“An alkaline battery is a type of primary battery whose energy is derived from the reaction of zinc metal and manganese dioxide. It is also a disposable battery.”
The alkaline battery gets its name from the fact that it uses an alkaline electrolyte of potassium hydroxide (KOH) rather than the acidic ammonium chloride (NH4Cl) or zinc chloride (ZnCl2) electrolyte used in zinc-carbon batteries. Other battery systems use alkaline electrolytes as well, but the active materials for the electrodes are different.
Alkaline batteries have a higher energy density and a longer shelf life than zinc-carbon batteries of the Leclanché cell or zinc chloride types while providing the same voltage.
To generate electricity, a typical battery requires three components:
Components of Alkaline Battery
A cell of an alkaline battery is a section of the battery. In a chemical power supply, a dry battery is the primary battery. It’s a disposable battery of some sort. It converts chemical energy into electrical energy by using manganese dioxide as the positive electrode and zinc cylinder as the negative electrode to power an external circuit. Because zinc is more active than manganese in the chemical reaction, zinc loses electrons and is oxidised, whereas manganese gains electrons and is reduced.
First half reaction,
Zn (s) + 2HO– (aq) → Zn(s) + H2O (l) + 2e– (e° = – 1.28 V)
Second half reaction,
2MnO2 (s) + H2O (l) + 2e– → Mn2O3 (s) + 2HO– (aq) (e° = + 0.15V)
Overall reaction,
Zn (s) + 2MnO2 (s) ⇌ Mn2O3 + Zno (s) (e° = 1.43 V)
Sometimes alkaline batteries occasionally leak or explode. This happens due to an internal short circuit. On removing the sealing ring, the electric fluid inside will flow out.
Note- If the fluid comes into contact with the skin, immediately wash it with water.
Since the air volume in alkaline batteries is very small, one should not be concerned about explosions; at most, the bottom of the negative electrode rushes out, usually within 20 cm, causing no serious injury to personnel.
There is no spontaneous combustion substance in alkaline batteries because alkaline batteries, unlike lithium batteries, do not spontaneously ignite.
1. There are four types of batteries based on the composition of the active materials in the plates. These are their names:
2. These batteries can also be classified as sealed or non-sealed depending on how they are assembled.
3. The alkaline battery is also classified as an enclosed pocket or open pocket battery based on the design of the plates.
Toys, flashlights, portable electronic circuits, breadboard circuits and digital cameras.
Frequently Asked Questions on How Do Alkaline Batteries Work
Q1
Alkaline batteries are disposable batteries with electrodes made of zinc and manganese dioxide. Potassium or sodium hydroxide is the alkaline electrolyte used. These batteries have a constant voltage and are more energy dense and leak resistant than carbon zinc batteries.
Q2
Primary batteries are alkaline batteries. The alkaline battery gets its name from its alkaline electrolyte of potassium hydroxide, as opposed to the zinc-carbon batteries’ acidic ammonium chloride or zinc chloride electrolyte.
Q3
It is dangerous to recharge alkaline batteries. If cycling is not maintained, too much heat can accumulate. This could result in an alkaline battery exploding, which is a bad scenario in any case.
Q4
The advantages of alkaline batteries are-
Q5
Due to the materials used, alkaline batteries last longer. The most noticeable distinction between alkaline and non-alkaline batteries is the amount of power they provide. Carbon batteries do not have the same lifespan as alkaline batteries.
Alkaline batteryAA, AAA, N, PP3 (9-volt).
Size comparison of alkaline batteries (left to right): C
Self-discharge rate<0.3%/monthTime durability5–10 yearsNominal cell voltage1.5 VAn alkaline battery (IEC code: L) is a type of primary battery where the electrolyte (most commonly potassium hydroxide) has a pH value above 7. Typically these batteries derive energy from the reaction between zinc metal and manganese dioxide.
Compared with zinc–carbon batteries of the Leclanché cell or zinc chloride types, alkaline batteries have a higher energy density and longer shelf life, yet provide the same voltage.
