Preparation And Electrode Application Of The Composited Nanodiamond/graphene

With the development of science and technology,energy storage and application of human society is an urgent problem to be solved.Lithium-ion batteries,considered to be the most promising energy storage and transmission equipment,can be widely used in military and civilian electronic products.Lithium-ion battery(LIBS)as an important energy storage and transmission media,has been widely used in the commercial field.The selection of functional materials and the design of special structures are key to achieving high performance devices.With high surface area,short diffusion distance,high electrons and ionic conductivity,it is an important factor that must be taken into account when selecting materials.For commercially available lithium-ion batteries,the current market for leading negative materials is graphite-based carbon-based materials,but because of its low theoretical capacity of lithium intercalation(372 mAh g-1),can not meet the needs of market products,researchers began to look for alternatives Graphite anode material.The amorphous carbon material has a good cycle stability,high specific capacity and other advantages,its application in the field of lithium-ion battery wider;elemental silicon has a high theoretical specific capacity(4200 mAh g-1),which is considered to be one of the most promising anode materials,but in the process of lithium/de-lithium,silicon particles volume expansion serious,resulting in silicon electrode powder,resulting in dramatic decline in capacity.In addition,the study found that SnO,SnO2 and other tin-based composite oxides,FeO,CoO,MoO and Cu2 O and other transition metal oxides,specific capacity greater than 600 mAh g-1,but in the battery charge and discharge process,the volume change is also very large,Resulting in the failure of the electrode material and even powder,resulting in its actual capacity is low and the cycle stability is not high,therefore,to find high-capacity,high stability of the anode material is an urgent need to solve the problem.Diamond is an allotrope of carbon,may become an excellent anode candidate material of lithium ion battery.Nanodiamond has high compressive strength,strong acid resistance,strong alkali,good biocompatibility,large specific surface area,high electron ion mobility,low coefficient of expansion,excellent thermal conductivity and has been caused widespread concern of scientific research workers.The introduction of nanodiamond can increase the adsorption of lithium ions to improve the reversible capacity and lithium ion transfer rate,and its hardness,structural stability.Nanodiamond and other carbon nanomaterials made of composite structure used in lithium battery anode material,will improve the performance of the negative and the battery.The main contents of this paper are as follows:(1)Preparation of carbon nanomaterials by microwave assisted synthesis.Nanodiamond /graphene composites(DND/GNSs)were prepared by adding nanodiamond powders with different mass ratios in the carbon precursor.SEM and TEM show that the samples for multilayer sheet structure,the surface has a certain degree of fold,such as corrugated,The nanodiamond particles are densely adsorbed on the surface of the corrugated graphene sheet.(2)The research on the optimum doping amount of DND/GNSs under different nanodiamond doping and samples GNSs,DND/GNSs-40,DND/GNSs-80,DND/GNSs-160 were studied.The electrochemical test shows that when the DND/GNSs is used as the anode material of lithium ion battery,the discharge specific capacity is 1342 mAh g-1,the first charge discharge efficiency is about 61%.With the increase of lithium ion battery charge and discharge times,discharge a slight decrease in specific capacity after 50 cycles,the charge discharge capacity reached 650 mAh g-1,higher than the theoretical cycle capacity of graphite 372 mAh g-1.The sample capacity retention rate was 59.9%,and the charge discharge Coulomb efficiency was close to 100%.(3)The lithium storage mechanism of DND/GNSs was investigated.The DND/GNSs pure carbon composites have more unique advantages compared with metal oxides or other silicon based anode materials.Nanodiamond powder has high hardness,good thermal conductivity,large specific surface area and stable structure,which can avoid the problem of capacity attenuation caused by the sharp change of the volume of the negative electrode during charging and discharging.When the chemical inert nanodiamond particles are deposited on the surface of the graphene sheet,no side reaction occurs between the two components so as to avoid the deterioration of the electrode during the charging and discharging process.Nanodiamond is 200 ~ 420 M2 g-1,nanodiamond of high density lithium ion to provide more storage locations and reduce the transmission path of the lithium ion,so as to shorten the charging time of the lithium ion battery,to further improve the performance of the battery.In this paper,nanodiamond/graphene composites are used to obtain new electrode materials,and the synergistic effect is formed.The high-performance pure carbon and lithium ion battery anode material is prepared to solve the problem that the specific capacity of commercial graphite anode is low?the discharge platform of new graphene anode is high,and the low coulombic efficiency.The preparation method of nanodiamond and graphene composites in this paper has the advantages of simple process,low cost and no pollution.Which provides important research ideas and experimental data for the design and manufacture of new nanodiamond-related composites and devices to improve the performance of various energy storage and transmission equipment.