M.Sc. Peter Burger

Electrochemical desalination is a promising technology for the selective recovery of Lithium-ions or other rare ions from spent electronics, contributing to a circular economy. Due to its high-energy efficiency and selective Lithium-ion recovery, this method offers a low environmental impact, making it a promising tool for recovering Lithium-ions from spent batteries. Few studies have examined electrochemical desalination as a tool to recover Lithium-ions from real spent battery solutions. In this work, solutions obtained from real shredding of Lithium-iron-phosphate (LFP) batteries inside a cooling water reservoir were used as a Lithium-rich source to obtain a high-purity Lithium-ion recovery solution. A 96%-pure Lithium-ion recovery solution was obtained while only requiring an energy input of 1.10 kWh/kg.

The development of efficient carbon-based materials is crucial for overcoming the performance limitations of traditional electrodes in capacitive deionization (CDI). However, the practical performance of heteroatom-doped carbon electrodes for desalination in complex multi-ion water matrices remains largely unexplored. In this work, we studied the ion selectivity toward Li+ and the removal efficiency of nitrogen‑sulfur co-doped and boron-doped carbon electrodes in brackish water, using multi-salt cation solutions containing monovalent (Li+, Na+, K+) and divalent (Ca2+, Mg2+) ions. These modifications enhanced charge distribution, wettability, and ion diffusion within the electrodes. As a result, the N,S-AC electrode exhibited pronounced lithium selectivity in brackish water, while the B-AC electrode delivered higher adsorption capacity. The B-AC electrode achieved both high capacity and enhanced lithium selectivity even under strong competition from Na+, Mg2+, and Ca2+. These findings demonstrate the distinct and complementary roles of N,S-co-doping and B-doping, offering valuable insights into how heteroatom engineering can advance CDI performance.