What kind of electrochemical cell is alkaline cell

Lead-acid batteries provide high currents and store charge for long periods of time, making them essential for vehicles. A lead storage battery, also known as a lead-acid battery, is the oldest type of rechargeable battery and one of the most common energy storage devices. Most people are accustomed to using them in vehicles, where they have the ability to provide high currents for cranking power. Although the batteries are reliable, they have a limited life, are heavy to ship, and contain toxic materials that require specific removal methods at the end of their useful life.

Lead-acid batteries have moderate power density and good response time. Depending on the power conversion technology incorporated, batteries can go from accepting energy to supplying energy instantaneously. Lead-acid batteries are affected by temperature and must be maintained in order to achieve maximum life expectancy. The cells initially had low capacity. Lead storage battery : A diagram showing how a lead storage battery consists of six two-volt cells connected in series.

The make up of each cell is also shown. Each plate consists of a rectangular lead grid. The holes of the grid are filled with a paste of red lead and 33 percent dilute sulfuric acid. This porous paste allows the acid to react with the lead inside the plate, which increases the surface area. Once dry, the plates are stacked with suitable separators and inserted into the battery container.

An odd number of plates is usually used, with one more negative plate than positive. Each alternate plate is connected. The paste contains carbon black, barium sulfate, and lignosulfonate. The barium sulfate acts as a seed crystal for the lead-to-lead sulfate reaction. The lignosulfonate prevents the negative plate from forming a solid mass during the discharge cycle, and instead enables the formation of long needle-like crystals. Carbon black counteracts the effect of inhibiting formation caused by the lignosulfonates.

The electrolyte loses much of its dissolved sulfuric acid and becomes primarily water. The discharge process is driven by the conduction of electrons from the negative plate back into the cell at the positive plate in the external circuit. This type of battery can be recharged. In the charged state, each cell contains negative plates of elemental lead Pb and positive plates of lead IV oxide PbO 2 in an electrolyte of approximately 4.

The charging process is driven by the forcible removal of electrons from the positive plate and the forcible introduction of them to the negative plate by the charging source.

The demand for many varieties of rechargeable batteries is due to their lower cost and lower environmental impact. A rechargeable battery is a type of electrical battery that is comprised of one or more electrochemical cells. It is known as a secondary cell because its electrochemical reactions are electrically reversible.

The U. Grid energy storage applications use rechargeable batteries for load-leveling. Load-leveling involves storing electric energy for use during peak load period. By charging batteries during periods of low electrical demand for use during periods of high demand, load-leveling helps eliminate the need for expensive peaking power plants and helps reduce the cost of generators over more hours of operation. As with all batteries, rechargeable batteries consist of an anode, a cathode, and an electrolyte.

During charging, the anode material is oxidized, producing electrons, and the cathode is reduced, consuming electrons. These electrons constitute the current flow in the external circuit. The electrolyte may serve as a simple buffer for internal ion flow between the electrodes, as in lithium-ion and nickel-cadmium cells, or it may be an active participant in the electrochemical reaction, as in lead-acid cells.

Several different combinations of chemicals are commonly used in rechargeable batteries. Different types include lead-acid, nickel-cadmium NiCd , nickel-metal hydride NiMH , lithium-ion Li-ion , lithium-ion polymer LiPo , and rechargeable alkaline batteries. Their ability to supply high-surge currents means that the cells maintain a relatively large power-to-weight ratio.

These features, along with their low cost, make them attractive for use in motor vehicles, which require high currents. NiMH batteries use positive electrodes of nickel oxyhydroxide NiOOH , as does the NiCd, but the negative electrodes use a hydrogen-absorbing alloy instead of cadmium.

A NiMH battery can have two to three times the capacity of a NiCd battery of equivalent size, and its energy density approaches that of a lithium-ion cell. The lithium-ion battery is a family of rechargeable batteries in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging. The negative electrode of a conventional lithium-ion cell is made from carbon.

The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. They are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities and only a slow loss of charge when not in use.

Lithium ion batteries are more expensive than NiCd batteries but operate over a wider temperature range while being smaller and lighter. They are fragile and thus need a protective circuit to limit peak voltages. Lithium-ion polymer LiPo batteries are usually composed of several identical secondary cells in parallel to increase the discharge-current capability. Their primary distinction from lithium-ion batteries is that their lithium salt electrolyte is not held in an organic solvent.

Instead, it is in a solid polymer composite, such as polyethylene oxide or polyacrylonitrile. The advantages of LiPo over the lithium-ion design include potentially lower cost of manufacture, adaptability to a wide variety of packaging shapes, reliability, and ruggedness. Their major disadvantage is that they hold less charge.

There are also rechargeable forms of alkaline batteries, which are a type of primary battery dependent upon the reaction between zinc Zn and manganese dioxide MnO 2. They are manufactured fully charged and have the ability to carry their charge for years, longer than most NiCd and NiMH batteries, which self-discharge. Rechargeable alkaline batteries can also have a high recharging efficiency and have less environmental impact than disposable cells.

Discuss the chemical transformations that occur in a lithium-ion battery during charge and discharge. Lithium-ion batteries Li-ion batteries, or LIBs are a family of rechargeable batteries in which lithium ions move from the negative electrode to the positive electrode during discharge. The ions follow the reverse path when the battery is charging. Li-ion batteries use a lithium compound as the electrode material. Lithium-ion batteries are common in consumer electronics.

They are one of the most popular types of rechargeable battery for portable electronics because they have one of the best energy densities and only a slow loss of charge when not in use. Laptop lithium-ion battery : The lithium-ion battery is good for use in portable electronics, including laptops. Beyond the field of consumer electronics, LIBs are also growing in popularity for military, electric vehicle, and aerospace applications. Research is yielding a stream of improvements to traditional LIB technology, focusing on energy density, durability, cost, and safety.

