Testing The World's First Solid-State Battery

The charge curve from the Donut Lab cell is a near-identical match to a standard NMC lithium-ion battery (3:55). This electrochemical fingerprint is fundamental to a cell's chemistry and cannot be arbitrarily changed, providing strong evidence that the battery uses lithium-ion chemistry rather than a novel solid-state design.

By comparing the voltage difference at 55% charge between 1C and 11C charging rates and dividing by the current difference (0.5V / 260A), the internal resistance was calculated at approximately 2 milliohms (4:20). This value precisely matches what would be expected from a liquid electrolyte lithium-ion cell of similar capacity, and aligns with Stanford's published NMC cell data.

The VTT-tested cell capacity came out to 94 Wh, yielding an energy density of approximately 298 Wh/kg at 315 grams (5:20). This is substantially lower than the 400 Wh/kg and 125 Wh cell capacity previously claimed at CES, raising serious questions about the accuracy of Donut Lab's marketing claims.

During 11C fast charging, the test had to be stopped when the cell exceeded 90°C, and a subsequent test peaked at 89°C (8:15). A 90°C safety cutoff is characteristic of lithium-ion battery testing protocols, not a battery supposedly rated for safe operation at 100°C, suggesting the cell behaves like a conventional lithium-ion battery with associated thermal runaway risks.