Battery Types and Operations Introduction

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Questions and Answers

Which of the following is NOT a requirement of a secondary battery?

Short time for a recharge

Long shelf-life in both charged & discharged conditions

High power to weight ratio

Compact and lightweight (correct)

What differentiates battery reactions from other oxidation/reduction processes?

The physical separation of the oxidation and reduction reactions (correct)

The interaction of gas rather than liquid components

The presence of the same chemical reactions occurring in parallel

The use of a single electrode for both reactions

Which component of a battery is primarily responsible for transferring electrons during the redox reaction?

Electrode (correct)

Separator

Insulator

Electrolyte

What type of reactions do lead-acid and alkaline batteries utilize in their operation?

Both oxidation and reduction reactions (C) Signup and view all the answers

What characteristic of a primary battery is emphasized in its requirements?

Economic and benign environmental properties (C) Signup and view all the answers

Which of the following correctly states a requirement for secondary batteries?

Must have a high energy density (D) Signup and view all the answers

In battery operation, the exchange of electrons corresponds to which of the following?

Current that passes through the load (D) Signup and view all the answers

What is the primary function of the electrolyte in a battery?

To allow the flow of charged ions between reactions (B) Signup and view all the answers

What must be minimized to derive maximum voltage from a battery?

Internal resistance of the cell (B) Signup and view all the answers

Which factor does not contribute to the capacity of a battery?

Electrode design (C) Signup and view all the answers

What is current a measure of in a battery system?

Rate of flow of electrons (C) Signup and view all the answers

In the expression for battery capacity, what does 'C' represent?

Charge in ampere hours (C) Signup and view all the answers

To achieve efficient discharge, which property of the electrolyte is preferred?

High conductance (A) Signup and view all the answers

What happens when a battery reaches its minimum voltage during discharge?

The battery is considered dead. (D) Signup and view all the answers

Which design consideration helps minimize internal resistance in a battery?

Keeping electrodes close to each other (D) Signup and view all the answers

What occurs to the viscosity of the electrolyte when the temperature decreases?

It increases. (C) Signup and view all the answers

What is the effect of overpotentials on battery performance?

They delay electrode reactions. (D) Signup and view all the answers

What may occur if a battery is overcharged?

Damage to the electrodes. (D) Signup and view all the answers

What is a primary cause of lead acid battery failure?

Corrosion of the lead grid. (D) Signup and view all the answers

Why should safety goggles be worn when working with batteries?

To protect against sulfuric acid exposure. (C) Signup and view all the answers

Which material is used for the positive electrode in nickel-metal hydride (NiMH) batteries?

Nickel hydroxide. (C) Signup and view all the answers

What distinguishes NiMH batteries in terms of energy density compared to Ni-Cd batteries?

NiMH batteries have approximately twice the energy density. (B) Signup and view all the answers

What is the main material used in the negative electrode of NiMH batteries?

Hydrogen-absorbing alloys. (A) Signup and view all the answers

How are the positive and negative plates arranged in cylindrical NiMH batteries?

Wound into a coil. (C) Signup and view all the answers

What happens to hydrogen in hydrogen-absorbing alloys during charge?

Hydrogen moves from the positive to the negative electrode. (B) Signup and view all the answers

Which type of alloy is particularly noted for its discharge efficiency and durability in battery applications?

AB5 type alloys (D) Signup and view all the answers

What is a key characteristic of nickel-metal hydride batteries during reactions?

There is no change in the electrolyte during reactions. (C) Signup and view all the answers

What happens to the cobalt ions during the charging process of the battery?

Cobalt ions are oxidized from the IV to III oxidation state. (A) Signup and view all the answers

What is the primary function of the hydrogen-absorbing alloy negative electrode?

To reduce gaseous oxygen during overcharge. (B) Signup and view all the answers

Which of the following is a major advantage of lithium-ion batteries compared to other types?

Designed to overcome safety problems associated with Lithium metal. (A) Signup and view all the answers

What distinguishes NiMH batteries from traditional nickel-cadmium batteries?

