From Cars to Combat Zones
by Kush Sutaria
Lithium Sulfur battery manufacturer Lyten recently announced that they would be buying all remaining Northvolt assets in Sweden and Germany. They claim to be acquiring 16GWh of existing battery manufacturing capacity and more than 15GWh of capacity under construction. That in itself is intriguing news, but that isn’t the part that caught our eye. What did catch our eye is recent online media suggesting that Lyten is planning to retrofit the factories to produce batteries for the US military.
Going into the intricacies of the Lyten acquisition is a rabbit hole of its own to go down. But this story brought on a question we wanted to explore - How much different are EV or stationary storage batteries to those used in the military? And what does the US military even need batteries for?
The growing need for military batteries
Global militaries use batteries everywhere. The modern soldier carries an increasingly sophisticated set of electronic equipment and small tactical unmanned vehicles rely on batteries as they are quieter, more efficient and less complex than using combustion engines. In addition, the complex logistics of transporting and storing fuel to the front lines make rechargeable batteries an attractive proposition.
Below are just a few uses for Lithium ion batteries in combat:
Portable Radios and Communications Equipment
Night vision goggles and thermal imagers
Medical Equipment
Small tactical drones and missiles
Large high altitude solar aircraft
Unmanned submarines
Jammers and electronic warfare
Explosive Ordnance Disposal (EOD) robots
The list goes on and on and on. And market forecasts predict strong growth for this market.
The global military battery market size was estimated at $1.40B in 2023 and is projected to grow to $1.85B by 2030, driven by rising defence budgets, modernization of armed forces and growing use of unmanned vehicles.
In 2023, ground based systems made up 47.74% of the revenue share, however marine platforms are expected to grow the most over the next 5 years. Submarines and unmanned boats rely heavily on batteries as they need to be silent and stealthy to avoid acoustic detection.
In 2023, non rechargeable batteries made up 48.87% of the revenue share. These batteries are often used in settings where recharging is impractical in the field. Rechargeable batteries are expected to grow the most over the next 5 years.
North America accounted for 15.49% of global market share in 2023, with the U.S dominating 78.0% of the North American Market.
So globally, militaries are becoming more and more dependent on batteries. However, for the US and other western allies, there is a big concern over the control China has over the battery supply chain.
The threat from China
The domination of China in the battery supply chain means that raw material supply, processing and manufacture of Lithium ion batteries currently can effectively be shut off by China in the event of a conflict. The US department of defence is so concerned about the reliance on China for batteries that it has published a Lithium Battery Strategy for how it sources and buys batteries. In their words:
Current dependence on potential adversaries for battery materials, coupled with the proliferation of DoD unique battery designs, creates challenges in securing critical battery supply chains. At the same time, skyrocketing demand for electric vehicles is driving the commercial market away from the smaller cell formats on which DoD depends. DoD must adapt quickly to leverage domestic and allied mining, processing, and battery production investments that make it possible to domestically manufacture the lithium-ion cells and battery packs that support our systems safely and affordably.
As part of the 2025 annual defence spending policy bill, this strategy will be updated, with a new version aiming to be in place by March 2026 (source). The Army, Navy and Marine Corps also hosted their first industry day for battery technology, which focused on standardizing the batteries used in the military.
What does the military want in a battery?
Why can’t we take the cells and batteries made for EVs and Stationary Storage and simply repurpose them for use in the military? Surely this would kill 2 birds with one stone right? Well maybe not.
First is the form factor, stationary storage and EV cells are getting bigger and bigger. Stationary Storage uses large prismatic cells in the 100s of Ah per cell and EV cells are also trending larger (think Tesla 4680 or BYD Blade cell). For a larger system needing many cells, this helps reduce cell quantity and therefore pack complexity, as well as increasing energy density. But the military often needs small form factor cells for lightweight and portable equipment. The need for lightweight cells and bespoke sizes also lends itself well to small pouch cells.
The military also wants a high degree of standardization. Ideally, they want a family of standard batteries suitable for a wide range of applications and scenarios. When you’re a soldier operating on the frontline or having to ship equipment to warzones overseas, it's a nightmare if every system has a different battery, each with their own connectors, chargers, charging protocols and operating limits. In addition, for the military to buy batteries quickly and in large quantities, testing procedures and quality assurance should all also be standardized. A standardized family of batteries means you can re-use batteries and chargers, reducing time to design military equipment and making procurement easy.
The STUB (Small Tactical Universal Battery) is an attempt to do just this. It's a family of 8 batteries of varying capacities but with a standard connector. This allows any STUB battery to operate in any device designed to use the STUB connector. The Army’s C5ISR center is leading this effort. The US Army actually has a whole website dedicated to batteries including information for the warfighter on how to use standard army batteries, military standards, and even business opportunities to work with the army.
Shelf Life. The nature of peace and war means that batteries may have to sit on the shelf for years in peacetime on the off chance that they are called into service. The military can’t wait for a war to break out to start making batteries and training operators. If the batteries are needed, they need to perform well straight away. This places a higher emphasis on calendar aging degradation as opposed to EV batteries which are used everyday and cycling is the main degradation driver. Military batteries may only be used once, or at most a few times, and so cycling performance is less important.
High energy density and power. If a soldier is carrying these batteries, they need to be light. And you need a lot of energy from one, as the runtime of your night vision goggles or flight time of your drone could be a life or death factor. The high energy density requirement, along with low cycle life requirement means that high silicon content anode Li-ion cells have been of great interest to the military.
Safety in wide operating conditions. The need for lightweight batteries means that often you can’t have a complex cooling system or thermal management system, the cells need to be safe from thermal runaway even without these protection features. Complicating matters, these batteries may be used in everything from the desert to the arctic and so need a wide operating temperature range. EV and stationary storage batteries always have a liquid cooling system and so can have a narrower optimum temperature range.
The challenge for Lyten
The above technical requirements on military batteries presents a challenge to Lyten in retrofitting existing battery factories to make military batteries.
Northvolt’s product line included pouch cells, which is good news in creating the lightweight, odd form factors that the military will need. Lyten’s Lithium Sulfur cells are also pouch cells. The delicate process and handling required for pouch cells however may make automated manufacturing more difficult for example than more sturdy cylindrical or prismatic cells.
The high safety and high shelf life chemistry will be another challenge. Northvolt’s Sodium ion probably won’t have the energy density, and their Lithium metal cell is probably not mature enough in terms of safety. If sticking with a li-ion based chemistry for the Northvolt production lines, it may be wise to either use high Nickel content cathodes or high silicon content anodes to get the energy density high enough. Lyten’s Lithium Sulfur batteries claim a 50% weight reduction compared with NMC and 75% compared with LFP, so it will be interesting to see if Lyten uses the Northvolt facilities to ramp up production of its Lithium Sulfur batteries for the military market.
Potentially the biggest challenge to Lyten will be to build these cells at a scale the US military wants, and with a supply chain which is acceptable to the US military. This would mean compliance in raw material sourcing, military quality standards and ITAR compliance, which for a factory outside the US may be difficult.
Locked and Loaded
There’s no denying the fact that military use of batteries is going to grow and grow, especially as the nature of combat changes, we’ve already seen the devastating use of drones in Ukraine. Soldiers will carry more wearable equipment needing power and vehicles across land, sea and air are becoming unmanned. If Lyten can get it right, it seems the U.S military will happily take all the batteries it can get.
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One of our biggest challenges is regaining control over critical metals. I still don’t get how we let this slip—how we were asleep while China locked down the supply. These aren’t just raw materials; they’re essential to defense and energy. How can we talk about fighting a war when we rely on a rival for the metals that power our weapons?