Metallic lithium, which is a critical and strategic metal for the world’s production of energy storage devices, is mainly produced from molten salt electrolysis. To increase the efficiency of the process, it is of utmost importance to prevent lithium recombination during the process to avoid energy waste. This research studies the behavior of the main variables involved in the reaction inside a Li-production experimental cell from the mass transfer, electrochemical and fluid dynamics standpoints. Simulations were done for a total electrolysis time interval of 600 s using a turbulent (k-ε) approach to solve the two-phase flow coupled to the lithium electrolysis process. To analyze the influence of cathode fluid dynamics in relation with the amount of recombined lithium, two configurations of the diaphragm were evaluated including the incorporation of a baffle at the bottom of the cell and the inclination of the diaphragm. The baffle reduced the amount of recombined lithium by 7 %, and the diaphragm with an inclination < 90° reduced the total recombined mass by 77 %, although it increased the energy consumption by 10 % with respect to the base case of a vertical diaphragm.

Molten salt electrolysis is an efficient process for obtaining metallic lithium but requires a considerable amount of energy. The use of a grooved diaphragm and rotating electrodes were studied using a numerical model representing an experimental lithium electrolytic cell with the finality to reduce the required energy. Simulations were conducted using a turbulent (k-ε) model to solve the two-phase flow coupled to the transient mass transport inside an electrolysis cell. The model also considers the recombination of Li with chlorine gas (Cl2), a back reaction that is detrimental to efficiency and energy consumption. The vertical diaphragm with grooves produces a reduction of 26.7% in energy consumption in comparison with the ungrooved design but increases by four times the amount of recombined lithium in the process. To decrease that recombination, the grooved diaphragm was inclined. The angle of 85° reduced the energy consumption by 23.5% with approximately the same recombined lithium mass when compared to the vertical ungrooved design. The use of a rotating cathode with at an angular velocity of 0.25 rad/s results in a 40% decrease in energy consumption in addition to a decrease of 87.4% in metallic Li reconversion, in comparison with non-porous ungrooved diaphragm design.