Preparation And Performance Of Melamine Resin And Graphene Composite Anode For Lithium Ion Batteries

Lithium-ion batteries(LIBs)have been widely used in portable electronic devices due to their high energy density,long cycle life and excellent safety.With the development of the electric vehicles,the power density and energy density of LIBs have needed to be further improved.Howerver,electrode materials is one of the most decisive factors to improving the electrochemical performance for LIBs.Graphite,the most commonly commercial anode material,has the low theoretical specific capacity(372 mAh/g),restricting the improvement of LIBs.Graphene,as a novel carbon material,exhibits excellent electrochemical performance due to its superior electronic conductivity,large specific surface areas and intriguing mechanical properties.Thus,graphene materials were chosen as research subjects to improve the specific capacity,cycling stability and rate performance for LIBs.In our current work,we took graphite-based carbon materials as the research object.A series of high performance composite anode materials of melamine resin/graphene lithium-ion battery were designed and synthesized in order to improve the specific capacity,cycle performance and rate performance of lithium-ion battery.Using freeze-drying,sintering and molten salt activation methods,polyvinyl alcohol(PVA)was used as dispersant and nucleating agent to synthesize melamine resin(MR)spheres with abundant heteroatoms and compounded with graphene oxide(GO).The composite is composed of N and O-doped hollow carbon spheres(DHCSs)and RGO.The unstacked RGO nanocrystals are covered with DHCSs spheres to form a uniform 3D porous network structure.Freeze drying can effectively prevent the agglomeration of MR spheres in GO network.KOH molten salt adjusts the pore structure of DHCSs/RGO.DHCSs/RGO annealed at 700?shows the best electrochemical performance.The discharge capacities at 0.1 A/g and 5 A/g were 1395 mAh/g and 606 mAh/g,respectively.At a current density of 2 A/g,the specific discharge capacity remained at 755 mAh/g after 600 cycles,the cycle stability is better than the results reported in the literature.This work provides a feasible method for fabrication of graphene-based nanocomposites with hollow and porous carbon architectures and inspires new insights into fabrication of high performance functional devices.