Electrochemical Performance Of Flexible Lithium-ion Battery And Electromagnetic Interference Based On Sputtering Carbon Nanotubes Macro-film

Carbon nanotubes(CNTs)have broad applications for their excellent electrical conductivity,However,CNTs prepared by common methods will contain some impurities,which will reduce their conductivity.The CNTs macro-film(CMF)based on CNTs bundles will also be affected by the impurities,and limited their applications in practical production.Therefore,increasing the electrical conductivity of the CMFs is an important step to realize their industrial applications.(1)In this study,a CMF/metal composite film with strong interface is prepared by magnetron sputtering method.The composite film inherits the surface morphology of the CMF substrate to a certain extent.In addition,it indicates light weight and flexibility.Furthermore,it also displayed a high electrical conductivity,which suggests its potential applications.(2)The prepared CMF@Al and CMF@Cu composite films were used as current collectors for cathod and anode,respectively.And the electrochemical performances of flexible lithium ion batteries(LIBs)based on the current collectors have been studied.Due to the electrical conductivity improvement of the current collector,the electrons transmission efficiency can be increased.The Li Co O₂/Graghite full cells based on CMF/metal composite shows higher rate and cycle performances than that prepared by traditional metal and original CMF current collectors.The specific capacity of the battery is 97.4 m Ah g^-1at 5 C after 200 cycles,which is much higher than that of traditional batteries(64 m Ah g^-1)and the CMF based batteries(54 m Ah g^-1).In addition,the electrochemical impedance spectroscopy(EIS)result indicates that internal impedance of the batteries was significantly reduced.And thereby output current of the batteries can be obtained.Moreover,the strong interface between CMF and metal can be achieved.Therefore the electrochemical peformance of the battery cannot be affected even after repeated folding operations.(3)The sheet resistance of the CMF@Cu composite film was tested by a four-probe tester,and it is found that the sheet resistance was reduced from 4.2?cm^-2to 0.17?cm^-2,and the corresponding electrical conductivity was increased from 390S cm^-1to 5.9*10³S cm^-1.According to the electromagnetic shielding theory,the increased electrical conductivity will demonstrate high electromagnetic shielding effectiveness(EMI SE).It can be observed that the SE of the CMF@Cu composite film tested by a vector network analyzer(VNA)could be improved from 35 d B to 101d B in frequency range from 2.6 GHz to 18 GHz.The results may be contributed by the synergistic effect of the three-dimensional structure of CMF and their high electrical conductivity for metallic coating.