Selenium @ Rice Husk derived Carbon Composite for Li-Se Batteries

Kuldeep, Kuldeep and M, Deepa (2018) Selenium @ Rice Husk derived Carbon Composite for Li-Se Batteries. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Lithium-Selenium secondary battery is similar to Lithium-Sulfur battery, but Li-Se batteries have some advantages like better electrochemical performance and good cyclability. It is due to better conductivity and weak bonding in elemental Selenium than Sulfur. However, lithium ions can react with both Selenium and Sulfur to produce polyanions. [1] Despite similarities; there are some disadvantages like toxicity and shuttle phenomenon (i.e., the back and forth movement of soluble polyselenides/polysulfides between both electrodes). We have developed selenium-carbon rice husk composites as cathodes for rechargeable Li–Se battery with excellent rate capability, cycling performance with high Coulombic efficiency. The cell was run in an ether-based electrolyte (1 M LiTFSI solution) with composite and found excellent electrochemical performance with an initial discharge capacity of 821.34 mA h gSe1-, and the remaining capacity was 319.16 mA h gSe1- even after 100 cycles with high Coulombic efficiency. A novel strategy is also applied by using polycarbazole in an advanced Lithium (Li)-Selenium (Se) to enhance the cycling stability, electrochemical performance as well as the storage capacity of the cell. Compared to pristine ball-milled Se, the Se@RHC hybrid with 70 % selenium shows a high Se utilization in the full Li-Se cell by giving a high capacity of 821.3 mA h gSe-1 compared to 421.5 mA h gSe-1 achieved for the cell with pristine Se. The main reason behind this exceptional electrochemical performance is that the excellent electronic conductivity of the composite and large surface of Rice-husk derived carbon (RHC) that can increase the reaction depth (or low-order polyselenides intermediates formed and were stabilized by RHC via volume expansion) and constrain the polyselenides. The excellent characteristics like high capacity and stability of cell demonstrate that Se-based active materials will be another promising cathode candidate for the future rechargeable lithium secondary batteries (LIBs).

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