Study On The Performance Of Zn-PANI Secondary Battery In Water System Electrolyte

Energy is one of the indispensable important parts in human's life and our work.With the development of society and the increasing of human demand for energy,the environmental problems caused by energy consumption are becoming more and more serious.For the sustainable development of society and economy,as well as human health,a clean,environmentally friendly,pollution-free,low-cost and high specific capacity green energy has drawn great attention of the government and researchers.Due to the advantages of the low-cost,green,safety and non-pollution,the zinc-polyaniline secondary battery possesses the potential for a new green energy storage device.However,bacause of the formation of zinc dendrite caused the short circuiting of the battery during the charge and discharge process of the zinc-polyaniline secondary battery,in addition,polyaniline degradation,zinc electrode corrosion,electrolyte pH and collector and diaphragm make the battery cycle life reduce,those problems hinder the industrial production of the zinc-polyaniline secondary battery.In this paper,aiming at the above problems,the following work has been carried out.In this paper,the electrochemical properties of the zinc electrode were studied in different acidic aqueous electrolytes containing varieties and different concentrations additives(monocarboxylates,dicarboxylates,tricarboxylates and mixed carboxylates)by the methods of cyclic voltammetry(CV),electrochemical impedance spectra(EIS),Tafel curves and scanning electron microscope(SEM).Then,to choose better electrolyte composition,the performances of the zinc electrode were compared in different aqueous electrolytes.The experimental results showed that the electrochemical properties of the zinc electrode could be improved in the chloride(Cl-)aqueous electrolyte containing a monocarboxylate(SP)and a dicarboxylate(SM),and the zinc electrode corrosion phenomenon was not easy to occur in this system.Then,a better electrolyte system was chosen by changing the pH and the composition concentration of the electrolyte.The experimental results showed that electrochemical performance,stability and reversibility of the zinc electrode were the best when the concentration of ZnCl2 was 0.20 mol dm-3,the concentration of NH4Cl was 0.50 mol dm-3,the concentration of SM was 0.10 mol dm-3,the concentration of SM was 0.20 mol dm-3,the concentration of Na2A was 0.25 mol dm-3 and the concentration of Na3B was 0.05 mol dm-3.Meanwhile,various analysis methods including Fourier transform infrared(FT-IR)spectrometer,UV-visible(UV)spectrometer,X-ray diffraction(XRD)and scanning electron microscopy(SEM)were used to compare the structure of polyaniline(PANI)obtained by two synthetic methods.It was found that different synthesis methods had no significant effect on the structure of polyaniline.Based on the study of the properties of the zinc electrode,in the chloride(Cl-)aqueous electrolyte containing varieties and different concentrations additives,the methods of cyclic voltammetry(CV),electrochemical impedance spectra(EIS),and charge-discharge were used to choose the optimum composition ratio and the optimum pH of the aqueous electrolyte by studying the electrochemical properties of the polyaniline in the aqueous electrolyte of different pHs.The results showed that polyaniline electrode displayed the best electrochemical activity when the electrolyte pH was about 4.0 and the concentration of ZnCl2,NH4Cl,SP,SM,Na2A and Na3B was 0.20,0.50,0.10,0.20,0.25 and 0.05 mol dm-3,respectively.This is consistent with the requirements of the zinc electrode for electrolyte composition ratio.The chemical and electrochemical stability properties of four blank current collectors materials:conductive cellophane,stainless steel mesh,soft graphite and carbon cloth in the electrolyte(0.50 mol dm-3 NH4Cl + 0.20 mol dm-3 ZnCl2 + 0,05 mol dm-3 Na3B + 0.20 mol dm-3 SM + 0.10 mol dm-3 SP + 0.25 mol dm-3 Na2A)were compared by CV,EIS and potentiodynamic polarization.Zinc-polyaniline secondary battery was assembled with the PANI film synthesized by chemical or electrochemical methods as the cathode,the zinc electrode polished as the anode,(0.50 mol dm-3 NH4Cl+0.20 mol dm-3 ZnCl2 0.05 mol dm-3 Na3B + 0.20 mol dm-3 SM + 0.10 mol dm-3 SP + 0.25 mol dm-3 Na2A)system as electrolyte.The performance effects of different charge upper limit voltage,discharge lower limit voltage,current density and diaphragm on the charge-discharge performance of zinc-polyaniline secondary battery were studied emphatically.The results displayed the optimum charge and discharge conditions:the electrolyte pH was about 4.0,the upper limit voltage of the charge was 1.5 V,the lower limit voltage of the discharge was 0.7 V,the current density was 40 mA g-1 and the absorbent paper was used as the separator,the zinc-polyaniline discharge capacity was up to 129.5 mAh g-1.The specific capacity of the battery could still be maintained at 94.3 mAh g-1,the coulombic efficiency of the battery was above 90%after 1000 charge-discharge cycles,and the zinc dendrite did not appear on the surface of the zinc electrode.