Preparation Of Porous Carbon Materials And Their Electrochemical Properties Based On The Diblock Copolymer Of XPS-b-PMMA

In this paper,the latest research development of supercapacitors and electrode materials were narrated,in detail.It is a very important fundamental scientific problem that the effect of pore size distribution and the specific surface area of carbon materials on electrochemical performances of electrochemical double layer capacitors?EDLCs?,deeply and systematically study it.However,regrettably for this problem has not a thorough and systematic research and a ll are basically limited to the qualitative description,have not experimental verifications.The main cause of this phenomenon is because the complexity of the system and the structure of porous carbon material are difficult to control.Hence,the idea was put forward to prepare the porous carbon material by carbonization the block copolymer at the high temperature.And the electrochemical properties of hierarchically porous carbon materials were investigated.Importantly,the relationship between the stru cture of block copolymer,pore structure,specific surface area,pore size distribution and electrochemical properties of the obtained porous carbon materials were explored.The main research route of this subject is the synthesis of block copolymer that the molecular weight is controllable,and the reaction of crosslinking using the Friedel-Crafts reaction,the porous carbon materials,and the high-performance supercapacitors.That is to say,the morphological structure by tailor the molecular weight distribution and/or volume fraction of PMMA in block copolymer of PS-b-PMMA,and then tailor the pore size distribution of porous carbon materials during the carbonization progress.Finally,the effects between the pore size distribution and specific surface area of porous carbon materials on electrochemical performances.The main contents are presented as follows:?1?The block copolymer of PS-b-PMMA with controlled molecular weight and narrow polydispersity were synthesized successfully using the atom tra nsfer radical polymerization?ATRP?in system of EC,the St and the MMA as the monomer,the Cu Br/BPY as the catalytic system and the MBP as the initiator.Based on it,the–CO–cross-linking bridges were introduced between linear PS chains using a Friedel-Crafts reaction and obtained the crosslinking block copolymer of x PS-b-PMMA.The cross-linked polystyrene as the carbon source and generated numerous micropores,the PMMA as the sacrificial block that disintegrated to form mesopores and macropores during the carbonization process.In this work,the macroinitiator PS-Br(Mn=15,281 g mol^-1)was successfully prepared by ATRP,and then the block copolymer of PS-b-PMMA with various molecular weight controllable and narrow distribution were successfully obtained by controlling the reaction conditions of ATRP,while the reserved block?x PS?remained unchanged.And the molecular weights of block copolymer were 19,011,21,368,22,918 and 25933 g mol^-1,and the volume fractions of PMMA(f _PMMA)were 19.62%,28.49%,33.42%and 41.28%.Obviously,the obtained porous carbon materials possess larger specific surface area and hierarchically porous structure.Finally,the electrode material of HPC₅ has excellent electrochemical properties,such as the high specific capacitance of 204 F g^-1 at a current density of 0.5 A g^-1,the excellent rate capability and the outstanding long cycle life.?2?The hierarchically porous carbon materials were successfully prepared through a simple KOH and HNO₃ activation process with suitable and controllable activating conditions:temperature of 700?,activation time of 2 h and the weight ratio that the KOH/precursor of 1:1.Obviously,the obtained porous carbon material has a high specific surface area of 2,436 m² g^-1 and pore size distribution from 1.8 nm to 3 nm.Finally,the obtained porous carbon material exhibits outstanding electrochemical properties,such as high specific capacitance of 382 F g^-1 at a current density of 0.5 A g^-1 and excellent rate performance of 73%.The excellent electrochemical properties mainly because the high specific surface area and hierarchically pores structure,and the obtained porous carbon material possess numerous oxygen groups,which can facilitate the wettability of electrode.