Soft chemical synthesis and electrochemical properties of Li0.90Mn0.90Ti0.10O2 with the Na0.44MnO2-type tunnel structure

We have successfully prepared Li0.44+xMn1−yTiyO2 having the Na0.44MnO2-type framework structure by ion-exchange technique in molten LiNO3 and LiNO3–LiOH salts at 270 °C from the precursor Na0.44Mn1−yTiyO2 synthesized at 800 °C using homogeneous and fine Mn–Ti hydroxides as starting materials. The needle-shaped particle length can be successfully reduced. The chemical composition and the crystal structure of Li0.44+xMn1−yTiyO2 were confirmed by using ICP–AES and XRD Rietveld analyses. The electrochemical measurements revealed that both the charge and discharge properties of the obtained Li0.44+xMn1−yTiyO2 samples were drastically improved. Especially, the obtained Li0.71Mn0.90Ti0.10O2 exhibited initial charge and discharge capacities of 176 and 212 mAh g−1, respectively, with an average discharge voltage of 3.56 V vs. Li/Li+. The resultant initial discharge energy density was achieved to be 755 Wh kg−1. A further chemical lithiation treatment was performed using LiI for the Li0.63MnO2 and Li0.71Mn0.90Ti0.10O2 samples. The electrochemical measurements between 4.8 and 2.5 V for the lithiated Li0.83MnO2 and Li0.90Mn0.90Ti0.10O2 samples showed the improvement of the initial charge capacities. The rate capability test revealed Li0.90Mn0.90Ti0.10O2 retains 81% of its discharge capacity in going from 1C to 5C rate. The excellent high rate capability and good cycling performance of Li0.90Mn0.90Ti0.10O2 is particularly attractive for electric vehicle applications.

Figure optionsDownload as PowerPoint slideHighlights
► Li0.83MnO2 and Li0.90Mn0.90Ti0.10O2 were synthesized by soft chemical processes.
► The Na0.44MnO2-type framework structure was confirmed by XRD Rietveld analysis.
► Electrochemical measurements revealed the high capacity and good rate capability.