CATL passes toughest aviation battery test at 350 Wh/kg, bringing eVTOL certification closer

CATL, the world's largest battery maker, has cleared a milestone for its aviation battery pack by passing a challenging thermal runaway test. For the first time, a prismatic-cell aviation system rated at 350 Wh/kg survived simultaneous thermal runaway triggers in two adjacent cells — a stricter scenario than the industry-standard test that isolates a single cell.

The entire process, from cell production to the propagation itself, was witnessed by China's Civil Aviation Administration, laying the groundwork for official government certification of airworthiness for the high-density battery. Safety, not raw performance, has long been the bottleneck for electric aviation; CATL has already achieved energy densities of up to 500 Wh/kg in the lab.

The 350 Wh/kg figure is well above what typical EV packs offer today, as mass-market electric cars rely on LFP chemistry with half the density. In aviation, where every extra kilogram directly cuts into payload or range, this density is what separates a profitable passenger-carrying eVTOL from an unviable concept.

High energy density usually comes from ternary chemistry, which is more volatile. Pairing that density with proven resistance to cascading thermal runaway was the harder engineering problem CATL appears to have solved.

The first vehicles to use the new battery will be Autoflight's passenger eVTOLs. CATL has backed Autoflight since 2024, and the partners have already collaborated on projects including a floating vertiport. For CATL, electric aviation is a genuine second act after its EV dominance and its growing footprint in electric vessels.

Scaling this into a full-fledged air taxi industry still depends on regulators, infrastructure, and public trust. But passing the toughest safety test is the first step toward eVTOLs becoming a certifiable aircraft category capable of carrying both cargo and passengers on electric propulsion alone.