Preparation Of New MnO₂-C Composite And Its Application In Alkaline Zinc Manganese Battery To Improve The Discharge Performance Of It

With the rapid development of electronic industry,a variety of small electronic products emerge in endlessly,which puts forward higher requirements for the performance of primary battery.Alkaline Zn Mn Battery has become an indispensable consumable in consumers’daily life because of its mature technology,stable performance,safety and reliability,convenient use,and no harmful heavy metal substances such as lead,mercury,cadmium,etc.Although the comprehensive cost performance of alkaline battery is high,the problems of low capacity,high electronic resistance of positive ring,serious polarization of high-power discharge,fast voltage drop in late discharge and low energy utilization rate make it difficult to meet the needs of various modern electrical appliances,so the performance improvement of alkaline Zn Mn Battery is imminent.Graphene has excellent electrical properties due to its special two-dimensional single atom layer structure.The electron mobility can reach 20000 cm²·v^-1·s^-1 at room temperature,and the theoretical specific surface area is up to 2600 m²·g^-1.It is because of these characteristics that it has a broad application prospect in the field of electrochemical energy storage.In order to improve the discharge performance of alkaline battery,starting from the modification of cathode materials,in order to reduce the electronic resistance of the positive ring of the battery,the graphene microchip prepared by liquid phase stripping method was introduced into the positive conductive agent,and a new mixing method was adopted to improve the dispersion of graphene in the positive mixed powder and promote the coating of graphene on the positive active material.The excellent electrical properties of graphene can be used to improve the conductivity of cathode materials.The specific research work of this paper is as follows:（1）Based on the liquid phase stripping method,the graphite was cut by N-methyl pyrrolidone（NMP）and water mixture.Firstly,the effect of different mass fraction of NMP on the shear efficiency and shear concentration was studied.The results show that the introduction of NMP in the shear process can improve the shear efficiency of graphite and the concentration of graphite micro flakes in the mixed solution.In the range of controllable cost,when the NMP content accounts for 20%of the mixed solvent,the graphite material with larger initial particle size can be cut to 33μm after 1-2 h shearing.The graphite micro sheet of about M.After a period of ultrasonic treatment,the particle size of graphite micro slice continued to decrease to 20μm.It is indicated that the mixed solvent can be inserted into the middle of graphite sheet layer.The concentration of graphite micro flakes in the prepared slurry can reach 3%.（2）The effects of the introduction of small particle size carbon black and homogenization pressure on the exfoliation efficiency,the conductivity of graphene and the stability of graphene slurry were studied by micro jet homogenization technology.The experimental results show that when the amount of carbon black with small particle size accounts for 0.5-1%of graphite,the particle size of graphite can be reduced to 7-10μm after5-6 times homogenization at 800 bar.The stripping efficiency and stripping effect were greatly improved.Through characterization,the prepared slurry with high solid content of graphene was well dispersed and stable,and there was no settlement within one month.The graphene powder prepared by spray drying has thin lamella,low impurity content,moisture content of 0.37%,loose density of 0.02 g·m L^-1,and powder conductivity of 800-900 S·cm^-1.（3）Graphene was used as a component of conductive agent and manganese dioxide was compounded to obtain composite cathode material,which was used in alkaline zinc manganese battery to test the discharge performance of the battery.The results show that when the amount of conductive agent is 6%of the mass of positive electrode and the amount of graphene is 10-30%of the amount of conductive agent,the positive resistance of LR6alkaline Zn Mn Battery can be significantly reduced,and the new electrical performance and discharge performance of the battery are improved,especially the high current discharge performance is increased by 5-10%.