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25 September 2014
Fulfilling the demand for batteries
We often hear some novices arguing that all the advanced battery systems come with higher energy densities; they are smaller in size and deliver thousands of charge/discharge cycles. Although some of the features mentioned here can be achieved, but they cannot be attained in a single batter with the present chemistry.
A battery can be designed to be small yet capable of storing high specific energy, but the cycle life is going to be short. On the other hand, another battery might be developed for better durability and load capacity and the cells are going to be heavier and bulky. A third model may offer longer service life and higher capacity but the production cost may make them so much expensive that they will not be an affordable option for average consumers. The manufacturers are well aware of the needs of general people and design their products accordingly. We can take the mobile phone market as an example of this smart adaptation. They have emphasized on low price, smaller size and higher energy density and durability is not the main focus point here.
Terms like lithium-ion (Li-ion) and nickel-metal-hydride (NiMH) does not necessarily refer to high specific energy. For instance, the NiMH for electric powertrain in vehicles comes with a specific energy of 45Wh/kg only, which is not that significant in comparison with lead acid. On the other hand, the consumer NiMH has approximately 90Wh/kg. The Li-ion battery for the electric and hybrid cars contain as low as 60Wh/kg which is almost equivalent to the nickel-cadmium. The Li-ion batteries designed for laptops and cell phones however come with two to three times this energy.
www.BatteryUniversity.com sponsored by Cadex asks lots of interesting questions. Some of them include, for portable solar stations, remote-controlled cars and electronic bicycles and cars, which battery is the most suitable one? It is important to keep in mind that you won’t find a battery that can fulfill every need and each application is unique. Despite being the best choice, not everyone can consider lithium-ion to be in their list due to their high price and necessity of an approved protection circuit. Without the Li-ion, we are left with the lead and nickel based options. It is the consumer electronic products that might have benefitted the most from the advancement of batteries. Higher volume reduced the price of Li-ion to some extent.
Now the question is, will the internal combustion engine of cars be replaced by battery? Surprisingly, we haven’t found a battery yet that is economic enough to allow long distance driving and have a lifetime equivalent to the vehicle although they are highly sought by people all over the world. Batteries work quite well with mobile units such as laptops, cameras and cell phones. The low price allows the batteries to be more affordable which is why the short lifetime of the batteries is acceptable by consumers. Although the fading capacity can be a concern but that does not raise any safety concerns.
As we analyze the characteristics of the battery systems and compare between the alternate sources of power, like the internal combustion engine and fuel cell, we come to the conclusion that battery is the best choice for stationary and portable units so far. For applications like ships, trains and aircrafts, the battery does not have the required capacity, reliability and endurance. Therefore I think the dividing line comes with the electric vehicles.
