Cell energy density

What it measures

Gravimetric energy density of the best demonstrated cell (watt-hours per kilogram) — the frontier number for the whole field, because it sets range and weight. Conventional Li-ion cells top out near 250–300 Wh/kg; solid-state and lithium-metal designs target 400–500. Watch the fine print: lab/sample cells beat production cells, so each figure is labelled by stage.

History