Hanneke Weitering is a writer and editor with AIN covering advanced air mobility and new flight technologies. She became an aviation journalist and joined the AIN team in the summer of 2022 after reporting on spaceflight and astronomy for six years at Space.com. After earning a bachelor’s degree in physics from the University of Tennessee, Knoxville, she moved to New York City to pursue a master’s degree in science, health, and environmental reporting at New York University&#039;s Arthur L. Carter Journalism Institute. She is now based in Seattle near Boeing Field and spends her free time exploring nature in the Pacific Northwest.

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Hanneke Weitering

To meet growing demand for drones in the U.S., aircraft battery developer Amprius has begun shipping its SiCore high-energy lithium-ion batteries from a pilot production line in Fremont, California, as contract manufacturing partners in China and South Korea continue to carry out mass production abroad.
Among the first customers to receive SiCore battery cells from the Fremont facility is Airbus subsidiary Aalto, which has been using them to power a solar-powered high-altitude pseudo satellite called <a href="https://www.ainonline.com/aviation-news/aerospace/2022-07-19/airbus-launches-connectivity-unit-solar-powered-zephyr">Zephyr</a>. Earlier this year, the autonomous Zephyr aircraft completed a record-setting 67-day flight using solar panels to charge Amprius’ batteries.
“Amprius’ SiCore cells represent a major advancement in energy performance, supporting the ultra-lightweight, long-endurance requirements of our high-altitude operations,” said Aalto chief technology officer Pierre-Antoine Aubourg. “Their silicon anode technology has already enabled Zephyr to operate in the stratosphere overnight for months at a time, an unprecedented milestone in persistent flight. We look forward to working with Amprius as we qualify their next-generation cells to power the future of Stratospace innovation.”
The recently expanded pilot production line at Amprius’ Fremont headquarters will prototype custom SiCore battery solutions for prospective customers who are in the qualification stage, in which the battery packs are integrated and tested before a new aircraft heads to production. Amprius president Tom Stepien told AIN that the qualification process can take anywhere between three and 18 months. If and when a customer settles on a configuration and places high-volume orders, those orders will ship from Amprius’ existing contract manufacturing partners overseas.
Amprius is the only battery manufacturer currently capable of producing lithium-ion batteries with an energy density of 500 Wh/kg, Stepien said. He noted that the company’s SiMaxx battery platform demonstrated an energy density of 517 Wh/kg in a recent exercise with the U.S. Army, outperforming expectations. According to Stepien, the high energy density combined with ultra-lightweight materials in Amprius’ batteries can double an electric aircraft’s range and endurance. “It’s about maximizing the value of the mission,” he said. “If you can have the same energy with less weight, or the same weight with more energy, then your mission, simplistically, should be twice as long.”

<h2>Aviation Industry Dominates Amprius’ Order Book</h2>
Since Amprius began commercializing its high-energy batteries in 2018, the company has engaged with hundreds of customers in the drone and light electric vehicle sectors. In the past two years alone, around 320 customers have sampled Amprius’ batteries, Stepien said. In its second-quarter financial filings, the company reported shipments to 93 customers, including 43 first-time buyers and 50 repeat customers. Aalto, <a href="https://www.ainonline.com/news-article/2022-10-31/bae-systems-taps-battery-maker-amprius-electric-aviation-and-defense">BAE Systems</a>, and the U.S. Army were among the recipients of those deliveries.
Amprius partly attributes the recent increase in demand for drone technologies to President Donald Trump’s June 2025 executive order promoting domestic drone manufacturing, as well as a Department of Defense directive issued in July that prioritizes American-made drones for procurement.
About 90% of the company’s revenues come from the aviation sector, with a majority of customers using SiCore batteries to power electric and hybrid-electric propulsion systems on uncrewed aerial vehicles (UAVs), or drones. It is also working with manufacturers of passenger-carrying electric aircraft with up to six seats, Stepien said.
The company has not disclosed many of its customers in the eVTOL sector, but it has <a href="https://www.ainonline.com/news-article/2023-11-07/battery-maker-amprius-secures-orders-three-electric-aircraft-developers">previously announced orders</a> from three undisclosed “premier electric aviation manufacturers.” Last year, California-based <a href="https://www.ainonline.com/news-article/2023-12-13/aibot-partners-honeywell-develop-flight-controls-autonomous-evtol-aircraft">Aibot</a> announced that it had selected Amprius to supply the batteries for its electric aircraft product line, which includes small quadcopter drones as well as a larger tilt-wing eVTOL aircraft that can be configured as a heavy-lift cargo drone or a six-passenger air taxi. Aibot just revealed the product line at the Commercial UAV Expo 2025 in Las Vegas on September 2.
Also on September 2, Amprius announced that European drone manufacturer Nordic Wing selected its SiCore cells to power its Astero ISR aircraft, a fixed-wing UAV designed for intelligence, surveillance, and reconnaissance (ISR) operations in combat scenarios.
“Amprius’ batteries have fundamentally changed how our drones operate in the field,” said Nordic Wing founder Jonas Dyhr. “With a significant increase in flight time, our drones can stay airborne longer, cover more ground, and deliver real-time intelligence without interruptions. This enhanced endurance doesn’t just improve performance; it redefines what’s possible in every mission and can mean the difference between success and failure.”

