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Questions and Answers
What is the primary advantage of lead-acid batteries in backup power applications?
What happens if a lead-acid battery is left in a partially charged condition?
What is the typical voltage provided by a standard car battery?
How does the concentration of sulfuric acid affect the performance of a lead-acid battery?
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What is a significant disadvantage of lead-acid batteries in terms of weight?
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What defines the voltage efficiency of a lead-acid battery?
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What might limit the total number of recharges a lead-acid battery can undergo?
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What is the average range of recharges possible for lead-acid batteries?
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What is a significant disadvantage of NiMH batteries compared to newer battery chemistries?
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Which of the following is NOT an application of NiMH batteries?
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In the construction of Li-ion batteries, which component acts as the anode?
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What happens to lithium at the anode during discharging in a Li-ion battery?
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Which electrolyte is commonly used in lithium-ion batteries?
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What is the primary function of the transition metal oxide in a Li-ion battery?
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What is emphasized by the term 'lithium ion' in lithium-ion batteries?
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Which reaction occurs at the cathode of a Li-ion battery?
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What is the chemical representation of lithiated graphite?
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Which material typically serves as the cathode during the discharge of a lithium-ion battery?
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What is the main advantage of lithium-ion batteries compared to nickel-cadmium batteries?
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What occurs during the discharge of a lithium-ion battery?
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Which of the following is a limitation of lithium-ion batteries?
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What is the self-discharge rate of lithium-ion batteries per month?
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How does the average voltage of a lithium-ion battery compare to nickel-cadmium cells?
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What is a main advantage of sodium-ion batteries over lithium-ion batteries?
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Which characteristic is desirable for the cathode in an electrochemical cell?
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What does a greater difference between the cathode and anode electrical potentials indicate?
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Which of the following statements about the anode is true?
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What is a necessary characteristic of the electrolyte in a battery?
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What is one advantage of solid polymeric electrolytes?
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Which of the following is true regarding liquid electrolytes?
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What role does the standard potential play in an electrochemical cell?
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What is a disadvantage of solid polymeric electrolytes?
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What is a main advantage of sodium-ion batteries compared to lithium-ion batteries?
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Which component in a lead-acid battery acts as the electrolyte?
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During discharge, what happens to lead atoms at the anode?
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What are the reducing and oxidizing agents in a lead-acid battery?
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What type of cell is a lead-acid battery classified as due to its electrolyte?
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What is the overall chemical reaction during the discharge of a lead-acid battery?
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Which of the following is NOT an essential challenge for sodium-ion batteries to achieve commercial feasibility?
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What is a likely application for sodium-ion batteries due to their characteristics?
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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.