Electrodes: Anode and Cathode Quiz
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Questions and Answers

What is the primary advantage of lead-acid batteries in backup power applications?

  • Ability to recharge quickly (correct)
  • High energy storage capacity
  • Low weight
  • High voltage output

    • What happens if a lead-acid battery is left in a partially charged condition?

  • It may experience sulfation (correct)
  • It will improve its energy density
  • It will have increased voltage output
  • It becomes more efficient

    • What is the typical voltage provided by a standard car battery?

  • 48 V
  • 12 V (correct)
  • 6 V
  • 24 V

    • How does the concentration of sulfuric acid affect the performance of a lead-acid battery?

    <p>Decreased concentrations lead to less cell potential</p> Signup and view all the answers

    What is a significant disadvantage of lead-acid batteries in terms of weight?

    <p>Their energy storage to weight ratio is low</p> Signup and view all the answers

    What defines the voltage efficiency of a lead-acid battery?

    <p>Average voltage during discharge divided by average voltage during charge</p> Signup and view all the answers

    What might limit the total number of recharges a lead-acid battery can undergo?

    <p>Design and operational conditions</p> Signup and view all the answers

    What is the average range of recharges possible for lead-acid batteries?

    <p>300 to 1500</p> Signup and view all the answers

    What is a significant disadvantage of NiMH batteries compared to newer battery chemistries?

    <p>Limited rapid charging</p> Signup and view all the answers

    Which of the following is NOT an application of NiMH batteries?

    <p>Grid storage</p> Signup and view all the answers

    In the construction of Li-ion batteries, which component acts as the anode?

    <p>Graphite</p> Signup and view all the answers

    What happens to lithium at the anode during discharging in a Li-ion battery?

    <p>It is deintercalated into the electrolyte</p> Signup and view all the answers

    Which electrolyte is commonly used in lithium-ion batteries?

    <p>Inert polar dry ether or carbonate</p> Signup and view all the answers

    What is the primary function of the transition metal oxide in a Li-ion battery?

    <p>Intercalate lithium ions</p> Signup and view all the answers

    What is emphasized by the term 'lithium ion' in lithium-ion batteries?

    <p>Absence of lithium metal</p> Signup and view all the answers

    Which reaction occurs at the cathode of a Li-ion battery?

    <p>Lithium intercalation into CoO2</p> Signup and view all the answers

    What is the chemical representation of lithiated graphite?

    <p>LixC6</p> Signup and view all the answers

    Which material typically serves as the cathode during the discharge of a lithium-ion battery?

    <p>Cobalt dioxide</p> Signup and view all the answers

    What is the main advantage of lithium-ion batteries compared to nickel-cadmium batteries?

    <p>Longer cycle life</p> Signup and view all the answers

    What occurs during the discharge of a lithium-ion battery?

    <p>Lithium ions are extracted from the anode</p> Signup and view all the answers

    Which of the following is a limitation of lithium-ion batteries?

    <p>High cost</p> Signup and view all the answers

    What is the self-discharge rate of lithium-ion batteries per month?

    <p>10%</p> Signup and view all the answers

    How does the average voltage of a lithium-ion battery compare to nickel-cadmium cells?

    <p>Equivalent to three Ni-Cd cells</p> Signup and view all the answers

    What is a main advantage of sodium-ion batteries over lithium-ion batteries?

    <p>Abundant raw material availability</p> Signup and view all the answers

    Which characteristic is desirable for the cathode in an electrochemical cell?

    <p>High redox potential</p> Signup and view all the answers

    What does a greater difference between the cathode and anode electrical potentials indicate?

    <p>Higher cell potential</p> Signup and view all the answers

    Which of the following statements about the anode is true?

    <p>It should have a low redox potential.</p> Signup and view all the answers

    What is a necessary characteristic of the electrolyte in a battery?

    <p>Nonreactivity with electrodes</p> Signup and view all the answers

    What is one advantage of solid polymeric electrolytes?

    <p>High energy density</p> Signup and view all the answers

    Which of the following is true regarding liquid electrolytes?

    <p>They operate well in low temperatures.</p> Signup and view all the answers

    What role does the standard potential play in an electrochemical cell?

    <p>It determines the voltage of the battery.</p> Signup and view all the answers

    What is a disadvantage of solid polymeric electrolytes?

    <p>Low ionic conductivities at room temperature</p> Signup and view all the answers

    What is a main advantage of sodium-ion batteries compared to lithium-ion batteries?

    <p>Greater availability of materials</p> Signup and view all the answers

    Which component in a lead-acid battery acts as the electrolyte?

    <p>Sulfuric acid solution (H2SO4)</p> Signup and view all the answers

    During discharge, what happens to lead atoms at the anode?

