Electrochemical characteristics of sulfur composite cathode for reversible lithium storage |
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Authors: | Xiangming He Jianguo Ren Li Wang Weihua Pu Chunrong Wan Changyin Jiang |
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Institution: | (1) Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, People’s Republic of China;(2) Nengkelou A317, Tsinghua University, Beijing, 100084, People’s Republic of China |
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Abstract: | The electrochemical characteristics of the sulfur composite cathode for reversible lithium storage were investigated. The
sulfur composites showed novel electrochemical characteristics as well as high specific capacity and good cycleability. The
sulfur composite presented the average discharge voltage of 1.9 V, which was just the half of conventional LiCoO2 cathode materials, indicating that the double cells in series presented the same working voltage as conventional LiCoO2 cells and meaning that the sulfur composite cells will have good interchangeability with conventional LiCoO2 cells. The overcharge test showed that the sulfur composite cell cannot be charged over 5.0 V, indicating that the sulfur
composite cell presented the intrinsic safety for overcharge. Overcharge can cause serious problems for the conventional Li
ion cells. The overcharge test also showed that the sulfur composite cell was destroyed when the cell was charged over 4.0 V,
resulting in that the cell cannot normally be discharged again. It is found, however, that the sulfur composite cell can be
discharged again at very low current density of a 0.002-C rate after the cell was overcharged. Being much safer than lithium
metal anode, the graphite anode was used to fabricate sulfur composite/graphite lithium ion cells with a prelithiated sulfur
composite cathode, which was produced by electrochemical lithiation. The charge/discharge and cycling characteristics of the
sulfur composite/graphite cell was investigated. The result showed that the sulfur composite/graphite cells can be normally
cycled and showed the different voltages from that of the cell with the lithium metal anode. This paves the effective way
to fabricate safer sulfur composite/graphite lithium ion cells. |
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Keywords: | Sulfur composite cathode materials Nonlithiated electrode materials Prelithiation Graphite Overcharge safety |
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