Study On The Electrochemical Properties And Battery Performance Of Chitosan-modified PbO₂ Prepared By Electrodeposition As Positive Electrode Of Lead-acid Batter

Lead-acid batteries are widely used in power and energy storage fields due to their affordability,easy recycling and high safety performance,but their further development and application are affected by the easy shedding of the positive active mass of PbO₂,short cycle life and low battery capacity.The capacity and lifetime of lead-acid batteries are intricately linked to the composition and characteristics of PbO₂.Improving the performance of PbO₂ is one of the key aspects to improve the capacity and cycle life of lead-acid batteries.Additive modification can effectively improve the electrochemical activity and stability of PbO₂,thus improving the capacity and cycling performance of lead-acid batteries and expanding the use of lead-acid batteries in production and life.In this paper,the effects of additives chitosan（CS）and sodium fluoride（Na F）on the performance of PbO₂ prepared by electrodeposition were investigated.Four PbO₂electrode materials were prepared by electrodeposition in the lead methanesulfonate system.The electrodeposition preparation process conditions were optimized,and the best preparation conditions were obtained by physical and electrochemical characterization as follows:deposition temperature of 60°C,deposition current density of 20 m A·cm^-2,deposition time of 60 min,and the dosage of additive CS was 1.5 g·L^-1.The PbO₂ phase prepared under this optimal condition wasβ-PbO₂,with fine and dense grains,flat surface,high electrochemical activity and high oxygen precipitation potential.The performance tests of the prepared series of PbO₂electrodes were carried out to analyze the relationship between the structure and performance of the modified electrodes.X-ray diffraction（XRD）,fourier transform infrared spectrometer（FTIR）,scanning electron microscope（SEM）and energy dispersive X-ray spectrometers（EDS）results showed that the PbO₂ on the plating layer of the four cathode materials wasβ-PbO₂,Na F and CS were successfully coated to the corresponding PbO₂ plating layer,and the addition of both CS and Na F made the PbO₂-CS-F electrode with fine PbO₂grains and flat surface.The linear sweep voltammetry（LSV）,cyclic voltammetry（CV）,electrochemical impedance spectroscopy（EIS）and scanning electrochemical microscope（SECM）tests showed that the PbO₂-CS-F electrode had a higher oxygen precipitation potential of 2.237 V,a higher exchange current density(j⁰=3.788×10^-7A·cm^-2),a lower charge transfer resistance（5.359Ω·cm²）,the highest electrochemical reactivity and the best stability among the series of electrode materials.The test results of inductively coupled Plasma optical emission spectrometer（ICP-OES）show that among the series electrode materials,the electrolyte of PbO₂-CS-F electrode has the lowest content of Pb,Cr,Mn and Fe elements after assembling each electrode material into a cell and cycling 500 times,the electrolyte of this electrode has the best bonding ability between PbO₂ and the substrate,and the corrosion of the substrate and the shedding of the active material are the least likely to occur.A series of PbO₂ electrode materials were assembled as lead-acid battery cathodes,and the relationship between each PbO₂ cathode material and battery performance was analyzed.Cycle life,multiplier performance and battery capacity performance of each cell were tested on a battery tester.The battery test results showed that the cycle life of PbO₂-CS-F cathode material was 3405 cycles at a charge-discharge rate of 2C,which was about 6.8 times higher than that of pure PbO₂ cathode material at high-rate.The specific capacity of discharge is stable at 196 m Ah·g^-1 for 500 cycles at 0.1C charge-discharge rate.The batteries assembled with the four cathode materials were tested at0.1C,0.2C,0.5C and 1C,respectively,and the PbO₂-CS-F cathode material has the higher discharge capacity among the series cathode materials at different charge-discharge rate,with a discharge capacity of 4257 m Ah at 0.1C,3451 m Ah at 0.2C,2667m Ah at 0.5C Among the series of cathode materials,PbO₂-CS-F cathode material has strong discharge capacity and exceptional cycle stability.The addition of chitosan（CS）and sodium fluoride（Na F）can increase the binding and electrochemical activity of PbO₂,resulting in the PbO₂-CS-F cathode material exhibiting excellent electrochemical and battery performance.