    <p>They lose electrons and become Pb2+ ions</p> Signup and view all the answers

    What are the reducing and oxidizing agents in a lead-acid battery?

    <p>Lead (Pb) and sulfate ions (SO42-)</p> Signup and view all the answers

    What type of cell is a lead-acid battery classified as due to its electrolyte?

    <p>Wet cell</p> Signup and view all the answers

    What is the overall chemical reaction during the discharge of a lead-acid battery?

    <p>Pb(s) + PbO2(s) + 4H+(aq) + 2SO42−(aq) → 2PbSO4(s) + 2H2O(l)</p> Signup and view all the answers

    Which of the following is NOT an essential challenge for sodium-ion batteries to achieve commercial feasibility?

    <p>Color stability</p> Signup and view all the answers

    What is a likely application for sodium-ion batteries due to their characteristics?

    <p>Stationary energy storage systems</p> Signup and view all the answers

    Study Notes

    Electrodes (Anode and Cathode)

    • Electrochemical cells consist of two electrodes with differing standard reaction potentials.
    • The cathode absorbs electrons and has a more positive standard potential, while the anode loses electrons and has a more negative potential.
    • Selection criteria for electrodes include the cathode’s need for high redox potential, specific capacity, and stability; the anode requires low redox potential, high specific capacity, and good conductivity.
    • Cell potential is calculated as Ecell = Ecathode - Eanode; larger potential differences result in higher voltages.

    Electrolytes

    • Electrolytes can be liquid, solid, polymer, or hybrid, requiring high ionic conductivity and non-reactivity with electrodes.
    • Traditional liquid electrolytes are low viscosity, high energy density, and operate between -40 °C and 60 °C, ensuring safety against flammability.
    • Solid polymer electrolytes offer flexibility and stability but usually have low ionic conductivity.

    Sodium-Ion Batteries

    • Sodium-ion batteries present a cost-effective alternative to lithium-ion batteries, leveraging the abundance of sodium minerals.
    • They are generally less energy-dense than lithium-ion batteries but suitable for stationary energy storage where cost-effectiveness is favored.
    • Research is ongoing to overcome limitations and enhance their commercial viability.

    Lead Acid Battery (Lead Accumulator)

    • Constructed with lead grids maximizing electrode surface area; anode is spongy lead, and cathode is lead dioxide, both submerged in sulfuric acid electrolyte.
    • The design allows the battery to function without separate compartments due to solid oxidizing and reducing agents kept apart by insulators.
    • The battery functions as a wet cell, crucial for backup power applications due to its reliability during outages.

    Discharging Reactions in Lead Acid Battery

    • At the anode: lead oxidizes to produce lead ions and electrons.
    • At the cathode: lead dioxide reduces and combines with hydrogen ions and electrons to form lead sulfate and water.
    • Overall discharge reaction involves lead, lead dioxide, and sulfate ions forming lead sulfate and water.

    Performance and Efficiency of Lead Acid Batteries

    • Voltage efficiency approximates 80%, allowing for effective charge and discharge.
    • Cycle longevity varies widely, with potential for over 2000 recharge cycles in sealed variants.
    • Typical voltage output of a car battery is 12V, capable of delivering high current without damage.

    Advantages and Disadvantages of Lead Acid Batteries

    • Highly efficient with minimal internal self-discharge.
    • Vulnerable to sulfation if left partially charged, risking damage.
    • Heavy weight limits energy storage to weight ratio, averaging around 35 Wh/kg.
    • Concentration of sulfuric acid decreases during discharge, affecting cell potential.

    Nickel-Metal Hydride (NiMH) Batteries

    • NiMH batteries are limited by lower voltage outputs compared to newer battery technologies, affecting compatibility.
    • They find application in consumer electronics, medical devices, hybrid vehicles, and renewable energy storage.

    Lithium-Ion (Li-Ion) Batteries

    • Composed of lithium-carbide intercalates as anodes and transition metal oxides as cathodes, typically using lithium salts as electrolytes.
    • Offers high energy density (150 Wh/kg) and long cycle life (400-1200 cycles).
    • Engineered for safety, mitigating risks linked with lithium metal reactivity, and can charge quickly without fully depleting.

    Limitations of Lithium-Ion Batteries

    • Experience self-discharge rates around 10% monthly and poor charge retention.
    • Higher production costs limit widespread accessibility.

    Emerging Alternatives: Sodium-Ion Batteries

    • Sodium-ion batteries leverage the abundant sodium element, posing a sustainable alternative to lithium-ion technologies.

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    Description

    Test your knowledge of electrochemical cells and the roles of anodes and cathodes. This quiz will explore the concepts of standard reaction potentials and the selection of materials for electrodes. Perfect for students studying electrochemistry.

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