Electrochemical Properties of Solution Synthesized Undoped and Aluminum Doped Lithium Manganate Thin Films
- PDF / 277,569 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 34 Downloads / 185 Views
S2.2.1
Electrochemical Properties of Solution Synthesized Undoped and Aluminum Doped Lithium Manganate Thin Films S.R. Das, N.K. Karan, S.B. Majumder, and R.S. Katiyar1 PO Box 23343, Department of Physics, University of Puerto Rico, San Juan, PR 00931
ABSTRACT The spinel structured lithium manganate (LMO) is a promising cathode material for lithium ion rechargeable micro-batteries due to its higher energy density, environmentally benign nature, and low cost. To date, self-discharge and capacity fading (4 and 3V range), especially at elevated temperatures, still remains major research issues of LMO based cathodes. In the present work we have successfully synthesized lithium manganate thin films by a cost effective solution growth technique. These films exhibited excellent reversible lithium ion intercalation behavior with a discharge capacity of about 55.08:Ahcm-2:m-1 at a load of 20:Acm-2. The Li+ diffusivity was found to increase by substituting a part of manganese with aluminum (Al) in LMO lattice. Al substituted LMO films exhibited better cycleability as compared to the undoped LMO films. Further studies are in progress to investigate the effect of Al substitution on the cycleability of the films. INTRODUCTION Thin film solid-state micro-batteries are promising as power sources for various microelectronic devices including back-up power for computer memory chips, micro sensors, miniature hearing aid, ultra-thin watches etc [1]. LiMn2O4 (LMO) is considered to be ideal cathode material for such thin film micro-battery for their higher energy density, lower cost, and environment benign nature. However, self-discharge, capacity fading with repeated cycling, especially at elevated temperatures; poor rate capability, etc., still remain the major research issues for the commercial adaptation of LMO as cathode material [2]. The formation of electrochemically inactive surface film has been reported to be responsible for the observed capacity loss during storage or repeated charge-discharge cycling [3]. To study the electrochemical properties of LMO based cathodes, porous composite (prepared using LMO powder, organic binder, and carbon black as conducting agent), has been used in most of the literature reports. As a result the reported electrochemical characteristics reflect the properties of the composite cathode and the delineation of the contribution solely due to LMO was difficult. Study of the electrochemical properties of LMO in thin film form, is considered to be an effective alternative to the above shortcomings as in thin film form the influence of binder and conductive agent is eliminated. The LiMn2O4 thin films are prepared by various thin film deposition techniques including sputtering, e-beam evaporation, pulsed laser deposition and electrostatic spray deposition. These methods have general problems including poor stoichiometry control over large area, lower deposition rate and higher deposition cost [4]. Solution synthesis is considered to be an effective alternative to overcome these problems, however, lim
Data Loading...
