Lithium is used in many fields due to its high energy density and unique electrochemical properties. Recently, there has been a strong increase in demand for lithium, so the extraction of lithium from natural water resources has become a remarkable research topic. One of the most effective methods of separating lithium from natural water sources is adsorption using lithium ion-sieve adsorbents. However, the powdered nature of the adsorbents makes them challenging to process. Recent studies have focused on developing adsorbents using different polymeric materials as substrates. In the thesis, as a new approach, flexible and free-standing polyurethane electrospun mat substrates were SURGXFHGDQGFRPELQHGZLWKȜ-MnO2 to extract lithium from aqueous systems, and their lithium extraction performance was investigated. $IWHUWKHIDEULFDWHGPDWVDQGȜ-MnO2 powder were characterized, the deposition process was performed, and filtration studies were carried out in synthetic lithium solution. Optimum conditions for lithium extraction for a sample volume of 10 mL were found as an adsorbent amount of 200 mg, and 200 mg/L initial Li+ concentration, and pH 12. In addition, lithium extraction performances have been improved by stacking mats and multi-stage filtration processes. Lithium extraction reached 76.6% when a 400 mg/L lithium solution and an 8-step filtration were used. Lithium extraction experiments were performed with salt lake brine containing high concentrations of various ions and showed that these ions reduced the lithium extraction. In the study PU electrospun mats for ^-MnO2 powder were found to be a promising substrate for lithium extraction from aqueous systems.