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A thermoelectric battery stores energy when charged by converting heat into chemical energy and produces electricity when discharged. Such systems potentially offer an alternative means of disposing of waste heat from plants that burn fossil fuels and/or nuclear energy. [1]
Thomas Johann Seebeck (1780–1831) discovered the thermoelectric effect in 1821. The symmetrical Peltier effect (Jean Charles Athanse Peltier, 1785–1845) uses an electric current to produce temperature differences. In the middle part of the twentieth century the thermo-electric generator was often used in place of galvanic batteries. [2]
In 2014 researchers demonstrated a prototype system that uses copper electrodes and ammonia as the electrolyte. The device converted some 29 percent of the battery's chemical energy into electricity. [1]
The ammonia electrolyte is only used as an anolyte (electrolyte surrounding an anode) that reacts with the copper electrode as waste heat warms the ammonia, generating electricity. When the reaction uses up the ammonia or depletes the copper ions in the electrolyte near the cathode the reaction stops. [1]
Waste heat then is used to distill the ammonia from the used anolyte. The ammonia is then added to the cathode chamber. The battery's polarity reverses and the anode becomes the cathode and vice versa. [1]
The system's power density was some maximum power density of 60+-3 1 W m−2(based on a single electrode), with a maximum energy density of 453 W h m−3 (normalized to the electrolyte volume), substantially higher than that of other liquid-centered thermal-electrics. [3] Power density increased with the number of batteries in the system. [1]
Volatilization of ammonia from the spent anolyte by heating (simulating distillation), and re-addition of this ammonia to the spent catholyte chamber with subsequent operation of this chamber as the anode (to regenerate copper on the other electrode), produced a maximum power density of 60 ± 3 W m−2, with an average discharge energy efficiency of 29% (electrical energy captured versus chemical energy in the starting solutions). An acid added to the catholyte increased power 126 ± 5 W m−2. [3]
Telluride based batteries convert 15 to 20 percent of heat to energy. [1]
Fulvalene diruthenium promises greater efficiency, but is too expensive for commercial use. [1]
A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic CCD for Cathode Current Departs. A conventional current describes the direction in which positive charges move. Electrons have a negative electrical charge, so the movement of electrons is opposite to that of the conventional current flow. Consequently, the mnemonic cathode current departs also means that electrons flow into the device's cathode from the external circuit. For example, the end of a household battery marked with a + (plus) is the cathode.
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference and identifiable chemical change. These reactions involve electrons moving via an electronically-conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. Electrodes are essential parts of batteries that can consist of a variety of materials depending on the type of battery.
An electrochemical cell is a device that generates electrical energy from chemical reactions. Electrical energy can also be applied to these cells to cause chemical reactions to occur. Electrochemical cells which generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells.
A fuel cell is an electrochemical cell that converts the chemical energy of a fuel and an oxidizing agent into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from substances that are already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. In comparison with other rechargeable batteries, Li-ion batteries are characterized by a higher specific energy, higher energy density, higher energy efficiency, longer cycle life and longer calendar life. Also noteworthy is a dramatic improvement in lithium-ion battery properties after their market introduction in 1991: within the next 30 years their volumetric energy density increased threefold, while their cost dropped tenfold.
A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous Oxidation-Reduction reactions. A common apparatus generally consists of two different metals, each immersed in separate beakers containing their respective metal ions in solution that are connected by a salt bridge or separated by a porous membrane.
A regenerative fuel cell or reverse fuel cell (RFC) is a fuel cell run in reverse mode, which consumes electricity and chemical B to produce chemical A. By definition, the process of any fuel cell could be reversed. However, a given device is usually optimized for operating in one mode and may not be built in such a way that it can be operated backwards. Standard fuel cells operated backwards generally do not make very efficient systems unless they are purpose-built to do so as with high-pressure electrolysers, regenerative fuel cells, solid-oxide electrolyser cells and unitized regenerative fuel cells.
A primary battery or primary cell is a battery that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell. In general, the electrochemical reaction occurring in the cell is not reversible, rendering the cell unrechargeable. As a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants. Primary cells are made in a range of standard sizes to power small household appliances such as flashlights and portable radios.
