A thin-film coating process for manufacturing thermal batteries could lead to create lighter batteries for future applications.

A thin-film coating process for manufacturing thermal batteries used in nuclear weapons and other munitions - invented at Sandia National Laboratories - will be industrialized under a new corporate partnership with a Maryland company. The process could lead to create lighter batteries for future applications.

A thermal battery is a nonrechargeable, single-use energy source that can remain inert for years at room temperature before becoming activated at temperatures as high as 1,100°F (~600°C). The thin-film coating process changes the way some thermal batteries have been made since the 1950s.

Sandia and ATB Inc., a Cockeysville, Md.-based manufacturer of thermal batteries, signed a cooperative research and development agreement to test the thin-film coating process for large-scale industrial production.

Sandia researchers also are looking into whether a patented binder used in the thin-film coating process has commercial applications. For example, researchers plan to explore whether the coating can be used in lithium-ion batteries in electric and hybrid vehicles, and in batteries used in the petroleum industry when drilling deep underground in hot geothermal environments.

Sandia researcher Frank Delnick led the effort to make the thermal battery components as thin-film coatings instead of pellets. The process will work best for thermal batteries that are active for a fraction of a second to a few minutes, he said. On average, thermal batteries made with thin-film coatings would use one-fifth to one-half the materials needed in their conventionally manufactured counterparts, Delnick said.

The new process also could allow manufacturers to produce different shapes of thermal batteries, Delnick said. Current thermal batteries are cylindrical and range in size from a man’s thumb to a one-pound coffee can. The first thermal battery made using the new process was slightly thicker than a postage stamp and about the size of a quarter, he said.

Sandia’s process uses relatively inexpensive equipment common in the paint industry that coats the battery components as thin films onto stainless steel foil. The coatings are held together and bonded to the foil using a patented binder. The binder must withstand temperatures of 660 to 1,100°F (~350 to 600°C), which are required to melt the salt electrolyte and activate the battery. Once activated, the binder must remain chemically and mechanically stable throughout the discharge of the battery without emitting gas or producing other side reactions that could adversely affect the performance of the battery, he said.

The coated materials in the batteries are much tougher than those in current models. Delnick expects that thin-film thermal batteries will perform much better in high-shock environments and will be much more amenable to automated manufacturing.

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