Ni-Cd Battery Technology, The sealed nickel-cadmium (or Ni-Cad) battery was introducedto meet the need for a compact rechargeable technology. It was successfully incorporated into a wide range of consumer products, such as power tools. Ni-Cad batteries are not suitable for applications requiring a large amount of energy storage. They are:
- Expensive and heavy
- Subject to capacity loss due to “memory effect” and prone to going dead in long term storage.
- Environmentally toxic – require special handling for disposal.
Nickel-metal-hydride (NiMH) battery This is a newer technology that was introduced in the 1970s. Although they perform batterthan Ni-Cad batteries, the chemistry has limitations:
- High Cost – limited deep discharge cycle life and shelf life
- Require tightly controlled voltage and current parameters during charging.
- Degrades if not used regularly.
- Unsuited for use in temperature extremes – permanent capacity loss.
Lithium-Ion Technology Lithium-ion (Li-ion) are commonly used in consumer devices such as lap top computers, cell phones, digital cameras, etc.; they are light weight and compact. Since their mass market commercial introduction a few years ago,problems have recently surfaced. Nearly six million lithium-ion batteries were recalled they overheated and were a potential fire hazard. Similar concerns caused Boeing to ground planes.Without adequate charge control and heat management, Li ion batteries are vulnerable to thermal runaway and pose significant safety issues. Should a Li ion cell container rupture and is exposed to moisture in the air, the ensuing chemical reaction will cause the materials within the battery to ignite. Such a chemical fire cannot be extinguished with water or conventional fire extinguishers. The electrolyte is also extremely toxic, which requires a special recycling/disposal facilities.Lithium is a rare earth material with limited supply subject to a high degree of price volatility.