Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, People's Republic of China.
Nanoscale. 2018 Sep 13;10(35):16935-16942. doi: 10.1039/c8nr05749d.
Lithium-sulfur batteries suffer from poor cycling stability and inferior rate capability, mainly caused by low conductivity and lithium polysulfide dissolution. To tackle these problems, this work demonstrates that Ti3C2Tx "clay", synthesized by selectively extracting the Al layers from the Ti3AlC2 phases with a mixture of HCl and LiF, is an effective host material for sulfur cathodes. To further enhance the rate performance and cycling stability of S/Ti3C2Tx composites, a single-walled carbon nanotube thin film was prepared by a simple vacuum filtration method and inserted between the cathode and the separator as an interlayer for Li-S batteries. The S/Ti3C2Tx composite with an interlayer could deliver a high initial discharge capacity of 1458 mA h g-1 at a current density of 0.1 A g-1 and an ultralow capacity decay of 0.04% per cycle at 0.8 A g-1 for over 1500 cycles was achieved. More importantly, a reversible capacity of 608 mA h g-1 was obtained at a high current density of 8.2 A g-1 (≈5C), demonstrating superior rate capability. These results suggest that the S/Ti3C2Tx composite is a promising sulfur cathode material and the introduction of the interlayer will pave the way for the future development and design of high-rate with long-cycle Li-S batteries.
锂硫电池存在循环稳定性差和倍率性能差的问题，主要是由于导电性差和多硫化锂的溶解。为了解决这些问题，本工作表明，通过用 HCl 和 LiF 的混合物选择性地从 Ti3AlC2 相中提取 Al 层，合成的 Ti3C2Tx“粘土”是一种有效的硫阴极宿主材料。为了进一步提高 S/Ti3C2Tx 复合材料的倍率性能和循环稳定性，通过简单的真空过滤方法制备了单层碳纳米管薄膜，并将其插入阴极和分离器之间作为 Li-S 电池的中间层。具有中间层的 S/Ti3C2Tx 复合材料在 0.1 A g-1 的电流密度下具有 1458 mA h g-1 的初始高放电容量，在 0.8 A g-1 下循环 1500 次后容量衰减率低至 0.04%/循环。更重要的是，在 8.2 A g-1（≈5C）的高电流密度下，可获得 608 mA h g-1 的可逆容量，表现出优异的倍率性能。这些结果表明，S/Ti3C2Tx 复合材料是一种很有前途的硫阴极材料，中间层的引入将为未来高倍率长循环 Li-S 电池的发展和设计铺平道路。
