Novel DNA-based polysulfide sieves incorporated with MOF providing excellent 3D Li+ pathway for high-performance lithium-sulfur batteries

초록

For enhancing the performance of lithium-sulfur batteries (LSBs), deoxyribonucleic acid (DNA) as a biomacromolecular adsorbing agent was incorporated into metal-organic frameworks (MOFs) to fabricate a MOF/carbon nanotube (CNT)@DNA double interlayer (MCDDI). Simulation calculations show that the adsorption energy (Ea) increased in the order of CNT-Li2S8 (-0.051 eV) < DNA(=N)-Li2S8 (-1.095 eV) < DNA (-P--O)-Li2S8 (-1.137 eV), confirming that DNA-functionalized conductive CNT (CNT@DNA) layer facing the cathode with abundant anchoring sites can block and inhibit the shuttle effect of lithium polysulfides. The MOF layer on the surface of the CNT@DNA layer provides 3D pathways to realize fast Li-ion transport and homogeneous Li deposition for inhibition of voltage polarization and dendritic Li growth. LSBs using the MCDDI exhibited a high specific capacity of 1126 mAh/g and stable cycling performance with a small capacity decay (851 mAh/g after 100 cycles) at 0.5C. A small polarization effect (Delta E = 0.33 V at 2C) is observed from the excellent rate performance. In addition, owing to the homogenous Li-ion fluxes, a high Li+ transference number (tLi+ = 0.62) and stable Li plating/stripping for a long cycle life (500 h, 1000 cycles) were achieved without Li dendrites.

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