A Reality Check on the Solid-State Mass-Production Race — China’s Late-2026 Announcement, and Korea/Japan’s 2027 Timeline

What’s the story: between the ‘world’s first mass production’ claim and the actual schedules

The race to mass-produce solid-state batteries comes down to three camps: GAC-affiliated Greater Bay Technology in China, which has declared GWh-scale production in 2026; Samsung SDI, targeting mass production in the second half of 2027; and Toyota, aiming for commercialization in 2027-2028. However, what each company calls ‘mass production’ differs in electrolyte system, process and raw-material sourcing, so they are hard to compare against the same finish line. This article separates declarations from verifiable facts and, from a patent perspective, points out that the bottleneck of mass production lies not only in the cell plant but also at the raw-material stage.

Starting with the industry picture, at InterBattery 2026, held at COEX in Seoul on March 11-14, 2026, Samsung SDI unveiled for the first time a pouch-type solid-state battery for physical AI (humanoid robots) and put forward its solid-state brand ‘SolidStack’. It is notable that the first application has widened from EVs to robots. Then, in reports in early July 2026, the Samsung SDI executive in charge of solid-state production development said that global customers (EV makers and humanoid robot developers) had responded positively to sample evaluations in terms of energy density and safety, and that the company was keeping its target of mass production in the second half of 2027.

In June 2023, Toyota announced that it would commercialize a solid-state EV in 2027-2028 targeting a charging time of 10 minutes or less and a range of 1,200km, and on October 12 of the same year it announced a cooperation with Idemitsu Kosan on developing mass-production technology for sulfide solid electrolytes and building a supply chain. The tension appeared in between. According to an April 14, 2026 report, Greater Bay unveiled A-samples with an energy density of 260-500Wh/kg and set a target of GWh-scale mass production and vehicle installation in 2026. If realized, it would be a ‘world’s first’ more than half a year ahead of Samsung SDI and Toyota.

This article answers three questions: why is solid-state mass production hard, what is the same and what is different about the three companies’ declarations, and which layers of rights should planning and IP staff track in this race.

Basic principle: the challenge of mass production lies less in chemistry than in ‘how you press’

The challenge of solid-state lies at the interface more than in the chemistry. A liquid electrolyte seeps into the contours of the electrode on its own and creates contact, but a solid electrolyte cannot. If particles and layers are not pressed tightly together, the bridge that lithium ions must cross is broken and resistance soars. That is why the core of solid-state manufacturing converges on ‘how uniformly and how continuously you can press’.

By analogy, the batch method is like baking, where dough is put in a mold and baked one tray at a time, while continuous pressing is closer to noodle-making, where dough is rolled out continuously by rollers on a conveyor. Samsung SDI has explained that many competitors rely on a batch-type warm isostatic press (WIP, equipment that applies warm liquid pressure evenly from all directions) process that presses cells all at once, whereas it uses a roll-press method that presses cells as they move continuously along the line. The company said this approach gives it an edge in productivity and cost reduction at the mass-production stage.

Another layer is the raw material. Sulfide solid electrolytes use lithium sulfide (Li₂S) as a key raw material. According to Toyota’s announcement, Idemitsu has been developing technology to produce lithium sulfide, which arises from by-products of petroleum refining, and cited the ‘softness and adhesiveness to other materials’ of sulfides as the reason they suit mass production. Idemitsu was reported on February 27, 2025 to have announced a plan to build a lithium sulfide facility with an annual capacity of 1,000 tons (an investment of about 21.3 billion yen). This means that tonne-scale supply of raw materials determines the mass-production schedule as much as the speed of the cell plant.

