The battery tech that ensures Covid-19 vaccine deliveries stay at ultra-low temperatures

Robust batteries made by Saft’s Tadiran brand have been used to support the roll-out of life-saving vaccines

One of the most significant logistical challenges when it comes to delivering Covid-19 vaccines is ensuring that the doses are kept at a constant low temperature. In the case of Pfizer / BioNTech’s vaccines, round-the-clock monitoring is needed to ensure they stay in a range of between -80°C and -60°C to remain effective.

To make it possible to keep the vaccines within this temperature range and deliver them at scale, Pfizer designed thermal shippers that use dry ice to maintain the doses at -70°C, or 10 degrees either side, for up to 10 days unopened. Each precious shipment is monitored by a GPS-enabled thermal sensor, which tracks its route and temperature continuously, from the factory floor until it is delivered to a vaccination center. 

Saft’s Tadiran batteries to ensure the cold chain of Covid-19 vaccines

The sensor needs battery power to enable it to log the temperature, however very few batteries can operate at such low temperatures. Tadiran, a Saft brand, makes a lithium thionyl chloride (LiSOCl2) battery that is used in temperature trackers for “cold chain” deliveries, such as shipments of frozen food or medical uses including delivering donor organs to hospitals. In these cases, it is also imperative that the temperature is tracked to make sure it stays within a certain range.

“Our batteries not only survive at such extreme temperatures, but they can operate,” says Sol Jacobs, Vice President and General Manager of Tadiran Batteries. “Other batteries could survive the low temperature, but they couldn’t perform.”

Bringing reliability to a time trial for global health challenge

So far, more than two million Tadiran batteries have been ordered by companies supplying temperature loggers to vaccine manufacturers, and more are being delivered as vaccine production ramps up around the world. The battery technology itself has been in use for a long time, so Tadiran has been able to scale up production very quickly to meet demand.

The battery works by using an electrolyte that is not water-based and so does not freeze. They are typically used by customers who require a highly reliable battery with a long lifespan, as well as the ability to work in extremely cold conditions, says Marc Henn, application engineering manager for Tadiran in Germany.  

Monitoring systems are also used by utility companies and for environmental purposes such as checking air quality. The batteries can last for a couple of decades, says Henn, and as a result are chosen for use in remote and hard-to-get-to places. The high level of reliability means they can also be used for emergency rescue equipment, which may not be touched for years, but has to work when it is needed. 

Long-duration batteries for ensuring temperatures control all along the delivery of Pfizer / BioNTech's COVID-19 vaccines

In the case of the Covid-19 vaccines, any interruption to the flow of temperature data would mean the shots in that shipment could not be used, something all governments and healthcare providers are desperate to avoid when they are racing to vaccinate as many people as possible and as quickly as possible, with limited supplies. 

The Covid-19 vaccination campaign is the biggest in history. Worldwide, more than 30.5 million doses a day were being given as of July 2021, with the International Monetary Fund recommending targets of vaccinating 40 percent of the population of every country by the end of this year and 60 percent by the middle of 2022, in order to end the pandemic. However, with billions of people worldwide still unvaccinated, and developed nations planning to deliver booster shots in the fall, vaccine monitoring will need battery power for some time to come.