# Next-generation lithium batteries: Engineering and performance

Why these batteries are built for cars, not grids

Source page: https://www.materialinsights.org/energy/e_li_next/sg-eng/

What this tab covers Engineering and operating performance: round-trip efficiency, whether power and energy can be scaled separately, footprint and siting, and safety.

These chemistries target vehicles and aircraft where weight matters, not grid storage. Efficiency and power data from independent sources are thin, and none yet has a stationary product.

#### Round-trip efficiency
Unfavourable

No independent efficiency data were found for commercial cells. Solid-state cells should approach lithium-ion once interface resistance is solved. Lithium-sulphur and especially lithium-air show a large gap between charge and discharge voltage, which wastes energy as heat; a review of lithium-air names round-trip efficiency as one of the main problems still to solve.^[14](https://ideas.repec.org/a/eee/appene/v204y2017icp780-806.html)

#### Power and energy decoupling
Unfavourable

Like other cell batteries, power and energy rise together with the number of cells. Lithium-air would in principle draw its oxygen from air, but practical designs need filtered or bottled oxygen, so no real decoupling exists.^[14](https://ideas.repec.org/a/eee/appene/v204y2017icp780-806.html)

#### Footprint and siting flexibility
Mixed

Compactness is the point. Factorial Energy reported a road test of well over 1,000 km on one charge, and the IEA expects solid-state to stay in premium vehicles until the first half of the 2030s, with robots as a possible early market. For grid storage, where space is rarely the constraint, this advantage is worth little.^[1](https://iea.org/reports/global-ev-outlook-2026/electric-vehicle-batteries)
 Factorial Energy road test range well over 1,000 km^[1](https://iea.org/reports/global-ev-outlook-2026/electric-vehicle-batteries)

#### Safety and thermal runaway risk
Mixed

Removing the flammable liquid electrolyte is the main safety gain the IEA attributes to solid-state designs. Lithium metal itself is highly reactive, though, and sulphide electrolytes bring a toxic gas risk. Any stationary use would fall under NFPA 855, whose 2026 edition now lists several newer chemistries by name and requires large-scale fire tests.^[1](https://iea.org/reports/global-ev-outlook-2026/electric-vehicle-batteries)^[4](https://www.energy-storage.news/nfpa-855-2026-edition-updates-and-what-they-mean-for-energy-storage-projects/)

#### Sources

1. [Global EV Outlook 2026: Electric vehicle batteries](https://iea.org/reports/global-ev-outlook-2026/electric-vehicle-batteries) International Energy Agency, 2026
2. [NFPA 855: 2026 edition updates and what they mean for energy storage projects](https://www.energy-storage.news/nfpa-855-2026-edition-updates-and-what-they-mean-for-energy-storage-projects/) Energy-Storage.news, 2026
3. [Advances and challenges in lithium-air batteries (Tan et al., Applied Energy 204, 780-806)](https://ideas.repec.org/a/eee/appene/v204y2017icp780-806.html) Applied Energy, 2017

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_li_next/index.md)
- [Overview](https://www.materialinsights.org/energy/e_li_next/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_li_next/correlation/index.md)
- [Science and technology](https://www.materialinsights.org/energy/e_li_next/sg-sci/index.md)
- [Economics](https://www.materialinsights.org/energy/e_li_next/sg-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_li_next/sg-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_li_next/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_li_next/links/index.md)