Preparation And Property Of Ti Nanowire Arrays And Porous Ti In Li-O₂ Batteries

Li-O2 batteries have a potentially high specific energy density in theory, but it can’t achieve the theoretical value in fact because of the cathode. However, preparing a nonadditive but highly active, conductive and stable cathode is challengeable. The stability of carbon materials is poor and the conductivity of metallic oxide is bad. Noble metal has good catalytic activity, but it’s too expensive. So finding a new kind of materials that meet the whole advantages is significant to Li-O2 batteries.Titanium(Ti) and its alloys are inexpensive metallic material with outstanding chemical stability. Ti nanowire arrays and porous Ti are prepared and tested in Li-O2 batteries.In this study, Ti nanowire arrays freestanding on Ti foams are prepared by a facile method of electroless wet corrosion. The etching is carried out in 1.25 wt % HF solution in different times. The etching time has an effect on morphology and when the etching time rising to 700 s, Ti nanowire arrays are got. Ti nanowire arrays have a large specific surface and a good performance in Li-O2 batteries. Good stability and conductivity of the cathodes endow the batteries remarkable durability, that cycling more than 650 rounds within a capacity limitation of 1000 m Ahg-1 at a current density of 5 Ag-1. Study of cathodes and electrolyte after cycling test demonstrates that, the stability of cathodes is significant to the durability. The specific capacity(5000 m Ahg-1 at a current density of 1 Ag-1) is higher than the pristine Ti foams.Porous Ti are prepared by using fusing Mg corrosion. Optimum preparation process of porous Ti is established. Porous Ti with micrometer pores generates at 650°C and is investigated as Li-O2 battery cathodes support. The size of pores is 2 micrometer, resulting in a capacity of 16000 m Ahg-1 at a current density of 1 Ag-1. The discharge overpotential is 2.5 V and the charge overpotential is 3.2 V at a current density of 2 Ag-1. It has a good recyclability that cycling more than 100 rounds within a capacity limitation of 1000 m Ahg-1 at a current density of 2 Ag-1. Porous Ti is an ideal support in Li-O2 batteries showing great potential in application.