School of Physics, State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, P.R. China.
Chemistry. 2018 Aug 1;24(43):11193-11199. doi: 10.1002/chem.201801925. Epub 2018 Jul 3.
Although rechargeable lithium-sulfur batteries are considered as advanced energy systems, their practical implementation is impeded by many factors, in particular the rapid capacity fade and low Coulomb efficiency caused by the shuttle effect. To overcome this problem for achieving longer cycle life and higher rate performance, anchoring materials for lithium polysulfides are highly desirable. In this work, for the first time, we report phosphorene-like MX (M=Ge, Sn; X=S, Se) monolayers as promising anchoring materials to restrain the lithium polysulfides shuttling. Our study provides fundamental selection criteria for the effective suppression of the polysulfides shuttling. Adsorption calculations reveal that polysulfide capture by the MX is through chemisorption with a suitable range of adsorption energies. Morever, we show that excellent surface diffusion of Li and polysulfides endow a fast charge/discharge rate for lithium-sulfur batteries. Graphene with desirable electronic properties is constructed to improve the electrical conductivity in the new graphene@MX heterostructures. Based on the strong anchoring ability, improved rate capability, and enhanced conductivity, MX-based composites hold great promise as an anchoring material for high-energy lithium-sulfur batteries.
虽然可充电锂硫电池被认为是先进的能源系统，但由于许多因素的限制，其实际应用受到阻碍，特别是由于穿梭效应导致的容量快速衰减和低库仑效率。为了克服这个问题，实现更长的循环寿命和更高的倍率性能，非常需要用于固定锂多硫化物的锚定材料。在这项工作中，我们首次报道了类黑磷烯 MX（M=Ge，Sn；X=S，Se）单层作为有前途的锚定材料，以抑制锂多硫化物的穿梭。我们的研究为有效抑制多硫化物的穿梭提供了基本的选择标准。吸附计算表明，MX 通过与合适吸附能范围的化学吸附来捕获多硫化物。此外，我们还表明，Li 和多硫化物的优异表面扩散赋予了锂硫电池快速的充放电速率。构建具有理想电子特性的石墨烯以提高新的石墨烯@MX 异质结构中的电导率。基于强的锚定能力、改善的倍率性能和增强的导电性，基于 MX 的复合材料有望成为高能锂硫电池的理想锚定材料。
