There are factors that represent as a challenge to have high performance Li-Air Battery as shown above. The following will discuss the primary limiting factors of lithium-oxygen battery.
Overpotential problem occur on lithium-oxygen batteries because the charging and discharging potentials deviate from standard potential. The overpotentials are the extra energy required to drive the reactions at a specific current density. Then, capacity of the battery is dependent on the clogging of reduction products in the porous cathode. In order to dissociate the lithium peroxide on charging, large potential difference is needed. Therefore, the use of catalyst plays an important role in reducing the overpotential problem observed in li-oxygen battery problem.
Second, catalysts can reduce the asymmetry problem between charge/discharge overpotentials in order to improve the round-trip efficiency of the lithium-oxygen battery. Catalyst can also help to dissociate the reduction product back to lithium metal and oxygen. Not only assisting the discharge reaction, but also increasing the capacity of the battery. Adding catalysts degrades the electrolyte solution which decreases the charge/discharge performance and also decreases the life of lithium – air batteries.
Diffusion and solubility
Diffusion and solubility is the most important mechanism in reaction kinetics of the battery. First, porous cathode must have good oxygen path for oxygen to pass through to electrolyte. At the same time, diffusion of the lithium ions from anodic side is important.
Solubility also plays important role in the kinetics reaction of the battery. Oxygen becomes less mobile while dissolve into the electrolyte compared to oxygen in gas phase. This effects the reaction kinetics and overall performance of the battery.
Therefore, designing the structure of battery that maximize the diffusion and solubility of oxygen through porous electrode at the cathode and also diffusion of lithium...