Issue 2, 2008

Chemical and structural instability of the chemically delithiated (1 – z) Li[Li1/3Mn2/3]O2·(z) Li[Co1–yNiy]O2 (0 ≤ y ≤ 1 and 0 ≤ z ≤ 1) solid solution cathodes

Abstract

The delithiated samples obtained by chemically extracting lithium from a series of O3 type layered (1 – z) Li[Li1/3Mn2/3]O2·(z) Li[Co1–yNiy]O2 solid solution samples by reacting with the oxidizer NO2BF4 in acetonitrile medium have been chemically and structurally characterized. The oxygen loss in the delithiated samples has been found to be determined by the amount of lithium in the transition metal layer of the O3 type layered structure. However, high Mn4+ content in the samples causes a decrease in oxygen loss and the lithium content in the transition metal layer is sensitively influenced by the tendency of Ni3+ to get reduced to Ni2+ and the consequent volatilization of lithium during synthesis. The chemically delithiated samples were found to adopt either the parent O3 type structure or the new P3 or O1 type structures depending upon the composition and synthesis temperature of the parent samples and the proton content inserted into the delithiated sample. For example, a high proton insertion resulting from a good cation ordering or a larger surface area seems to favor the transformation of the initial O3 structure to the P3 or O1 structure. However, such phase transformations were not evident in the electrochemically delithiated solid solution samples.

Graphical abstract: Chemical and structural instability of the chemically delithiated (1 – z) Li[Li1/3Mn2/3]O2·(z) Li[Co1–yNiy]O2 (0 ≤ y ≤ 1 and 0 ≤ z ≤ 1) solid solution cathodes

Article information

Article type
Paper
Submitted
30 Aug 2007
Accepted
22 Oct 2007
First published
05 Nov 2007

J. Mater. Chem., 2008,18, 190-198

Chemical and structural instability of the chemically delithiated (1 – z) Li[Li1/3Mn2/3]O2·(z) Li[Co1–yNiy]O2 (0 ≤ y ≤ 1 and 0 ≤ z ≤ 1) solid solution cathodes

T. A. Arunkumar, E. Alvarez and A. Manthiram, J. Mater. Chem., 2008, 18, 190 DOI: 10.1039/B713326J

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