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Ch.20 - Electrochemistry
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.20 - ElectrochemistryProblem 80b
Chapter 20, Problem 80b

Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries. (b) Which material has a higher percentage of lithium? Does this help to explain why batteries made with LiMn2O4 cathodes deliver less power on discharging?

Verified step by step guidance
1
insert step 1> Calculate the molar mass of LiMn_2O_4 by adding the atomic masses of lithium (Li), manganese (Mn), and oxygen (O).
insert step 2> Calculate the molar mass of LiCoO_2 by adding the atomic masses of lithium (Li), cobalt (Co), and oxygen (O).
insert step 3> Determine the percentage of lithium in LiMn_2O_4 by dividing the atomic mass of lithium by the molar mass of LiMn_2O_4 and multiplying by 100.
insert step 4> Determine the percentage of lithium in LiCoO_2 by dividing the atomic mass of lithium by the molar mass of LiCoO_2 and multiplying by 100.
insert step 5> Compare the percentages of lithium in both compounds to determine which has a higher percentage of lithium, and discuss how this relates to the power delivery of the batteries.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Lithium Content in Cathodes

The lithium content in a cathode material is crucial for determining the energy capacity and performance of a lithium-ion battery. LiMn2O4 contains less lithium per formula unit compared to LiCoO2, which affects the overall energy density of the battery. Understanding the stoichiometry of these compounds helps in evaluating their efficiency and power delivery.
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Battery Power Delivery

The power delivery of a battery is influenced by its internal resistance and the rate at which lithium ions can move between the anode and cathode. LiMn2O4, while being more stable and safer, has a lower conductivity compared to LiCoO2, which can lead to reduced power output during discharge. This relationship between material properties and performance is essential for battery design.
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Electrochemical Properties of Cathode Materials

The electrochemical properties of cathode materials, such as voltage, capacity, and stability, play a significant role in battery performance. LiCoO2 typically offers higher voltage and energy density, making it suitable for applications requiring high power. In contrast, LiMn2O4, while safer and more environmentally friendly, may sacrifice some of these properties, leading to lower power delivery.
Related Practice
Textbook Question

In some applications nickel–cadmium batteries have been replaced by nickel–zinc batteries. The overall cell reaction for this relatively new battery is: 2 H2O(l) + 2 NiO(OH)(s) + Zn(s) → 2 Ni(OH)2(s) + Zn(OH)2(s) (c) A single nickel–cadmium cell has a voltage of 1.30 V. Based on the difference in the standard reduction potentials of Cd2+ and Zn2+, what voltage would you estimate a nickel–zinc battery will produce? (d) Would you expect the specific energy density of a nickel–zinc battery to be higher or lower than that of a nickel–cadmium battery?

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Textbook Question

Li-ion batteries used in automobiles typically use a LiMn2O4 cathode in place of the LiCoO2 cathode found in most Li-ion batteries. (a) Calculate the mass percent lithium in each electrode material.

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Textbook Question

(a) Which reaction is spontaneous in the hydrogen fuel cell: hydrogen gas plus oxygen gas makes water, or water makes hydrogen gas plus oxygen gas?

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