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New Gen 3.5 Solid-State Battery, 381 Wh/kg Finally Goes Mass Production!
6/10TL;DR
ProLogium says its 381 Wh/kg all-solid-state battery has moved into industrial production, promising lighter long-range EVs and very fast charging, but cost, durability and large-scale automotive manufacturing remain unresolved.
KEY POINTS
A major jump in energy density
At 381 watt-hours per kilogram, ProLogium's new cell stands well above many current EV batteries. LFP cells typically sit around 160 to 200 Wh/kg, while high-nickel lithium-ion cells can approach 300 Wh/kg at cell level. That gap could let automakers either extend range with the same pack size or cut pack mass while keeping range similar.
Why lighter batteries matter
Higher cell energy density does not translate directly into double vehicle range because battery packs also include cooling, electronics, wiring and structure. Even so, a lighter pack can improve acceleration, handling, braking and efficiency. That makes the chemistry especially appealing for premium and performance EVs, where every kilogram matters.
Evidence for a true all-solid-state design
The battery uses a ceramic solid electrolyte, a silicon-based anode and a nickel-rich cathode. A reported thermal vacuum test exposed the cell to 120 C for 6 hours, after which weight loss was said to be below 0.05% against a 0.5% limit. Such a result would help distinguish a genuine all-solid-state architecture from semi-solid designs that still rely partly on liquid electrolyte.
Fast charging could be the breakthrough feature
ProLogium has not published a confirmed charging time for the exact 381 Wh/kg cell. However, an earlier cell on the same platform reportedly reached 5% to 60% in 8 minutes and 5% to 80% in about 8.5 minutes under independent verification. If similar performance carries over, a 10% to 80% session could approach roughly 7 minutes, though that remains an estimate rather than a specification.
Cycle life is strong, but not dominant
The company says the battery can deliver more than 1,200 fast-charge cycles between 10% and 80%. Depending on vehicle efficiency and pack size, that could translate to about 350,000 kilometers of driving, enough for many owners. Yet LFP batteries can reach several thousand cycles in some applications, showing that solid-state does not automatically win on longevity.
Silicon brings both advantage and risk
The use of silicon is central to the high energy density because silicon stores far more lithium than conventional graphite. But it also expands and contracts heavily during charging and discharging, which can damage electrodes and interfaces over time. That means durability remains one of the hardest engineering problems for this class of battery.
Production has started, but EV scale is still limited
ProLogium has reportedly shipped about 2.4 million cells since 2013, mostly small cells for electronics and car audio rather than large automotive packs. Its factory in Taiwan is sized at roughly 2 GWh a year, enough in theory for about 25,000 vehicles depending on battery size. That is a meaningful industrial step, but far from the scale needed to reshape the global EV market.
France expansion shows the long timeline
The company has broken ground on its first overseas plant in France. Initial capacity is expected at about 0.8 GWh in 2028, rising to around 4 GWh by 2030. Those figures underline how slowly even promising battery technologies move from pilot production to automotive volume.
Cost may decide everything
No price per kilowatt-hour has been disclosed, leaving the core commercial question unanswered. ProLogium is developing a next-generation design with a fully inorganic electrolyte to improve cost competitiveness. That matters because solid-state batteries are racing against lithium-ion technologies that are still getting cheaper, more durable and more energy dense each year.
The real competition is timing
Mercedes-Benz's investment signals serious industry interest, but no major production EV has yet been publicly launched with these cells. If automotive deployment slips toward 2029 or later, conventional lithium-ion may narrow the advantage further. The contest is no longer about proving a lab concept, but about building billions of cells reliably and affordably before incumbent technology gets good enough.
CONCLUSION
ProLogium's battery marks a credible advance for all-solid-state cells, especially in energy density and potential charging speed. Whether it becomes a true EV breakthrough now depends less on chemistry than on cost, durability and the ability to scale automotive production before lithium-ion closes the gap.
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