Studies On High-quality Few-layer Graphene Applied In Lithium-ion Battery

Graphene is a single atomic layer of carbon atoms with honeycomb like two-dimensional crystal structure.The unique two-dimensional crystal structure enable graphene possess excellent properties of electrical conductivity and thermal conductivity.The properties of high-quality few-layer graphene with non-functionnal groups and defects are similar to intrinsic graphene.It has important application prospects to promote the rate proformance,reduce internal resistance,and improve cycle properties by adding high-quality few-layer graphene as conductive additives into lithium-ion battery.In this dissertation,the influnce on the performance of lithium-ion battery is studied by adding high-quality few-layer graphene into cathode material and aluminum foil coating,respectively.The main results and conclusions are as follows:Firstly,1 wt% graphene and 5 wt % sp are added into the LiFePO4(LFP),respectively.The four-point measurement shows that the resistivity of graphene-LFP composites is lower than the sp-LFP composites,Which indicate the excellent electrical conductivity of graphene.following by assembling and electrochemistry testing the batteries.As a result,The battery with small quantities of graphene added exhibit outstanding rate performance,low internal resisitivity and stable cycle property.Secondly,High-quality few-layer graphene is employed as additive to prepare coating slurry of aluminum foil.The graphene-based coating aluminum foils are obtained by spreading the slurry mentioned above on aluminium foils.Compare with the lithium-ion battery with non-coating aluminum foils as current collectors,the battery using graphene-based coating aluminum foil as current collectors show higher rate capacity,lower internal resistance and higher cycle capacity retention ratio.Lastly,we have an outlook for the next research plan by this dissertation.