Comparison: the schedules and approaches of the three players

Item	Samsung SDI	Toyota (+Idemitsu)	Greater Bay (GAC-affiliated)
Target timing	Mass production in H2 2027	Commercialization in 2027-2028	Target of GWh-scale production and vehicle installation in 2026
First application	Robots (physical AI) → expanding to EVs and mobile	EVs (1,200km, charging in 10 min or less target)	EVs
Disclosed specs	Energy density 900Wh/L (presented in March 2024)	Mostly target figures disclosed	260-500Wh/kg A-samples, 2-3C fast charging
Electrolyte and process features	Sulfide, silver-carbon (Ag-C) coating, continuous roll-press pressing	Sulfide, in-house lithium sulfide supply chain (1,000 t/yr plan)	Deep-eutectic-based composite electrolyte system (company description)
Verification status	Customer sample evaluations under way	Pilot facility stage	Mass-production proof unconfirmed — needs verification in H2

What this table says: The camp with the earliest target (2026) also has the widest energy-density range (260-500Wh/kg) and the lowest level of verification. Samsung SDI and Toyota, by contrast, have later schedules but have disclosed mass-production infrastructure first, in the form of process (continuous pressing) and raw material (1,000 tons of lithium sulfide).

Here we add one insight the original missed. The electrolyte that Greater Bay itself describes as distinct from semi-solid and quasi-solid systems is a ‘deep-eutectic-based composite electrolyte’ (a deep eutectic is a phenomenon in which mixing two components greatly lowers the melting point). It may belong to a different family from sulfide inorganic solid electrolytes, so the question ‘who will mass-produce solid-state first’ should in effect be read as ‘which definition of solid-state will be mass-produced first’. This difference in definition carries over not only to marketing but also to the literal interpretation of patent claims.

Patent perspective: one step ahead of the cell, raw-material equipment claims

Solid-state patent competition is often discussed in terms of electrolyte composition or cell structure, but in the mass-production phase, rights at the raw-material manufacturing stage also become subject to FTO (freedom-to-operate, i.e., infringement risk) review. In their 2023 cooperation announcement, Toyota and Idemitsu stated that the two companies are world leaders in the number of registered patents related to all-solid-state batteries and sulfide solid electrolytes. An example that shows the lithium sulfide manufacturing stage among these is US10239027B2 in the name of Idemitsu.

Bibliographic data: US10239027B2 (title “Device for producing lithium sulfide, and method for producing lithium sulfide”, applicant Idemitsu Kosan Co., Ltd.) has a priority date of December 16, 2014, a filing date of December 16, 2015 and a grant date of March 26, 2019; its legal status on Google Patents is Active, with an anticipated expiration date of December 16, 2035. The publication is US20170368515A1, and EP3235787B1 and JP6697398B2 are granted as family members.

Gist of the claims (restated): The apparatus claim has as its elements a reaction vessel in which lithium hydroxide powder is brought into contact with hydrogen sulfide gas, an internal stirring blade, a first heater that maintains the temperature of the inner wall in contact with the powder, and a second heater that prevents water condensation on the inner wall not in contact with the powder. The method claim loads at least 0.1kg of lithium hydroxide per liter of vessel capacity without organic solvent, flows hydrogen sulfide at 5L per minute or less per kilogram of lithium hydroxide, and stirs.

• Nature of the scope of rights: It reaches directly into the equipment and processes of material makers that mass-produce lithium sulfide, not cell makers.
• Design-around options: Using a lithium raw material other than lithium hydroxide (for example, a dry or reduction process using lithium carbonate or lithium sulfate) or choosing a solvent-based process may leave room to lack an element of the claims. Conditions outside the numerical limits of the method claim (0.1kg/L, 5L/min/kg) are also points where literal distance can be gained.
• Design-around scenario (counterargument): However, if conditions that deviate only slightly from the numbers achieve the same function (preventing condensation and high-purity solvent-free synthesis) in the same way, they may become subject to a doctrine-of-equivalents analysis. Conversely, from the patentee’s side, the reaction of lithium hydroxide and hydrogen sulfide itself is long-known chemistry, so the inventive step of the equipment configuration may be disputed against the prior art.

