Kumar Pushpendra, Wu Feng-Yu, Hu Lung-Hao, Ali Abbas Syed, Ming Jun, Lin Chia-Nan, Fang Jason, Chu Chih-Wei, Li Lain-Jong
Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan.
Nanoscale. 2015 May 7;7(17):8093-100. doi: 10.1039/c5nr00885a.
Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (∼70% capacity retention after 250 cycles), good coulombic efficiency (∼98%) and high capacity (∼1500 mA h g(-1)) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes.
单质硫（S）因其极高的容量，已被证明是锂硫电池等储能装置中一种优异的正极材料。与硫正极相关的主要挑战包括结构退化、循环性能差以及在循环过程中多硫化物溶解导致的固体电解质界面不稳定。其他人所做的大量努力表明，对硫材料进行封装可改善其循环性能。为使这种方法适用于大规模应用，使用低成本技术和材料已成为基于硫的锂离子电池的一个关键且新的重点。在此，我们提议使用低温喷涂工艺来制备石墨烯/硫电极材料，其中油墨由石墨烯薄片和通过研磨低成本硫粉制备的微米级硫颗粒组成。发现硫颗粒被高导电性的石墨烯薄片良好地承载，因此获得了优异的循环性能（250次循环后容量保持率约为70%）、良好的库仑效率（约98%）和高容量（约1500 mA h g⁻¹）。所提出的方法不需要高温退火或烘烤；因此，另一个很大的优势是能够制造柔性锂离子电池。我们还展示了两种使用喷涂石墨烯/硫电极的柔性电池。
