Targeted electro-redox facilitating efficient delithiation of lithium manganese ion-sieve selective electrode

Abstract

The electrically switched ion exchange (ESIX), as the most promising technique for the efficient extraction of lithium from brine, especially the lithium manganese ion-sieve membrane electrode, possesses the advantages of high selectivity, high adsorption capacity, and high stability. And to enable the simultaneous lithium intercalation and de-intercalation at the cathode and anode, respectively, the selective electrode ought to be delithiated before use. Traditional chemical and electrochemical delithiation and electrochemical techniques consume enormous amounts of reagents and energy, respectively. Thermodynamics and electrochemical analysis indicated that the cathodic reaction induced the high cell voltage, which in turn caused the emitting of toxic gases and high energy consumption. Thus, in this study, a targeted-redox system was adopted to alleviate the above problems. By adding excessive Cu2+ into the cathode compartment, the cell voltages in 5 h reduced from 3 V to about 1.5 V and further reduced to 1.2 V if diluted HCl was also added. With lower cell voltage and higher current density, a higher delithiation rate can be reached (95.83 %). Furthermore, Cu2+ can be regenerated by bubbling O2 under an acidic atmosphere, which enables the re-utilization of the cathodic solution. The targeted electro-redox system can reduce 2980.49 J of the energy consumption compared with the current electrochemical delithiation method, meanwhile, the utilization of cheaper counter electrode makes it economically viable.