Cuberg, a startup battery company based in Emeryville, California, has verified the performance of its cell-level battery – 369 Watt-hours per kilogram at a discharge rate of C/20. This was verified in testing at the Idaho National Laboratory (INL), with Cuberg cells demonstrating a specific power of 2,000 Watts per kilogram.

C Rate is the charge and discharge rate for a battery. Note the differing duration of a battery’s ability to provide a given amperage. Credit // Sustainable Skies

Electric motors manage to extract 85 to 97 percent of the energy contained in the battery, resulting in a 10:1 ratio of fuel energy density between gas engines and electric motors, respectively.
Cuberg’s announcement highlighted an exceptional combination of specific energy, specific power, and cycle life in an independent testing and verification process conducted on behalf of the U.S. Department of Energy. The results, including up to 80% increase in specific energy relative to Li-ion cells of comparable high-power output, represent a major step forward in the performance and maturity of battery technology for the future of electric mobility. Online publication Sustainable Skies has analyzed Cuberg’s results in detail, and the provided charts can be found in their full writeup “Cuberg Batteries – Some Real Numbers“.
While the global market for batteries to power electric mobility is expected to reach $300B per year by 20301, increasing power demands are driving Li-ion battery technology to its physical limits on performance and safety. Cuberg’s batteries, based on its breakthrough lithium metal technology, are optimally designed for successful commercialization. The batteries deliver greatly increased range and capacity with competitive cost of ownership under realistic operating conditions. In addition, Cuberg’s batteries use a non-flammable proprietary electrolyte that provides substantial safety advantages over Li-ion batteries.
Critically, Cuberg has achieved these industry-leading results in a pouch cell using technology that capitalizes on the scale and quality of the existing Li-ion manufacturing ecosystem. These strengths will ultimately allow Cuberg to bring next-gen batteries to the automotive market, delivering significant improvements in range and cost while preserving the substantial deployed capital base of Li-ion manufacturing.

Cuberg CEO Richard Wang
“Cuberg’s mission is to deliver next-gen batteries to power the rise of electric mobility, and an essential part of our strategy is to achieve independent verification and transparency of our results,” said Richard Wang, co-founder and CEO of Cuberg. “We are gratified to receive this verification by INL of the industry-leading performance and reliability of our technology, and excited to be working with our customers to begin full-scale flight testing in their aircrafts in the next year.”
Three key battery performance measures need to be optimized in balance for successful aviation commercialization: specific energy, which allows for longer flight times and ranges at a given weight; specific power output, which enables greater aircraft weights and payload capacity; and cycle life, which impacts cost of ownership. INL’s testing on Cuberg’s 5-Ah (amp-hour) battery cells indicated specific energy of 369 Wh/kg, specific power of 2,000 W/kg, and 370 cycles with C/2 charging before the cells reached end of life at an 80% capacity cut-off. Batteries providing in excess of 350 Wh/kg of specific energy represent a critical threshold for the electric aviation market. Cuberg is the first company to successfully combine this level of energy with high power and competitive cycle life under realistic operating conditions. Full testing results can be seen here.
Why it’s important: As emphasized by Liangbing Hu, the Herbert Rabin Distinguished Professor and Director of the Center for Materials Innovation, Materials Science, and Engineering at the University of Maryland, “the delivery of highly efficient, cost-effective and safe battery technology at scale is essential to enable the future of electric mobility. Passing the 350 Wh/kg threshold under realistic operating conditions is an important advancement and an impressive achievement.” Cuberg’s announcement represents a major milestone in the advancement of battery performance and maturity for the future of electrified aerial mobility.
Related:
- Cuberg’s Battery Produces 70% Increase in Flight Time for Drones
- OXIS Energy to Develop Lightweight Battery Cell for Bye Aerospace eFlyer
Sources // Cuberg Press Release; Sustainable Skies
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