Li Qing, Ma Zhipeng, Li Jiaojiao, Liu Zhan, Fan Lukai, Qin Xiujuan, Shao Guangjie
Hebei Key Laboratory of Applied Chemistry, Hebei Key Laboratory of Heavy Metal Deep-Remediation in Water and Resource Reuse, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China.
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
ACS Appl Mater Interfaces. 2020 Aug 5;12(31):35049-35057. doi: 10.1021/acsami.0c09583. Epub 2020 Jul 27.
Owing to their low cost and high theoretical energy density, lithium-sulfur (Li-S) batteries are highly promising as a contender for the post-lithium-ion battery era. However, the intrinsic low reversible conversion ability of lithium polysulfides to sulfur/LiS during charging/discharging seriously hinders the sulfur utilization, resulting in poor cycling life of batteries. Herein, we report an improvement of core-shell-structured sulfur nanospheres@ultrathin δ-MnO nanosheet electrode materials prepared by a simple precipitation reaction method, in which the ultrathin δ-MnO nanosheets as a catalytic layer can promote the chemical adsorption of lithium polysulfides and their conversion rates to sulfur/LS. Using a combination of the UV-visible adsorption spectra and first-principles calculation, the results indicate that the Mn-O coordination center on the surface of the MnO structure plays an efficient catalytic role in the conversion reaction of lithium polysulfides to insoluble S/LiS. The sulfur nanospheres@ultrathin δ-MnO nanosheet composite with a high S mass ratio of 82 wt % reveals a high specific capacity of 846 mA h g at 1 C rate and good cycling stability. Moreover, the areal capacity of the electrode with a high sulfur loading mass of 10 mg cm is 5.2 mA h cm, approaching the practical application standard at a current density of 1 mA cm.
由于锂硫（Li-S）电池成本低且理论能量密度高，作为锂离子电池时代后的有力竞争者极具前景。然而，多硫化锂在充电/放电过程中固有的低可逆转化为硫/LiS的能力严重阻碍了硫的利用，导致电池循环寿命较差。在此，我们报道了通过简单沉淀反应法制备的核壳结构硫纳米球@超薄δ-MnO纳米片电极材料的改进，其中超薄δ-MnO纳米片作为催化层可促进多硫化锂的化学吸附及其向硫/LS的转化率。结合紫外可见吸收光谱和第一性原理计算，结果表明MnO结构表面的Mn-O配位中心在多硫化锂转化为不溶性S/LiS的反应中起有效催化作用。具有82 wt%高硫质量比的硫纳米球@超薄δ-MnO纳米片复合材料在1 C倍率下显示出846 mA h g的高比容量和良好的循环稳定性。此外，硫负载质量为10 mg cm的电极的面积容量为5.2 mA h cm，在1 mA cm的电流密度下接近实际应用标准。
