Eve Energy has unveiled two new all-solid-state battery models, Longquan Number 3 and Longquan Number 4, as the Chinese manufacturer – a supplier to both Tesla and Mercedes Benz – moves closer to the commercialisation of next-generation cell technologies for both automotive and consumer applications.
The two batteries rolled off the production line at a launch event at the company’s Chengdu facility on 17 March.
The Longquan No. 4 cell is a 60Ah-format battery designed for electric vehicle applications, while the Longquan No. 3 targets consumer electronics and is engineered to operate under significantly lower pressure conditions.
The company claims the automotive-focused Longquan No. 4 can operate at pressures of 5MPa or below, while the Longquan No. 3 is designed for low-pressure environments below 2MPa, which addresses one of the key challenges associated with solid-state battery design.
Solid-state batteries replace the liquid electrolyte used in conventional lithium-ion cells with a solid material, offering the potential for improved safety, higher energy density and greater thermal stability. However, maintaining stable interfaces between electrodes and electrolytes often requires external pressure, which complicates system design and scaling.
The introduction of a low-pressure solid-state cell is significant, as reducing stack pressure is widely seen as critical to enabling practical, manufacturable battery systems.
Building on the ‘Longquan’ platform
The latest cells form part of Eve Energy’s broader Longquan series, which has been under development as a multi-generation platform for solid-state technologies. In 2025, the company introduced the Longquan No. 2 cell, a smaller-format solid-state battery targeting applications such as robotics, low-altitude aircraft and AI systems. That earlier design achieved energy densities of around 300Wh/kg and was produced at the same Chengdu base now supporting larger-format cells.
The progression from 10Ah to 60Ah cells indicates a move towards automotive-scale deployment. Increasing capacity while maintaining stability is a key hurdle in solid-state battery development, particularly for electric vehicle applications.
Eve Energy has previously indicated that its solid-state strategy is based on sulfide and halide electrolyte systems, which are among the leading candidates for high-performance cells due to their ionic conductivity and compatibility with lithium metal anodes.
Core Breakthrough, Solidify the Future
Yiwei Lithium Energy Longquan No. 3 & Longquan No. 4 All-Solid-State Battery Off-line Ceremony © Eve Energy
Solid-state batteries remain at an early stage of commercialisation. While many manufacturers have announced prototype cells and pilot production lines, large-scale manufacturing continues to face challenges related to cost, materials stability and process complexity.
Eve Energy’s Chengdu facility is intended to address these issues through pilot-scale production. The site has been developed to support cells ranging from 10Ah to 60Ah, with plans to expand manufacturing capacity further as the technology matures.
The company has also signalled ambitions to increase energy density to around 400Wh/kg in future iterations, placing its technology within the range targeted by solid-state developers globally.
Main photo: a generic image of an EV battery pack on a production line (© Shutterstock)
