Name: primary, rechargeable batteries and fuel cells
Uploaded: 2020-09-24T15:06:52.000Z
Duration: 3 min 12 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Physical Science

Forces and Interactions

3.2.9-12.M

Batteries and Fuel Cells

Las baterías son celdas voltaicas que se utilizan como fuentes eléctricas portátiles. Se clasifican en baterías primarias o no recargables y secundarias o recargables. La batería principal común es la batería seca.Contiene una caja de zinc como ánodo y un cátodo de grafito sumergido en una pasta electrolítica ácida y húmeda de óxido de manganeso y cloruro de amonio. El zinc se oxida en cloruro de zinc, y el óxido de manganeso se reduce a óxido de manganeso sólido generando un potencial de 1, 5 voltios. Cuando funcionan, los electrodos se agotan, lo que hace que las baterías se sequen de un solo uso.Las baterías alcalinas son similares, pero utilizan un electrolito alcalino que prolonga su vida útil y de almacenamiento. Las baterías de plomo-ácido son baterías secundarias que se utilizan principalmente en automóviles. Por lo general, tienen seis celdas electroquímicas conectadas en serie, que generan un potencial total de 12 voltios.Cada celda tiene un ánodo de plomo y un cátodo de óxido de plomo sumergido en ácido sulfúrico. Durante la descarga, las reacciones redox depositan sulfato de plomo sólido en ambos en electrodos, que se vuelven a convertir durante la recarga mediante el uso de una fuente de alimentación externa. Las baterías recargables de níquel-cadmio contienen un cátodo de oxihidróxido de níquel, un ánodo de cadmio, y un electrolito de hidróxido de potasio.Cuando funcionan, el ánodo se oxida a hidróxido de cadmio sólido, y el cátodo se reduce a hidróxido de níquel sólido, generando un potencial de celda de 1, 3 voltios. Sin embargo, la toxicidad del cadmio lleva al reemplazo de las baterías de níquel-cadmio por baterías de hidruro metálico de níquel ecológicas. Aquí, el cátodo sigue siendo el mismo, pero el ánodo es una aleación que absorbe hidrógeno.La reacción anódica implica la formación de agua a partir de hidrógeno. Las baterías de iones de litio son las baterías secundarias más nuevas. El metal de litio liviano hace que estas baterías sean portátiles con alta densidad de energía.Una batería de iones de litio contiene un ánodo de grafito litiado y un cátodo de óxido de metal de transición de litio. Cuando se carga, el metal de transición se oxida, mientras que los iones de litio se incorporan entre las capas de grafito anódico. Tras la descarga, los iones de litio fluyen del ánodo al cátodo generando un potencial de 3, 7 voltios.Por último, las baterías de combustible son baterías voltaicas que requieren un suministro externo continuo de reactivos redox para la producción de energía. Una batería de combustible de hidrógeno típica utiliza hidrógeno y oxígeno del aire para generar una corriente mientras emite agua. Los electrodos de grafito contienen catalizadores a base de platino para acelerar la reacción redox.

