Adsorption of Li+ by imprinted capacitor deionization — A new method for selective recovery of valuable lithium in acidic solutions

With the continuous development of the global society, people's demand for lithium is increasing. Recovering valuable lithium from waste lithium-ion batteries and fly ash is essential for environmental protection and energy saving. We have developed a new imprinted capacitance deionization technology (N@Li + -IPDI), which can selectively recover lithium ion from acidic solution (pH = 2) under complex environment. The recovery capacity of N@Li + -IPDI electrode material was up to 20.26 mg/g. Separation of Li + from Na + , K + , and Al 3+ was achieved based on the size effect. Separation from Mg 2+ was due to the higher hydration energy of Mg 2+ (1940 kJ/mol) than Li + (510 kJ/mol). After 5 regeneration cycles, recovery effect of N@Li + -IPDI was 93.42 % of original. Through density functional theory (DFT) modeling, bond length of Li + -O was 2.04–2.05 Å, and adsorption energy of 2H12C4-Li + (−33.66 Kcal/mol) was the largest among the five ions. In addition, energy and structure of deprotonation process were studied, and the energy required for deprotonation was 6.33 kJ/mol, which was the reason Li + adsorption is difficult in acidic environment. This research provides a new green ion recovery technology with excellent selectivity , high adsorption and conductivity for Li + recovery in acid solution, to meet the challenge of growing demand for lithium.