Solid-state battery.
Chasing a moving target.

Last year, BYD showed a car with an ordinary liquid-electrolyte battery that adds about 400 kilometers of range in five minutes. That was supposed to be solid-state's party trick.

Solid-state batteries have been chasing targets like that for years. The idea is simple. Today's lithium-ion cells use a flammable liquid to carry charge between the electrodes. Swap that liquid for a solid layer of ceramic or sulfide and you get a battery that holds far more energy for its weight, charges faster, and doesn't catch fire when it's crushed. Meanwhile, the battery it's supposed to replace keeps improving. Liquid cells keep charging faster, and lithium iron phosphate (LFP) keeps getting cheaper. Solid-state cells still cost several times as much per kilowatt-hour, and China's new national battery plan only targets "initial large-scale application" of them by 2030.

Even so, 2027 is a crucial window for solid-state battery stocks. Samsung SDI plans mass production in the second half, Toyota is holding a 2027–28 launch window, reportedly for Lexus, and CATL, BYD, and Geely are all targeting trial production. Every major battery maker has the date on its calendar.

US solid-state battery stocks are down this year anyway. QuantumScape has lost more than half its value, and SES AI trades under a dollar with a warning from the NYSE. The market stopped paying for announcements a while ago.

The giants decide when this happens, and everyone else is trying to get a giant to say yes:

• Deciders: the battery and car giants setting the timeline.
• Suitors: the US pure-plays that need a giant to adopt their technology.
• Suppliers: the solid electrolyte makers that sell to everyone.
• Private: the IPOs and SPACs that will reprice the group.

Solid-state is a rounding error on each of these companies' revenue today. They'll still decide whether it becomes a 2028 product or a 2032 one.

Toyota NYSE: TM

Toyota has more than 1,300 solid-state patent filings, the deepest pile in the industry. It has also pushed back its own targets before. The difference this time is that Japan's industry ministry approved its production plan in 2024, and the supply chain is being built: Idemitsu on electrolyte and Sumitomo Metal Mining on cathodes. The first cars are due in the 2027–28 window, reportedly flagship Lexus models. When one rolls off the line, every stock on this list moves.

Samsung SDI KRX: 006400

Samsung SDI has the most concrete plan outside China: mass production in the second half of 2027 at Ulsan, part of a 25 trillion won investment plan that runs to 2040. The smart part is who buys first. Not carmakers but humanoid robots, which have no room for a big pack, need hours of runtime and will pay a premium a car buyer never would. Samples are already out with EV, robot and other AI hardware customers.

CATL SZSE: 300750

CATL is the world's biggest battery maker and the most honest clock in the industry. It's building a 2027 trial line for sulfide-based solid-state cells, but its chairman has said flatly that reaching a million cars before 2030 is "very unlikely." China's national plan now says the same thing. When the company with the most to lose from solid-state says 2030, believe it.

The US pure-plays. Each has technology the giants want to test and no business to fall back on if they don't adopt it, which makes these the riskiest solid-state battery stocks on the list.

QuantumScape NASDAQ: QS

QuantumScape doesn't want to build gigafactories. It wants to license its ceramic separator and production process to automakers and collect fees. Volkswagen's battery unit PowerCo has agreed terms for a license covering up to 85 gigawatt-hours a year, to be signed once QuantumScape hits its milestones, and Honda signed a multi-year development deal in June after a long technical review. Its Eagle pilot line has been running since February.

The market isn't convinced. In July the two sides cut the maximum development payments to $75.4 million from $130.7 million, VW's commercial target is still the end of the decade, and QuantumScape burns about a quarter of a billion dollars a year. The stock is down more than half this year. A second automaker license with real money attached is what changes that.

Solid Power NASDAQ: SLDP

Solid Power sells the ingredient. It makes sulfide electrolyte powder that's designed to run on existing lithium-ion production lines, which is why BMW, Samsung SDI and SK On all work with it. Its new continuous electrolyte line is due to start up this quarter, lifting capacity to 75 tonnes a year.

It also has about $419 million in liquidity, no debt and operating expenses of about $30 million a quarter. That's more than three years of runway while it negotiates a Korean manufacturing joint venture, targeted for announcement by the end of 2026. At around half a billion dollars in market value, the market is pricing it like a long shot.

Factorial NASDAQ: FAC

Factorial has the best road test in the sector: Mercedes drove a modified EQS 1,205 kilometers on one charge with its cells. Mercedes, Stellantis, Hyundai and Kia are investors. So is In-Q-Tel, the CIA-backed venture fund, and that tells you where Factorial's first money comes from: drones and defense, which will pay for lightweight cells now. In September it signed a joint development deal with Mitsui Kinzoku to build its cell manufacturing process around Mitsui's sulfide electrolyte. First revenue is expected in 2027, and its cash runs into early 2028.

Every solid-state cell needs a new ingredient that almost nobody makes at scale: the solid electrolyte itself.

Idemitsu Kosan TYO: 5019

Idemitsu is an oil refiner that figured out decades ago how to turn waste sulfur from refining into lithium sulfide, the raw material for sulfide electrolytes. It has been Toyota's partner since 2013 and is building a large electrolyte pilot plant in Chiba, partly funded by the Japanese government, due in 2027. It says it will sell to "various customers," not just Toyota. The stock trades on oil margins, so you're buying the battery business with a refinery wrapped around it.

The IPO pipeline is where the next valuation marks for solid-state battery stocks come from.

ProLogium NASDAQ: TDAC → PRLG, pending

ProLogium is a Taiwanese maker of lithium-ceramic cells that has shipped millions of them since 2013. It's merging with a SPAC at a $3.8 billion valuation to list as PRLG, and the money funds a gigafactory in Dunkirk, France, backed by up to €1.4 billion in French subsidies. Its 356 watt-hours per kilogram in third-party testing is lower than the lab records others announce, but it comes from a product it actually sells. The vote hasn't happened yet.

WeLion New Energy

WeLion makes the semi-solid battery pack in NIO's cars, still part liquid, and the closest thing to solid-state that consumers can buy today. It's raising about ¥2 billion at a roughly ¥20 billion valuation and has started the preparation process for a listing in Shenzhen. When it lists, it'll set the first public price for semi-solid cells at scale.

QingTao Energy

QingTao filed to list in Hong Kong in April, and its numbers are the sector's warning label. It lost ¥1.3 billion in 2025, and its EV battery business ran a gross margin of negative 111.6% (negative 26.5% across the company), meaning it lost more than a dollar on every dollar of car batteries it sold. That's what mass production looks like before the costs come down.

The bridge is the destination.

For years, robots, drones and aircraft were pitched as a stopgap: sell to them at a premium until car volume arrives. But the car market is a moving target. Liquid lithium-ion keeps charging faster, LFP keeps getting cheaper, and sodium-ion is coming in underneath. By the time solid-state gets near cost parity, the cell it's chasing will be better and cheaper again.

Where liquid cells can't catch up is weight and safety. A drone that flies twice as long, a humanoid that works a full shift, an electric aircraft that doesn't carry a fire risk: those buyers pay for energy per kilogram, not per dollar, and they pay now. That's not a bridge. It's the market.

In 2027, value solid-state battery stocks on what flies and walks, not what drives. The ones already selling there are building a real business. The ones still waiting on a car contract are waiting on a target that keeps moving.