Their first challenge was to develop a novel electrolyte. A lithium-CO₂ battery consists of two electrodes — an anode made of lithium and a cathode made of carbon — and an electrolyte, a solution that helps carry charged particles back and forth between the electrodes as the battery is charged and discharged. For their system, they needed an electrolyte made of amine plus captured CO₂ dissolved in a solvent — and it needed to promote chemical reactions on the carbon cathode as the battery discharged.

They started by testing possible solvents. They mixed their CO₂-absorbing amine with a series of solvents frequently used in batteries and then bubbled CO₂ through the resulting solution to see if CO₂ could be dissolved at high concentrations in this unconventional chemical environment. None of the amine-solvent solutions exhibited observable changes when the CO₂ was introduced, suggesting that they might all be viable solvent candidates.