Rational design of pulse-electrolysis protocols promotes molten-salt electrorefining

•Pulse-electrolysis strategy is employed to improve the interfacial microenvironment of electrodes.•Duty ratio is identified as a critical factor for inhibiting the deterioration of the interfacial microenvironment.•In situ X-ray computed tomography (CT) is used to monitor electrode morphological evolution.•Optimized pulse protocol exhibits enhanced electrolysis efficiency of molten-salt electrorefining. Molten-salt electrorefining (MSE) is currently the primary method for purifying many elements, offering promise for the sustainable upcycling of spent metals in the future. However, the conventional constant-current electrolysis protocol inevitably leads to deterioration of the microenvironment near the electrode, leading to reaction runaway and process inefficiency. In this work, we comprehensively studied for the first time the effect of constant- and pulse-electrolysis protocols on environmental evolution in electrode–electrolyte interfaces during the MSE of Ti, using a computer model. The results showed that compared to constant electrolysis, pulse-electrolysis protocols could effectively regulate the interfacial microenvironment and improve the electrorefining efficiency. Furthermore, a correlation between interfacial reconstruction and pulse parameters was established, indicating that the duty ratio was the key factor in inhibiting the deterioration of the interfacial microenvironment. To further verify the simulation results, the real-time morphological evolution of the electrodes during electrolysis was monitored by a novel in situ X-ray computed tomography (CT) technology under pulse-electrolysis protocols. The experimental results indicated that the pulse-electrolysis protocols enhanced the interfacial microenvironment and promoted electrolysis efficiency. Collectively, this work demonstrated that MSE could be effectively advanced by rationally designing the pulse-electrolysis protocols, facilitating its large-scale application in industry.