Transition metal dichalcogenides (TMDs) have emerged as promising nanomaterials with many energy storage applications. Here, their potential for high-energy-density batteries is discussed.
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Transition Metal Dichalcogenides: An Overview
Transition metal dichalcogenides (TMDs) are a new family of 2D nanomaterials with the chemical formula MX2, where M is a transition metal from groups IV-VI (Mo, Ta, and W) and X is a chalcogen from groups VI-A (S, Te, and Se).
These materials have a layered structure with two hexagonal planes of chalcogen atoms separated by a layer of transition metal atoms. Molybdenum disulfide (MoS2) is the most extensively researched TMD and has been studied for various high-energy density energy solutions.
These materials can be semiconductors or metals depending on the oxidation state of their metal atoms and have potential applications in energy storage, nanotribology, catalysts, and optoelectronics.
Why Are Transition Metal Dichalcogenides Used for Energy Storage?
The growing demand for sustainable and affordable energy storage drives the need for electrochemical storage devices such as rechargeable batteries. These devices are essential for many applications, from portable electronics to electric vehicles and powering the electrical grid, as part of the global transition towards clean energy.
Lithium-ion batteries have achieved widespread adoption in electric vehicles and portable electronic devices, with graphite as the primary anode material. However, the low theoretical capacity of graphite (372 mAh g−1) hampers its extensive deployment.
Transition metal dichalcogenides, similar to graphene, have become popular for energy storage due to their unique X-M-X layered structure and electrochemical properties. In addition, they have higher theoretical capacity (600–1200 mAh g−1) than graphene/graphite, making them excellent candidates for high-capacity and rechargeable LIBs.
Their high electrochemical stability can be attributed to the large energy band gap and strong covalent bonds between atomic layers, making TMDs resistant to corrosion and degradation in electrochemical environments.
The 2D architecture of these materials provides more active sites for foreign ions, enhances contact between the electrode and electrolyte, and increases ion migration kinetics. In addition, TMDs have a higher voltage platform, which helps to prevent dendrite formation and improve battery safety. This makes them ideal candidates for next-generation anode materials.
Vanadium-based dichalcogenides are particularly interesting due to vanadium's various valence states during electrochemical reactions. In addition, these materials can be obtained in monolayers and nanolayers through exfoliation.
TMDs have the potential as cathode materials in solid-state batteries due to their ability to store and release significant cations, resulting in a high specific capacity.
TMDs exhibit lithium-ion intercalation and capacitive energy storage mechanisms, providing a high capacity for energy storage and creating a double-layer capacitor with high capacitance, respectively. In addition, the layered structure of TMDs offers a large surface area, which promotes lithium-ion diffusion and can enhance battery performance.
Using TMDs for High Energy Density Batteries
2D TMD Catalysts Improve Lithium-Air Battery Energy Storage
Researchers from the University of Illinois at Chicago developed 2D transition metal dichalcogenides catalysts for lithium-air batteries, allowing them to hold up to ten times more energy than traditional lithium batteries. The findings were published in the journal Advanced Materials.
The team synthesized 15 types of transition metal dichalcogenides and tested their performance inside batteries during charging and discharging. These catalysts synergized with the electrolyte, leading to faster recharge and more efficient discharge and storage.
The researchers attributed this improvement to the 2D TMDs' high electronic conductivity, fast electron transfer, and bi-functionality in speeding up both charging and discharging reactions occurring in the batteries.
This innovative design can significantly improve the range of electric vehicles, allowing them to travel up to 400 to 500 miles per charge.
Molybdenum Disulfide Cathode Enables Stable Li-CO2 Battery with 7x Higher Energy Density than Li-Ion Battery
A study published in Advanced Materials developed a rechargeable Li-CO2 battery that can cycle up to 500 times, significantly improving from the previous limit of less than 100 cycles.
The battery uses molybdenum disulfide (MoS2) as a cathode catalyst, which helps to prevent the carbon build-up that had previously caused the battery to fail. The researchers achieved this breakthrough by creating a single multi-component composite instead of separate products, which made charging more efficient.
Although Li-CO2 batteries may not be as promising as Li-S batteries due to their reliance on rare molybdenum, they can reach an energy density of up to 1,876 Wh/kg (7 times more than traditional Li-ion batteries), which could be a game-changer in energy storage.
