Rechargeable battery
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Rechargeable batteries (also known as Secondary cells) are batteries that can be restored to full charge by the application of electrical energy. They come in many different designs using different chemistry. They are also called storage battery, secondary cell or accu/akku (short for accumulator). Attempting to recharge non-rechargeable batteries may lead to a battery explosion. Some types of rechargeable batteries are susceptible to damage due to reverse charging if they are fully discharged; other types need to be fully discharged occasionally in order to maintain the capacity for deep discharge. There exist fully integrated battery chargers that optimize the charging current.
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[edit] A comparison of rechargeable batteries
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- Nickel-iron battery: This is a very robust battery which is tolerant of abuse, (overcharge, overdischarge, short-circuiting and thermal shock) and can have very long life even if so treated. It is often used in backup situations where it can be continuously charged and can last for 20 years. Its limitations, namely, low specific energy, poor charge retention, and poor low-temperature performance, and its high cost of manufacture compared with the lead-acid battery led to a decline in usage along with it having the lowest energy-to-weight ratio. Its chemical composition is nickel(III) oxide-hydroxide for the cathode, iron for the anode, and potassium hydroxide for the electrolyte. This battery chemistry has been produced since 1903.
- Lead-acid battery:
- Wet lead acid battery: The major advantage of this chemistry is its low cost[1] - a large battery (e.g. 70 Ah) is relatively cheap when compared to other chemistries. However, this battery chemistry has lower energy density than other battery chemistries available today. Its applications include vehicles, alarm systems, and uninterruptible power supplies. This battery chemistry was invented in 1859.
- Gel battery: A type of VRLA battery that uses gelified electrolyte. Unlike a traditional wet-cell lead-acid battery, the cells of a gel battery are valve-regulated. Its applications include automobiles, motorcycle, boats, aircraft, and other motorized vehicles.
- Absorbed glass mat: A type of VRLA battery. The plates in an AGM battery may be flat like wetcell lead-acid batteries, or they may be wound in tight spirals. In cylindrical AGM's, the plates are thin and wound, like most consumer disposable and rechargeable cells, into spirals so they are also sometimes referred to as spiral wound. Its chemical composition are electrolytes absorbed into a fiberglass mat.
- Nickel cadmium battery: This chemistry gives the longest cycle life (over 1500 cycles), but has low energy density compared to some of the other chemistries. Batteries using older technology suffer from memory effect, but this has been reduced drastically in modern batteries. Cadmium is toxic to most life forms, so poses environmental concerns. Its chemical composition is nickel for the cathode and cadmium for the anode. It is used in many domestic applications, but is being superseded by Li-ion and Ni-MH types. It has been mass produced since 1946.
- Nickel metal hydride battery: Similar to a nickel-cadmium (NiCd) battery but has a hydride absorbing alloy for the anode instead of cadmium; therefore, it is less detrimental to the environment. A NiMH battery can have two to three times the capacity of an equivalent size NiCd and the memory effect is not as significant. However, compared to the lithium ion chemistry, the volumetric energy density is lower and self-discharge is higher. Its chemical compostition is nickel for the cathode and a hydride absorbing alloy for the anode. Applications include hybrid vehicles such as the Toyota Prius and consumer electronics. It was made available in 1983.
- Lithium ion battery: A relatively modern battery chemistry that offers a very high charge density (i.e. a light battery will store a lot of energy) and which does not suffer from any memory effect whatsoever. Its chemical composition is LiCoO2, LiMn2O4, LiNiO2 or Li-Ph for the cathode and carbon for the anode. Applications include laptops, modern camera phones, some rechargeable MP3 players, and most other portable rechargeable digital equipment. It was released c1990.
- Lithium ion polymer battery: Similar characteristics to lithium-ion, but with slightly less charge density and a greater life cycle degradation rate. An advantage over regular lithium-ion is ultra-slim design (as little as 1mm thin). Applications include ultra-slim cells for PDAs. Released in 1996.
- Sodium-sulfur battery: Exhibits a high energy density, high efficiency of charge/discharge (89—92%), long cycle life, and is made from inexpensive, non-toxic materials. However, the operating temperature of 300 to 350 °C and the highly corrosive nature of sodium make it suitable only for large-scale non-mobile applications. A suggested application is grid energy storage in the electric grid.
