Ethylene tar is a prospective precursor for preparing carbonaceous materials,which is regarded as a representative soft carbon material after carbonization.However,the introduction of oxygen can influence the morpholo...Ethylene tar is a prospective precursor for preparing carbonaceous materials,which is regarded as a representative soft carbon material after carbonization.However,the introduction of oxygen can influence the morphology of the final carbonaceous materials.For the introduction of oxygen,dealkylation and dehydrogenation will be promoted and the molecules can be linked more effectively.For the subsequent carbonization,the biphenyl structures caused by the deoxygenation via the elimination of CO_(2),as well as the reserved aromatic ether bonds,can facilitate the strong cross-linking,which will restrain the movement of the carbon layers and the formation of the graphitic structures.After the graphitization treatment at 2800℃,the oxidized pitch can lead to short-range ordered and long-range unordered structures,while the sample without oxidation can result in long-range ordered graphitic structures.It can be proved that a simple oxidation-carbonization treatment can transform ethylene tar into hard carbon structures.展开更多
High energy density and low cost make lithium-sulfur(Li-S)batteries as one of the next generation's promising energy storage systems.However,the following problems need to be solved before commercialization:(i)the...High energy density and low cost make lithium-sulfur(Li-S)batteries as one of the next generation's promising energy storage systems.However,the following problems need to be solved before commercialization:(i)the shuttling effect and sluggish redox kinetics of lithium polysulfides in sulfur cathode;(ii)the formation of lithium dendrites and the crack of solid electrolyte interphase;(iii)the large volume changes during charge and discharge processes.MXenes,as newly emerging two-dimensional transition metal carbides/nitrides/carbonitrides,have attracted widespread attention due to their abundant active surface terminals,adjustable vacancies,and high electrical conductivity.Designing MXene-based heterogeneous structures is expected to solve the stacking problem induced by hydrogen bonds or Van der Waals force and to provide other charming physiochemical properties.Herein,we generalize the design principles of MXene-based heterostructures and their functions,i.e.,adsorption and catalysis in advanced conversion-based Li-S batteries.Firstly,the physiochemical properties of MXene and MXene-based heterostructures are briefly introduced.Secondly,the catalytic functions of MXene-based heterostructures with the compositional constituents including carbon materials,metal compounds,organic frameworks,polymers,single atoms and special high-entropy MXenes are comprehensively summarized in sulfur cathodes and lithium anodes.Finally,the challenges of MXene-based heterostructure in current Li-S batteries are pointed out and we also provide some enlightenments for future developments in high-energy-density Li-S batteries.展开更多
基金financially supported by the National Natural Science Foundation of China(22075081,52372045 and U1710252)the Fundamental Research Funds for the Central Universities(JKD01231701)+1 种基金China Postdoctoral Science Foundation(2023M731084)Shanghai Sailing Program of China(23YF1408900).
文摘Ethylene tar is a prospective precursor for preparing carbonaceous materials,which is regarded as a representative soft carbon material after carbonization.However,the introduction of oxygen can influence the morphology of the final carbonaceous materials.For the introduction of oxygen,dealkylation and dehydrogenation will be promoted and the molecules can be linked more effectively.For the subsequent carbonization,the biphenyl structures caused by the deoxygenation via the elimination of CO_(2),as well as the reserved aromatic ether bonds,can facilitate the strong cross-linking,which will restrain the movement of the carbon layers and the formation of the graphitic structures.After the graphitization treatment at 2800℃,the oxidized pitch can lead to short-range ordered and long-range unordered structures,while the sample without oxidation can result in long-range ordered graphitic structures.It can be proved that a simple oxidation-carbonization treatment can transform ethylene tar into hard carbon structures.
基金This work was financially supported by the National Key R&D Program(No.2021YFA1201503)the National Natural Science Foundation of China(Nos.22075081,21972164,and 22279161)+1 种基金the Fundamental Research Funds for the Central Universities(No.JKD01231701)the Natural Science Foundation of Jiangsu Province(No.BK 20210130).
文摘High energy density and low cost make lithium-sulfur(Li-S)batteries as one of the next generation's promising energy storage systems.However,the following problems need to be solved before commercialization:(i)the shuttling effect and sluggish redox kinetics of lithium polysulfides in sulfur cathode;(ii)the formation of lithium dendrites and the crack of solid electrolyte interphase;(iii)the large volume changes during charge and discharge processes.MXenes,as newly emerging two-dimensional transition metal carbides/nitrides/carbonitrides,have attracted widespread attention due to their abundant active surface terminals,adjustable vacancies,and high electrical conductivity.Designing MXene-based heterogeneous structures is expected to solve the stacking problem induced by hydrogen bonds or Van der Waals force and to provide other charming physiochemical properties.Herein,we generalize the design principles of MXene-based heterostructures and their functions,i.e.,adsorption and catalysis in advanced conversion-based Li-S batteries.Firstly,the physiochemical properties of MXene and MXene-based heterostructures are briefly introduced.Secondly,the catalytic functions of MXene-based heterostructures with the compositional constituents including carbon materials,metal compounds,organic frameworks,polymers,single atoms and special high-entropy MXenes are comprehensively summarized in sulfur cathodes and lithium anodes.Finally,the challenges of MXene-based heterostructure in current Li-S batteries are pointed out and we also provide some enlightenments for future developments in high-energy-density Li-S batteries.
