Yao Weiqi, Zheng Weizhong, Xu Jie, Tian Chengxiang, Han Kun, Sun Weizhen, Xiao Shengxiong
The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Laboratory of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China.
State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
ACS Nano. 2021 Apr 27;15(4):7114-7130. doi: 10.1021/acsnano.1c00270. Epub 2021 Mar 25.
Lithium-sulfur (Li-S) batteries are severely hindered by the low sulfur utilization and short cycling life, especially at high rates. One of the effective solutions to address these problems is to improve the sulfiphilicity of lithium polysulfides (LiPSs) and the lithiophilicity of the lithium anode. However, it is a great challenge to simultaneously optimize both aspects. Herein, by incorporating the merits of strong absorbability and high conductivity of SnS with good catalytic capability of ZnS, a ZnS-SnS heterojunction coated with a polydopamine-derived N-doped carbon shell (denoted as ZnS-SnS@NC) with uniform cubic morphology was obtained and compared with the ZnS-SnS@NC heterostructure and its single-component counterparts (SnS@NC and SnS@NC). Theoretical calculations, XANES, and Raman spectrum were utilized to elucidate rapid anchoring-diffusion-transformation of LiPSs, inhibition of the shuttling effect, and improvement of the sulfur electrochemistry of bimetal ZnS-SnS heterostructure at the molecular level. When applied as a modification layer coated on the separator, the ZnS-SnS@NC-based cell with optimized lithiophilicity and sulfiphilicity enables desirable sulfur electrochemistry, including high reversibility of 1149 mAh g for 300 cycles at 0.2 C, high rate performance of 661 mAh g at 10 C, and long cycle life with a low fading rate of 0.0126% each cycle after 2000 cycles at 4 C. Furthermore, a favorable areal capacity of 8.27 mAh cm is maintained under high sulfur mass loading of 10.3 mg cm. This work furnishes a feasible scheme to the rational design of bimetal sulfides heterostructures and boosts the development of other electrochemical applications.
锂硫（Li-S）电池受到低硫利用率和短循环寿命的严重阻碍，尤其是在高倍率下。解决这些问题的有效方法之一是提高多硫化锂（LiPSs）的亲硫性和锂负极的亲锂性。然而，同时优化这两个方面是一个巨大的挑战。在此，通过结合具有良好催化能力的ZnS的强吸附性和高导电性以及SnS的优点，获得了一种涂覆有多巴胺衍生的N掺杂碳壳（表示为ZnS-SnS@NC）且具有均匀立方形态的ZnS-SnS异质结，并将其与ZnS-SnS@NC异质结构及其单组分对应物（SnS@NC和SnS@NC）进行了比较。利用理论计算、X射线吸收近边结构（XANES）和拉曼光谱在分子水平上阐明了LiPSs的快速锚定-扩散-转化、穿梭效应的抑制以及双金属ZnS-SnS异质结构的硫电化学性能的改善。当用作涂覆在隔膜上的改性层时，具有优化亲锂性和亲硫性的基于ZnS-SnS@NC的电池具有理想的硫电化学性能，包括在0.2 C下300次循环时1149 mAh g的高可逆性、在10 C下661 mAh g的高倍率性能以及在4 C下2000次循环后每个循环低至0.0126%的低衰减率的长循环寿命。此外，在10.3 mg cm的高硫质量负载下，保持了8.27 mAh cm的良好面积容量。这项工作为双金属硫化物异质结构的合理设计提供了一个可行的方案，并推动了其他电化学应用的发展。