Chemistry, performance, cost, and safety characteristics vary with the type of LIB. Voltaic cells are composed of two half-cell reactions oxidation-reduction linked together via a semipermeable membrane generally a salt bath and a wire Figure 1.

Each side of the cell contains a metal that acts as an electrode. One of the electrodes is termed the cathode, and the other is termed the anode. The side of the cell containing the cathode is reduced, meaning it gains electrons and acts as the oxidizing agent for the anode. The side of the cell containing the anode is where oxidation occurs, meaning it loses electrons and acts as the reducing agent for the cathode.

The two electrodes are each submerged in an electrolyte, a compound that consists of ions. This electrolyte acts as a concentration gradient for both sides of the half reaction, facilitating the process of the electron transfer through the wire. This movement of electrons is what produces energy and is used to power the battery. The cell is separated into two compartments because the chemical reaction is spontaneous. If the reaction was to occur without this separation, energy in the form of heat would be released and the battery would not be effective.

Figure 1: A Zinc-Copper Voltaic cell. The voltaic cell is providing the electricity needed to power the light-bulb. Figure 2: Primary versus Secondary Batteries.

Primary batteries left are non-rechargeable and disposable. Secondary batteries right are rechargeable, like this cellular phone battery. Primary batteries are non-rechargeable and disposable. The electrochemical reactions in these batteries are non-reversible. The materials in the electrodes are completely utilized and therefore cannot regenerate electricity. Primary batteries are often used when long periods of storage are required, as they have a much lower discharge rate than secondary batteries.

Use of primary batteries is exemplified by smoke detectors, flashlights, and most remote controls. Secondary batteries are rechargeable.

These batteries undergo electrochemical reactions that can be readily reversed. The chemical reactions that occur in secondary batteries are reversible because the components that react are not completely used up. Rechargeable batteries need an external electrical source to recharge them after they have expended their energy.

Wet cell batteries contain a liquid electrolyte. They can be either primary or secondary batteries. Due to the liquid nature of wet cells, insulator sheets are used to separate the anode and the cathode. Types of wet cells include Daniell cells, Leclanche cells originally used in dry cells , Bunsen cells, Weston cells, Chromic acid cells, and Grove cells. The lead-acid cells in automobile batteries are wet cells. In dry cell batteries, no free liquid is present. Instead the electrolyte is a paste, just moist enough to allow current flow.

This allows the dry cell battery to be operated in any position without worrying about spilling its contents. This is why dry cell batteries are commonly used in products which are frequently moved around and inverted, such as portable electronic devices. Dry cell batteries can be either primary or secondary batteries. The most common dry cell battery is the Leclanche cell.

The capacity of a battery depends directly on the quantity of electrode and electrolyte material inside the cell. This is caused by side chemical reactions that do not produce current.

The rate of side reactions can be slowed by lowering temperature. Warmer temperatures can also lower the performance of the battery, by speeding up the side chemical reactions. Primary batteries become polarized with use. This is when hydrogen accumulates at the cathode, reducing the battery's effectiveness. Depolarizers can be used to remove this build up of hydrogen. Secondary batteries self-discharge even more rapidly.

Rechargeable batteries gradually lose capacity after every recharge cycle due to deterioration. This is caused by active materials falling off the electrodes or electrolytes moving away from the electrodes.

Peukert's law can be used to approximate relationships between current, capacity, and discharge time. This is represented by the equation.

While some alkaline batteries are rechargeable, most are not. Attempts to recharge an alkaline battery that is not rechargeable often leads to rupture of the battery and leakage of the potassium hydroxide electrolyte.

Visit this site to learn more about alkaline batteries. Secondary batteries are rechargeable. These are the types of batteries found in devices such as smartphones, electronic tablets, and automobiles.

Nickel-cadmium , or NiCd, batteries Figure 3 consist of a nickel-plated cathode, cadmium-plated anode, and a potassium hydroxide electrode.

The positive and negative plates, which are prevented from shorting by the separator, are rolled together and put into the case. The voltage is about 1. When properly treated, a NiCd battery can be recharged about times. Cadmium is a toxic heavy metal so NiCd batteries should never be opened or put into the regular trash. Visit this site for more information about nickel cadmium rechargeable batteries. Lithium ion batteries Figure 4 are among the most popular rechargeable batteries and are used in many portable electronic devices.

With the coefficients representing moles, x is no more than about 0. The battery voltage is about 3. Lithium batteries are popular because they can provide a large amount current, are lighter than comparable batteries of other types, produce a nearly constant voltage as they discharge, and only slowly lose their charge when stored. Visit this site for more information about lithium ion batteries. The lead acid battery Figure 5 is the type of secondary battery used in your automobile.

It is inexpensive and capable of producing the high current required by automobile starter motors. The reactions for a lead acid battery are. Each cell produces 2 V, so six cells are connected in series to produce a V car battery. Lead acid batteries are heavy and contain a caustic liquid electrolyte, but are often still the battery of choice because of their high current density.

Since these batteries contain a significant amount of lead, they must always be disposed of properly. Visit this site for more information about lead acid batteries.

A fuel cell is a device that converts chemical energy into electrical energy. Fuel cells are similar to batteries but require a continuous source of fuel, often hydrogen.

They will continue to produce electricity as long as fuel is available. Hydrogen fuel cells have been used to supply power for satellites, space capsules, automobiles, boats, and submarines Figure 6.

The voltage is about 0.