baterias y celdas de combustible

Una batería es una celda galvánica que se utiliza como fuente de energía eléctrica para aplicaciones específicas. Las baterías modernas existen en una multitud de formas para adaptarse a diversas aplicaciones, desde diminutas baterías de botón como las que alimentan relojes de pulsera hasta las baterías más grandes utilizadas para suministrar energía de reserva a las redes eléctricas municipales. Algunas baterías están diseñadas para aplicaciones de un solo uso y no se pueden recargar (celdas primarias), mientras que otras se basan en reacciones de celda convenientemente reversibles que permiten la recarga mediante una fuente de alimentación externa (celdas secundarias).
 Baterías de un solo uso (primarias)
 Una celda seca es una batería principal común que utiliza zinc como contenedor y ánodo (terminal “–”) y una varilla de grafito como cátodo (terminal “+”). La lata de Zn se llena con una pasta electrolítica que contiene óxido de manganeso (IV), cloruro de zinc (II), cloruro de amonio y agua. Una varilla de grafito se sumerge en la pasta electrolítica para completar la celda. La reacción de celda espontánea implica:
 <img alt="Eq1" src="/files/ftp_upload/11439/11439_Equation_1.png" style="text-align: center; height: 168px;" />
 El voltaje (potencial de celda) de una celda seca es de aproximadamente 1,5 V (Ecelda ~ 1,5 V). Las celdas secas están disponibles en varios tamaños (por ejemplo, D, C, AA, AAA). Todos los tamaños de celdas secas comprenden los mismos componentes y presentan el mismo voltaje, pero las celdas más grandes contienen mayores cantidades de reactivos redox y, por lo tanto, son capaces de transferir cantidades de carga proporcionalmente mayores. Al igual que otras celdas galvánicas, las celdas secas se pueden conectar en serie para producir baterías con mayores salidas de voltaje, si es necesario. 
 Las baterías alcalinas fueron diseñadas alrededor de las mismas parejas redox que la celda seca. Como su nombre lo indica, estos tipos de baterías utilizan electrolitos alcalinos, a menudo hidróxido de potasio. Las reacciones son
 <img alt="Eq2" src="/files/ftp_upload/11439/11439_Equation_2.png" style="text-align: center; height: 130px;" />
 Una pila alcalina puede suministrar entre tres y cinco veces la energía de una pila seca de tamaño similar (Ecelda = +1,43 V). Las baterías alcalinas son propensas a fugas de hidróxido de potasio, por lo que deben retirarse de los dispositivos para su almacenamiento a largo plazo. Aunque algunas pilas alcalinas son recargables, la mayoría no lo son.
 Baterías recargables (secundarias)
 Las baterías de níquel-cadmio, o NiCd, constan de un cátodo chapado en níquel, un ánodo chapado en cadmio y un electrodo de hidróxido de potasio. Las placas positiva y negativa, las cuales el separador evita que hagan cortocircuito, se enrollan juntas y se colocan en la caja. Este diseño permite que la celda NiCd proporcione mucha más corriente que una pila alcalina de tamaño similar. Las reacciones son
 <img alt="Eq3" src="/files/ftp_upload/11439/11439_Equation_3.png" style="text-align: center; height: 130px;" />
 Si se trata correctamente, una batería NiCd puede recargarse unas 1000 veces (Ecelda ~ 1,3 V). El cadmio es un metal pesado tóxico, por lo que las baterías de NiCd nunca deben romperse ni incinerarse, y deben desecharse de acuerdo con las directrices pertinentes acerca de residuos tóxicos.
 Las baterías de iones de litio se encuentran entre las baterías recargables más populares y se utilizan en muchos dispositivos electrónicos portátiles. Las reacciones son
 <img alt="Eq4" src="/files/ftp_upload/11439/11439_Equation_4.png" style="text-align: center; height: 130px;" />
 La estequiometría variable de la reacción de celda conduce a la variación en los voltajes de celda, pero para condiciones típicas, x no suele ser superior a 0,5, y el voltaje de celda es de aproximadamente 3,7 V (Ecelda ~ 3,7). Las baterías de litio son populares porque pueden proporcionar una gran cantidad de corriente, son más ligeras que los otros tipos de baterías comparables, producen un voltaje casi constante a medida que se descargan y sólo pierden lentamente su carga al estar almacenadas. 
 La batería de plomo-ácido es también un tipo de batería secundaria que se usa comúnmente en los automóviles. Es económica y capaz de producir la alta corriente requerida por los motores de arranque de los automóviles. Las reacciones para una batería de plomo-ácido son
 <img alt="Eq5" src="/files/ftp_upload/11439/11439_Equation_5.png" style="text-align: center; height: 160px;" />
 Cada celda produce 2 V (Ecelda ~ 2 V), por lo que seis celdas se conectan en serie para producir una batería de automóvil de 12 V. Las baterías de plomo-ácido son pesadas y contienen un electrolito líquido cáustico, H2SO4 (ac), pero a menudo siguen siendo la batería de elección debido a su alta densidad de corriente. Puesto que estas baterías contienen una cantidad significativa de plomo, siempre deben desecharse correctamente.
 Celdas de combustible
 Una celda de combustible es una celda galvánica que utiliza combustibles tradicionales, más a menudo hidrógeno o metano, que son continuamente alimentados en la celda junto con un oxidante. Dentro de la celda, el combustible y el oxidante experimentan la misma química redox que cuando están en combustión, pero a través de un electroquímico catalizado que es perceptiblemente más eficiente. Por ejemplo, una típica celda de combustible de hidrógeno utiliza electrodos de grafito incrustados con catalizadores a base de platino para acelerar las dos reacciones de semi-celda:
 <img alt="Eq6" src="/files/ftp_upload/11439/11439_Equation_6.png" style="text-align: center; height: 130px;" />
 Estos tipos de pilas de combustible suelen producir voltajes de aproximadamente 1,23 V (Ecelda ~ 1,23 V). En comparación con un motor de combustión interna, la eficiencia energética de una celda de combustible que utiliza la misma reacción redox suele ser más del doble (~20%–25% para un motor frente a ~50%–75% para una celda de combustible). Las celdas de combustible de hidrógeno se utilizan comúnmente en misiones espaciales extendidas, y se han desarrollado prototipos para vehículos personales.
 Este texto es adaptado de <a href="https://openstax.org/books/chemistry-2e/pages/17-5-batteries-and-fuel-cells"> Openstax, Química 2e, Sección 17.5: Baterías y Celdas de Combustible. </a>

