Role of Rare-Earth Element Doping in the Cycleability of LiMn2O4 Cathodes for Li-ion Rechargeable Batteries
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0972-AA06-12
Role of Rare-Earth Element Doping in the Cycleability of LiMn2O4 Cathodes for Li-ion Rechargeable Batteries Rahul Singhal1, Maharaj S Tomar1, Osbert Oviedo1, Suprem R. Das2, and Ram S. Katiyar2 1 Physics, University of Puerto Rico, P.O. Box 9016, Mayaguez, 00680, Puerto Rico 2 Physics, University of Puerto Rico, P.O. Box 23343, San Juan, 00931, Puerto Rico
Abstract We have synthesized spinel LiMn1.99Nd0.01O4 and LiMn1.99Ce0.01O4 powder by chemical synthesis method. The synthesized powders were used to prepare cathodes for Li ion coin cells. The structural and electrochemical properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry and charge-discharge studies, respectively. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation in the cell. The charge-discharge characteristics for LiMn1.99Ce0.01O4 were obtained in 3.5 V – 4.8 V voltage range, while for LiMn1.99Nd0.01O4 the charge-discharge were carried out in 3.4 V - 4.4 V range. The initial discharge capacities of LiMn1.99Ce0.01O4 and LiMn1.99Nd0.01O4 were obtained as 134mAh/g and 149 mAh/g, respectively. The coin cells were tested for up to 25 charge-discharge cycles and after 25 cycles the discharge capacities were determined to 79.5 mAh/g and 132 mAh/g for LiMn1.99Ce0.01O4 and LiMn1.99Nd0.01O4 cathodes respectively. However, by doping with a small concentration of rare earth materials, like Ce and Nd reduces the capacity fading in pure LiMn2O4 cathodes making it suitable for Li-ion battery applications. Key words:
Li-ion battery, LiMn2O4, cyclic voltammetry, spinel cathode, discharge capacity
Introduction: High energy density of rechargeable Li ion batteries, among all rechargeable batteries make it suitable for portable electronic devices e.g. laptop, cellular phones, digital camera etc. In recent years, a number of efforts are being made by various researchers towards the development of high performance rechargeable Li ion batteries with high specific capacity, long cycleability, and calendar life [1-3]. The performance of a battery largely depends upon the active materials present in the cathode. The commercial Li ion batteries based on LiCoO2 cathode materials, have several drawbacks e.g. high cost and toxicity of cobalt. Lithium manganate (LiMn2O4) (LMO) spinel cathode materials are found to be suitable alternate to LiCoO2 due to being economical and non-toxic [4-6]. However, LiMn2O4 suffers from structural instability and severe capacity loss during cycling, prevents this material to commercialized it as a cathode in Li-ion rechargeable batteries [7,8]. However, the phase transformations and volume changes in spinel LiMn2O4 are mostly reported, to affects the capacity. Kang and Goodenough [9] prepared LiMn2O4 via sol-gel method. They reported that there is no capacity fading in 3V range, while in 4V ranges the discharge capacity decreased by 10% of its initial value after 40 cycles. The capacity fading in 4V has been attributed to the loss * Co
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