A University of Delaware-led team reported a battery-based direct air capture system built around a symmetric nickel-hydroxide electrochemical cell. In a 48-hour test, its separate 9 × 300-cm² stack used 0.83 MWh per tonne of CO₂. The study, published September 22, 2026, also reports a 5,000-hour test on a smaller, 25-cm² cell.
A battery cell built to capture CO₂ from air
The device uses nickel-hydroxide electrodes and a hydroxide-exchange membrane to capture carbon dioxide directly from air. In direct air capture, or DAC, a system removes CO₂ from the surrounding atmosphere rather than from a concentrated industrial exhaust stream.
How voltage reversal moves CO₂ through the cell
Reversing the applied voltage switches the electrodes’ roles and reverses the hydroxide-related chemistry. Changes in hydroxide concentration shift the local pH, converting CO₂ into carbonate or bicarbonate. These compounds cross the membrane; on the lower-pH side, the reaction releases CO₂.
Two laboratory tests, two configurations
The team tested a 25-cm² laboratory cell and a separate, larger stack. Their reported durations belong to different test articles.
| Test article | Area or configuration | Reported test duration |
| Laboratory cell | 25 cm² | 5,000 hours |
| Electrochemical stack | 9 × 300 cm² | 48 hours |
What the stack test measured
During the 48-hour test, the 9 × 300-cm² stack used 132 kJ per mole of CO₂, equivalent to 0.83 MWh per tonne. The reported CO₂ flux was 0.19 mol CO₂ m⁻² h⁻¹, or 75 kg CO₂ m⁻² yr⁻¹. The team also reported that the pilot-scale stack met a 300-Pa pressure-drop requirement for direct air capture.