Baterias y Celdas de Combustible

Una batería es una celda galvánica que se utiliza como fuente de energía eléctrica para aplicaciones específicas. Las baterías modernas existen en una multitud de formas para ...

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primary, rechargeable batteries and fuel cells

Batteries and fuel cells are galvanic cells that supply electrical power for many applications. They range from tiny button batteries in wristwatches to large systems that can provide backup energy to municipal power grids. Some are primary cells, which are single-use and cannot be recharged. Others are secondary cells, which use reversible reactions and can be charged again by an external power source.

A common primary battery is the dry cell. It uses zinc as both the container and the anode, or negative terminal, and a graphite rod as the cathode, or positive terminal. The zinc can holds an electrolyte paste with manganese(IV) oxide, zinc(II) chloride, ammonium chloride, and water. A dry cell has a voltage of about 1.5 V. It comes in sizes such as D, C, AA, and AAA. These sizes use the same parts and the same voltage, but larger cells contain more reactants and can transfer more charge. Dry cells can also be connected in series to increase voltage.

Alkaline batteries use the same redox couples as dry cells, but they use an alkaline electrolyte, often potassium hydroxide. They can deliver about three to five times the energy of a dry cell of similar size and have a cell potential of about 1.43 V. These batteries can leak potassium hydroxide, so they should be removed from devices during long-term storage. Some alkaline batteries are rechargeable, but most are not.

Rechargeable batteries include nickel-cadmium, or NiCd, batteries, lithium-ion batteries, and lead-acid batteries. A NiCd battery has a nickel-plated cathode, a cadmium-plated anode, and a potassium hydroxide electrode. The positive and negative plates are rolled together with a separator to keep them from shorting. This design lets a NiCd cell deliver much more current than a similar-sized alkaline battery. When treated properly, it can be recharged about 1000 times, and its cell potential is about 1.3 V. Cadmium is toxic, so NiCd batteries should not be ruptured or burned and must be disposed of as toxic waste.

