Conductive Metal Organic Framework as Trapping Cathode Additive for High Performance Lithium-Sulfur Batteries

Lithium-Sulfur (Li-S) batteries with high capacity and energy density have arisen as one of the most promising secondary batteries. However, higher order lithium polysulfide (LiPSs) shuttling and insulating nature of sulfur cathode results in capacity degradation and premature failure of the cell [1]. Here for the first time, we have implemented conductive Cu metal-based Metal organic framework (Cu-MOF) as a Li-S battery cathode material. Cu-MOF cathode catalyst not only reduce the LiPSs shuttle effect but also increase the conductivity of Li-S battery cathode [2]. Here, Cu-MOF pore morphology will trap the polysulfides and further prevent LiPSs shuttling. In addition, the well-defined architecture of organic ligands of Cu-MOF also participate to explicate the involved surface-binding mechanisms of S and polysulfide products. Furthermore, Cu-MOF improve the diffusion rate of Li ions, shackling LiPSs, upsurging conduction of electrons/ions, and regulating the deposition of Li 2 S 2 /Li 2 S towards cathode side [3]. Furthermore, sulfur active material is well percolated inside the pores of conductive Cu-MOF which shows the long-cycling performance as shown in Figure 1. Benefiting from the unique fibrous, porous, interwoven structure, the conductive MOF@S-composite cathode demonstrates a high initial capacity of 1671 mAh g –1 at 0.05 C rate with a good coulombic efficiency of >95% and the outstanding capacity of 849 mAh g -1 cycles even after 200 cycles at the 0.5 C-rate with coulombic efficiency of 98.3%. It is believed that, the experimental findings and mechanistic understanding of Cu-MOF cathode in this work will open a new avenue for the further development of other conductive MOFs in the Li-S batteries. Figure 1: Cycling performance of S@Cu-MOF composite at 0.5 C-rate. References Mingyue Wang, Zhongchao Bai, Ting Yang, Chuanhao Nie, Xun Xu, Yunxiao Wang, Jian Yang, Shixue Dou, and Nana Wan."Advances in High Sulfur Loading Cathodes for Practical Lithium-Sulfur Batteries." Energy Mater , no.12 (2022): 2201585. Dan Luo, Chaojie Li, Yongguang Zhang, Qianyi Ma, Chuyin Ma, Yihang Nie, Matthew Li, Xuefei Weng, Rong Huang, Yan Zhao, Lingling Shui, Xin Wang, Zhongwei Chen. "Design of Quasi-MOF Nanospheres as a Dynamic Electrocatalyst toward Accelerated Sulfur Reduction Reaction for High-Performance Lithium–Sulfur Batteries." Mater , no.34 (2022): 210554. Jun Zhang, Ye Shi, Yu Ding, Lele Peng, Wenkui Zhang, Guihua Yu. "A Conductive Molecular Framework Derived Li2S/N,P-Codoped Carbon Cathode for Advanced Lithium–Sulfur Batteries." Energy Mater , no.7 (2017): 1602876. Figure 1