Until recently, Amprius’ pilot line in Fremont was focused on SiMaxx batteries, a more advanced and costly platform that the company is producing in-house at a much lower volume. That’s because SiMaxx batteries require highly specialized manufacturing processes that are capital-intensive and difficult to scale.
Featuring 100% silicon anode lithium-ion cells, the SiMaxx line offers the highest energy density commercially available—500 Wh/kg—along with <a href="https://www.ainonline.com/news-article/2023-08-04/amprius-declares-breakthrough-aviation-battery-technology">ultra-fast charging speeds</a>. SiCore batteries, on the other hand, deliver up to 400 Wh/kg with reduced charging speeds at a fraction of the cost compared with the SiMaxx line. Amprius launched the SiCore line in 2024 as a low-cost, scalable alternative to SiMaxx. Because SiCore batteries can be made using the same equipment and techniques as other lithium-ion batteries, production is easier to outsource.
“These contract manufacturers are making cells that are standard anodes, and the next day, they’re making cells that use the silicon anodes from Amprius [with the] same standard equipment,” Stepien told AIN. “SiCore is good enough in many cases, and since it is using standard equipment, we can price it lower than SiMaxx.”
<h2>Boosting Domestic Battery Production</h2>
Bringing SiCore production to Fremont might help U.S.-based customers avoid some import tariffs early on, but not for long. Customers in the qualification stage could order a couple hundred battery cells from Fremont for testing, but larger orders for serial production will still come from factories in China and South Korea.
“Customers recognize that if they have to prescribe the country of origin for the batteries that they may be paying higher for the U.S. compared to other parts of the world,” Stepien said. However, he noted that 86% of Amprius’ revenues from batteries in the last quarter came from international sales and were not subject to U.S. tariffs. At the same time, customers within the country have begun to ask for “U.S.-made” batteries, he said.
In 2023, Amprius announced plans to build a large-scale production facility in Brighton, Colorado, but those plans were put on hold indefinitely earlier this year. “Our ability to move forward with the design and the capacity in Brighton is really dependent on a number of macro things going on, not the least of which is tariffs, government incentives, supply and demand,” Amprius chief financial officer Sandra Wallach told investors in a recent earnings call.
“At this point, we have more than enough capacity…to serve the foreseeable future,” she said, “but we are keeping those lines of communication open if something does change that would make it more economically viable to move forward with Brighton at this time.”
<h2>Amprius Scores $10.5 Million Defense Contract&nbsp;</h2>
To help meet demand for a domestic battery supply, Amprius is bringing new capabilities to its Fremont line, including electrode manufacturing, with the help of a $10.5 million contract it received from the U.S. government’s Defense Innovation Unit in July.
As part of that contract, Amprius will work to begin qualifying battery components and materials—including separators, cathodes, and anode powders—made by the U.S. and its NATO or “Five Eyes” partner countries. According to Stepien, this will help establish a supply chain for batteries that complies with the U.S. National Defense Authorization Act (NDAA), which prohibits federal agencies from procuring certain products from China, as well as the trading policies of partner nations.

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