Trace doping by fluoride and sulfur to enhance adsorption capacity of manganese oxides for lithium recovery

Abstract

The H1.6Mn1.6O4 (HMO) derived from Li1.6Mn1.6O4 (LMO) has been aroused enormously attention due to high adsorption capacity. Through surface trace doping of F and S (LMO-R, R = F, S), the cycling stabilities and adsorption abilities of Li1.6Mn1.6O4 are improved. The adsorption uptakes are increased from 26.1 mg/g (before doping) to 33.4 and 27.9 mg/g at Li+ concentration of 12 mmol/L, respectively. In addition, first-principles calculations further confirm that F and S substitutes for O at 32e sites, leading to an improvement of the Li+ uptake rate. The Li+ adsorption capacities in the cycling process are enhanced by F and S doped, which may result from improving the charge density and offering more charge carriers that can participate in the ad/desorption reaction. The effect of the F and S substitution on adsorption capacity is discussed.