For Samsung SDI’s continuous roll-press pressing and Greater Bay’s composite electrolyte, this article was unable to verify corresponding patent numbers. As they cannot be confirmed from published patent information, tracking of published applications using keywords such as continuous-pressing solid-state cell manufacturing methods and deep-eutectic composite electrolyte compositions is needed. Greater Bay was reported to have filed more than 50 related patent applications, but the publication numbers and claim scope have not been confirmed from public sources.

Limits and outlook

There is also a second wall: price. The original article reported that, according to SNE Research, the current price of solid-state batteries is 400-600 dollars per kWh, 5-7 times that of LFP packs (81 dollars) and 3-5 times that of NCM packs (128 dollars). The bottleneck is the solid electrolyte. Even by the outlook of a domestic solid-electrolyte company, at an annual production scale of tens of tons it costs about 20 times as much as liquid electrolyte, and only falls to around 10 times at hundreds of tons. That is why ‘mass production’ in 2027 does not mean ‘an affordable price’, and also why markets that pay a premium for safety, such as robots and UAM, become the first gateway.

The optimistic outlook is that between 2026 and 2028 all three camps start up mass-production lines and solid-state takes root starting with premium markets. There is also an opposite scenario. If GWh-scale lines cannot gain speed while maintaining interface quality, ‘mass production’ may remain small pilot shipments, and if tonne-scale supply of raw materials such as lithium sulfide is delayed, utilization may not rise even when the cell plant is ready. This is the scenario in which the gap between the declaration date and the actual date of GWh shipments widens.

The strategic alternative is to track the solid-state race in three layers of rights and supply chain: ‘cell chemistry’, ‘pressing process’ and ‘raw-material sourcing’. Cell announcement news shows only the first layer, but actual mass-production speed and FTO risk are likely to be decided in the second and third layers.

Practical action: Planning and IP staff reviewing a sulfide solid-state materials or cell business should check the manufacturing process of their lithium sulfide supplier (whether the raw material is lithium hydroxide, whether it is solvent-free, and the gas-flow conditions) before signing a supply contract, and prepare an element-by-element comparison chart against the claims of US10239027B2 and its family (EP3235787B1, JP6697398B2).

Items requiring verification

• The official source of the ’10→80% in 7 minutes’ charging figure for Samsung SDI’s solid-state battery (not confirmed from primary sources in this article)
• Whether Toyota’s range target was ‘raised’ from 1,000km to 1,200km, or had been 1,200km since the 2023 announcement
• The original SNE Research report and reference date for the solid-state price (400-600 dollars per kWh) and LFP/NCM pack prices
• Whether Greater Bay’s composite electrolyte is based on an inorganic solid electrolyte and whether the cell contains a liquid component
• The construction site and start-up timing of Idemitsu’s lithium sulfide facility

Sources

1. Samsung SDI Newsroom, Samsung SDI Unveils All-Solid-State Battery for Physical AI (InterBattery 2026, 2026-03)
2. Korea JoongAng Daily, Samsung SDI targets 2027 mass production of solid-state batteries as global clients praise safety (2026-07-01)
3. Electronic Times (etnews), Samsung SDI unveils solid-state battery mass-production roadmap at InterBattery (2024-03-05)
4. Toyota Global Newsroom, Idemitsu and Toyota Announce Beginning of Cooperation toward Mass Production of All-Solid-State Batteries for BEVs (2023-10-12)
5. Aju Business Daily, Toyota declares commercialization of ’10-minute charge, 1,200km range’ solid-state EV in 2027 (2023-06-13)
6. Electrek, Toyota’s all-solid-state EV battery plans just got a lift from Japan’s oil giant (2025-02-27)
7. CnEVPost, GAC-backed Greater Bay claims breakthrough in solid-state batteries with new prototype roll-out (2026-04-14)
8. Google Patents, US10239027B2 – Device for producing lithium sulfide, and method for producing lithium sulfide (Idemitsu Kosan Co., Ltd.)
9. SNE Research solid-state battery price analysis (as cited in the original)