Study On Modification Of Electrolyte And Carbon Felt Current Collector Of Aqueous Lead-manganese Battery

Lead-acid battery has a wide range of applications in large-scale energy storage systems due to their high safety,mature process,low cost,and mature recycling technology,so no battery has been able to completely replace it so far.A new chemical battery based on the redox process of Mn O₂/Mn²⁺and Pb SO₄/Pb,the lead-manganese battery,has been presented as a solution to the issues of plate grid corrosion and irreversible softening of the positive active material during the cycle of lead-acid batteries.Lead-manganese batteries,which use lead sulfate as the negative active material and manganese sulfate as the positive active material,have long cycle life and high energy density,strong multiplier performance,high power density,and good economic efficiency,and are promising to become a battery technology for large-scale energy storage applications.However,lead-manganese batteries also have some disadvantages.The positive reaction mechanism of lead-manganese battery is the dissolution-precipitation reaction of Mn O₂/Mn²⁺,which leads to problems such as Mn O₂flaking in the collector,and poor conductivity of the deposited Mn O₂weakening the kinetic drive and impairing its multiplication performance and discharge capacity.These problems can be alleviated by adding additives to the electrolyte and make the battery have better performance.For example,adding sodium sulfate to the electrolyte as a supporting electrolyte can make the deposited manganese dioxide have a larger specific surface area and smaller particle size.Moreover,adding the surfactant cetyl trimethyl ammonium bromide to the electrolyte can increase manganese dioxide porosity and reduce capacity attenuation.The selection and modification of the current collector is also a key research direction for further improving the performance of lead-manganese batteries.Carbon felt electrode is used as the positive collector in lead-manganese batteries because it has a high specific surface area,low resistance,high stability,acid and alkali corrosion resistance,and a low price.Nevertheless,carbon felt is hydrophobic,which makes electrolyte utilization inefficient.Therefore,it is usually modified and then applied to lead-manganese batteries.In this study,the major work is divided into two sections:lead-manganese battery electrolyte additions and carbon felt current collector modification.The main research contents are as follows:（1）After adding supporting electrolyte to the electrolyte,the rate performance and discharge capacity of lead-manganese battery are improved.The supporting electrolyte can increase the conductivity of the electrolyte and reduce the ohmic impedance.At the same time,the supporting electrolyte cations can be adsorbed on the carbon felt,thus affecting the adsorption of Mn²⁺and deposition of Mn O₂.The porosity of manganese dioxide deposited during the charging process is increased to enhance its electrochemical activity,after adding ammonium sulfate,the discharge capacity of the battery increased by 22.34%;（2）After adding surfactant to the electrolyte,the rate performance and discharge capacity of lead-manganese battery are improved.The hydrophilic groups of surfactants have a strong coulomb effect on the electrode surface,and they can form micelles between the solid-liquid interface,which can be used as a template in the deposition process of manganese dioxide,and can effectively regulate its crystal size and microstructure,after adding tetrabutyl ammonium iodide（TBAI）,the discharge capacity of the battery increased by 19.09%;（3）After sulfuric acid oxidation modification,the surface of carbon felt produced oxygen-containing functional groups,increased hydrophilicity and REDOX reaction active sites.When applied to lead-manganese batteries,it can increase the utilization rate of electrolyte,provide more REDOX active sites for the positive electrode of lead-manganese batteries,and further improve the rate performance and capacity of lead-manganese batteries.