Preparation And Corrosion Performance Of Conductive Polymers On The Surface Of Anode Copper Current Collectors Of High Capacity Lithium-Ion Batteries

Lithium-ion batteries,as one of the new energy storage devices,are recognized as an efficient secondary battery due to their high energy density,high power density,and long cycle life,and are widely used as power sources in portable electronic devices and electric vehicles.However,The copper current collectors of lithium-ion batteries will undergo a corrosion reaction under the electrolyte operating conditions,resulting in a decrease in battery lives and performances.In this paper,conductive polymer coatings(single polypyrrole coating,polypyrrole/polyaniline composite coating,polypyrrole/graphene oxide composite coating)were prepared on the surface of copper foils,then the electrochemical behavior of copper foils and the three polymer coatings were analyzed at room temperature by electrochemical impedance spectroscopy,polarization curve and other electrochemical methods,the main research results are as follows:(1)Cyclic voltammetry was used to prepare polypyrrole coating on copper foil surface with oxalic acid as dopant.The coating is dense and uniform.After corrosion for 500h in the electrolyte of the lithium ion battery,the open circuit potential(Eocp)of the coating is significantly higher than that of the copper substrate.The results of electrochemical impedance spectroscopy showed that after corrosion in electrolyte for 500h,the charge transfer resistance(Rt)of the coating was 4.518E3Ω.cm2,which was still about 7 times that of copper foil,indicating that the polymer coating can improve the corrosion resistance of the copper current collector effectively.(2)The graphene oxide is dispersed in the synthetic solution,and the polypyrrole/graphene oxide composite coating prepared on the copper foil surface by cyclic voltammetry.The composite coating had a stacked layer structure.Compared with a single polypyrrole coating,it can be found that the doping of graphene oxide caused the corrosion potential of the polypyrrole coating to increase by more than 250mV,while the corrosion current density was significantly reduced by an order of magnitude.Compared with single polypyrrole coating and polypyrrole/graphene oxide composite coating,the polypyrrole/polyaniline composite coating prepared by cyclic voltammetry had the highest density of the internal structure.The results of the electrochemical corrosion experiments show that the polypyrrole/polyaniline composite coating maintained the highest open circuit potential throughout the entire corrosion process,and the Rt value of polypyrrole/polyaniline composite coating was 2.734E4Ω.cm2 after corrosion for 144h,which was significantly higher than the other two coatings,indicating that the polypyrrole/polyaniline composite coating provided the best protection for the copper substrate.