Carbon materials derived from biomass have been applied widely in Li-S batteries; however, the mineral matter present in the biomass could impact the properties of the carbons and affect the electrochemical performance. This work removes mineral matter from palm kernel shells to identify the effect of minerals on the physicochemical properties of the activated carbon and correlate them to the electrochemical performance in Li-S batteries. The content of minerals such as silicon, iron, and potassium, were reduced by acid washing. The textural, and conductive properties of the activated carbon were increased by the absence of minerals. Electrochemical results reveal that the demineralized sample used as a sulfur host can increase 23% the capacity for high charge and discharge rates. Hence, the removal of mineral matter in the biomass is an important step to consider in the application of activated carbons as sulfur hosts in Li-S batteries.