Synthesis and Lithium Intercalation Properties of Na0.5-xLixMnO2+δ and Na0.5-xMnO2+δ Cathodes

摘要

Na0.5-xLixMnO2+δ oxides were synthesized byreducing sodium permanganate with sodium iodide in aqueoussolutions followed by firing at 500-800℃. The sample fired at500℃ had a layer structure, whereas those fired at T≥600℃had a tunnel structure. Ion-exchange and sodium-extractionreactions of Na0.5-xMnO2+δgave, respectively, Na0.5-xLixMnO2+δand Na0.5-xMnO2+δ maintaining the layer or tunnel structures.The ion-exchanged samples exhibited better electrochemicalproperties than the sodium-extracted samples. The layeredNa0.06Li0.46MnO2.16 obtained by the ion-exchange reactionexhibited an initial capacity of about 225 mAh/g at 3.8-1.8 V,and the tunnel Na0.16Li0.38MnO2.08 obtained by the ion-exchangereaction exhibited an initial capacity of about 170 mAh/g at 3.8-1.8 V.