The creation of a circular economy is seen as one of the key challenges in recycling spent Li-ion batteries and would vastly diminish pressures faced in the initial extraction stage of the life cycle. Molten salts (MS) possess a set of excellent electrochemical properties and have been used to recycle metals and non-metals in the battery, metallurgical, nuclear and planetary science sectors. However, an in-depth and clear visual understanding of the electrochemical reduction process is still lacking. Here, we have overcome this challenge by developing a bespoke, miniaturised electrochemical cell enabling real-time X-ray imaging studies. A combination of X-ray radiography and tomography provide an opportunity to non-destructively reveal detailed microstructural evaluation of the electrochemical cell during the pyro-chemical process. Moreover, we have found that significant amounts of CO/CO₂ accumulated at the anode surface may lead to undesired operational consequences.