Construction Of High Efficient Interface Materials For Zinc-Air Battery

Zn–air battery is one of the promising metal-air batteries due to their high theoretical energy density,abundant reserves,and pollution-free properties.These advantages make them can be used as high-performance energy systems for mobile devices and electronic devices.However,problems such as expensive catalysts,poor matching of membrane electrode performance,and inefficient charge/mass transfer severely restrict the commercialization of zinc-air batteries.Three parts of studies focused on the ionomer of air electrodes,and high-efficiency nuclear transfer gel electrolyte in alkaline zinc-air batteries was carried out in this thesis.(1)Based on Nafion's perfluorohydrophobic skeleton,the weakly basic N,N-dimethylethylenediamine was partially substituted onto the sulfonic acid groups to obtain the Nafion-DMA-x alkaline ionomers.The substitution ratio was optimized,and the Nafion-DMA-20 was screened to be the best-performed one.The efficient OH-transportation channels inside Nafion-DMA-20 makes it can deliver a max power density of 326 m W/cm² and the specific capacity of 777 m Ah/g_zn in a zinc-oxygen battery.(2)PVA-C₆H₁₂O₇-KOH gel electrolyte membranes were prepared using polyethanol as the matrix,D-Gluconic acid as the additive and potassium hydroxide as the electrolyte.D-Gluconic acid anions in the electrolyte membrane can efficiently modify the reaction behavior beteen Zn²⁺and OH-,which therefore regulates precipitation rate between Zn²⁺and OH^-around the air electrode.The optimized PVA-C₆H₁₂O₇-0.2M flexible zinc-oxygen batteries can be stably discharged with a maximum current density of 20 m A/cm²,and discharged 290 min at 10 m A/cm².(3)Based on work 2,a PVA-C₆H₁₂O₇-0-0.2M membrane with ABA layered-structure was designed and synthesized.Layers A has no additives,while layer B has 0.2 mol/L D-C₆H₁₂O₇.The layered-structure membrane has better ionic conductivity and water retention ability than the single-layer one.More importantly,the ABA structure can confine the zinc hydroxide to precipitate aloof from the air electrode,protect the zinc electrode from passivating.The PVA-C₆H₁₂O₇-0-0.2M flexible zinc-oxygen battery therefore can discharge at 1.15 V with a current density 45m A/cm²,and discharge for 590 min at 10 m A/cm².Therefore,we have successfully regulated the interface behavior inside the air electrode and at the electrode-membrane boundary.We believe there material designs can promote the development of high performance metal-air batteries.