The alkaline battery gets its name because it has an alkaline electrolyte of potassium hydroxide (KOH) instead of the acidic ammonium chloride (NH4Cl) or zinc chloride (ZnCl2) electrolyte of the zinc–carbon batteries. Other battery systems also use alkaline electrolytes, but they use different active materials for the electrodes.
Alkaline batteries account for 80% of manufactured batteries in the US and over 10 billion individual units produced worldwide. In Japan, alkaline batteries account for 46% of all primary battery sales. In Switzerland, alkaline batteries account for 68%, in the UK 60% and in the EU 47% of all battery sales including secondary types.[1][2][3][4][5] Alkaline batteries contain zinc (Zn) and manganese dioxide (MnO2) (Health codes 1), which is a cumulative neurotoxin and can be toxic in higher concentrations. However, compared to other battery types, the toxicity of alkaline batteries is moderate.[6]
Alkaline batteries are used in many household items such as MP3 players, CD players, digital cameras, toys, flashlights, and radios.
History
[
edit
]
Thomas Edison's nickel–iron batteries manufactured under the "Exide" brand, originally developed in 1901 by Thomas Edison used a potassium hydroxide electrolyte.Batteries with alkaline (rather than acid) electrolyte were first developed by Waldemar Jungner in 1899, and, working independently, Thomas Edison in 1901. The modern alkaline dry battery, using the zinc/manganese dioxide chemistry, was invented by the Canadian engineer Lewis Urry in the 1950s in Canada before he started working for Union Carbide's Eveready Battery division in Cleveland, OH, building on earlier work by Edison.[7][8] On October 9, 1957, Urry, Karl Kordesch, and P. A. Marsal filed US patent (2,960,558) for the alkaline battery. It was granted in 1960 and was assigned to the Union Carbide Corporation.[9]
When alkaline batteries were introduced in the late 1960s, their zinc electrodes (in common with the then ubiquitous carbon-zinc cells) had a surface film of mercury amalgam. Its purpose was to control electrolytic action on impurities in the zinc; that unwanted electrolytic action would reduce shelf life and promote leakage. When reductions in mercury content were mandated by various legislatures, it became necessary to greatly improve the purity and consistency of the zinc.[10]
Chemistry
[
edit
]
In an alkaline battery, the negative electrode is zinc and the positive electrode is manganese dioxide (MnO2). The alkaline electrolyte of potassium hydroxide (KOH) is not consumed during the reaction (it is regenerated), only the zinc and MnO2 are consumed during discharge. The concentration of alkaline electrolyte of potassium hydroxide remains constant, as there are equal amounts of OH− anions consumed and produced in the two half-reactions occurring at the electrodes.
The two half-reactions are:
e− from the reductant in the cell:
Zn(s) + 2OH aq ) → ZnO(s) + HO(l) + 2
(E°ox = +1.28 V)
(E°
e− to the oxidizer in the cell:
2MnO2(s) + 2H2O(l) + 2e− → 2MnO(OH)(s) + 2OH−(aq)
[11]
The overall reaction (sum of anodic and cathodic reactions) is:
Zn(s) + 2MnO2(s) <-> ZnO(s) + Mn2O3(s)
(E°cell = E°ox + E°red = nominally +1.5 V)
Capacity
[
edit
]
Several sizes of button and coin cells. Some are alkaline and others are silver oxide. Two 9 VThe capacity of an alkaline battery is greater than an equal size Leclanché cell or zinc chloride cell because the manganese dioxide is purer and denser, and less space is taken up by internal components such as electrodes. An alkaline cell can provide between three and five times the capacity of an acidic cell.
The capacity of an alkaline battery is strongly dependent on the load. An AA-sized alkaline battery might have an effective capacity of 3000 mAh at low drain, but at a load of 1 ampere, which is common for digital cameras, the capacity could be as little as 700 mAh.[12] The voltage of the battery declines steadily during use, so the total usable capacity depends on the cutoff voltage of the application.
