Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, 325035, P. R. China.
Zhejiang Engineering Research Center for Electrochemical Energy Materials and Devices, Institute of New Materials and Industrial Technologies, Wenzhou University, Wenzhou, Zhejiang, 325035, P. R. China.
ChemSusChem. 2023 Jun 9;16(11):e202202379. doi: 10.1002/cssc.202202379. Epub 2023 Apr 19.
Herein, we investigated in detail the effect of metal valences in different cobalt-based organic framework compounds on the kinetics of sulfur reaction in lithium-sulfur batteries (LSBs). On this basis, two organic framework compounds of zeolite-imidazole-based cobalt organic framework compound (Co-ZIF) and tetrakis(4-benzoic acid) porphyrinato-Co chloride [Co-TBP(III)] with different valences were constructed as the functional intercalation separators of LSBs, and explored the effects of different valences on improving the reaction kinetics of polysulfides and inhibiting the shuttle effect. Experiments and theoretical calculations prove that Co exhibits the best catalytic activity. This is mainly due to the fact that +2 valence shows a strong adsorption energy for polysulfides and a higher Fermi level compared with +3 valence, thus improving the efficiency of the rapid catalytic conversion of sulfur species. As expected, the discharge specific capacity of Co-ZIF as the catalytic layer of the LSBs reached 772.7 mAh g at a high current density of 5 C. More importantly, the initial specific capacity is 839.6 mAh g at high current 3 C, and after 720 cycles, the attenuation rate of per cycle is only 0.092 %, and the coulombic efficiency remains above 92 %.
在此，我们详细研究了不同钴基有机框架化合物中金属价态对锂硫电池 (LSB) 中硫反应动力学的影响。在此基础上，构建了沸石咪唑酯钴有机框架化合物 (Co-ZIF) 和四(4-苯甲酸)卟啉-Co 氯化物 [Co-TBP(III)] 两种不同价态的有机框架化合物作为 LSB 的功能性插层分离器，并探讨了不同价态对提高多硫化物反应动力学和抑制穿梭效应的影响。实验和理论计算证明 Co 表现出最好的催化活性。这主要是因为+2 价对多硫化物表现出很强的吸附能，并且与+3 价相比具有更高的费米能级，从而提高了硫物种快速催化转化的效率。不出所料，作为 LSB 催化层的 Co-ZIF 的放电比容量在 5C 的高电流密度下达到 772.7 mAh·g。更重要的是，在高电流 3C 下的初始比容量为 839.6 mAh·g，经过 720 次循环后，每个循环的衰减率仅为 0.092%，库仑效率保持在 92%以上。
