review paper published in 2021 has gathered some interesting statistics regarding research on MoS2-based supercapacitors. The study found that China dominated publications on MoS2 supercapacitors, whereas the United States’ based research gained the most citations. Through bibliometric analyses, this study has assisted researchers in choosing optimal preparation techniques and research collaborations. The possibilities offered by MoS2-based materials as a solid foundation for improved storage capacity were also covered in the study.
Leading Manufacturers of Supercapacitors
TDK Global is one of the top producers of supercapacitors in the world, producing EDLCs with a maximum capacitance of 500mF and an extremely thin packaging of 0.45 mm thickness. The large capacitance and low resistance of TDK's EDLCs make them ideal for energy storage systems and peak output auxiliary power supply, among other applications.
Another well-known producer with a wide selection of high-performance supercapacitors in surface-mount and radial construction is KEMET. Their supercapacitors are most effective when used in low voltage, DC hold-up applications, such as integrated microprocessor systems with flash memory.
Shenzhen Liron Electronics
China is one of the world leaders in supercapacitor research and manufacturing. Shenzhen Liron Electronics Co., Ltd. is China's leading capacitor manufacturer with a product range covering 10,000 kinds of specifications from 6.3V to 600V, -55 °C to 130 °C having customization facilities according to the customers' requirements and an annual production of over 20 million capacitors.
Challenges Associated with MoS2-based Supercapacitors
Despite many promising results, some challenges still need to be addressed for MoS2-based supercapacitors, including scalability of the synthesis process for MoS2, since most MoS2 synthesis methods produce small quantities of the material, which is not practical for large-scale production. Another challenge is the stability of the material during cycling since MoS2-based electrodes can degrade over time, leading to a decreased performance.
Future of MoS2-based Supercapacitors
The future of supercapacitor technologies looks bright since, by optimizing the properties of MoS2 and other 2D nanomaterials, it would be possible to develop supercapacitors that can compete with or even surpass the performance of batteries in certain applications.
For instance, electric vehicles (EVs) require high-capacity batteries to provide a sufficient driving range, but batteries have several drawbacks, including long charging times and limited lifespan. Therefore MoS2-based supercapacitors could be used with batteries to provide the high power required for acceleration and regenerative braking, while the batteries could provide the energy storage needed for the driving range. Moreover, supercapacitors could also be used in renewable solar energy systems to store excess energy generated during high output and deliver it during low output.
References and Further Reading
Bello, I. T., Adio, S. A., Oladipo, A. O., Adedokun, O., Mathevula, L. E., & Dhlamini, M. S. (2021). Molybdenum sulfide‐based supercapacitors: from synthetic, bibliometric, and qualitative perspectives. International Journal of Energy Research. doi.org/10.1002/er.6690
Bisinfotech. (2022). [Online] Top 7 supercapacitors manufacturers in the world. Available at: https://www.bisinfotech.com/top-7-supercapacitors-manufacturers-in-the-world/ (Accessed on March 27, 2023)
Cherusseri, J., Choudhary, N., Kumar, K. S., Jung, Y., & Thomas, J. (2019). Recent trends in transition metal dichalcogenide based supercapacitor electrodes. Nanoscale Horizons. doi.org/10.1039/C9NH00152B
Ghosh, S., Yadav, S., Devi, A., & Thomas, T. (2022). Techno-economic understanding of Indian energy-storage market: A perspective on green materials-based supercapacitor technologies. Renewable and Sustainable Energy Reviews. doi.org/10.1016/j.rser.2022.112412
Huang, K. J., Wang, L., Liu, Y. J., Liu, Y. M., Wang, H. B., Gan, T., & Wang, L. L. (2013). Layered MoS2–graphene composites for supercapacitor applications with enhanced capacitive performance. International journal of hydrogen energy. doi.org/10.1016/j.ijhydene.2013.08.112
KAMET a YAGEO company. [Online] Available at: https://www.kemet.com/en/us.html
Screw capacitor, snap in capacitor exporter. [Online] Shenzhen Liron Electronics Co., Ltd. Available at: https://www.chinacapacitor.com/about-us.html
TDK Corporation. (2023, March 27). Retrieved March 27, 2023, from https://www.tdk.com/en/index.html
Tobis, M., Sroka, S., & Frąckowiak, E. (2021). Supercapacitor with Carbon/MoS2 Composites. Frontiers in Energy Research. https://www.frontiersin.org/articles/10.3389/fenrg.2021.647878/full
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