HPQ Silicon reports 6,696 mAh from GEN4 silicon anode in 21700 format, 45% above graphite baseline

HPQ Silicon has announced a significant breakthrough in battery technology with its 21700 cylindrical cells incorporating Novacium’s GEN4 silicon-based anode material. These cells achieved an average discharge capacity exceeding 6,600 mAh, with a record cell reaching 6,696 mAh, representing a 45% improvement over conventional graphite cells, which typically deliver between 4,800 and 5,000 mAh. The energy density metrics are also impressive, with 319.9 Wh/kg gravimetric and 906.2 Wh/L volumetric energy density recorded under standard testing conditions. This milestone builds on a clear progression in HPQ’s silicon anode development, moving from earlier generations in the 18650 format to the current 21700 cells. The GEN4 cells outperform the previous GEN3 iteration by approximately 9%, while the company’s graphite baseline in the same format is substantially lower. The development journey has seen steady increases in capacity, starting from 2,778 mAh in 18650 graphite cells to over 6,600 mAh in the latest GEN4 21700 cells, with future targets aiming to reach 7,000 mAh. HPQ emphasises that these results stem from development and validation testing rather than commercial production, with the cells manufactured by an industrial partner. The company holds exclusive rights to commercialise Novacium’s GEN3 and GEN4 materials in North America under the ENDURA+ brand. Bernard Tourillon, HPQ’s President and CEO, highlighted the achievement as confirmation of an industrially viable, high-performance battery solution progressing through the commercialisation pathway, despite the material not yet being fully optimised. The advancement places HPQ among a select group of developers worldwide capable of producing 21700 cells with capacities above 6,500 mAh, comparable to firms such as Molicel, EVE Energy, and Amprius. This development could have significant implications for electric vehicle and energy storage markets, where higher capacity and energy density batteries are critical for extending range and reducing weight. Continued optimisation and scaling of this technology will be closely watched as HPQ moves towards commercial production.