Switched Discharge Device for Enhanced Energy Extraction from Li-Ion 18650
Round 1
Reviewer 1 Report
In this manuscript, “Switched discharge device for enhanced energy extraction from 2 Li-Ion 18650 “, the authors have demonstrated a charge/discharge and measurement device (Switched discharge device) based on ‘metal-oxide semiconductor field-effect transistors’ towards improved energy extraction from Li-ion batteries. A detailed investigation has been carried out with an example of Li-ion 18650 cell. Overall, this manuscript is suitable for publication in the topical collection (Advances in Battery Energy Storage and Applications) of the journal “Batteries”, after including the following corrections in the revised manuscript to further improve the quality.
1. The abbreviation of the terms should be written when they are introduced first in the manuscript. For example, the ‘metal-oxide semiconductor field-effect transistors’ should be written when it is abbreviated first at page 2 & line 66.
2. Overall figure quality should be improved in the revised manuscript (Figure 4 to 6). Professional plotting software such as Origin could be used to plot the data for better appearance.
3. In Figure 7, the various parts of the device should be indexed in the figure for the benefit of readers.
4. Figure A1 could be rearranged in a ‘Landscape’ orientation for better clarity.
5. The reference section of the manuscript is poor. The important & very relevant references should be included in the revised manuscript.
Author Response
- The abbreviation of the terms should be written when they are introduced first in the manuscript. For example, the ‘metal-oxide semiconductor field-effect transistors’ should be written when it is abbreviated first at page 2 & line 66.
A: We reviewed the full article and corrected the issue described.
- Overall figure quality should be improved in the revised manuscript (Figure 4 to 6). Professional plotting software such as Origin could be used to plot the data for better appearance.
A: We corrected the quality of the pictures in the revised manuscript and modified it based also on reviewer 2 request
- In Figure 7, the various parts of the device should be indexed in the figure for the benefit of readers.
A: The figure was modified as requested.
- Figure A1 could be rearranged in a ‘Landscape’ orientation for better clarity.
A: The figure was modified as requested.
- The reference section of the manuscript is poor. The important & very relevant references should be included in the revised manuscript.
A: The reference section has been updated.
Reviewer 2 Report
Overall, the paper has good analysis and experimental results. Below are few of my comments:
1) Abstract: What is EIS? All abbreviations must be expanded for the first time used in the paper.
2) Page 1, [Error! Reference 38 source not found.] need to have a reference.
3) Page 3, second paragraph, Is it EC-Lab software or Ec-Lab software? Must be consistent throughout the paper.
4) What is VSP, BMS? Check for all other abbreviations throughout the paper.
5) Is there a legend for Fig. 9?
6) Fig 11 must be of high resolution. Also, the legends and axis labels must be clear.
7) What is RDS in Table 5?
8) Section 4.1: Sentence must be reworded: “In terms of average power dissipation, two accumulators alternately switched at 1C and 50% duty-cycle is producing lower thermal dissipation than discharging continuously the same accumulators at 1C.”
Author Response
Overall, the paper has good analysis and experimental results. Below are few of my comments:
1) Abstract: What is EIS? All abbreviations must be expanded for the first time used in the paper.
A: Electrochemical Impedance Spectroscopy, abbreviation added in abstract.
2) Page 1, [Error! Reference 38 source not found.] need to have a reference.
A: The reference was corrected.
3) Page 3, second paragraph, Is it EC-Lab software or Ec-Lab software? Must be consistent throughout the paper.
A: EC-Lab software, issue corrected
4) What is VSP, BMS? Check for all other abbreviations throughout the paper.
A: VSP is the name of a tool (potentiostat) not an acronym. BMS is battery management system, was explained in the third row of introduction.
5) Is there a legend for Fig. 9?
A: Yes, at page9 of the revised manuscript
6) Fig 11 must be of high resolution. Also, the legends and axis labels must be clear.
A: Fig.11 has high resolution, we have expanded it's size to be visible.
7) What is RDS in Table 5?
A: (RDS) - drain-source MOSFET resistance during conduction, added to legend
8) Section 4.1: Sentence must be reworded: “In terms of average power dissipation, two accumulators alternately switched at 1C and 50% duty-cycle is producing lower thermal dissipation than discharging continuously the same accumulators at 1C.”
A: Rephrased as: Two accumulators alternately switched at 1C and 50% duty-cycle have lower thermal dissipation than the same accumulators discharged continuously at 1C.
Reviewer 3 Report
it is nice to see that a novel Li-Ion charge/discharge and measurement device using fast switching MOSFET was designed and fabricated. I have some minor suggestions:
1) i suggest that using "Battery"(or cell) instead of "accumulator" as the battery is more common in this kind of research.
2) the x-axis of Fig.4 and Fig.5 should use the logarthmic coordinate.
3) The reference should be fixed in page1 line 37
Author Response
1) I suggest that using "Battery"(or cell) instead of "accumulator" as the battery is more common in this kind of research.
A: The word “accumulator" was replaced with “battery” or “cell” except when discussing about banks of accumulators
2) the x-axis of Fig.4 and Fig.5 should use the logarthmic coordinate.
