Rechargeable battery
Rechargeable batteries 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.
A comparison of rechargable batteries
| Battery type | Description | Composition | Energy density ( MJ/kg ) |
Density | Development status |
|---|---|---|---|---|---|
| Nickel-iron battery | With a nominal cell voltage of 1.2V, it 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. | Nickel(III) oxide-hydroxide cathode, iron anode, potassium hydroxide electrolyte | Produced from 1903 | ||
| Lead-acid battery | Wet battery: commonly used in vehicles, alarm systems and uninterruptible power supplies. Used to be used as an "A" or "wet" battery in valve/vacuum tube radio sets. The major advantage of this chemistry is its low cost - 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. | 0.11 | Invented 1859 | ||
| Gel battery: a lead-acid battery with gelified electrolyte. It is one of the types of VRLA battery. Rechargeable gel batteries are primarily used in automobiles, boats, aircraft, and other motorized vehicles. Unlike a traditional wet-cell lead-acid battery, the cells of a gel battery are valve-regulated. | gelified electrolyte | ||||
| Absorbed glass mat: a lead-acid battery in which the electrolyte is absorbed into a fiberglass mat. It is one of the types of VRLA battery. The plates in an AGM Battery may be flat like wetcell lead-acid batteries, or they may be wound in tight spiral. 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. | |||||
| Nickel cadmium battery | used in many domestic applications but being superseded by Li-ion and Ni-MH types. This chemistry gives the longest cycle life (over 1500 cycles), but has low energy density compared to some of the other chemistries. Ni-Cd cells using older technology suffer from memory effect, but this has been reduced drastically in modern batteries. | Mass produced from 1946 | |||
| Nickel metal hydride battery | similar to a nickel-cadmium (NiCd) battery but has a hydride absorbing alloy for the anode instead of cadmium, which is an environmental hazard; therefore, it is less detrimental to the environment. Like in NiCd batteries, nickel is the cathode. 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. Applications of NiMH type batteries includes hybrid vehicles such as the Toyota Prius and consumer electronics | 0.22 | Made avaidable 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. Used in laptops (notebook PCs), modern camera phones, some rechargeable MP3 players and most other portable rechargeable digital equipment. | 0.54 to 0.72 | Released c1990 | ||
| Lithium ion polymer battery | similar characteristics to lithium-ion, but with slightly less charge density and a greater life cycle degradation rate. This battery chemistry can be used for any battery to suit the manufacturer's needs, such as ultra-thin (1 mm thick) cells for the latest PDAs. | Released 1996 | |||
| Aluminium battery | potentially twenty times the energy density of the best currently available rechargable batteries. | In research stage | |||
| NaS 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 | ||||
| Zinc-air battery | While this is technically a fuel cell, it is sold on the retail market in the form of a single-use long-lasting emergency cell phone battery that cannot be recharged. | ||||
| Nickel-zinc battery | are 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 use molten salts as an electrolyte. They offer 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. Operating temperatures of 400 to 700°C however brings problems of thermal management and safety and places more stringent requirements on the rest of the battery components. | 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.[1] As of 2004 chemist Stuart Licht of the University of Massachusetts in Boston was leading research into a Super-iron battery. | In research stage | |||
| 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. | zinc bromide electrolyte |
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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 torches, rechargeable batteries may be replaced by clockwork mechanisms or dynamos.
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.
Reverse charging may lead to explosion, leakage, damage to the battery and/or to the device or charger. Old and new batteries and batteries of varying types or brands should not be mixed in the same circuit.