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Amprius Batteries Power First Stratospheric Flight for BAE Systems Drone

Silicon Anode Batteries Help BAE Systems Reach New Heights

Amprius Technologies, Inc. (“Amprius” or the “Company”) (NYSE: AMPX), a leader in next-generation lithium-ion batteries with its Silicon Anode Platform, today announced that its high-density batteries played a significant role in powering BAE Systems' first successful stratospheric flight trial. PHASA-35, the High-Altitude Pseudo Satellite (HAPS) Uncrewed Aerial System (UAS) designed by BAE Systems’ subsidiary Prismatic Ltd., is planned to operate above the weather and conventional air traffic.

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During a recent test flight, the PHASA-35 crossed an altitude of more than 66,000 feet, reaching the stratosphere, before landing successfully. The trial, completed last month in New Mexico, allowed engineers to assess the experimental solar-electric drone within the edges of the planet’s atmosphere.

“Amprius is proud to be recognized as a key partner to BAE Systems supporting their development of the PHASA-35®,” said Dr. Kang Sun, Chief Executive Offer of Amprius. “This ultralight platform provides an alternative and flexible approach to traditional systems such as satellites or conventionally powered aircraft. As we develop our next-generation of industry-leading silicon anode batteries, we look forward to helping BAE Systems and Prismatic further enhance the capabilities of their PHASA-35 aircraft.”

Dave Corfield, CEO of Prismatic, added, "Collaborating with outstanding partners like Amprius has been instrumental in establishing PHASA-35 as the forefront solution for next-generation applications in long endurance, high altitude, and communications. Our technology holds immense promise for the future, offering extensive possibilities for communication networks, including 4G and 5G. Its versatile applications, from disaster relief to border protection, present a compelling alternative to conventional airborne and satellite systems."

PHASA-35's first stratospheric flight marks a remarkable achievement, showcasing BAE Systems' commitment to technological innovation and market expansion. As a High-Altitude Long Endurance (HALE) vehicle, the PHASA-35® (standing for Persistent High Altitude Solar Aircraft) is powered by the Sun during the day and by batteries overnight. The long-life battery and highly efficient solar technology allow the aircraft to potentially maintain flight for up to a year, operating in the upper regions of Earth’s atmosphere. The novel aero structure design and advanced solar technology make PHASA-35® a game changer in the air and space market.

Amprius announced in October of 2022 that it had entered into a three-year cooperation agreement with BAE Systems. Both parties agreed to investigate business opportunities enabled by the use and supply of Amprius’ silicon anode batteries for electric products being developed by BAE Systems in the UK. For more information, please visit Amprius’ investor relations website at

Click here for additional images of the PHASA-35.

About Amprius Technologies, Inc.

Amprius Technologies, Inc. is a leading manufacturer of high-energy and high-power lithium-ion batteries producing the industry’s highest known energy density cells. The company’s commercially available batteries deliver up to 450 Wh/kg and 1,150 Wh/L. The company’s corporate headquarters is in Fremont, California where it maintains an R&D lab and a pilot manufacturing facility for the fabrication of silicon anodes and cells. To serve customer demand, Amprius recently entered into a lease agreement for an approximately 774,000 square foot facility in Brighton, Colorado. For additional information, please visit Also, see the company’s LinkedIn and Twitter pages.

About BAE Systems

At BAE Systems, our advanced defence technology protects people and national security, and keeps critical information and infrastructure secure. We search for new ways to provide our customers with a competitive edge across the air, maritime, land and cyber domains. We employ a skilled workforce of 90,500 people in more than 40 countries, and work closely with local partners to support economic development by transferring knowledge, skills and technology.

Forward-Looking Statements

This press release includes "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, each as amended. Forward-looking statements may be identified by the use of words such as "estimate," "plan," "project," "forecast," "intend," "expect," "anticipate," "believe," "seek" or other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. These forward-looking statements include, but are not limited to, statements regarding the performance of Amprius’ batteries. These statements are based on various assumptions, whether or not identified in this press release, and on the current expectations of Amprius’ management and are not predictions of actual performance. Actual results could differ materially from these forward-looking statements as a result of certain risks and uncertainties. These forward-looking statements are subject to a number of risks and uncertainties, including Amprius’ liquidity position; risks related to the rollout of Amprius’ business and the timing of expected business milestones; the effects of competition on Amprius’ business; supply shortages in the materials necessary for the production of Amprius' products; and changes in domestic and foreign business, market, financial, political and legal conditions. More information on these risks and uncertainties that may impact the operations and projections discussed herein can be found in the documents we filed from time to time with the Securities and Exchange Commission (the "SEC"), all of which are available on the SEC’s website at There may be additional risks that Amprius does not presently know or that Amprius currently believes are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. In addition, forward-looking statements reflect Amprius’ expectations, plans or forecasts of future events and views as of the date of this press release. These forward-looking statements should not be relied upon as representing Amprius’ assessments as of any date subsequent to the date of this press release. Accordingly, undue reliance should not be placed upon the forward-looking statements. Except as required by law, Amprius specifically disclaims any obligation to update any forward-looking statements.


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