| Lithium-air（Li-air） battery as a new type of battery system has triggered worldwide interest due to its extremely high theory energy density. However, the development of Li-air battery is in its infancy stage and many key scientific and technical problems need to be solved. This includes low energy conversion efficiency, unstable cathode structure, the corrosion and pulverization of the lithium anode and low energy density for practical application, etc. What all these described above are inseparable in the design and synthesis of electrode for Li-air battery. Based on these problems, some works on synthesizing catalysts, cathode design, anode modification /protection and the battery design have been carried out in this paper:Co3O4 with urchin-like was successfully synthesized via a novel hydrothermal and calcination method. When employed as cathode catalysts for Li-air battery, superior electrochemical performance-including round-trip efficiency, specific capacity, and cycling stability-were obtained. The discharge product-Li2O2 was also investigated via SEM and XRD techniques, and found the addition of catalysts can reduce Li2O2 size and crystallinity, the small size could promote the electron transport and the low crystallinity of Li2O2 is also in favour of electrons and ions transportation, which could effectively reduce the charging overpotential. Besides, the addition of Co3O4 catalyst could tailor the cathode structure and facilitate the mass transfer and finally improve the cycling stability.Free-standing Co3O4 NSs/CP cathode was successfully synthesized via a facile and efficient electrodeposition method. Due to series of properties including excellent catalytic properties, suitable channel structure and stable cathode architecture. When directly employed as air cathode, the Li-air battery shows excellent electrochemical performance includes high special capacity, good rate performance and superior cycling performance. The cell with Co3O4 NSs/CP cathode exhibits a higher discharge capacity of 2159 m Ah g-1 with the cut-off voltage restricted to 2.4 V under a current density of 100 m A g-1. Even the current density was rised to 500 m A g-1, the cell with Co3O4 NSs/CP cathode can still reach 542 m Ah g-1. For the cycling performance, the cell with Co3O4 NSs/CP cathode could stability cycle 49 laps with capacity limited to 500 m Ah g-1 under the current density of 100 m A g-1.A protective film which contains Li F was obtained on very reactive Li metal by a facile while very effective electrochemical strategy. This film could effectively suppress the corrosion and pulverization of the lithium anode and play a positive protective effect. When used as anode in Li-air battery superior cycle stability-more than 100 stable cycles was obtained with a fixed capacity of 1000 m A h g-1 at a current density of 300 m A g-1 is obtained. Besides, we also investigated the evolution of morphology and composition, and found the lithium anode with pretreatment could effectively remit the problems of corrosion and pulverization.Flexible Ti O2 NAs/CT cathode was successfully fabricated via a seeds-assisted method. When it directly used as air cathode in Li-air battery superior electrochemical performance including overpotential, specific capacity, rate performance and cycling stability were obtained. The Li-air battery with Ti O2 NAs/CT cathode exhibits superior cycle stability, as high as 256 stable cycles was obtained with a fixed capacity of 500 m A h g-1 at a current density of 100 m A g-1 is obtained. Based on the flexible properties of Ti O2 NAs/CT cathode, flexible Li-air was successfully assembled and excellent electrochemical performance was also obtained. Besides, the futile cathode was could be recovered after rinsed with dilute acid, which can greatly improve the utilization of air cathode. |
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