Surface trace doping of Na enhancing structure stability and adsorption properties of Li1.6Mn1.6O4 for Li+ recovery

Li1.6Mn1.6O4 (LMO) is a dominant adsorbent for lithium recovery from solutions resulted from its high theoretical adsorption uptake and a low loss rate of Mn, which can potentially be further improved by trace doping. We achieve stable cycling and high adsorption capacity of Li1.6Mn1.6O4 from aqueous lithium resources by Na doped (LMO-Na). The Mn dissolution is decreased from 5.4% (bare adsorbent) to 4.4%, and the uptake is increased from 33.5 mg/g to 33.9 mg/g (CLi+: 24 mmol/L). Furthermore, DFT calculations predict that Na replace for Li at 16d sites, result in an enhancement of the Li+ adsorption rate and structure stability of LMO. The loss rate of Mn in cycling process is restrained by Na doped, which may result from reducing the content of low valent Mn3+ and improving the structural stability of material. The effect of Na substitution on adsorption capacity and structure stability is discussed.