Synergetic effect of block and catalysis on polysulfides by functionalized bilayer modification on the separator for lithium-sulfur batteries
Yitian Ma, Linqing Chang, Dawei Yi, Meng Liu, Peichun Wang, Shuliang Luo, Zhiyun Zhang, Yan Yuan, H. J. Lü
Abstract
One crucial problem hindering the commercial application of lithium-sulfur batteries with high theoretical specific energy is the ceaseless shuttle of soluble lithium polysulfides (LiPSs) between cathodes and anodes, which usually leads to rapid capacity fade and serious self-discharge issues. Herein, a unique bilayer coating strategy designed to modify the polypropylene separator was developed in this study, which consisted of a bottom zeolite (SSZ-13) layer serving as a LiPS movement barrier and a top ZnS layer used for accelerating redox processes of LiPSs. Benefiting from the synergetic effect, the bilayer-modified separator offers absolute block capability to LiPS diffusion, moreover, significant catalysis effect on sulfur species conversion, as well as outstanding lithium-ion (Li+) conductivity, excellent electrolyte wettability, and desirable mechanical properties. Consequently, the assembled lithium-sulfur cell with the SSZ-13/ZnS@polypropylene separator demonstrates excellent cycle stability and rate capability, showcasing a capacity decay rate of only 0.052% per cycle at 1 C over 500 cycles.