Evolution Mechanism And New Flocculant Of Alkaline Electrolytes For Aluminum Air Batteries

Aluminum air battery is a high specific energy battery system that uses oxygen in the air as positive electrode active material,aluminum alloy as negative electrode,and salt or alkaline solution as an electrolyte.The energy density of aluminum-air batteries is much higher than that of lithium-ion batteries.It has rich raw material sources,safety and environmental protection,and is one of the most promising metal-air batteries at present.However,there are still many problems with the aluminum air battery as a chemical power source.To achieve marketization and industrialization,it is also necessary to understand the main factors of the decline in battery performance and solve the problem of product separation in the later stage of battery discharge.This article mainly studies the electrolyte composition changes of aluminum-air batteries during the discharge process are studied,and the main substances that lead to the decrease in electrical conductivity are explored to provide a method basis for achieving online separation of aluminum-air battery products and improving battery performance.In addition,the electrolyte additive of aluminum-air battery to reduce the deposition of Al(OH)3 colloid in the battery pack and enhance the life of the electrolyteIn this paper,using acid-base titration,infrared(FT-IR),scanning electron microscope(SEM),nuclear magnetic(NMR)and other characterization methods,the concentration of lye,ion morphology,and precipitated product particle size of the electrolyte during the discharge of the aluminum air battery were studied.Changes in several areas.The results show that:during the discharge of the electrolyte,the NaOH concentration in the electrolyte gradually decreases.The concentration of aluminate ions in the discharge product of the electrolyte increases and the variety increases Among them,the content of Al(OH)4-is always the main component of the discharge product.On this basis,as the battery discharge process occurs,the electrolyte will Produces small amounts of other polyaluminate ions.The particle size of the solute in the electrolyte increases,and as the battery discharges,the morphology of the solute in the electrolyte changes from spherical to plate-like.The electrolyte is prone to carbonation in standbyAlCl3 solution is used as a flocculant to accumulate a large amount of Al(OH)3 colloid produced during the discharge of aluminum-air batteries.The effects of the flocculant on battery performance and cathode and anode were tested through electrochemical experiments and a three-electrode system,and the way in which the flocculant was added and the precipitation morphology at the end of the battery discharge were studied.The results show that the use of 2 mol/L AlCl3 solution as the flocculant can accelerate the sedimentation rate of Al(OH)3 colloid in the electrolyte of the aluminum-air battery by directly dropping the electrolyte into the battery during operation.The precipitate flows out of the battery pack through the circulation process,which reduces the viscosity of the electrolyte and improves the performance of the electrolyte.Electrochemical performance tests show that:the flocculant AlCl3 solution is mainly through the double hydrolysis of Al3+ and the discharge intermediate product Al(OH)4-,The precipitate that produces a small amount of fine particles can be used as seed crystals to accelerate the deposition of Al(OH)3 colloid suspended in the electrolyte The battery discharge results show that after adding the flocculant after 5 hours of battery operation,the discharge performance of the battery is obviously improved Three-electrode system and crystal type analysis show that the addition of flocculant AlCl3 solution will not affect the anode and cathode of the aluminum-air battery,and the crystal structure of the final discharge product has not changed.