Unlike Leclanché cells, the alkaline cell delivers about as much capacity on intermittent or continuous light loads. On a heavy load, capacity is reduced on continuous discharge compared with intermittent discharge, but the reduction is less than for Leclanche cells.
Voltage
[
edit
]
The nominal voltage of a fresh alkaline cell as established by manufacturer standards is 1.5 V. The actual zero-load voltage of a new alkaline battery ranges from 1.50 to 1.65 V, depending on the purity of the manganese dioxide used and the contents of zinc oxide in the electrolyte. The voltage delivered to a load decreases as the current drawn increases and as the cell discharges. A cell is considered fully discharged when the voltage drops to about 0.9 V.[13] Cells connected in series produce a voltage equal to the sum of the voltages of each cell (e.g., three cells generate about 4.5 V when new).
AA battery voltage vs capacity, at zero-load and 330 mW load[14] Capacity 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Zero-load 1.59 1.44 1.38 1.34 1.32 1.30 1.28 1.26 1.23 1.20 1.10 330 mW 1.49 1.35 1.27 1.20 1.16 1.12 1.10 1.08 1.04 0.98 0.62Current
[
edit
]
The amount of electrical current an alkaline battery can deliver is roughly proportional to its physical size. This is a result of decreasing internal resistance as the internal surface area of the cell increases. A rule of thumb is that an AA alkaline battery can deliver 700 mA without any significant heating. Larger cells, such as C and D cells, can deliver more current. Applications requiring currents of several amperes such as powerful portable audio equipment require D-sized cells to handle the increased load.
In comparison, Lithium-ion and Ni-MH batteries can handle 2 amperes with ease on the standard AA size.[15]
Construction
[
edit
]
Alkaline batteryAlkaline batteries are manufactured in standard cylindrical forms interchangeable with zinc–carbon batteries, and in button forms. Several individual cells may be interconnected to form a true "battery", such as the 9-volt PP3-size battery.
A cylindrical cell is contained in a drawn stainless steel can, which is the cathode connection. The positive electrode mixture is a compressed paste of manganese dioxide with carbon powder added for increased conductivity. The paste may be pressed into the can or deposited as pre-molded rings. The hollow center of the cathode is lined with a separator, which prevents contact of the electrode materials and short-circuiting of the cell. The separator is made of a non-woven layer of cellulose or a synthetic polymer. The separator must conduct ions and remain stable in the highly alkaline electrolyte solution.
The negative electrode is composed of a dispersion of zinc powder in a gel containing the potassium hydroxide electrolyte. The zinc powder provides more surface area for chemical reactions to take place, compared to a metal can. This lowers the internal resistance of the cell. To prevent gassing of the cell at the end of its life, more manganese dioxide is used than required to react with all the zinc. Also, a plastic-made gasket is usually added to increase leakage resistance.
The cell is then wrapped in aluminium foil, a plastic film, or rarely, cardboard, which acts as a final layer of leak protection as well as providing a surface on which logos and labels can be printed.
When describing AAA, AA, C, sub-C and D size cells, the negative electrode is connected to the flat end, and the positive terminal is the end with the raised button. This is usually reversed in button cells, with the flat-ended cylindrical can being the positive terminal.
