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HRL Labs video demonstrates principle of thermal battery based on advanced metal hydrides for EV heating and cooling

In 2011, the Advanced Research Projects Agency - Energy (ARPA-E) awarded $2.7 million to a team comprising researchers from the University of Utah, HRL Laboratories and GM Global R&D for a project to develop a new generation of high-density thermal battery based on advanced metal hydrides. (Earlier post.) The goal of the project, part of ARPA-E’s HEATS (High Energy Advanced Thermal Storage) portfolio, was to develop a compact thermal battery for climate control in electric vehicles. Such a thermal battery would provide heating and cooling without draining the electric battery, in effect, extending the driving range of EVs per electric charge.

As described in a paper in press in the Journal of Alloys and Compounds, the developed system uses a pair of thermodynamically matched metal hydrides as energy storage media: (1) catalyzed MgH2 as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV0.62Mn1.5 alloy as the matching low temperature hydride. HRL has now released a video demonstrating the principle behind the work on thermal battery technology.

The thermal battery has a hot side and a cold side. When it discharges, the metal hydride on the cold side releases hydrogen gas and cools. This hydrogen flows to the hot side where it is absorbed into another metal hydride, heating the hot side.

In the video, Dr. John J. Vajo, HRL Laboratories’ principal investigator, notes that a small droplet of water placed on the cool side freezes as the hydrogen is released and the temperature drops. The cold hydride reaches temperatures below 0° C (32° F), while the hot hydride reaches maximum temperatures of 75° C (165° F).

Thermal battery technology offers a number of unique features—including rapid cooling, shock and vibration resistance, silence, and miniaturization—that could prove useful in other real-world applications.


  • Zhigang Zak Fang, Chengshang Zhou, Peng Fan, Kent S. Udell, Robert C. Bowman, John J. Vajo, Justin J. Purewal, Bidzina Kekelia (2015) “Metal hydrides based high energy density thermal battery,” Journal of Alloys and Compounds doi: 10.1016/j.jallcom.2014.12.260


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