Lithium-ion batteries are widely used in portable electronic devices. Their reaction has variable stoichiometry, so the voltage can vary, but under typical conditions the cell potential is about 3.7 V. These batteries are popular because they can provide a large amount of current, are lighter than comparable batteries of other types, and keep a nearly constant voltage as they discharge. They also lose charge slowly during storage. Lead-acid batteries are common in automobiles. They are inexpensive and can deliver the high current needed by starter motors. Each cell produces 2 V, so six cells are connected in series to make a 12-V car battery. These batteries are heavy and contain a caustic sulfuric acid electrolyte, and they also contain a significant amount of lead, so they must be disposed of properly.

A fuel cell is also a galvanic cell, but it uses a fuel that is continuously fed into the cell along with an oxidant. The fuel is often hydrogen or methane. Inside the cell, the same redox chemistry that occurs in combustion is carried out by a catalyzed electrochemical process that is much more efficient. A typical hydrogen fuel cell uses graphite electrodes with platinum-based catalysts to speed the half-cell reactions. These fuel cells usually produce about 1.23 V. Compared with an internal combustion engine, a fuel cell using the same redox reaction is typically more than twice as efficient. Hydrogen fuel cells are used on extended space missions, and prototypes for personal vehicles have been developed.

Primary, Rechargeable Batteries and Fuel Cells

primary-rechargeable-batteries-and-fuel-cells

balancing redox equations

Redox Reactions and Half-Reaction Balancing

Redox reactions involve electron transfer and changes in oxidation number. In electrochemistry, these reactions connect chemical changes with electrical energy. They also power technologies such as industrial metal processing and rechargeable batteries used in electric vehicles. Oxidation number is a way to track how an atom's electronic environment changes compared with the pure element, where the oxidation number is zero. For a simple ionic compound, the oxidation number matches the ion...

electromotive force

Cell Voltage and Electron Flow

Electric current is the flow of electric charge through a conducting medium or a solution. In wires, that charge is carried by electrons. In some solutions, ions can also move and carry charge. When electrons move through a wire, they produce an electric current. This idea connects to redox reactions, where electrons are lost and gained. In the spontaneous reaction between zinc and copper ions, zinc is oxidized to zinc ions. Copper ions are reduced to solid copper. Even so, this direct...

voltaic/galvanic cells

Galvanic Cells and Battery Reactions

Galvanic cells use spontaneous redox reactions to produce electric current. A common example is a disposable AA battery, which powers devices by turning chemical energy into electrical energy. Another example is a copper wire placed in silver nitrate solution, where the solution slowly turns bright blue and a grey solid forms on the wire. In the copper and silver reaction, copper is oxidized and silver ions are reduced. Copper forms cuprous ions, which give the solution its blue color. At the...

standard electrode potentials

Using Electrode Potentials to Predict Reactions

Electrode potentials help predict whether a redox reaction will happen on its own. A redox reaction involves electron transfer. In electrochemistry, the measured value is called cell potential or cell voltage. It shows the energy linked to charge transfer and is measured in volts, where 1 volt equals 1 joule per coulomb. A single half-cell cannot be measured by itself because electron transfer needs both a donor and a receiver. For that reason, scientists measure the difference between two...

cell potential and free energy

Redox Cell Potential, ΔG°, and K

Redox cell potential connects chemical energy, free energy change, and the equilibrium constant in an electrochemical cell. In these reactions, chemical energy is converted into electrical energy. That link helps predict whether a reaction is spontaneous and how far it may proceed. Thermodynamics is the study of how heat and other forms of energy are related. In an electrochemical cell, cell potential can also reflect oxidizing strength or reducing strength. A similar idea appears in acid-base...

the nernst equation

Cell Potential Under Changing Conditions

Cell potential changes when a redox reaction does not run at standard conditions. Standard cell potentials connect with standard free energy change, ΔG°, and the equilibrium constant K, but those relationships only hold at 1 M concentration, 298 K, and 1 atmosphere. A zinc(II) and tin(II) redox cell with E°cell = +0.291 V and ΔG° = −56.2 kJ is spontaneous under those standard conditions. As a cell discharges, the reactant concentration changes and the cell potential steadily drops. Many redox...

