Influence of Switching on the Aging of High Power Lithium-Ion Cells

Round 1

Reviewer 1 Report

General comment and recommendation

This paper deal with the influence of the multilevel inverter, which is an interesting approach to replace the bidirectional AC/DC-converter, to the battery lifetime. The focus is on 18650 cell (Samsung 25R). The baseline for the testing is represented by eight reference tests with continuous current flow performed at the average and the maximum current for charge and discharge respectively.

The paper addressed the open question on whether the switching has a negative impact on the battery lifetime. The authors concluded that the pulse cycling has an impact. It is observed a linear-like capacity fade and a linear-like increase of pulse resistance for all aging protocols. In addition, the switching during charging seems to have rather positive effect on the aging behavior of the anode in terms of SEI-resistance increase.

 

Specific comments

Please specify the current for the C-rate.

Please specify the equivalent circuit for the EIS, which in turn gives data of Fig. 9.

Author Response

"Please see the attachment." 

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript researches the influence of switching on the aging of high power lithium-ion cells. The main comments are as follows:
1. The topology and principle of multilevel inverters should be introduced at the beginning of the manuscript.
2. High switching frequency will cause the battery temperature to rise, which will exacerbate battery aging. The authors can test the temperature change.
3. What is the basis for the author to choose the switching frequency of 50Hz and 10kHz? The power switches rarely operate at 50Hz.

Author Response

"Please see the attachment." 

Author Response File: Author Response.docx

Reviewer 3 Report

The paper presents the evaluation of the influence of pulsed cycling on the aging of a high power lithium-ion cell. The following comments are for the authors of the paper.

1. In the keywords, is 18650 suppose to be listed since it is a figure?
2. Some acronyms were not spelled out the first time they appeared in the paper, e.g., DOD.
3. As part of the theory, the VI or VT characteristics of the battery should be presented.
4. Also, the mathematical dynamics of the operation of the battery is required.
5. Figure 1 shows the check-up test for the aging. How could this be related to the nominal operation of the battery without considering aging? 
6. A set up model was given in Figure 2, however, the mathematical formulations and analysis of the control topology were not presented to boost the theory of the paper.
7. What factors are likely to affect the aging of the battery apart from those discussed in the text? 
8.  The paper has some grammatical errors. In the conclusion is it who or which are more sensitive? 

Author Response

"Please see the attachment." 

Author Response File: Author Response.docx

Reviewer 4 Report

This is an interesting manuscript, with a lot of work done.

So, if this reviewer understands the work properly, the affect of switching on the aging is minimal. This is good and it could be ascribed as strength of the Li-ion battery. When the state of charge is well between 0 - 100%, the battery functions solely on insertion/extraction of Li ion and the contribution of capacitor is minimum.

This reviewer is interested to know that when the battery is near full state of charge (for example, most 12 V SLI batteries do - and if they are Li-ion), what could be the outcome of the research? Similarly, when the SoC is near 0%, what could be the outcome?

Also, the studies are conducted after conditioning the batteries for few cycles (if this reviewer understands it right), the batteries are technically new. What would be the outcome of this research on the batteries which have been using, for example, 1000 cycles?

Overall, this reviewer support the publication of this manuscript.

Author Response

"Please see the attachment."

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Accept. Though the authors did not answer some of the earlier queries.

Comment 4: The theory of the paper is quite weak. The mathematical modeling of the lithium-ion cells is required.
Comment 5: Scenarios with and without aging of the cells for the voltage and current variables should be displayed.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf