The electrochemical performance and electrode reactions using ordered mesoporous β-MnO 2 modified with Pd as a cathode catalyst for rechargeable Li-air batteries was reported. Well-ordered mesoporous β-MnO 2 was prepared using mesoporous silica KIT-6 as a template under hydrothermal synthesis of Mn(NO 3 ) 2 · H 2 O. The obtained mesoporous β-MnO 2 shows narrow pore size distribution of 1 nm. With the dispersion of small amounts of Pd to β-MnO 2 , mesoporous β-MnO 2 exhibited a high initial discharge capacity of 817 mAh/g -cat. with high reversible capacity. Charging potential is suppressed at 3.6 V vs. Li/Li + , which is highly effective for preventing the decomposition of organic electrolyte. The mesoporous β-MnO 2 /Pd electrode shows good rate capability and cycle stability. Ex-situ and in-situ XRD results suggested that the observed capacity comes primarily from the oxidation of Li + to Li 2 O 2 followed by Li 2 O after discharge to 2.0 V vs. Li/Li + . Electron spin resonance measurements suggest that the formation of superoxide anion radicals contributs to the oxidation of Li + and the radicals were recovered during charge. Ex-situ FTIR measurement suggested that no electrolyte decomposition was observed and no Li 2 CO 3 was formed during discharge when ethylene carbonate (EC)-diethyl carbonate (DEC) (3:7), which is highly stable for Li-air battery, was used as the electrolyte.The coming new energy economy must be based on a cheap and sustainable energy supply. Combined with sustainable resources such as wind and solar power, chemical energy storage using batteries can contribute to a potential solution. Currently, battery research and development is focused on energy storage and conversion with highenergy high-power density and reliable safety. 1-4 Metal-air batteries have attracted considerable attention because of their extremely large specific capacity. The reason for such a large specific capacity is that these cells consist of lithium metal as an anode and an air electrode for activation of oxygen in air; hence these metal-air batteries have a simple structure. Among the various metal-air battery systems, the lithium-air battery is the most attractive because it has the highest energy density per unit weight. The cell discharge reaction occurs between Li and oxygen to yield Li 2 O or Li 2 O 2 , with a theoretical discharge voltage of ca. 3.0 V and a theoretical specific energy density up to 5200 Wh/kg -Li . In practice, the storage of oxygen in the battery is unnecessary, because air can be directly used. Therefore, the theoretical specific energy (excluding oxygen) is 11.140 kWh/kg -Li , which is much higher than that of other advanced batteries and methanol direct fuel cells. Abraham and Jiang reported an Li-air battery using a nonaqueous electrolyte. 5 They suggested that lithium peroxide is a discharge product based on 2(Li + + e − ) + O 2 → Li 2 O 2 , which resulted in a theoretical voltage of 2.96 V. However, because of low oxygen solubility in a nonaqueous electrolyte, the reported power density ...

No abstract

No abstract

Mesoporous cobalt oxide (Co 3 O 4 ) was studied for air electrode of Li-air rechargeable battery. In this study, mesoporous Co 3 O 4 with an average pore radius of 3.09 nm and BET surface area of 99 m 2 /g was successfully prepared by using mesoporous SiO 2 for template. Prepared mesoporous Co 3 O 4 was applied for air electrode of Li-air battery after mixing with Pd and it was found that the cell showed a reasonably large discharge capacity of 481 mAh/g -cat. at 0.1 mA/cm 2 at the initial cycle. Energy efficiency for charge and discharge was estimated to be ca. 75%. Raman spectroscopy suggests that the main product during discharge was Li 2 O 2 and formation of Li 2 CO 3 was hardly observed.

not Available.