Lab lithium-metal cells reach 602.5Wh/kg

A 10Ah pouch cell has crossed a threshold that matters in the air: Tianmushan Lab and Tsinghua University report energy density of 602.5Wh/kg for a lithium-metal battery in laboratory testing. The result, published in Nature Communications, is aimed at drones and electric vertical take-off and landing aircraft, whose flight endurance is constrained by the energy their batteries can carry.

The researchers changed the electrolyte, the material that carries lithium ions between the battery’s electrodes. Their additive creates a thin protective film on the cathode during high-voltage cycling and a stable interface on the lithium-metal anode. The intended effect is twofold: reduce damage at the cathode and suppress lithium dendrites, needle-like growths that can raise safety risks, while improving lithium-ion transport.

The performance depends on the cathode paired with the lithium-metal anode. With high-nickel ternary cathodes, the cells reached 550.7 Wh/kg and retained 80% of their capacity after 180 cycles. With lithium-rich manganese-based cathodes, reversible specific energy rose to 602.5Wh/kg—more than 50% above current mainstream power batteries, according to the report.

That matters because commercial lithium batteries using graphite anodes are approaching their theoretical energy density limit of approximately 350 Wh/kg, the researchers say. More energy in the same battery mass could eventually give drones and eVTOL aircraft more endurance, but the technology remains at the laboratory research stage and must still be scaled before mass commercial application.

So what changes, concretely? For now, nothing changes for a buyer: the cells remain at the laboratory research stage, and the team says further technical iterations are required before mass commercial application. The result does, however, point to a route for addressing the trade-off between energy density, cycle life and safety that has challenged lithium-metal batteries.