Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi, Kerala 682 022, India.
Department of Applied Chemistry, Cochin University of Science and Technology, Kochi, Kerala 682 022, India.
J Colloid Interface Sci. 2019 Feb 1;535:287-299. doi: 10.1016/j.jcis.2018.09.096. Epub 2018 Oct 1.
Lithium-sulfur (Li-S) cells are emerging as the dominant constituents of the next generation battery technology, offering high theoretical capacity around 1675 mA h g and the additional advantages of low cost and non-toxic nature. Activated carbon, derived from natural resources is being extensively investigated for applications as electrode materials in high power supercapacitors and for making composite electrodes for designing high energy density electrochemical cells. The present work is aimed at introducing the potential of the composite cathode of sulfur with the biomass-derived, steam activated carbon (AC) along with the free-standing and flexible film of carbon nanotubes as the interlayer for designing efficient Li-S cells. The composite obtained by impregnating sulfur particles into the pores of coconut shell derived and steam activated carbon, subjected to efficient acid washing procedures to attain maximum purity, called as the activated carbon-sulfur (ACS) is used as the composite cathode material. The flexible film of acid-functionalized carbon nanotubes termed as the CNTF placed between the composite cathode and the separator material serves as an active interlayer to boost the performance efficiency of the assembled Li-S cells. The ACS composite is synthesized by the solvothermal method, and the flexible CNTF is obtained by solution casting. The Li-S cells assembled with the ACS composite as the active cathode material and the CNTF as the interlayer are found to exhibit quite impressive discharge capacity and cycling stability. These cells deliver an initial discharge capacity of 1562 mA h g at 0.05 C rate and retain 71% of the initial capacity at 1 C rate after 200 cycles. The conducting and the porous network of the ACS helps to enhance the overall electrical conductivity of the sulfur composite cathode and the highly conducting CNTF interlayer accelerates the electrochemical activity taking place in the cell. The interlayer restricts the polysulfides from migrating to the anode and thereby suppresses the polysulfide shuttle phenomenon. The use of the coconut shell derived, steam activated and acid washed carbon for making the composite cathode with sulfur and the CNTF interlayer, obtained by the acid functionalization of carbon nanotubes is a novel approach to realize Li-S cells with high capacity and excellent cycling stability, which has not yet been pursued in detail.
锂硫（Li-S）电池作为下一代电池技术的主导组成部分而崭露头角，其理论容量高达 1675 mA h g，具有低成本和无毒等额外优势。活性炭来源于天然资源，正被广泛研究作为高功率超级电容器的电极材料，以及用于设计高能量密度电化学电池的复合电极。本工作旨在介绍将硫与生物质衍生的蒸汽活性炭（AC）以及作为中间层的独立式和柔性碳纳米管薄膜复合作为高效 Li-S 电池的阴极的潜力。通过将硫颗粒浸渍到椰子壳衍生的和蒸汽活化的多孔碳中，然后进行有效的酸洗处理以达到最大纯度，得到的复合材料称为活性炭-硫（ACS），用作复合阴极材料。置于复合阴极和隔离材料之间的酸化功能化碳纳米管柔性薄膜称为 CNTF，用作活性中间层，以提高组装的 Li-S 电池的性能效率。ACS 复合材料通过溶剂热法合成，柔性 CNTF 通过溶液浇铸获得。组装的 Li-S 电池采用 ACS 复合材料作为活性阴极材料，CNTF 作为中间层，表现出相当令人印象深刻的放电容量和循环稳定性。这些电池在 0.05 C 速率下的初始放电容量为 1562 mA h g，在 200 次循环后以 1 C 速率保留初始容量的 71%。ACS 的导电和多孔网络有助于提高硫复合阴极的整体电导率，而高度导电的 CNTF 中间层则加速了电池中的电化学活性。中间层限制多硫化物向阳极迁移，从而抑制多硫化物穿梭现象。使用椰子壳衍生的、蒸汽活化的和酸处理的碳来制备含有硫和 CNTF 中间层的复合材料阴极，以及通过酸化碳纳米管获得的 CNTF 中间层，是实现具有高容量和优异循环稳定性的 Li-S 电池的一种新方法，尚未详细研究。