Energy harvesting (EH) – also known as power harvesting,energy scavenging, or ambient power – is the process by which energy is derived from external sources, then stored for use by small, wireless autonomous devices, like those used in wearable electronics, condition monitoring, and wireless sensor networks.
Zinc–air batteries (non-rechargeable), and zinc–air fuel cells are metal–air batteries powered by oxidizing zinc with oxygen from the air. These batteries have high energy densities and are relatively inexpensive to produce. Sizes range from very small button cells for hearing aids, larger batteries used in film cameras that previously used mercury batteries, to very large batteries used for electric vehicle propulsion and grid-scale energy storage.
A flow battery, or redox flow battery, is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a membrane. Ion transfer inside the cell occurs through the membrane while both liquids circulate in their own respective space. Cell voltage is chemically determined by the Nernst equation and ranges, in practical applications, from 1.0 to 2.43 volts. The energy capacity is a function of the electrolyte volume and the power is a function of the surface area of the electrodes.
Molten-salt batteries are a class of battery that uses molten salts as an electrolyte and offers both a high energy density and a high power density. Traditional non-rechargeable thermal batteries can be stored in their solid state at room temperature for long periods of time before being activated by heating. Rechargeable liquid-metal batteries are used for industrial power backup, special electric vehicles and for grid energy storage, to balance out intermittent renewable power sources such as solar panels and wind turbines.
An alkali-metal thermal-to-electric converter is a thermally regenerative electrochemical device for the direct conversion of heat to electrical energy. It is characterized by high potential efficiencies and no moving parts except for the working fluid, which make it a candidate for space power applications.
In battery technology, a concentration cell is a limited form of a galvanic cell that has two equivalent half-cells of the same composition differing only in concentrations. One can calculate the potential developed by such a cell using the Nernst equation. A concentration cell produces a small voltage as it attempts to reach chemical equilibrium, which occurs when the concentration of reactant in both half-cells are equal. Because an order of magnitude concentration difference produces less than 60 millivolts at room temperature, concentration cells are not typically used for energy storage.
Nanobatteries are fabricated batteries employing technology at the nanoscale, particles that measure less than 100 nanometers or 10−7 meters. These batteries may be nano in size or may use nanotechnology in a macro scale battery. Nanoscale batteries can be combined to function as a macrobattery such as within a nanopore battery.
A lithium-ion capacitor is a hybrid type of capacitor classified as a type of supercapacitor. It is called a hybrid because the anode is the same as those used in lithium-ion batteries and the cathode is the same as those used in supercapacitors. Activated carbon is typically used as the cathode. The anode of the LIC consists of carbon material which is often pre-doped with lithium ions. This pre-doping process lowers the potential of the anode and allows a relatively high output voltage compared to other supercapacitors.
The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this fuel cell glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but a few.
A solid oxide electrolyzer cell (SOEC) is a solid oxide fuel cell that runs in regenerative mode to achieve the electrolysis of water by using a solid oxide, or ceramic, electrolyte to produce hydrogen gas and oxygen. The production of pure hydrogen is compelling because it is a clean fuel that can be stored, making it a potential alternative to batteries, methane, and other energy sources. Electrolysis is currently the most promising method of hydrogen production from water due to high efficiency of conversion and relatively low required energy input when compared to thermochemical and photocatalytic methods.
In electrochemistry, a thermogalvanic cell is a kind of galvanic cell in which heat is employed to provide electrical power directly. These cells are electrochemical cells in which the two electrodes are deliberately maintained at different temperatures. This temperature difference generates a potential difference between the electrodes. The electrodes can be of identical composition and the electrolyte solution homogeneous. This is usually the case in these cells. This is in contrast to galvanic cells in which electrodes and/or solutions of different composition provide the electromotive potential. As long as there is a difference in temperature between the electrodes a current will flow through the circuit. A thermogalvanic cell can be seen as analogous to a concentration cell but instead of running on differences in the concentration/pressure of the reactants they make use of differences in the "concentrations" of thermal energy. The principal application of thermogalvanic cells is the production of electricity from low-temperature heat sources. Their energetic efficiency is low, in the range of 0.1% to 1% for conversion of heat into electricity.
