Methods for making high-purity LiFSI salts and intermediate products using one, the other, or both of a reactive-solvent removal/replacement method and an LiFSI purification method. In some embodiments, the reactive-solvent removal/replacement method includes using non-reactive anhydrous organic solvents to remove and/or replace one or more reactive solvents in a crude LiFSI. In some embodiments, the LiFSI purification method includes using anhydrous organic solvents to remove impurities, such as synthesis impurities, from a crude LiFSI. In some embodiments, crude LiFSI can be made using an aqueous-based neutralization process. LiFSI salts and products made using methods of the disclosure are also described, as are uses of such salts and products and electrochemical devices that include such salts and products.