Recharging of alkaline batteries
[
edit
]
Some alkaline batteries are designed to be recharged a few times, and are described as rechargeable alkaline batteries. Attempts to recharge standard alkaline batteries may cause rupture, or the leaking of hazardous liquids that corrode the equipment. However, it is reported that standard alkaline batteries can often be recharged a few times (typically not more than ten), albeit with reduced capacity after each charge; chargers are available commercially. The UK consumer organisation Which? reported that it tested two such chargers with Energizer alkaline batteries, finding that battery capacity dropped on average to 10% of its original value, with huge variations, after two cycles (without stating how depleted they were before recharging) after recharging them two times.[16]
In 2017 Gautam G. Yadav published papers reporting that alkaline batteries made by interleaving the interlayers with copper ions could be recharged for over 6,000 cycles due to the theoretical second electron capacity of manganese dioxide.[clarification needed][17][18] The energy density of these rechargeable batteries with copper intercalated manganese dioxide is reported to be over 160 Wh/L, the best among the aqueous-based chemistries.[18] It could be capable of energy densities comparable to lithium-ion (at least 250 Wh/L) if zinc utilization in the batteries were improved.[17]
Leaks
[
edit
]
Potassium compound leakage inside an alkaline batteryAlkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation.[note 1] The risk of this can be reduced by storing batteries in a dry place and at room temperature. Damage from leakage is mitigated by removing batteries when storing devices. Applying reverse current (such as by recharging disposable-grade cells, or by mixing batteries of different types or state of charge in the same device) can increase the risk of leakage.[citation needed]
All batteries gradually self-discharge (whether installed in a device or not) and dead batteries eventually leak. Extremely high temperatures can also cause batteries to rupture and leak (such as in a car during summer) as well as decrease the shelf life of the battery.
The reason for leaks is that as batteries discharge – either through usage or gradual self-discharge – the chemistry of the cells changes and some hydrogen gas is generated. This out-gassing increases pressure in the battery. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both. In addition, as the battery ages, its steel outer canister may gradually corrode or rust, which can further contribute to containment failure.
Once a leak has formed due to corrosion of the outer steel shell, potassium hydroxide absorbs carbon dioxide from the air to form a feathery crystalline structure of potassium carbonate that grows and spreads out from the battery over time, following along metal electrodes to circuit boards where it commences oxidation of copper tracks and other components, leading to permanent circuitry damage.
The leaking crystalline growths can also emerge from seams around battery covers to form a furry coating outside the device, that corrodes any objects in contact with the leaking device.
Disposal
[
edit
]
Since alkaline batteries were made with less mercury beginning in 1996, alkaline batteries are allowed to be disposed of as regular domestic waste in some locations. However, older alkaline batteries with mercury, and the remaining other heavy metals and corrosive chemicals in all batteries (new and old), still present problems for disposal—especially in landfills.[19][20] There is also the issue of simplifying the disposal of batteries by excluding them all from domestic waste, so that the most toxic batteries are diverted from general waste streams.
Disposal varies by jurisdiction. For example, the state of California considers all batteries as hazardous waste when discarded, and has banned the disposal of batteries in domestic waste.[21] In Europe, battery disposal is controlled by the WEEE Directive and Battery Directive regulations, and as such alkaline batteries must not be thrown in with domestic waste. In the EU, most stores that sell batteries are required by law to accept old batteries for recycling.
Recycling
[
edit
]
The use of disposable batteries increases by 5–6% every year. In the past, used batteries ended up at landfill sites, but in 2004, disposal of alkaline batteries at landfill sites was forbidden by an EU regulation. EU member countries are committed to recycling 50% of alkaline batteries by 2016. The need for recycling thus amounts to 125000 tons per year. The share of alkaline batteries is approximately 80% of the whole.[citation needed]
In the US, only one state, California, requires all alkaline batteries to be recycled. Vermont also has a statewide alkaline battery collection program.[22] In other US states, individuals can purchase battery recycling kits used to ship batteries to recyclers. Some stores such as IKEA also collect alkaline batteries for recycling. However, some chain stores that advertise battery recycling (such as Best Buy) accept rechargeable batteries only, and generally do not accept alkaline batteries.[23]
For recycling, the metals from crushed alkaline batteries are mechanically separated, and the waste black mass is treated chemically to separate zinc, manganese dioxide and potassium hydroxide.
See also
[
edit
]
Notes
[
edit
]
This alkali particularly attacks aluminium, a common material for flashlights , which can be damaged by leaking alkaline batteries.
References
[
edit
]
For more information, please visit Half Cell Solar Panels, 250w Solar Panel Polycrystalline Factories, Panel 455w.