Disposable (or primary) batteries are non-rechargeable cells in which the electrochemical reaction is not reversible. Primary batteries completely deplete the material in one or both of their electrodes.

All batteries have positive and negative terminals, marked (+) and (-) respectively. Batteries also contain two electrodes: a cathode which is connected to the positive terminal and an anode connected to the negative one. The electrodes must not touch each other, and are separated by the electrolyte, which facilitates the flow of electric charge between the electrodes. Finally, a collector conducts the charge to the battery's exterior and through the load.

When a battery is inserted into an electrical device, the device completes the circuit between the two terminals and triggers electrochemical reactions within the battery. The anode undergoes an oxidation reaction with the electrolyte and releases electrons, while the cathode undergoes a reduction reaction and absorbs the free electrons. The product of these two reactions is electricity, which is channeled out of the battery and into the device.

Battery Chemistry

Manufacturers produce batteries using many different types of reactant chemicals. A battery's chemistry determines its size, voltage, and intended use.

Zinc-carbon batteries use a zinc can that functions both as a container and the battery's negative terminal. The positive terminal consists of a carbon rod. They have a short shelf life and low energy density, but are among the least expensive primary batteries to manufacture. Zinc-carbon batteries are often labeled and marketed as "general purpose."

Zinc-chloride batteries use purer chemicals than zinc-carbon batteries, giving them a longer shelf life and better energy density. They are often labeled as "heavy duty" to differentiate them from zinc-carbon types.

Alkaline manganese dioxide products use zinc and manganese dioxide as reactive elements. Alkaline batteries derive their name from the use of a potassium hydroxide (alkaline) electrolyte, rather than the ammonium chloride or zinc chloride electrolytes used in zinc-carbon batteries. They are an improvement over zinc-carbon batteries, with higher energy density and longer shelf life, and account for almost 80% of manufactured batteries in the United States.

Silver oxide batteries use zinc and silver oxide as the negative and positive electrodes, respectively. They have a very high energy-to-weight ratio, and are expensive to produce due to the cost of silver. They are typically manufactured as small cell batteries in order to limit the amount of silver used.

Zinc-air batteries oxidize zinc using oxygen from the air. They feature high energy densities and are relatively inexpensive to produce. Zinc-air batteries are manufactured in various sizes for many different applications, from hearing aids to electric vehicles.

Lithium thionyl chloride batteries are specialty devices with very high energy densities. They are typically not sold to consumer markets, and are often installed in devices that limit consumer battery replacement. Lithium thionyl chloride batteries are suitable for low temperature applications, and can maintain 50% capacity down to -55°C .

Lithium manganese dioxide batteries are very common and make up 80% of the lithium battery market. They are versatile devices with a long shelf life, low cost, and high energy density.

Specifications

The Engineering360 SpecSearch database contains information about a variety of standardized sizes and shapes of primary batteries. These specifications can be classified by consumer sizes, which are commonly available for general purpose applications, and non-consumer sizes for specialized uses such as photography and instrumentation. Batteries manufactured for specialty use come in a variety of shapes and sizes.

When selecting primary batteries, buyers may also specify the product's voltage, capacity and intended applications.

Consumer Sizes

• Round batteries are taller than their diameter and have terminals on each end. Depending on the active materials used, they typically produce between 1.2 and 3 volts when fresh. Round batteries are commonly available in a variety of sizes, including AAA, AA, C and D.
• 9-Volt or PP3 batteries consist of six individual 1.5 V cells within a can. They are typically used in smoke detectors, alarms, and other consumer products.

Non-consumer Sizes

• AAAA batteries are used in small devices such as laser pointers, penlights and glucose meters.
• A batteries are approximately the same length as the AA size, but with a larger diameter. They are commonly used in older laptop batteries and consumer battery packs.
• N batteries are roughly three-fifths the length of an AA battery. Similarly to AAAA batteries, they are used in small device applications.
• Sub-C batteries are typically used in consumer battery packs for power tools or radio-controlled vehicles.

• Fractional batteries are expressed as a fractional number combined with a common battery size. For example, a 1/2AA battery is half the length of an AA battery but shares the same diameter. Common fractional batteries include 1/3AA, 2/3AA, 1/2A, 2/3A, 4/5Cs and 1/2D.

Specialty Cells

• Battery packs consist of batteries bundled together with a connector for use in phones, radio-controlled vehicles and other consumer devices.
• Coin or button cells are available in numerous sizes and are used in watches, calculators and hearing aids.
• Lantern batteries typically produce 6 V and have spring or screw terminals.
• Prismatic cells are rectangular batteries which have slightly lower energy densities than traditional cylindrical cells. Although prismatic cells are expensive to manufacture, their unique construction offers a more efficient use of space, especially in designing battery packs.

Voltage

Battery voltage refers to the electric potential difference between the positive and negative terminal. Manufacturers typically specify the battery's nominal voltage, although its actual discharge voltage can vary depending on the battery's charge and current. For example, a battery cell with a nominal voltage of 2 V actually discharges between 1.7 and 2.0 volts at a given time. Most round consumer batteries carry a nominal voltage of 1.5 V, while a car battery is typically 12 volts. Depending on the battery materials and application, voltage can range from a fraction of a volt to several kilovolts.

Capacity

The amount of charge a primary battery can store is known as its capacity. Charge is typically measured in amp-hours or milliamp-hours (Ah or mAh). Most manufacturers specify capacity as the constant current that a new battery can supply for 20 hours. For example, a battery rated at 200 Ah can supply 10 A over a 20 hour period at room temperature. If the current supply to the same battery is increased, the capacity will then decrease.

Applications

Batteries are manufactured for use in numerous applications.

• Consumer batteries are used for general purpose consumer applications, such as cameras, radio-controlled cars, toys, and laptops.
• Energy batteries are manufactured for use in oil, natural gas and solar applications.
• Industrial batteries are deep cycle batteries used in forklifts and other industrial applications.
• Medical batteries are used for life support systems, hearing aids and wheelchairs.
• Military batteries are often manufactured to MIL-SPEC requirements.
• Transportation batteries are designed for use in aircraft, boats, automobiles and electric vehicles.
• Stand-by/UPS batteries are used in uninterruptible power supplies (UPS) for emergency lighting and alarms.

References

Electrochemistry Encyclopedia - Non-rechargeable Batteries

Image credits:

Heter Battery Technology Co., Ltd. | Varta Microbattery Inc. | EIS