Metal–CO₂ batteries (MCBs) are an emerging technology capable of simultaneous electrical energy storage and CO2 reduction (CO2R). However, existing MCBs are constrained by sluggish kinetics and gas electrode deactivation due to the accumulation of solid discharge products. These issues persist even when incorporating expensive catalysts and advanced nanostructures. Moreover, conventional MCBs negate their carbon sequestration benefit during charging, as the CO₂R reactions are reversed. To overcome these kinetic limitations and solid blockage issues, a first-of-its-kind liquid Gallium-CO2 battery (LGaCB) has been demonstrated. Drawing inspiration from molten carbonate fuel cells and recent work on CO₂R in liquid gallium, the LGaCB utilizes a molten carbonate electrolyte and a gallium-based anode. By operating at high temperatures and discharging the solid products – Ga2O3 and carbon – into the liquid gallium anolyte, it is able to accelerate reaction kinetics significantly while preventing electrode deactivation. Even with a basic, open-atmosphere setup, the LGaCB achieves an operating power density of 13 mW/cm² during repeated charge–discharge cycles and a maximum power density of 75 mW/cm² during polarization curve testing. This is 5 – 10 times the best of low-temperature MCBs reported in open literature. Furthermore, carbon formed during discharge is not re-oxidized during the charging process, making the system inherently carbon-negative. The solid discharge products have been characterized via X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). To enable further investigation of the LGaCB system operation mechanisms, a customized cell has been designed and constructed for analysis of the product gases and investigation of the cell reactions under various feed conditions. The results of these studies will be discussed in this presentation.
