Efforts to extend military drone endurance have triggered growing interest in alternatives to lithium batteries, including fuel cells, solar-powered systems, and hybrid power architectures.
“The industry is shifting from a focus on ‘How long can it fly?’ to ‘How quickly can it get back in the fight?’” Doron Myersdorf, CEO of StoreDot, said. “In high-intensity conflict, a drone that flies for 2 hours but takes 4 hours to charge is often less valuable than a drone that flies for 40 minutes but is back in the air in 5.”
Battery manufacturers recognize the endurance problem; however, despite new developments in alternative power sources, lithium remains the only technology that meets the military’s energy density, power, and reliability needs.
The race to improve endurance is not eliminating lithium, but redefining its role within a drone’s architecture.
Lithium is the default power choice because it delivers both energy density and the power needed for takeoff, maneuvering, and tactical payloads.
“When you think about batteries, you’re dealing with high specific energy, hours per kilogram,” American Lithium Energy’s Chief Strategy Officer, William Michael Hadala Jr., said. “They have rechargeability, fast charge for burst loads, as well as high power output for tactical load.”
Hadala explained how lithium-ion is the military’s battery of choice as NiCad and lead-acid systems have been phased out for environmental and performance reasons. He does not see that changing anytime soon.
“Lithium-ion is going to be around at least until 2040,” Hadala told Build Better.
The tradeoff is endurance. Flight time depends on payload, conditions, and aircraft design, but lithium batteries remain constrained by how much energy can be stored onboard.
“There’s not going to be a single alternative method of power that’s going to replace lithium-ion batteries,” Hadala said.
One recent development is a palm-sized solid oxide fuel cell microreactor that researchers believe could significantly extend drone endurance.
“The battery is never going to give you the range you need,” said Eric D. Wachsman, Director of the Maryland Energy Innovation Institute.
Researchers argue that compact SOFC systems could extend endurance beyond what lithium alone can provide.
Researchers say improved ceramic insulation allows the system to operate at around 600°C while remaining structurally stable, potentially opening the door to compact drone integration.
Flight range depends on the drone’s architecture, including the platform design, payload, and fuel configuration. Myersdorf said fuel cells, in certain configurations, can offer multiple times the endurance of battery-powered drones.
Hydrogen fuel cell systems have demonstrated multi-hour drone flights in certain prototypes, compared with the tens of minutes typical of battery-only configurations.
But moving from lab demonstration to field deployment presents challenges.
“The largest gap for drone integration is power management,” fuel cell researcher Tetsuya Yamada said. “Most current drones are designed around lithium-ion batteries, and using a solid oxide fuel cell as a primary power source would require redesigning the power conversion hardware and control architecture.”
Fuel cells perform best under steady loads. Drone missions demand rapid bursts of power during takeoff and maneuvering. This mismatch introduces integration complexity.
Startup time is another constraint.
“If a fuel cell takes 20 minutes to heat up before the drone can take off, it’s useless for ‘scramble’ missions,” Myersdorf said. “A technology is ready when it can provide 100% thrust in under 60 seconds from a ‘cold’ state.”
Durability and simplicity also matter.
“Manufacturers aren’t just looking for better specs; they are looking for reliability that rivals a diesel engine,” Myersdorf said. “Until an alternative power source can survive a ‘drop test’ and be refueled by a soldier wearing heavy gloves in a rainstorm, it remains a ‘project’ rather than a ‘product.’”
Executives believe alternative power systems are more likely to enter drones through hybrid architectures than outright replacement.
In such designs, a fuel-based generator extends cruise endurance, while a lithium battery supplies peak discharge, startup reliability, and system stability.
Executives say the real signal of disruption will be operational milestones like rapid cold-start capability, scalable fuel logistics, and integration into operational fleets. Endurance is secondary.
For now, the competitive focus is shifting toward turnaround time, fast charging, ruggedization, and repeatable deployment cycles.
Until an alternative can match lithium’s reliability, simplicity, and field readiness, battery executives remain confident that lithium will stay embedded at the center of military drone power.
