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Li-ion batteries are a type of electrochemical battery, but there are also many different battery types in existence, and some are starting to challenge Li-ion's dominance.
As electronics advance and our power consumption becomes greater, scientists and companies are trying to find innovative ways to challenge energy storage status quo.
While electrochemical batteries currently offer the best value for money and performance, thermal batteries have shown some promise in the past. The properties of electrochemical and thermal batteries are being combined at the commercial level by Texel to create thermochemical batteries that could offer a more cost-effective alternative to electrochemical batteries.
Thermal Energy Storage Batteries
Many people know about electrochemical batteries thanks to Li-ion batteries' rise in standard technologies, but what about thermal energy storage batteries? Where electrochemical batteries shuttle ions between the electrode to charge/discharge the battery, thermal batteries work in a much different manner.
Thermal energy batteries work by storing and releasing thermal energy, and metal hydride materials have been widely used in these types of batteries over the years. In these batteries, energy is taken from its surroundings and stored (causing an internal temperature change), where it can be later released. These batteries have shown a lot of promise in terms of their high energy density. However, on their own, they have not been cost-effective enough for commercialization.
However, there has been a renewed interest in the field of late. One of the ways to make thermal-based batteries more feasible has been to combine thermal and electrochemical batteries' principles into a single battery, which is duly noted as the thermochemical battery.
The Commercial Development of Thermochemical Batteries
Thanks to a partnership between Texel and Arizona State University, thermochemical batteries are being developed, taking principles from the conventional electrochemical batteries (such as Li-ion batteries) that we see every day and from the thermal energy storage batteries described above.
Like many of the thermal batteries in existence, the thermoelectrical batteries use metal hydride materials to facilitate energy storage. The battery being developed provides a different way of storing energy and was initially developed at Savannah River National Laboratory (SRNL). The cooperation agreement signed between Texel and Arizona State University (which is an exclusive license) aims to commercialize thermochemical batteries in the United States.
The license to produce the batteries was originally signed in 2018. They also signed the rights to a V4-Stirling convertor back in 2012, originally developed by Ford and Kockums (a Military submarine manufacturing company). Texel is now in the final process of development, commercialization and industrialization of the technology. The hope is that these batteries will hit the market soon.
How the Thermochemical Batteries Work
The electrical output of a thermochemical battery is similar to electrochemical batteries. However, the key difference (and this is where they take principles from thermal batteries) is that they can be charged by electricity and by any heat source—such as flared natural gas.
When the battery is charged via a heat source, it still produces an electrical output. However, because they can be charged by multiple means (including already existing heat environments), the battery is much more cost-effective than both electrochemical and thermal batteries, and the storage cost could be as low as 2 cents per kWh. The thermal energy is converted into an electrical output using the V4-Stirling convertor, enabling the battery to have a total energy efficiency (electrical and heat energy) of around 90%.
The thermochemical metal hydride battery being developed by Texel has a hot and a cold side, consisting of metal hydrides and hydrogen in a closed cyclic process. When the hot side of the battery is charged via either an electrical or thermal energy source, the resulting chemical reaction within the battery causes the hydrogen to move from the hot side to the cold side, storing energy within the battery. It has been stipulated that the energy could be stored for up to 100 years with minimal energy loss.
When the stored hydrogen atoms are forced from the cold side back to the hot side, thermal energy is released from the metal hydrides, and the ‘hot side’ becomes hot again. The heat is then transferred into the V4-Stiring convertor, causing it to spin, and the generation of kinetic energy forces a generator to produce electricity.
Overall, some of the defining features of this new battery technology include:
- It is 100% circular
- The technology is 100% recyclable
- There are no issues regarding degradation
- They have a high energy density
- Long storage duration of over 100 years
- Can be charged by multiple sources
- No rare Earth elements are included
As these thermochemical metal hydride batteries are on the cusp of commercialization, it will be fascinating to see how much of an impact they can make in a Li-ion dominated market.
References and Further Reading
Texel. Technology. [Online]. Available at: https://www.txles.com/technology/
Texel. About. [Online]. Available at: https://www.txles.com/about/
Cision [Online]. Available at: https://news.cision.com/texel-energy-storage/r/texel-signs-an-agreement-with-arizona-state-university-to-move-new-battery-technology-towards-commer,c3242766
El Kharbachi A., et al. (2020) Metal Hydrides and Related Materials. Energy Carriers for Novel Hydrogen and Electrochemical Storage, J. Phys. Chem., https://doi.org/10.1021/acs.jpcc.0c01806
Fang Z. Z., et al. (2015) Metal hydrides based high energy density thermal battery. https://doi.org/10.1016/j.jallcom.2014.12.260