Controlled Synthesis Of Nitrogen-doped Graphdiyne And Its Energy Storage Research

Graphdiyne(GDY),an emerging carbon material,has become a widely used material in electrochemistry since it was first successfully synthesized in 2010.As a new type of twodimensional carbon allotrope,GDY possesses sp and sp2 hybridized carbon atoms,which uniformly arrangement induce the asymmetric distribution of the surface charge leading to intrinsic electrochemical activities.Compared to traditional carbon electrodes,the large conjugated rings also significantly improve the electron transfer.Up to now,GDY has attracted increasing attention and research interest as electrode materials in Lithium-ion batteries(LIBs)and Sodium-ion(SIBs).Further functionalization of GDY is an urgent issue in order to meet the capacity and stability requirements of battery devices.This thesis mainly focuses on the combination of two functionalization strategies,heteroatom doping and metal compounding,which optimize the performance of Li/Na storage capacity.This work systematically investigates the effects of the chemical structure,synthesis process,aggregation and metal nanoparticle compounding ofN-doped GDY.The structure-performance relationship of N-doped GDY can be systematically investigated by researching the key factors which influence the electrochemical performance.The main contents are as follows.1.Adaptive interfacial contact between copper nanoparticles and triazine functionalized Graphdiyne substrate for improved lithium/sodium storageDue to the high reactivity,nanoscale particles extremely suffer from chronic uncontrollable aggregation,which signi ficantly hinders storage capacity in lithium-ion batteries(LIBs)and sodium-ion batteries(SlBs).It is an effective strategy through introducing components with proper affinity to synergistically improve the stability of nanoscale materials.Herein,we report a synthesis method to in-situ prepare stable metallic copper nanoparticles(Cu NPs)loaded on triphenyl-substituted triazinyl GDY(TPTG)substrates.The existence of sp carbon in acetylenic linkers and nitrogen heteroatom in triazine groups synergistically stabilizes the Cu NPs loaded on TPTG substrates.Calculations results show that the Interaction between GDY and Cu NPs at the contact interface improves the Li/Na storage capacity.Cu NPs loaded on TPTG exhibit reversible volume change during the charge-discharge process,which induces improved ultra-stable cycling performance while used as electrode.Moreover,TPTG@Cu electrode materials are tested to further investigate the intrinsic association of size effect and performance of electrode materials.Significantly,composite materials show superior cycling stability during insertion/extraction process over 4000 cycles in LIBs and 14000 cycles in SIBs.2.Preparation of triphenyl-amine GDY with concomitant assembled morphology and its application for lithium-ion storageThe formation process of heteroatom-doped GDY is closely related to the specific preparation method,experimental conditions and other factors.And it has a significant impact on the aggregation and properties of the prepared products.Investigating the morphology changes during the synthesis process of N-doped GDY can deepen the understanding of intrinsic association.Therefore,a gas-liquid interfacial approach is developed for preparing triphenyl-amine GDY(TPN-GDY).The nitrogen heteroatoms are included in a form of tertiary amine substituted by three benzene rings,which can efficiently adjust the bonding situation of carbon in TPN-GDY and expand the size of the pores distributing on the carbon plane.Concomitant morphology containing nanoparticles and leaf-like structure are formed during synthesis process.The microscopic morphology and ratio of these two components can be tuned through simply adjusting the reaction conditions.Interestingly,continuous deposition of TPNGDY powder from gas/liquid reaction interface is observed,which can be ascribed to the tunable aggregation of TPN-GDY during the reaction process.The as-prepared TPN-GDY powder shows high surface area,multi-level porous structure and good conductivity compare to TPN-GDY prepared on classical solid substrates.As a result,good electrochemical performances in lithium-ion batteries are exhibited,include high reversible capacity,good rate performance,and long cycling stability.