Introduction to battery-management systems- COURSERA WEEK 02 QUIZ -1.2.2 ANSWERS

 

Introduction to battery-management systems- COURSERA WEEK 02  QUIZ -1.2.2 ANSWERS

Practice quiz for lesson 1.2.2

Total points 3

1.

Question 1

Which of the following statements are true concerning intercalation compounds? Select all that apply.

1 / 1 point

Lithium moves automatically from high-concentration regions of the compound to low-concentration regions of the compound via diffusion

Correct

Yes. This is the principal mechanism for lithium movement inside an electrode particle.

Lithium forms a strong chemical bond with the compound when it intercalates into its crystal structure

The compound must have an open crystal structure, allowing insertion or extraction of lithium ions in the vacant spaces

Correct

Yes. This is how lithium enters or exits the electrode.

When Li$^+$ enters the compound, the compound also must have an ability to accept compensating electrons from the external circuit

Correct

Yes. This is how electrical current flows.

2.

Question 2

In addition to the electrode materials themselves, what else might we expect to find in the positive-electrode region of a lithium-ion cell? Select all that apply.

1 / 1 point

Electrolyte.

Correct

Yes, the electrolyte permeates the cell, including the voids between the particles in the positive electrode.

Binders.

Correct

Yes. Binders such as polyvinylidene difluoride (PVDF) are often used to "glue together" particles so that the overall electrode structure does not disintegrate under the repeated stresses of cycling.

Conductive additives.

Correct

Yes. Many positive-electrode active materials do not conduct electron current very well, and so conductive additives such as carbon black are often added.

Electrolyte additives.

Correct

Yes. Proprietary compounds are often added to the electrolyte to improve performance and to slow down aging processes.

3.

Question 3

When discharging a lithium-ion cell, which of the following are true? Select all that apply.

1 / 1 point

Lithium diffuses from the center of a negative-electrode particle toward its surface

Correct

Yes. As lithium exits the surface of the particle, it creates a local low-concentration region. Then, lithium diffuses from the high-concentration region in the center of the particle toward the surface.

Lithium diffuses from the center of a positive-electrode particle toward its surface

Lithium at the surface of negative-electrode particles give up electrons and enter the electrolyte as Li$^+$ cations

Correct

Yes. During discharge, the negative electrode gives up electrons to the external circuit and corresponding cations to the electrolyte.

Lithium at the surface of positive-electrode particles give up electrons and enter the electrolyte as Li$^+$ cations

Li$^+$ cations diffuse through the electrolyte from high-concentration regions to low-concentration regions

Correct

Yes. In particular, Li$^+$ diffuses from the negative-electrode region toward the positive-electrode region.