Optimization of Air Electrode for Li/Air Batteries

Abstract

The effects of carbon microstructure and loading on the performance of Li/air batteries were investigated. We found that the capacities of Li/air batteries were related to both the specific capacity per unit weight of the carbon source (mAhnormalg−1) and the carbon locating per unit area (gcm−2) . Therefore, the product of these two parameters [i.e., the area-specific capacity (mAhcm−2) ] was introduced to optimize the performance of the air electrode. At the fixed electrolyte amount (100μL/cell) , the best area-specific capacity of 13.1mAhcm−2 was obtained at a carbon loading of 15.1mgcm−2 . Further increase or decrease in the carbon loading led to a reduced area-specific capacity. The capacities of air electrodes increased with increasing mesopore volumes of the carbon sources. The uniformity of the pore sizes also played an important role in determining the electrochemical performances of the Li/air batteries. At fixed carbon loading and discharge rates, the capacity increased significantly with increasing electrolyte amounts. This phenomenon was explained by the formation of extra triphase regions in the air electrodes. After optimizing the electrode and electrolyte parameters, a high capacity of 1756mAhnormalg−1 carbon was obtained for Li/air batteries operated in ambient oxygen pressure (0.21 atm).

Metal–Air Batteries with High Energy Density: Li–Air versus Zn–Air

“…[ 30,31 ] The specifi c capacity is proportional to the surface area, because the surface area of the carbon dictates the number of the electrochemical active sites available to form lithium oxides. This means that carbon with a higher surface area is benefi cial for obtaining higher specifi c capacity.…”

The Lithium/Air Battery: Still an Emerging System or a Practical Reality?

“…[ 14,15 ] Many researchers are now focusing on the development of advanced catalysts and cathode substrates to improve effi ciency and cycle life using mostly organic electrolytes. Materials used as cathode supports comprise porous carbon, [16][17][18][19] graphene, [ 20 ] carbon nanotubes (CNT) or carbon nanofi bers (CNF) [ 21,22 ] with catalysts such as metal oxides (MnO 2 , [23][24][25][26] Co 3 O 4 , [ 27,28 ] noble metals, [ 7,[29][30][31] and others. [ 32,33 ] At an industrial level, in 2009 IBM launched the "Battery 500" project, which had the ambitious aim of developing a Li/air battery that could ensure a 500 mile driving range, [ 34 ] and it was thought that soon enough this technology would make it to practical applications.…”

Charge-discharge Performance and Energy Density of MH/Air Secondary Battery using A₂B₇ Type Hydrogen Storage Alloys

“…While commercially available metal/air batteries are limited to be a primary zinc/air battery, many efforts have been done to realize secondary metal/air batteries, [1][2][3][4][5][6][7][8] in which the discharge products of the air battery using less noble metals such as lithium and magnesium induce the plugging of the positive electrode, resulting in a small discharge capacity, a difficulty of a high current operation, and a poor cycleability. We have also developed a different type of air battery from them, which comprises the negative electrode using hydrogen storage alloys in combination with an alkaline aqueous electrolyte.…”