EGDMA shows the best performance as indicated by the lowest energy consumption (13.9  0.5 kWh kg -1 LiOH) and the highest current efficiency (69.0  0.6%), and a molar flux of 3.86  0.03 mmol h -1 . This was followed by the P(LiSTFSI-IBMA)-10% EGDMA composition with an energy consumption of 15.8  0.6 kWh kg -1 LiOH and a current efficiency of 63.0  0.7%. The P(LiMTFSI-IBMA)-2.5% EGDMA membrane showed the highest energy consumption and lowest current efficiency of the three, i.e., 17.2  0.6 kWh kg -1 LiOH and 53  2%, respectively, despite showing the lowest voltage overpotential among the three. These results correlate well with the water uptake of the membranes, where the high-water uptake of the lowest crosslinked membrane results in good ionic conductivity but with the lowest transport number, hence resulting in lower current efficiencies. This is due to the undesired leakage of OH -anions through the cation exchange membrane and the high OH -ion mobility associated with the Grotthuss mechanism. This behaviour has also been observed in membranes for NaOH processing, where OH -ion leakage through the cation exchange membranes lowered the current efficiency of the process. This result will be of high importance in processes where high concentrations of the products are required highlighting the benefits of the work reported here which could guide the design of membranes for these processes.