Structural Regulation And Energy Storage Of Polymers Derived Multiple Active Sites Carbonaceous Materials

Porous carbon materials（PCs）are widly applied to energy storage electrodes owing to their prominent electrical conductivity,high specific surface area and adjustable porous structure.However,their commercialization progress is hampered by lower specific capacity and complex systhesis routes.In this paper,some cheaper micromolecule carbon sources including pyrrole,thiophene,benzene,p-phenylenediamine and tris（4-bromobenzene）amineare are firstly employed to produce conjugated microporous polymers（CMPs）via one step polymerization process,with subsequent annealing treatment,hierarchical microporous carbon materials（HPCs）are fabricated via utilizing CMPs as precursors.Based on the regulating of porous distribution,active sites and structure,the systhesised PCs are applied to electrochemical fields of supercapacitors（SCs）,sodium ions batteries（SIBs）and lithium sulfur batteries（LSBs）to enhance their energy density.The contents are list as follows:（1）A hypercrosslinked polymerization approach is employed to fabricate 3D hypercrosslinked polymers（HCPs）with adjustable micropore size distribution.With subquent annealing treatment,furher deriving micro-dominant HPCs with large surface area(1200 m² g^-1),high micropores proportion（>70%）and multiple active sites（N:4.5 at%,S:5.8 at%）.When served as SCs electrode,the abundant microporous structure contributes high electrical double-layer capacitor,macropores serves as the reservoir for electrolyte ions and mesopores channels are in favour of the transport of electrolyte ions,hence facilitating the utilization ratio of active sites,causing the most of the pseudocapacitance contributions are not controlled by charge transfer or diffusion,and finally realizing fast electrochemical energy storage behaviors.（2）Utilizing hypercrosslinked polymerization reaction achiving the accurately regulated of N/S active sites according to the stating feeding ratio（thiophene/pyrrole）,and further exploring the structure-activity relationship between carbonaceous materials with different N/S active sites raito and sodium storage capapbility.As a result,the materials with 80%S proportion delivers the highest reversible capapcity(562 m A h g^-1),abundant capacity contribution mechanism（pseudo-capacitance contribution,physical adsorption capacitance contribution and carbon lattice insertion capacitance contribution）and superior cycling stability.Furthermore,a novle Buchwald-Hartwig（B-H）cross-coupling reactions is employed to produce N-rich CMPs with analogy COF structure（PTPA）,with subsquently annealing treatment,a well-designed microporous carbon materials（NMC）with large specific surface area(816 m² g^-1),high pore volume(0.68 cm³ g^-1)and high N active sites proportion.When served as SIBs anode,NMC delivers an excellent sodium storage capability relative to the commercial hard carbon(314 vs.181 m A h g^-1)based on their“three steps”sodium storage mechanism.（3）Utilizing the hypercrosslinked polymerization reaction catalyst（FeCl₃）as polar sites precursors,via space nano-confined effect limit the growth of Fe₂O₃ crystal nucleus,achieve in-situ formed 3D continuous N-doped microporous carbon confined Fe₂O₃nanocrystals（Fe₂O₃/N-MC）.Subsquently,Fe₂O₃/N-MC is served as sulfur carrier for LSBs,aiming at enhancing sulfur loading,restraining the“shuttle effects”and facilitating interface conversion of polysulfides.At a current density of 1 C,the S@Fe₂O₃/N-MC cathode deliver a conspicuous area capacity(4.46 m A h cm^-2)at high areal loading(5.1 mg cm^-2)and lean electrolyte/sulfur（E/S）ratio as low as 7.5:1μL mg^-1,which shows broad commercial prospects.（4）Utilizing the electrospinning technique integrate conductive agent（GO）,polar sites precursors（FeCl₃）into PAN nanofibers,and incorporate several vulcanization accelerator（MBS）during the PAN sulfuration reactions to fabricate SPAN nanofibers,aiming at optimizing the“shuttle effects”of long-chain polysulfides in conventional C/S electrodes.When served as LSBs cathode,the interwoven nanofiber structures not only can facilitate the nucleation/growth/decomposion of Li₂S,but also release the volume expansion during charge/discharge process.In addition,the incorporation of MBS,Fe_1-xS and r GO can enhance the S active sites proportion,facilitate polysulfides conversion reaction and accelerate charge transfer of electrolyte.Hence constructing excellent LSBs cathode with large reversible capacity and long cyciling stability.