AI-rewritten: This is a summary of an article from MIT Technology Review, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

---

WeLion New Energy is developing semi-solid-state batteries designed to offer greater safety and energy density than standard lithium-ion cells for electric cars, boats, and drones. While lithium-ion batteries use a flammable liquid electrolyte that poses fire risks, WeLion’s approach uses a part-liquid, part-solid electrolyte to improve performance. The company currently focuses on semi-solid-state technology because fully solid-state cells are extremely difficult to manufacture.

In 2023, WeLion partnered with Shanghai-based EV-maker Nio to release a battery pack with an energy density of 360 watt-hours per kilogram (wh/kg). This is significantly higher than the 200 wh/kg average for lithium-ion packs and allows for a range of over 1,000 kilometers. However, only about 200 packs were manufactured due to high production costs. WeLion has also built batteries for cargo ships through a subsidiary and plans to launch new semi-solid-state batteries for drones with an energy density of 410 wh/kg by the end of this year.

WeLion engineers achieved a tested energy density of 824 wh/kg in 2025, which is more than three times that of standard lithium-ion batteries. Despite these impressive lab results, the company declined to provide details on how many times the cell can be charged or how its capacity degrades over time, noting the prototype is far from commercialization. The company faces challenges scaling production and competing on cost against larger Chinese battery makers like CATL. WeLion intends to introduce its first all-solid-state battery for cars in 2027 with an expected energy density of 400 wh/kg.