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Synthesis of Li2S nanosheets coated carbon materials

wallpapers Tech 2021-04-28
Lithium sulfide (Li2S) is considered a promising and safer cathode material for energy storage batteries due to its compatibility with lithium-free metal anodes. However, due to the insulating properties of Li2S, its electrochemical performance is poor, so the practical application of Li2S electrodes is still far away. In this paper, a chemical method is proposed to synthesize the Li2S nanosheet coated carbon material KetjenBlack (LS@KB) composite, which can be coated on different current concentrators without the addition of adhesive. The high contact area between the Kb nanoparticles and the Li2S nanosheets effectively improves the conductivity of the cathode, which makes the weight ratio of Li2S reach 83%.In addition, we demonstrate that the well-wrapped LS@KB structure enhances the physical constraints of the polysulfide compounds, thus improving the cyclization.
Therefore, the synthesized LS@KB cathode has a stable cycling performance (1000 cycles) with a fading rate of 0.03% per cycle at a rate of 0.5C. This room-temperature preparation strategy overcomes the main defects in the preparation of Li2S, such as high temperature, harmful gas release, complex production process and high cost, making it a promising light, safe cathode material for portable electronic equipment.
Because lithium-sulfur batteries have a much higher theoretical energy density than the most advanced lithium-ion batteries, they are an attractive option for the next generation of energy storage. However, due to the large change of sulfur cathode volume and the uncontrollable deposition of Li2S2/Li2S, the cycle life is significantly destroyed and the voltage polarization is increased. To address these challenges, we developed a columnar caprolactam/acetamide eutectic solvent electrolyte that can dissolve all lithium polysulfides and lithium sulfides (Li2S8-Li2S). The electrolyte has a high specific capacity (1360 mAh g−1) and reasonable circulation stability. In addition, this low-cost eutectic solvent-based electrolyte is difficult to ignite compared to a conventional ether electrolyte with a low flash point (approximately 2°C), thus significantly improving the safety of the battery. This study provides a new way to improve the safety and performance of lithium-sulfur batteries.

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