Electrochemical characterization of polypyrrole–LiNi1/3Mn1/3Co1/3O2 composite cathode material for aqueous rechargeable lithium batteries
A series of polypyrrole (PPy)–LiNi1/3Mn1/3Co1/3O2 composite electrodes are formed by physical mixing of polypyrrole with LiNi1/3Mn1/3Co1/3O2 cathode material. LiNi1/3Mn1/3Co1/3O2 is synthesized by reaction under autogenic pressure at elevated temperature method. Highly resolved splitting of 006/102 and 108/110 peaks in the XRD pattern provide an evidence to well-ordered layered structure of the compound. The ratios of the intensities of 003 and 104 peaks are found to be >1, which indicate no pronounced mixing of the cation. Cyclic voltammetry and AC impedance studies revealed that the addition of polypyrrole significantly decreases the charge-transfer resistance of LiNi1/3Mn1/3Co1/3O2 electrodes. The electrochemical reactivity of PPy–LiNi1/3Mn1/3Co1/3O2 composite electrode is examined during lithium ion insertion and de-insertion by galvanostatic charge–discharge testing; 10 wt.% PPy–LiNi1/3Mn1/3Co1/3O2 composite electrode exhibits better electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiNi1/3Mn1/3Co1/3O2 electrode. The cell with 10 wt.% PPy added cathode shows significant improvement in the electrochemical performance compared with that having pristine cathode. The capacity remains about 70% of the initial value after 50 cycles while for cell with pristine cathode only about 28% of initial capacity remains after 40 cycles.
KeywordsPolypyrrole Cathode material Aqueous lithium-ion batteries AC impedance spectroscopy
The authors gratefully acknowledge the financial support from the Department of Science and Technology, Government of India. Authors wish to thank Sri. A. V. S. Murthy, honorary secretary, Rashtreeya Sikshana Samiti Trust, Bangalore, and Dr. P. Yashoda, Principal, S.S.M.R.V. Degree College, for their support and encouragement. We also thank the Department of Chemistry, St. Joseph’s College, Bangalore for XRD data. R.B. Shivashankaraiah thank the management of Dayananda Sagar Institution, Bangalore for giving permission to carryout research work.
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