Synthesis and cathodic properties of LiCo1-yRhyO2 (0≤y≤0.2) and LiRhO2.
Subba Rao, G. V.
Chowdari, B. V. R.
Li, S. F. Y.
Date of Issue2001
School of Materials Science and Engineering
Compounds of the formula LiCo12yRhyO2 (0.0 ≤ y ≤ 0.20 and y=1.0) have been synthesized by high temperature solid-state reaction and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and infrared spectroscopy. Single-phase materials were obtained for y ≤ 0.10 and y=1.0 as observed by XRD. However, IR and electrochemical data indicate that the true solid solubility may be y ≤ 0.05. Their cathodic behavior in coin cells with Li metal as anode and a liquid electrolyte has been examined. Cyclic voltammograms and galvanostatic charge/discharge curves show that for y = 0.05, the phase transformation occurring at x = 0.5 in Li1-xCoO2 is suppressed and the deintercalation voltage is decreased. The compositions with y = 0.05 and 0.10 show improved cathodic behavior and discharge capacity retention compared to LiCoO2 (y = 0) at 0.14C rate in the voltage range 2.7-4.3 V up to 18 cycles. Electrochemical studies on LiRhO2 show that phase transitions occur on charge/discharge cycling (varying x in Li12xRhO2) in the voltage window 3.2-3.7 V and these are reversible. This compound shows an initial charge capacity of 162 mAh/g when charged to 4.0 V (vs. Li metal), corresponding to x = 0.85 in Li1-xRhO2. After an initial loss of 40 mAh/g in capacity, the discharge capacity retention corresponds to 90% after 18 cycles with respect to the initial discharge capacity in the voltage window, 2.7-4.0 V.
Journal of the electrochemical society
© 2001 The Electrochemical Society. This paper was published in Journal of The Electrochemical Society and is made available as an electronic reprint (preprint) with permission of The Electrochemical Society. The paper can be found at the following DOI: [http://dx.doi.org/10.1149/1.1410968]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.