A recent research by Tejs Vegge, a senior scientist who works in the Materials Research Division at Risø DTU, (Risø National Laboratory for Sustainable Energy) states that Li-air batteries promise the much needed energy break-through for the electric cars.
The energy density of Li-air batteries is claimed to be more than that of petrol and diesel where the combustion engine utilizing fossil fuel offers only 30% energy efficiency. It is anticipated that if the research is successful and if the high density Li-air batteries become feasible, we will be seeing electric powered trucks on the road.
The latest and advanced electric car batteries of today use Lithium (Li) a silver-white colored soft and lightest metal in place of heavy lead (Pb). But Lithium is exceedingly reactive to humidity and corrodes rapidly when exposed to water and oxygen and is always stored under kerosene. The light weight and high energy density advantage of Lithium is already realized in the use of rechargeable Li-ion batteries in gadgets such as cameras, mobile phones and MP3 and MP4 music players. The market for lithium battery is anticipated to grow faster. Lithium a naturally occurring metal, which can be extracted both from the soil and the water, because of its limited availability the extraction becomes costlier. The advantage of lithium is that it can be recycled again from the old batteries for reuse.
The Li-air battery is observed needing a high level voltage of current to recharge the battery after the normal discharge. With an equilibrium voltage of 3 V the Li-air battery needed 4.5 V to get charged when compared to a Li-ion battery with an over voltage requirement of just 10%. The high voltage requirement for recharging the battery also made an impact on the components utilized thus limiting the number of recharges. The cyclic energy loss during the charging and recharging process of Li-air batteries is observed to be nearly 40% and the researchers are trying to lower the level to 10% as available in Li-ion batteries.
The prototypes of Li-air battery currently performs around 50 charges and the researchers are facing a challenge to make the batteries to recharge a minimum of 300 times to cover 800 km in one charge so that a battery can be utilized for running 250,000 km in its life time. The recharge time also poses a problem when compared to the refueling of petrol, which can be completed in minutes. The Li-air battery though possesses the same amount of energy as that of petrol it substantially takes more time for recharging.
Source: http://www.risoe.dk/