Influence of thickness on the properties of solution-derived LiMn₂O₄ thin films

Abstract

LiMn₂O₄ thin films of different thickness were derived from solution deposition and heat treated by rapid thermal annealing. The phase identification and surface morphology were studied by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the films were examined by galvanostatic charge-discharge experiments and electrochemical impedance spectroscopy. LiMn₂O₄ thin films of different thickness derived from solution deposition and rapid thermal annealing are homogeneous and crack free with the grain size between 20 nm and 50 nm. The specific capacity of these films is between 42 and 47 µAh·cm²·µm⁻¹. The capacity decreases with the increase of discharge current density. The capacity loss per cycle increases from 0.012% to 0.16% after being cycled 50 times as the film thickness increases from 0.18 µm to 1.04 µm. The lithium diffusion coefficients of these films are in the same order of 10⁻¹¹ cm²·s⁻¹.

Keywords

lithium manganese oxides / thin films / diffusion / electrochemical properties

References

[1] Kim H. K., Seong T. Y., Yoon Y. S. Characteristics of Rapid-thermal-annealed LiNi_1−xCo_xO₂ Cathode Films for All-Solid-State Rechargeable Thin Film Microbatteries[J]. Thin Solid Films, 2004, 447–448: 619-625.

[2] Choi W. G., Yoon S. G. Structural and Electrical Properties of LiCoO₂ Thin-Film Cathodes Deposited on Planar and Trench Structures by Liquid-delivery Metalorganic Chemical Vapour Deposition[J]. J. Power Sources, 2004, 125: 236-241.

[3] Liao C. L., Lee Y. H., Yu H. C., . Structure Characterization and Electrochemical Properties of RF Sputtered Lithium Nickel Cobalt Oxide Thin Films[J]. Electrochim. Acta, 2004, 50: 461-466.

[4] Rho Y., Kanamura T. Fabrication of Thin Film Electrodes for All Solid State Rechargeable Lithium Batteries[J]. J. Electroanal. Chem., 2005, 559: 69-75.

[5] Das S. R., Istevao R., Fachini S. B., . Structural and Electrochemical Properties of Nanocrystalline Li_xMn₂O₄ Thin Film Cathodes (x=1.0−1.4)[J]. J. Power Sources, 2006, 158: 518-523.

[6] Shih F. Y., Fung K. Z. Effect of Chitosan on Stabilization of Acetates-containing Solution: a Novel Precursor for LiMn₂O₄ Film Deposition[J]. J. Power Sources, 2006, 159: 1370-1376.

[7] Dokko K., Anzue N., Mohamedi M., . Raman Spectro-electrochemistry of LiCo_xMn_2−xO₄ Thin Film Electrodes for 5 V Lithium Batteries[J]. Electrochem. Commun., 2004, 6: 384-386.

[8] Moon H. S., Park J. W. Improvement of Cyclability of LiMn₂O₄ Thin Films by Transition-Metal Substitution[J]. J. Power Sources, 2003, 119–121: 717-720.

[9] Chung K. Y., Kim K. B. Investigations into Capacity Fading as a Result of a Jahn-Teller Distortion in 4 V LiMn₂O₄ Thin Film Electrodes[J]. Electrochim. Acta, 2004, 49: 3327-3337.

[10] Shih F. Y., Fung K. Z. Effect of Annealing Temperature on Electrochemical Performance of Thin-film LiMn₂O₄ Cathode[ J]. J. Power Sources, 2006, 159: 179-185.

[11] Tang S. B., Lai M. O., Lu L. Properties of Nano-Crystalline LiMn₂O₄ Thin Films Deposited by Pulsed Laser Deposition[ J]. Electrochim. Acta, 2006, 52: 1161-1168.

[12] Wu X. M., He Z. Q., Xu M. F., . Characterization and Electrochemical Properties of LiMn₂O₄ Thin Films Prepared by Soluton Deposition[J]. J. Wuhan University of Technology-Mater. Sci. Ed., 2006, 21: 54-56.

[13] Wu X. M., He Z. Q., Ma M. Y., . Influence of the Processing Conditions on the Morphology of Solution-deposited LiMn₂O₄ Thin Films by Spin Coating[J]. J. Functional Mater., 2006, 37: 155-159.

[14] Joshi P. C., Krupanidhi S. B. Structural and Electrical Studies on Rapid Thermally Processed Ferroelectric Bi₄Ti₃O₁₂ Thin Films by Metallo-organic Solution Deposition[J]. J. Appl. Phy., 1992, 72: 5827-5833.

[15] Ho C., Raistrick I. D., Huggins R. A. Application of A-C Techniques to the Study of Lithium Diffusion in Tungsten Trioxide Thin Films[J]. J. Electrochem. Soc., 1980, 127: 343-350.

[16] Funabiki A., Inaba M., Ogumi Z., . Impedance Study on the Electrochemical Lithium Intercalation into Natural Graphite Powder[J]. J. Electrochem. Soc., 1998, 145: 172-178.