Functionalized Graphene And Its Modification And Relative Nanocomposites As Anode Materials For Energy Storage

The purpose of this paper is to prepare the negative materials with good electrochemical performance for sodium and potassium ion batteries,ensures that the materials have the excellent cycle performance and the rate performance,improve the specific capacity of material,and expand its production as far as possible,enable it to have the value of commercial application.This research content of this paper mainly includes the following aspects:Firstly,the development of sodium-ion batteries is hindered by the poor Na⁺transport kinetics and structural instability of electrode materials during Na⁺intercalation/deintercalation.This work through to the traditional chemical oxidation method?Hummer?to prepare the graphite oxide,and carries on the simple two-step heat treatment,the preparation of the oxygen enriched with surface enhancement ability graphene materials.By changing the temperature of the second heat treatment step,the content of oxygen-functional groups on the surface are controlled and their properties in sodium ion batteries are tested.Based on the experimental results,the preparation of FGS-700 have the best test performance,the preparation of the electrode have the specific capacity of 603 mAh g^-1 under the current density of 0.05 A g^-1,and under the current density of 10 A g^-1,the specific capacity can still maintain in 214 mAh g^-1,which show the excellent performance.In addition,with the current density of 5A g^-1,it could almost no attenuation after 10,000 cycles and shows the excellent cycle performance.The present work demonstrates that the surface oxygen functionalization is an effective strategy to develop high performance graphene-based anodes due to the surface-enhanced Na storage with improved reaction kinetics and suppressed structural variation.Secondly,in order to gain the more excellent performance of carbon anode materials for sodium ion batteries.This work by introducing the quantum dots of cobalt on the surface of functionalized graphene,to catalyzed the Solid Electrolyte Interphase film,and prepared the composites of graphene with cobalt quantum dots.The catalytic action of the composite materials was controlled by changing the content of cobalt and the properties in sodium ion batteries were tested.Based on the experimental results,the preparation of the composite materials have the high specific capacity,the preparation of the electrode have the specific capacity of 721 mAh g^-11 under the current density of 0.05 A g^-1.And under the current density of 10A g^-1,the specific capacity can still be maintained at 242 mAh g^-1,which shows the good rate performance.This work demonstrates that the introduction of cobalt can effectively improve the SEI membrane on the surface of the electrode,and improve the reaction kinetics of the electrode and enhance its sodium ion storage capacity.