- Nickel-zinc battery: A type of rechargeable battery commonly used in the light electric vehicle sector. The battery is still not commonly found in the mass market, but they are considered as the next generation batteries used for high drain applications, and is expected to replace lead-acid batteries because of their higher energy to mass ratio and higher power to mass ratio (up to 75% lighter for the same power), and are relatively cheap compared to nickel-cadmium batteries (expected to be priced somewhere in between NiCd and lead-acids, but have twice the energy storing capacity).
- Molten salt battery: High temperature electric battery that offers both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means of a high conductivity molten salt electrolyte. They are used in services where high energy density and high power density are required. These features make rechargeable molten salt batteries the most promising batteries for powering electric vehicles. However, operating temperatures of 400 to 700°C bring problems with thermal management and safety, and places more stringent requirements on the rest of the battery components. Its composition includes a molten salt electrolyte.
- Super iron battery: A new class of rechargeable electric battery. "Super-iron" is a moniker for a special kind of ferrate salt (iron(VI)): potassium ferrate or barium ferrate, as used in this new class of batteries.[2] As of 2004, chemist Stuart Licht of the University of Massachusetts in Boston was leading research into a Super-iron battery.
- Zinc bromide battery: A type of hybrid flow battery. A solution of zinc bromide is stored in two tanks. When the battery is charged or discharged the solutions (electrolytes) are pumped through a reactor and back into the tanks. One tank is used to store the electrolyte for the positive electrode reactions and the other for the negative. Its composition includes a zinc bromide electrolyte.
- Rechargeable alkaline battery: A variety of alkaline battery that can be recharged. It was first released in 1993, but is now out of production in most parts of the world. It is still being sold in Canada under the brand Pure Energy.
| Battery type | Energy/weight (MJ/kg) |
Energy/weight (Wh/kg) |
Energy/size (Wh/L) |
Power/weight (W/kg) |
Charge/ discharge efficiency (%) | Energy/ consumer-price | Self- discharge rate (%/month) | Time durability | Cycle durability (# of cycles) | Nominal cell voltage (V) |
|---|---|---|---|---|---|---|---|---|---|---|
| Nickel-iron battery | 0.18 | 50 | 100 | 20%-40% | 1.2 | |||||
| Wet lead-acid battery | 0.11-0.14 | 30-40 | 60-75 | 180 | 70%-92% | 5-8 Wh/US$ | 3%-4% | 500-800 | 2.0 | |
| Gel lead-acid battery | ||||||||||
| Absorbed glass mat lead-acid battery | ||||||||||
| Nickel-cadmium battery | 0.14-0.22 | 40-60 | 50-150 | 150 | 20% | 2000 | 1.2 | |||
| Nickel metal hydride battery | 0.11-0.29 | 30-80 | 140-300 | 250-1000 | 20% | 1000 | 1.2 | |||
| Lithium ion battery | 0.58 | 160 | 270 | 1800 | 5%-10% | 1200 | 3.6 | |||
| Lithium ion polymer battery | 0.47-0.72 | 130-200 | 300 | long | 3.7 | |||||
| NaS Battery | 89%-92% | |||||||||
| Nickel-zinc battery | 0.22 | 60 | 170 | high | ||||||
| Molten salt battery | ||||||||||
| Super iron battery | ||||||||||
| Zinc bromide battery | ||||||||||
| Rechargeable alkaline battery | 1.5 |
[edit] Recharging
The energy used to recharge rechargeable batteries mostly comes from mains electricity using an adapter unit. Recharging from solar panels is also attractive. Recharging from the 12V battery of a car is also possible. Use of a hand generator is also possible, but it is not clear if such devices are commercially made.
For uses like radios and flashlights, rechargeable batteries may be replaced by clockwork mechanisms or dynamos.
[edit] Reverse charging
Reverse charging is when a rechargeable battery is recharged with its polarity reversed. Reverse charging can occur under a number of circumstances. The two most important being:
- When a battery is incorrectly inserted into a charger
- When multiple batteries are used in series in a device. When one battery completely discharges ahead of the rest, the other batteries in series may force the discharged battery to discharge to below zero voltage.