concentration cells

Cell Potential from Concentration Differences

Concentration cells are voltaic cells that use two almost identical half-cells. The half-cells use the same electrode and the same half-reaction. They differ only in the concentration of one redox species, so the cell potential depends on that concentration difference. In a concentration cell, the Nernst equation can be used to find the cell potential. For the zinc example shown, the calculated cell potential is positive. A positive cell potential means the overall reaction is spontaneous. <br...

batteries and fuel cells

Batteries and fuel cells are galvanic cells that supply electrical power for many applications. They range from tiny button batteries in wristwatches to large systems that can provide backup energy to municipal power grids. Some are primary cells, which are single-use and cannot be recharged. Others are secondary cells, which use reversible reactions and can be charged again by an external power source. A common primary battery is the dry cell. It uses zinc as both the container and the anode,...

corrosion

Rusting and Metal Protection

Corrosion is the natural breakdown of metals through electrochemical reactions. It can appear as rust on iron, tarnish on silver, or a blue-green patina on copper. In each case, the metal is oxidized. Some corrosion products can protect the surface, while others keep damaging the metal. Rusting is the harmful type of corrosion seen in iron. It happens when iron is exposed to oxygen and water. A galvanic cell forms on the iron surface, and this drives oxidation at the anodic region and...

electrolysis

Electrolysis in Batteries and Metal Production

Electrolysis uses electrical energy to drive a nonspontaneous redox reaction. In a galvanic cell, a spontaneous redox reaction does electrical work on the surroundings by sending electrons through an external circuit. In electrolysis, an external circuit does work on the redox system by applying a voltage large enough to force the reaction in the opposite direction. This process is used in several real-world settings. Recharging a battery is one example, because an outside power source drives...

key terms and concepts

Explore dry cells, alkaline batteries, NiCd, lithium-ion, and lead-acid batteries, plus how hydrogen fuel cells turn fuel into electricity more efficiently.

Primary, Rechargeable Batteries and Fuel Cells | JoVE K12

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Motion And Stability: Forces And Interactions

HS-PS2-5

Physics

Arizona Science Standards

HS.P1

HS.P1U3.4

HS+Phy.P4

HS+Phy.P4U2.7

HS.P4

HS.P4U3.9

Alabama Course of Study Science

Matter and Its Interactions

9-12.PS.3.4

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Motion and Stability: Forces and Interactions

Texas Essential Knowledge and Skills

PHYS.6

PHYS.6.D

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South Carolina College and Career Ready Science Standards

Energy

P-PS3-3

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3.2.9-12.I

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3.2.9-12.J

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3.2.9-12.K

Gravitation

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Electric Charges

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Sources and Properties of Electric Charge

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Coulomb's Law

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The Principle of Superposition and the Gravitational Field

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Electric Field

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Magnetic Fields

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Magnetic Field due to Moving Charges

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Electromagnetic Fields

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Students who demonstrate understanding can use mathematical representations of Newton's Law of Gravitation and Coulomb's Law to describe and predict the gravitational and electrostatic forces between objects. Clarifying Statement: Emphasis is on both quantitative and conceptual descriptions of gravitational and electric fields. Assessment Boundry: Assessment is limited to systems with two objects.

3.2.9-12.L

Energy Transfer in Chemical Reactions

Chemical reactions require sufficient energy to cause the matter to collide with enough precision and force that old chemical bonds can be broken and new ...

A battery is a galvanic cell that is used as a source of electrical power for specific applications. Modern batteries exist in a multitude of forms to ...

Students who demonstrate understanding can plan and conduct an investigation to provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current. Clarifying Statement: N/A Assessment Boundry: Assessment is limited to designing and conducting investigations with provided materials and tools.

Primary, Rechargeable Batteries and Fuel Cells

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