A rechargeable alkaline battery (also known as alkaline rechargeable or rechargeable alkaline manganese (RAM)) is a type of alkaline battery capable of recharging for repeated use. The first generation rechargeable alkaline batteries were introduced by Union Carbide and Mallory in the early 1970s. Several patents were introduced after the termination of Union Carbide products and finally, in 1986, Battery Technologies Inc. of Canada was established to commercially develop 2nd generation products based on the patent. Their first product licensed and sold commercially is to Rayovac under the trademark "Updates". The following year, the battery "Pure Energy" was released by Pure Energy. After reformulating the renewal into mercury-free in 1995, the next licensed licensed lithium-free alkali and including ALCAVA, AccuCell, Grandcell and EnviroCell. Patents and subsequent advances in technology have been introduced. The formats include AAA, AA, C, D, and a 9-volt battery snap-on. The rechargeable alkaline batteries are fully manufactured and have the ability to hold their payload for years, longer than NiCd and NiMH batteries, which are self-discharge. Rechargeable alkaline batteries can have high refueling efficiency and have less environmental impact than disposable cells.
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Rechargeable cell construction
Unlike disposable alkaline batteries, rechargeable alkaline batteries are designed by manufacturers to be rechargeable. The rechargeable alkaline cell is built very similar to a single-use alkaline cell. The cathode paste is pressed into a steel can that forms the positive terminal of the battery. The negative electrode consists of a zinc powder suspended in a gel, with contact of a steel nail that runs to the base of the cell to form a negative terminal. Features of different rechargeable alkaline from disposable alkaline cells include the presence of barium sulfate or other additives in the cathode blend, which improves cycling and increases capacity by preventing the formation of insoluble manganese compounds. The cathode also has a catalyst to reunite the formed hydrogen; hydrogen is produced when the fine zinc grains made during refilling are sacrificed by the electrolyte. Zinc oxide is added to the cathode mixture to reduce the formation of hydrogen gas; Zinc oxide dissociates to form oxygen. The separator between anode and cathode is formulated to be highly resistant to the growth of zinc grains, which can penetrate and shorten cells.
The cells are produced in a filled state, ready for use.
Although this battery can be used on any device that supports standard sizes (AA, AAA, C, D, etc.), these batteries are formulated to last the longest in periodic usage items. This type of battery is more suitable for use on flammable devices such as remote control or for devices used periodically such as flashlight, television remote control handset, portable radio, etc. If the battery runs less than 25%, it can be recharged for hundreds of cycles up to about 1.42 V. If they are discarded less than 50%, they can be almost fully charged for several dozen cycles, up to about 1.32V. After deep discharge, they can be carried to their original high capacity load only after several charging cycles.
Maps Rechargeable alkaline battery
Disposable Alkalines
Manufacturers do not support charging disposable alkaline batteries, and warn that it may be dangerous. Despite this suggestion, the alkaline battery has been refilled, and the charger is available. The capacity of the rechargeable alkaline battery decreases with the amount of recharge, until it becomes unusable after typically about ten cycles. Low ripple current is not suitable for disposable alkaline batteries; more suitable is the pulsed current at a rate of 40 to 200 pulses per second, with an 80% duty cycle. Pulse refilling seems to reduce the risk of electrolytes - usually potassium hydroxide (KOH) - leakage. Low charging current to prevent rapid gas production that can damage cells. Cells that have leaked electrolytes are a safety hazard and are not suitable for reuse. A fully rechargeable cell recharge is less successful than just a partially depleted cell, especially if the cell is kept empty - the battery charger producer does not claim to recharge the dead cell.
Trying to recharge an exhausted alkaline battery can cause gas production in the canister. As tubes are normally sealed, the pressure generated by rapid gas accumulation can open the pressure retaining seal and cause electrolyte leakage. Potassium hydroxide in electrolytes is corrosive and can cause injury and damage, especially battery contact corrosion in equipment.
When the alkaline battery is released, the chemicals inside the battery react to create an electric current. When chemicals are used and products of the reaction accumulate, eventually the battery can no longer provide enough current, and the battery runs out. By moving the current through the battery in the reverse direction, the equilibrium can be diverted back to the original reactant. Different batteries depend on different chemical reactions. Some reactions are easily reversed, some are not. The reactions used in most alkaline batteries fall into the latter category. In particular, the zinc metal produced by moving backflow through the cell generally will not return to its original location in the cell, and may form crystals that destroy the separating layer between the battery anode and the electrolyte.
Comparison with other rechargeable batteries
The rechargeable alkaline batteries, at one time, are cheaper than other types of refills. Cells can be produced in a fully charged state and maintain capacity well. Their capacity is about 2/3 primary cells. They are dry cell construction, completely covered and do not require maintenance. Cells have a limited life cycle, which is affected by deep discharge; the first cycle gives the largest capacity, and if very depleted the cell can only provide 20 cycles. The available energy at each cycle decreases. Like primary alkaline cells, they have relatively high internal resistance, making them unsuitable for high current discharges (eg, their full capacity utilization in an hour).
Unlike rechargeable alkaline batteries, NiMH batteries can last anywhere from a few hundred to a thousand (or more) deep discharge cycles, resulting in a long useful life; Their limitations are now more usually based on age than on cycles. NiMH battery capacity close to alkaline batteries. Unlike alkaline batteries (rechargeable or otherwise), internal resistance is low. This makes them suitable for high drawing applications. The level of self-discharge is proportional, at least up to six months.
Environmental issues
Rechargeable alkaline batteries are developed from primary alkaline batteries, designed to withstand leaks that can cause recharging, so they can be recharged safely many times.
According to the EnviroCell and PureEnergy websites and according to the old Rayovac packaging, this manufacturer's rechargeable alkaline batteries have no mercury or cadmium.
See also
- List of battery types
- List of battery sizes
- Battery type comparison
- Battery recycling
References
External links
- Alkaline battery charging
- Potassium hydroxide MSDS from JTBaker
- A patent describing an alkaline battery charger
Source of the article : Wikipedia
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