Soft chemical synthesis and electrochemical properties of Li sub(0.90)Mn sub(0.90)Ti sub(0.10)O sub(2) with the Na sub(0.44)MnO sub(2)-type tunnel structure

• Published in: Journal of power sources Vol. 244; pp. 382 - 388
• Main Authors: Akimoto, J, Hayakawa, H, Ishida, N, Funabiki, F, Kijima, N, Shibuya, H, Imaizumi, J
• Format: Journal Article
• Language: English
• Published: 15.12.2013
• Subjects: Charge; Discharge; Electric potential; Emission analysis; Energy density; Hydroxides; Inductively coupled plasma; Spectroscopy
• ISSN: 0378-7753

We have successfully prepared Li sub(0.44+x)Mn sub(1-y)Ti sub(y)O sub(2) having the Na sub(0.44)MnO sub(2)-type framework structure by ion-exchange technique in molten LiNO sub(3) and LiNO sub(3)-LiOH salts at 270 degree C from the precursor Li sub(0.44)Mn sub(1-y)Ti sub(y)O sub(2) synthesized at 800 degree 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 Li sub(0.44+x)Mn sub(1-y)Ti sub(y)O sub(2) were confirmed by using ICP-AES and XRD Rietveld analyses. The electrochemical measurements revealed that both the charge and discharge properties of the obtained Li sub(0.44+x)Mn sub(1-y)Ti sub(y)O sub(2) samples were drastically improved. Especially, the obtained Li sub(0.71)Mn sub(0.90)Ti sub(0.10)O sub(2) exhibited initial charge and discharge capacities of 176 and 212 mAh g super(-1), respectively, with an average discharge voltage of 3.56 V vs. Li/Li super(+). The resultant initial discharge energy density was achieved to be 755 Wh kg super(-1). A further chemical lithiation treatment was performed using Lil for the Li sub(0.63)MnO sub(2) and Li sub(0.71)Mn sub(0.90)Ti sub(0.10)O sub(2) samples. The electrochemical measurements between 4.8 and 2.5 V for the lithiated Li sub(0.83)MnO sub(2) and Li sub(0.90)Mn sub(0.90)Ti sub(0.10)O sub(2) samples showed the improvement of the initial charge capacities. The rate capability test revealed Li sub(0.90)Mn sub(0.90)Ti sub(0.10)O sub(2) retains 81% of its discharge capacity in going from 1C to 5C rate. The excellent high rate capability and good cycling performance of Li sub(0.90)Mn sub(0.90)Ti sub(0.10)O sub(2) is particularly attractive for electric vehicle applications.