Homework 3
ECE 777AE - Spring 2024
Due on March 20, 2024
1. Develop your own algorithm (Matlab preferred but not required) to calculate the dif-fusivity (D) using the Galvanostatic Intermittent Titration Technique (GITT) voltage profile presented in figure 1 for all the presented pulses (states of charge). The GITT data can be found in the file titled ”GITT SIB WTe2 cell.xlsx” attached to the assign-ment. Submit the source code you wrote.
Consider:
❼ τ = 900 s
❼ electrode volume = 0.075 cm3
❼ electrode surface area = 7.55 cm2
Figure 1: GITT of a sodium-ion battery where WTe2 is the active material.
2. Using the specification of the cell INR-21700-P42A (file titled ”INR21700.pdf” in the assignment), create a battery testing script using the blocks presented in appendix 1 to simulate the profile presented in the figure 2. Describe the tiles and values used in your test script.
Hint: Keep in mind that commonly in battery/cell testing the current is the input in the script while voltage is the output. You do not need to download the battery testing script software for this problem, you can present the testing tiles/blocks in your written submission.
Figure 2: An example of the charging profile with a CCCV step.
3. Consider the blocks presented in figure 3, from the Admiral Instruments software. Explain why is a CCCV step relevant when either charging or discharging a cell or battery?
Figure 3: CCVC tile in battery tester software.
4. Consider that a thin wire with diameter 5 mm and electronic conductivity 4.8 × 107 S m−1 . Assuming that the wire presents 1028 free electrons per cubic meter when an electric field of 12 mV m−1 is applied. Find:
(a) The current density.
(b) The charge density of free electrons.
(c) The current in the wire.