Laptop batteries have evolved over a period of time to reach the present technology and performance levels. The chemical structure of batteries varies from each other. Each type of battery has features unique to it. Lets learn more.
Today laptop batteries can be broadly classified into three categories depending upon the chemical process involved in power generation. They are Nickel Cadmium(NiCd) batteries, Nickel Metal Hydride(NiMH) batteries and Lithium Ion(Li-ion) batteries.
…but before getting into details of different types of batteries for laptop computer you must understand the following terms
Now moving towards features of various laptop batteries…
NiCd batteries were the first rechargeable batteries for notebook computers. They powered most of the older laptop models. The chemical structure of NICd batteries is represented below
These are low cost and versatile batteries with high output current capability. Best cycle count is achieved with this type of battery. With proper maintenance NiCD delivers over 1000 charge cycles. These Offer about 30% less capacity compared to the NiMH. NiCd batteries are capable of handling higher loads.
On the down side these batteries are affected by the dreaded memory effect which leads to loss in capacity ( caused due to the crystalline formation by the nickel plate). NiCd laptop batteries are high maintenance batteries that require regular discharge cycles to prevent memory effect.
NiCd batteries consist of heavy metals like Cadmium(Cd) which have adverse effects on the environment. The drive to create environment friendly batteries led to powerful products like NiMH and LiON batteries taking over from NiCd batteries.
NiMH batteries were a significant improvement over NiCd batteries due to lower cost, safety, reliability and capacity. This was a step ahead towards creating green(environment friendly) batteries.
The chemical structure of NICd batteries is represented below
NiMH batteries are a good value for price but then they fall short in the expected life cycle. They provide 20% to 30% greater capacity than NiCd batteries.
The performance is excellent when new but trails off quickly after few hundred cycles. This happens because of decreased capacity and rising internal resistance within the cell. NiMH is affected by the memory effect to a certain extent. Thus these high maintenance batteries require regular discharge cycles to prevent memory effect. It must be fully discharged prior to recharging for maximum charge effectiveness.
LiON are the most popular laptop batteries now days. They overcome the memory effect of the NiMH batteries. LiON batteries are somewhat lighter in weight than NiMH batteries. However the prices of the LiON batteries are a bit on the higher side because of the high manufacturing expenses.
The structure of Li-ion batteries is different. They make use of material like graphite along with lithiated transition metal. One example of such Lithium-transition metal combo is Lithium Cobalt Oxide. The electrolyte used is lithium salt dissolved in a mixture of organic carbonates. It basically consists of a spiral wound roll consisting of the two electrodes. The electrodes are separated by a microporous film which contains the electrolyte solution. The whole of this arrangement is sealed in a metallic case.
LiON batteries can be used for more cycles as compared to NiMH. These are low maintenance batteries that offer high energy. These do not require periodic full discharge. No trickle charge is applied once the battery reaches full charge. The charging process of a Li-ion is, in many ways, simpler and cleaner than that of nickel-based systems.
On the downside these batteries gradually loose charge acceptance as a part of aging, even if not used. Lithium Ion batteries power most of the modern laptop models.
Batteries for laptop computers have been undergoing a lot of technological changes of late. Li-Polymer is such a technology which could power tomorrow’s laptop batteries. Fuel Cell technology is another revolutionary concept which is being explored.