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The lithium-air battery, Li-air for short, is a metal-air battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow. It is an all-solid-state battery. Originally proposed in the 1970s as a possible power source for battery electric vehicles, Li-air batteries recaptured scientific interest in the late 2000s due to advances in materials technology and an increasing demand for renewable energy sources. The major appeal of the Li-air battery is the extremely high specific energy, a measure of the amount of energy a battery can store for a given weight. A lithium-air battery has an energy density (per kilogram) comparable to gasoline. Li-air batteries gain this advantage in specific energy since they use oxygen from the air instead of storing an oxidizer internally. The technology requires significant advances in multiple fields before a viable commercial implementation can be developed. Four approaches are active: aprotic,〔〔 aqueous,〔 solid state,〔 and mixed aqueous/aprotic.〔 Metal-air batteries, specifically zinc-air, have received attention due to the potential for high energy densities. The theoretical specific energy densities for metal-air batteries are higher than for ion-based approaches, due to the use of atmospheric oxygen as the cathode, eliminating a traditional cathode structure. Recently, lithium-air batteries have been proposed as the next step in lithium battery architecture, due to the high energy density of lithium with respect to air (3840 mA·h/g).〔 A major driver in lithium-air battery development is the automotive sector. The energy density of gasoline is approximately 13 kW·h/kg, which corresponds to 1.7 kW·h/kg of energy provided to the wheels after losses. The theoretical energy density of the lithium-air battery is 12 kW·h/kg (43.2 MJ/kg) excluding the oxygen mass. It has been theorized that the same 1.7 kW·h/kg could reach the wheels using Li-air after losses from over-potentials, other cell components and battery pack auxiliaries, given the much higher efficiency of electric motors.〔 Lithium-air batteries have the potential of 5–15 times the specific energy of current lithium-ion batteries.〔 == History == Lithium batteries have received attention since the 1970s. The first commercial lithium cells emerged during the 1990s. Lithium batteries offer high performance due to their intrinsic high specific energy densities.〔 In the mid-1990s, Kuzhikalail M. Abraham and co-workers demonstrated the first non-aqueous Li–air battery with the use of a Li negative electrode (anode), a porous carbon positive electrode (cathode), and a gel polymer electrolyte membrane that served as both the separator and ion-transporting medium.〔〔 Oxygen from the atmosphere enters the pores of the carbon cathode to serve as the cathode active material. Under discharge this oxygen was reduced and the products stored in the pores of the carbon electrode. The Li ion conducting gel polymer electrolytes were based on polyacrylonitrile (PAN)〔 and polyvinylidene fluoride (PVdF).〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lithium–air battery」の詳細全文を読む スポンサード リンク
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