The study shows that operando potassium K-edge XANES can be successfully employed to effectively study the evolution of charge carrier species during an electrochemical process. The potential of XANES to monitor the speciation of alkaline charge carriers, in a host of different battery and other electrochemical processes, has exciting future potential in characterization and development of new materials. EXPERIMENTAL SECTION Material Synthesis. LC-PB preparation is based on wet chemical precipitation method. Equimolar concentrations of Fe(NO 3 ) 3 and K 4 Fe(CN) 6 solutions (5 mmol in 15 mL in DI water) were mixed together through dropwise addition. The solution was heated to 60 °C and kept under vigorous stirring for 2 hours. The resulting blue precipitate was separated via centrifugation at 10,000 rpm for 5 minutes and washed 5 times with acetone and DI water. The resulting precipitate was dried in a vacuum oven at 80 °C for 3 hours.