How Rechargeable NiMH Batteries Evolve Gradually Through Times
The widespread use of Rechargeable NiMH Batteries owes its roots to the early years of development of rechargeable battery technology. The first rechargeable battery was the lead-acid battery invented in 1859 by a French physicist by name Gaston Planté. Widespread electrification in Europe led to the use of storage batteries for portable lighting systems, telegraphy, and back-up power. The most remarkable use of these batteries was for electric cars and probably here the rechargeable batteries found the largest market. But eventually, internal combustion engines prevailed for a host of advantages and so petrol-driven cars replaced electric cars.
Nickel cadmium cells made its appearance in 1900 and found acceptance where more power was needed. But, a drawback of both lead-acid and nickel-cadmium batteries was they produced a lot of gas when overcharged. A German engineer by name Neumann plugged this issue by making possible a sealed version. By 1960s sealed batteries were widely available. For most part of the last century lead-acid and Nickel-Cadmium batteries dominated the market. Even today small lead-acid battery packs provide the initial bursts of power in almost all cars, whereas nickel-cadmium batteries provide emergency backup power for aircraft and trains.
Technological evolution is an inevitable part of our life. It is not surprising therefore that better batteries sooner or later had to make their appearance. Nickel-metal hydride battery came into the market in 1989. These batteries had an advantage of storing twice as much energy as that of lead-acid batteries for identical weights.
Rechargeable NiMH Batteries have become all-encompassing in today's technological climate, powering everything from laptops and cellular phones to hybrid electric vehicles. The development of NiMH battery traces its origin to the nickel-hydrogen batteries used for aerospace applications. Nickel-hydrogen batteries were specifically suited to aerospace applications because of their exceptional life cycle and acceptable specific energy. But, the drawbacks were poor volumetric efficiency and the need for tanks of hydrogen gas and platinum catalysts. NiMH batteries overcame this problem by configuring a battery using metal hydride storage materials as one of the electrodes. The sustained work done in multi-component metal hydride alloys has been singularly responsible for the current generation of high performance and durable Rechargeable NiMH Batteries. These are in use today in nearly every application you can think of.
The NiMH battery is actually an alkaline storage battery because it uses potassium hydroxide as the electrolyte. Rechargeable alkaline batteries found wide application for the following key reasons.
* High electrolyte conductivity.
* The battery system can be sealed to plug leakage problems.
* Operable over wide temperature ranges.
* Longer life and durability compensating for higher initial costs.
* Higher energy density and lower cost per watt-hour.
One significant technological development in Rechargeable NiMH Batteries is in the field of battery packs used in hybrid electric vehicles. The battery packs are now considerably reduced in size, weight, and cost, without compromising in power, reliability, and life expectancy. This has enabled these batteries to be selected for mass production of hybrid electric vehicles (HEVs) of makes such as Honda Insight and Toyota Prius. Adapting the NiMH battery technology to cars was no mean feat because the way batteries work for hybrid cars is very different from the way they work in portable devices. Rechargeable NiMH Batteries in laptops and cell phones are designed to discharge over a period of several days. Batteries for hybrid cars, on the other hand, need to sustain for several years and must endure umpteen cycles of absorbing power, regenerative braking, and supplying short bursts of power. Hopefully, in the near future rechargeable NiMH Batteries or its successors will have wider and more extensive applications and will make us use gas engines less and less.