Researchers Developed High-Energy and Long-Life Lithium-Sulfur Batteries Using Lithiated Metallic Nanosheets
Researchers at the University of Cambridge and The Faraday Institution have developed a highly-performing lithium-sulfur (Li-S) battery using lithiated molybdenum disulfide (LixMoS2) nanosheets. Their design, outlined in a paper published in Nature Energy, has promising properties for creating next-generation battery solutions that can store more energy.
The LixMoS2 nanosheets significantly improved the absorption of lithium polysulfides and enhanced the transport of lithium ions, resulting in remarkable energy densities of 441 Wh kg−1 and 735 Wh l−1. In addition, the batteries retained 85.2% of their capacity after 200 operating cycles.
This study provides foundational knowledge that could be translated into commercially feasible battery technology with the potential to create the next generation of energy storage devices.
Future Outlooks and Challenges
Transition metal dichalcogenides have emerged as a promising electrode material for high-density batteries due to their high capacity, long-term cycles, and high-speed performance.
However, the large-scale synthesis of high-quality, impurity-free metal dichalcogenides nanosheets remains a challenge, and their pseudocapacitive behavior causes irreversible electrolyte consumption, leading to low efficiency.
Adding carbon materials can improve stability and conductivity but reduce volumetric energy density. Therefore, a low-cost, high-efficiency synthetic method is needed for large-scale TMD production and the balanced design of TMD-based architectures to enhance electrochemical performance.
References and Further Reading
Majidi, L., Yasaei, P., Warburton, R. E., Fuladi, S., Cavin, J., Hu, X., ... & Salehi‐Khojin, A. (2019). New class of electrocatalysts based on 2D transition metal dichalcogenides in ionic liquid. Advanced Materials, 31(4), p. 1804453. https://onlinelibrary.wiley.com/doi/10.1002/adma.201804453
Ahmadiparidari, A., Warburton, R. E., Majidi, L., Asadi, M., Chamaani, A., Jokisaari, J. R., ... & Salehi‐Khojin, A. (2019). A long‐cycle‐life lithium–CO2 battery with carbon neutrality. Advanced Materials, 31(40), p. 1902518. https://onlinelibrary.wiley.com/doi/10.1002/adma.201902518
Li, Z., Sami, I., Yang, J., Li, J., Kumar, R. V., & Chhowalla, M. (2023). Lithiated metallic molybdenum disulfide nanosheets for high-performance lithium–sulfur batteries. Nature Energy, pp. 1-10. https://www.nature.com/articles/s41560-022-01175-7
Wang, T., Kakarla, A. K., & Yu, J. S. (2022). 2D transition metal dichalcogenides (TMD)-based nanomaterials for lithium/sodium-ion batteries. In 2D Nanomaterials. CRC Press. pp. 341-360. https://www.taylorfrancis.com/chapters/edit/10.1201/9781003178453-20/
Tariq, Z., Rehman, S. U., Butt, F. K., & Li, C. (2022). Vanadium Dichalcogenides-Based 2D Nanomaterials for Batteries. In Energy Applications of 2D Nanomaterials. CRC Press. pp. 269-282. https://www.taylorfrancis.com/chapters/edit/10.1201/9781003178422-17/
Rafiei-Sarmazdeh, Z., Morteza Zahedi-Dizaji, S., & Kafi Kang, A. (2020). Two-Dimensional Nanomaterials. IntechOpen. doi.org/10.5772/intechopen.85263
Liu, B. (2022). Transition Metal Dichalcogenides for High− Performance Aqueous Zinc Ion Batteries. Batteries, 8(7), p. 62. https://www.mdpi.com/2313-0105/8/7/62
Wang, D., Liu, L. M., Zhao, S. J., Hu, Z. Y., & Liu, H. (2016). Potential application of metal dichalcogenides double-layered heterostructures as anode materials for Li-ion batteries. The Journal of Physical Chemistry C, 120(9), pp. 4779-4788. https://pubs.acs.org/doi/10.1021/acs.jpcc.5b11677
Askari, M. B., Salarizadeh, P., Veisi, P., Samiei, E., Saeidfirozeh, H., Tourchi Moghadam, M. T., & Di Bartolomeo, A. (2023). Transition-Metal Dichalcogenides in Electrochemical Batteries and Solar Cells. Micromachines, 14(3), p. 691. https://www.mdpi.com/2072-666X/14/3/691
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