NiMH batteries provide higher energy density. (A) Signup and view all the answers

What is typically used as the electrolyte in nickel-metal hydride batteries?

Potassium hydroxide solution. (B) Signup and view all the answers

During discharge, what state do the lithium ions migrate to?

From the lithium graphite anode to the CoO2 cathode. (D) Signup and view all the answers

Which of the following is NOT a type of hydrogen-absorbing alloy mentioned?

AC3 (B) Signup and view all the answers

What is the average voltage equivalent of a lithium-ion battery compared to nickel-cadmium cells?

Equivalent to three Ni-Cd cells. (B) Signup and view all the answers

What is one significant limitation of lithium-ion batteries?

They have a high self-discharge rate of about 10% per month. (C) Signup and view all the answers

During the process of sealing a battery, what is maintained constant within the battery?

Internal pressure (C) Signup and view all the answers

Study Notes

Battery Types

Rechargeable batteries are also known as storage cells or accumulators, including lead-acid, nickel-cadmium, and lithium-ion batteries.

Requirements of Battery Types

Primary Batteries: Should be compact, lightweight, economical, have benign environmental properties, high energy density, longer shelf life, provide constant voltage, and long discharge periods.
Secondary Batteries: Need long shelf life in both charged and discharged conditions, longer cycle life, high power-to-weight ratio, quick recharge times, high voltage, and high energy density.

Basic Battery Operation

Batteries operate through electron exchange between oxidation and reduction reactions, which are physically separated to allow for a load to be connected.
The electrochemical potential difference corresponds to the battery voltage, while electron flow represents current.

Key Components

Must include electrodes (site of electron transfer) and electrolytes (medium for ion exchange).
Internal resistance, electrode materials, and electrolyte conductivity are critical for maximizing battery performance.

Cell Potential Equation

The battery voltage (cell potential) is calculated with the formula:
- Cell potential = (EC - EA) - |ηA - ηC| - i Rcell
Maximize voltage by ensuring high electrode potential difference, fast reaction rates, and low internal resistance.

Current and Capacity

Current reflects the uniform flow of electrons and is measured in amperes per second.
Battery capacity is measured in ampere-hours (Ah) and is influenced by the size, active material mass, and discharge conditions.

Safety Considerations

Electrolyte conductivity is crucial; decreased temperature raises viscosity and lowers potential.
Overcharging can damage electrodes and lead to explosions, necessitating safety precautions, especially when handling corrosive materials like sulfuric acid.

Nickel-Metal Hydride (NiMH) Batteries

Developed to provide higher energy densities and support sophisticated electronic devices.
Constructed with nickel hydroxide positive plates and hydrogen-absorbing alloys for the negative side.

Hydrogen-Absorbing Alloys

Capable of absorbing hydrogen up to a thousand times their volume while facilitating efficient charge and discharge cycles.
Classified into AB, AB2, AB5, and A2B types based on metal combinations.

NiMH Battery Characteristics

NiMH batteries offer about twice the energy density of Ni-Cd batteries with similar operating voltages.
Charging and discharging involve the movement of hydrogen ions without altering the electrolyte composition.

Advantages of NiMH Batteries

Higher energy density and capacity (1000mAh to 3000mAh).
Safer and environmentally friendly compared to older technologies.

Lithium-Ion Batteries

Designed to address safety issues related to lithium metal.
Long cycle life (400-1200 cycles) and greater energy density than nickel-based batteries.
Can recharge before full discharge, optimized for internal device charging.

Limitations of Lithium-Ion Batteries

Prone to poor charge retention with a self-discharge rate of approximately 10% per month.
Higher manufacturing costs compared to some alternatives.

Performance Comparison

A typical lithium-ion battery can store 150 watt-hours per kilogram, in contrast to lead-acid batteries' 25 watt-hours per kilogram.

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Description

Explore the different types of batteries, including primary and secondary batteries, and understand their requirements. This quiz will also cover the basic operation of batteries, focusing on key components such as electrodes and electrolytes. Test your knowledge on how batteries work and their applications.