Solid-state batteries in 2026: what is real for energy storage, and how they are tested

#Policy is pushing

Three measures in 2026 put solid-state batteries at the top of China’s battery agenda:

• The five-year plan. On 28 September 2026 the Ministry of Industry and Information Technology and six other departments issued the battery industry plan for 2026–2030. It focuses on all-solid-state batteries and expects them to reach a larger industrial scale for the first time by 2030. It names the open problems — ionic conductivity, cycle stability and cost — and calls for high-performance solid electrolytes to be scaled up. The same plan sets a target of 15,000 cycles for long-life lithium-ion cells.
• Tax. Lithium-ion batteries pay a 2% consumption tax from 1 September 2026, rising to 4% from 1 September 2027. Solid-state and sodium-ion batteries are exempt until 31 December 2028.
• Definitions. A national standard on terminology and classification for solid-state batteries in electric vehicles (numbered GB/T 43568-2026 and effective from 1 July 2026, according to SMM) ends the marketing free-for-all.

#What counts as "solid-state"

The classification is based on how ions move between the electrodes:

The draft set a measurable test: after heating at 120 °C for six hours in near-vacuum, a solid-state battery may lose no more than 0.5% of its mass. In the validation runs, solid-state samples stayed below that limit; hybrid cells lost between 1.68% and 10.33%. In other words, most of what was sold as "solid-state" until now is a hybrid solid–liquid battery.

#Where the industry stands

Market data from SMM for the third quarter of 2026 show an industry between pilot lines and mass production:

• China produced 70 tonnes of sulfide electrolyte from January to August 2026 — more than the whole of 2025, but only about a fifth of the full-year forecast. Capacity utilisation was under 6% in August.
• Lithium sulfide output, a key precursor, was 52.9 tonnes in the same period; China makes about 95% of the world’s supply.
• Large cell projects have been announced, but many are still being built.

MIT Technology Review describes the remaining hurdles: dendrites that can short the cell, solid electrolytes that crack, and production that needs defect-free ceramic layers and dry rooms. Manufacturers expect price parity with lithium-ion packs only in the mid-2030s.

#First storage projects

Storage is not the first market for all-solid-state cells — cars, drones and ships pay more for energy density. But semi-solid cells are already appearing in stationary storage:

• WeLion, one of the leading semi-solid makers, has 11 GWh a year of capacity at four Chinese sites and 18 GWh under construction, according to MIT Technology Review; its cells cost more than conventional lithium-ion.
• SMM reports semi-solid storage framework agreements by WeLion in Hungary (150 MWh) and Romania (50 MWh), and an all-solid-state storage project of 6 GWh in Hukou, Jiangxi, whose first phase was due to start trial production at the end of September.

For storage buyers, the pitch is safety: less or no flammable liquid electrolyte should mean less risk of thermal runaway and fire spread. That is exactly what has to be proven.

#How solid-state storage is tested

There is no separate certification route for solid-state or semi-solid storage. The existing standards are written for lithium batteries in general and apply to the product as built:

1. China: GB 44240-2024, the mandatory safety standard for lithium batteries in electrical energy storage, and the GB/T 36276 series for performance.
2. International: IEC 62619 for industrial lithium cells and batteries, including the thermal propagation test, and IEC 62933-5-2 for system safety.
3. North America: UL 1973 for the battery, UL 9540 for the system and UL 9540A for fire behaviour — the test that will show whether a solid-state cell really stops propagation.
4. Transport: UN 38.3 before any shipment. Semi-solid and solid-state lithium cells are still lithium-ion batteries for transport purposes.

Two practical points follow. First, a "no thermal runaway" claim is only as good as the UL 9540A cell and module data and the IEC 62619 propagation result behind it. Second, new chemistries often need new test set-ups: cells that do not vent in the usual way, higher operating temperatures for some electrolytes, and different behaviour under crush and nail penetration. Plan these with the laboratory before samples are built.

#What to watch in 2027

• Whether the first all-solid-state storage lines move from trial to steady production.
• Cost: the tax exemption helps until 2028, but cells still cost more than LFP.
• Test data: the first published UL 9540A and IEC 62619 results for semi-solid and solid-state storage products will show how much safety margin the technology really adds.