The best demonstrated cell reaches 410 Wh/kg against 250 for conventional Li-ion — but conventional packs cost $115/kWh, and solid-state has to ride that curve down. No solid-state cell is in a series-production vehicle yet.
ProLogium — Gen 3.5 Lithium Ceramic Battery, Taoyuan, Taiwan — ProLogium began mass production of its Gen 3.5 Lithium Ceramic Battery at its Taiwan giga-plant on 2 Sep 2026. The 185.4 Ah large-format cell measured 381 Wh/kg and 903 Wh/L in third-party TÜV testing, and qualifies as all-solid-state under GB/T 43568-2026: after six hours under vacuum at 120°C it lost under 0.05% of its weight, against a 0.5% ceiling. The energy density and the classification are independently measured, which is rare in this field; what the announcement does not give is a production volume, a cost, or a named vehicle programme.
QuantumScape / Honda R&D — QuantumScape signed a multi-year joint research agreement with Honda R&D to co-develop its lithium-metal solid-state battery platform and the associated manufacturing processes — following Honda's completion of a hands-on technology evaluation and benchmarking. A second major automaker (alongside VW's PowerCo) validating QuantumScape's cells, though both sides stress development and manufacturing scale-up, not yet commercial production.
QuantumScape — QuantumScape shipped B-samples of its QSE-5 lithium-metal cell (~844 Wh/L) to automotive customers for qualification — a step from prototype toward a product.
Samsung SDI — Samsung SDI began running a dedicated sulfide solid-state pilot line, shipping sample cells to automakers — the first major maker to move from lab to a pilot production line.
CATL — CATL announced a 'condensed' (semi-solid) cell rated ~500 Wh/kg — the first credible claim to roughly double conventional energy density, initially aimed at aviation.
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