A: The figures were modified as requested in the revised manuscript
3) The reference should be fixed in page1 line 37
A: Reference was fixed.
Reviewer 4 Report
Surducan and co-workers investigated charge/discharge behaviour with continuous and discontinuous mode on lithium-ion 18650 cells. The relatively simple work illustrated that the battery capacity and performance under different pulsed modes (including in pulsed mode on one cell or in switching mode on two cells in parallel) showed more superior. However, the overall manuscript is rather like a practical report without further discussion on the difference in physical mechanisms that will be helpful for setting up charge/discharge protocols in further applications. Therefore, I would not recommend until the quality of the manuscript has been improved.
Formatting issues:
(1) In line 37: The reference database in Endnote was crashed (‘Error! Reference source not found.’)
(2) Reference 16: The website is no longer available. It would be helpful if authors summarise the specification of Panasonic NCR18650BF in a table in terms of:
(a) materials in cathode used (As the authors investigated only one specific type of Li-ion battery);
(b) rated capacity, capacity (minimum and typical) at particular conditions;
(c) nominal voltage;
(d) charging information (e.g., charging method, voltage and current) and discharging information.
Scientific issues:
(1) In Line 219: Could the authors comment on the increase of ohmic resistance R1 and connector resistance R2 with the increase of SOC, and the decrease of inductance L2 with the increase of SOC?
(2) In Line 259: Could the author explain the reasons of the disagreement on your calculated optimum frequency and practical specific frequency?
(3) In Figure 11: Could the author comment on the existence of a small second peak within the dead-band?
(4) In Figure 11: There is quite a long response time (dead-time) from ON to OFF mode (around 800 ns), but a very short response time (dead-time) from OFF to ON (around 100 ns). Could author provide more details on those?
Author Response
Formatting issues:
(1) In line 37: The reference database in Endnote was crashed (‘Error! Reference source not found.’)
A: The reference was corrected.
(2) Reference 16: The website is no longer available. It would be helpful if authors summarise the specification of Panasonic NCR18650BF in a table in terms of:
(a) materials in cathode used (As the authors investigated only one specific type of Li-ion battery);
(b) rated capacity, capacity (minimum and typical) at particular conditions;
(c) nominal voltage;
(d) charging information (e.g., charging method, voltage and current) and discharging information.
A: A new table has been added to the revised manuscript at page 4 with the battery specifications as requested. The link was also corrected.
Scientific issues:
(1) In Line 219: Could the authors comment on the increase of ohmic resistance R1 and connector resistance R2 with the increase of SOC, and the decrease of inductance L2 with the increase of SOC?
A: The Nyquist equivalent circuit can estimate the electrochemical behaviour of a variety of batteries. However, the accuracy of its parameters depends on the specific equivalent circuit used for parameters identification. The ohmic resistance R1 is one of the main parameters in battery analysis. Its increase is mostly due to the temperature rise that can occur in the cell [17]. Temperature rise will also affect the measurement system resistance R2. We associate the decreasing of L2 towards the end of discharge with a reduced electron flow that minimize the induced voltage effect. We also updated the manuscript in page 7 before figure6.
(2) In Line 259: Could the author explain the reasons of the disagreement on your calculated optimum frequency and practical specific frequency?
A: In literature, the optimum frequency corresponding to the minimum impedance is measured by EIS technique in which a small perturbation sinusoidal signal is applied to the battery. In our EIS measurements, this signal had 100mA amplitude and has been applied in a frequency range of 0.1 Hz up to 10 kHz. In the case of pulsed discharge, the rectangular current pulses create a strong perturbation in the battery chemistry. Considering the fact that the switching circuit (battery socket, PCB, MOSFETs, load) adds parasitical inductances and capacitances, a different specific frequency exists. In our opinion the specific frequency that corresponds to a maximum output of a pulsed discharge is dependent on the external circuit. We updated also the manuscript in page 13 before Conclusions.
(3) In Figure 11: Could the author comment on the existence of a small second peak within the dead-band?
A: The second peak is an artifact caused by capacitor C5 charge (fig.A1) which rejects (in tandem with C2) the ripple caused by dead-time during normal use of SWD. Explanations have been added in figure 11.
Reviewer 5 Report
In the work, Switched discharge device for enhanced energy extraction from 3 Li-Ion 18650 is presented. The work is well presented and analyzed. It can be accepted in the present form.
Author Response
In the work, Switched discharge device for enhanced energy extraction from 3 Li-Ion 18650 is presented. The work is well presented and analyzed. It can be accepted in the present form.
A: Thank you for understanding the complexity of designing and manufacturing an embedded device for pulsed discharge testing and the gain provided by switched discharge.
Round 2
Reviewer 4 Report
In your latest manuscript, there are still an inconsistent use of word: accumulator, but not cells or battery as other reviewer suggested.
Author Response
Response to Reviewer 4:
In your latest manuscript, there are still an inconsistent use of word: accumulator, but not cells or battery as other reviewer suggested.
A: We have checked again our manuscript and replaced the “accumulator” word with cell or battery as suggested, except in the Conclusion section where we refer to a bank of accumulators.
