The SiCore 500 platform is designed to hit 500 Wh/kg using manufacturing infrastructure Amprius already operates at scale
(Image courtesy of Amprius Technologies)
Amprius Technologies has introduced a second-generation SiCore battery cell that reaches 500 Wh/kg at a 1C continuous discharge rate, using the same lithium-ion manufacturing equipment, processes, and cell formats already installed across its contract manufacturing network. The company puts that figure at up to twice the energy density of conventional graphite-based cells, the chemistry still standard across most commercial lithium-ion production. The approach is intended to give customers a path from qualification to volume with no specialized tooling required, for long-endurance aviation platforms such as high-altitude pseudo-satellites.
SiCore 500 built for existing manufacturing lines
Previous cells that cleared 500 Wh/kg relied on specialized materials handling and non-standard cell construction, and none reached commercial volume. Second-generation SiCore is the first Amprius platform designed to hit that same energy figure using standard equipment and processes rather than a bespoke production line.
The company frames the approach as a way to extend its highest-performing tier without departing from its asset-light manufacturing model, which relies on contract manufacturers rather than company-owned factories for volume production. Building a record-setting cell on infrastructure that already exists across that partner network removes the capital and lead-time risk that typically comes with scaling a new chemistry through purpose-built lines, a factor that matters as much to a procurement team assessing supply continuity as it does to Amprius’ own balance sheet.
500 Wh/kg cell targets HAPS and fixed-wing endurance
The new SiCore cell is built for sustained, low-rate discharge profiles rather than high-power bursts, the pattern typical of high-altitude platform stations (HAPS), fixed-wing drones, and other long-endurance aircraft. The 500 Wh/kg and 1C figures describe the cell’s rated capability rather than how it will actually run in service. HAPS platforms draw power far more gently than that benchmark rate implies, banking daytime solar energy to trickle-discharge through the night, a different design target from a cell built to sustain repeated high-current draws.
In HAPS operation, stored energy and battery weight decide whether persistent stratospheric flight is possible. Fixed-wing platforms bank daytime solar energy to fly through the night, while lighter-than-air designs draw on stored power for propulsion and station keeping.
The cell will be offered in customer-specific formats as well as the standard small uncrewed aircraft systems (sUAS) pouch format defined by SAE JA1016, an existing industry form factor rather than a proprietary one, which shortens the design-in work for manufacturers already building around that standard. Higher specific energy can add flight time, range, or payload capacity without adding weight elsewhere.
Zephyr flights demonstrate silicon anode cells in service
Amprius has supplied battery cells to AALTO HAPS, an Airbus subsidiary, since 2018 across multiple generations of the Zephyr platform. AALTO’s own account of the record flight describes 67 days, six hours and 52 minutes of continuous stratospheric operation that wrapped up in April 2025, extending the platform’s previous 64-day mark. The flights demonstrate Amprius’ silicon anode chemistry holding up under exactly the kind of multi-week, low-rate discharge cycling the new SiCore 500 platform is designed around.
“Energy density is fundamental to Zephyr’s endurance,” said Pierre-Antoine Aubourg, COO at AALTO HAPS. “Our longstanding relationship with Amprius has focused on advancing the energy storage required for persistent stratospheric flight. Continued gains in specific energy can meaningfully extend flight duration and expand mission capability.”
Dr. Ionel Stefan, CTO of Amprius, said reaching 500 Wh/kg is a significant technical milestone, but how the company reached it matters as much as the number. “By achieving that performance level on conventional manufacturing equipment, our aviation customers can qualify this cell knowing that we have designed a cost-effective, scalable path to volume behind it,” he said.
Commercial availability set for Q4 2026
Commercial availability is expected in the fourth quarter of 2026. Initial production is planned at the company’s Fremont, California facility, with volume output intended to scale through Amprius’ existing global contract manufacturing partners rather than new dedicated lines.
The company’s own forward-looking disclosures note that performance achieved in testing or limited production does not always carry through unchanged once a cell moves to commercial volume, a standard caveat attached to any new battery platform moving toward scale.
Stay ahead in the electrification revolution. Explore more breakthroughs from leading innovators in electric commercial transport – visit our news page.