Prepartion And Electrochemical Performance Research Of Porous Carbon And Composite Anode Materials

Conjugated microporous polymer?CMP?,a three-dimensional macromolecular polymer formed by the?-conjugated skeleton,has the advantages of large specific area,diverse building blocks and tuned chemical components.And it is an ideal porous carbon precursor.By tailoring monomer structure,we synthesized sulfer and nitrogen co-doped CMP.Sulfer and nitrogen co-doped porous carbon was prepared by the high temperature pyrolysis CMP,where the introduction of sulfer and nitrogen generated more defects and provided abundant lithium storage active sites.By changing monomer structure,we also prepared sulfur-containing CMP.CMP has many active sites?C?C?bonded metal ions,and S atoms with high chemical activity also have the possibility of bonding metal ions.By using these unique physical and chemical properties of CMP,we prepared Fe₃O₄ and sulfur-containing porous carbon composites?Fe₃O₄-SPC?to overcome the shortcomings of poor cycling performance of Fe₃O₄.Conjugated microporous polymer was synthesized via a Pd?0?/CuI catalyzed Sonogashira-Hagihara cross-coupling polycondensation.Hierarchical spherical porous CMP?HSCMP?and tubular CMP?TCMP?were prepared by using different monomers?4,7-dibromobenzo[c][1,2,5]thiadiazole and 1,4-dibromo-naphthalene?and1,3,5-triethynylbenzene,respectively.Then,SNHSPC and PCNT can be obtained by high-temperature pyrolysis HSCMP and TCMP,and the morphology of SNHSPC and PCNT have not changed.SEM,TEM,TEM-EDX and BET prove that SNHSPC is hierarchical spherical porous network structure composed of carbon nanofiber,which has a large specific surface area and large pore volume.At the same time,N and S elements are distributed in SNHSPC.SNHSPC feature unique morphology,abundant pore structure and homogeneous S and N co-doping,which enable a superior super lithium storage behavior.Commercial mesoporous carbon?MC?has a large specific surface area and good electrical conductivity.Fe₃O₄/mesorporous carbon?Fe₃O₄-MC?composite was prepared by pyrolysis the mixture of MC,Fe?NO₃?₃·9H₂O and Fe?CH₃COO?₂·4H₂O.XRD result proves that Fe₃O₄ crystals are being in the Fe₃O₄-MC composite.The SEM indicates MC are covered by Fe₃O₄ nanoparticles.TEM reveals that Fe₃O₄nanoparticles are existed in Fe₃O₄-MC composite.BET analysis proves that the specific surface area of Fe₃O₄-MC composite is distinctly lower than that of MC,indicating some pores of MC are filled by Fe₃O₄ nanoparticles.The above novel structure is beneficial to improving the electrochemical performance of Fe₃O₄-MC composite.Thiophene containing conjugated microporous polymer?SCMP?derived sulfur-enriched porous carbon supported Fe₃O₄ nanoparticles was successfully synthesized from the mixture of SCMP and ferric salt.XRD results prove that sulfur-enriched porous carbon supported Fe₃O₄ nanoparticles?Fe₃O₄-SPC?contain crystalline Fe₃O₄ with a face-centered-cubic structure.SEM images reveal that Fe₃O₄-SPC are hierarchical agglomerates constituted by nanoparticles with a range of20-50 nm.TEM and TEM-EDX results further prove that Fe₃O₄ nanoparticles are embedded in the SPC nanoparticles,which can effectively buffer the huge volume changes of Fe₃O₄ nanoparticles.Nitrogen adsorption/desorption analysis reveals that Fe₃O₄-SPC are mesoporous materials with a surface area of 60.3 m²·g^-1.These special structures enable Fe₃O₄-SPC show wonderful cycling performance(897.2 mAh·g^-1after 300 cycles at 600 mA·g^-1).