Preparation and Lithium Adsorption Properties of Low-dimensional Cubic Li_4Mn_5O_(12) Nanostructure

Pure β-MnO2 oxide was synthesized by hydrothermal synthesis of MnSO4-H2O and(NH4)2S2O8.Spinel-type Li4Mn5O12 precursors were synthesized via low temperature solid-phase reaction.Furthermore,MnO2 ion-sieves with Li+ selective adsorption property were prepared by the acid treatment process to completely extract Li+ from the spinel Li4Mn5O12 precursor.The effects of hydrothermal and solid-phase reaction process on the nanostructure,chemical stability and ion-exchange property of the ion-sieve material were examined with XRD,HRTEM,SAED,and Li+ selective adsorption measurements.The results show that Li4Mn5O12 precursor and final MnO2 ion-sieve are effectively controlled within low-dimensional structure,indicating that low temperature solid-phase reaction is more favorable to control the nanocrystalline structure than traditional high-temperature calcination process.The Li+ selective adsorption capacity is improved remarkably to 6.6 mmol/g at equilibrium and about 5.0 mmol/g at the initial Li+ concentration of only 5.0 mmol/L,which is significant for lithium extraction from aqueous solutions with very low lithium content.