A Bottom-Up Approach to Lithium-Ion Battery Cost Modeling with a Focus on Cathode Active Materials
Round 1
Reviewer 1 Report
The manuscript is very nicely presented and the work provided could help the battery market and the researchers. The authors described a model able to visualize the role of the price fluctutation of the raw materials into the overall cost of the battery pack. This is clearly missing in nowadays model. It is a pioneer work because of course some points could be improved. However i recommend to be published as it is. Only few minor comments/questions come into my mind:
- line 157: "a prelithiation of the cathode is assumed". How is this prelithiation done from experimental point of view? I doubt that it is something done in industry....usually playing with the balancing is the first factor. Could you maybe make this point more clear?
- sulfate-based precursors for transition metals is used in the model. Why such a choice? In the literature, mainly nitrate or acetate based precursors are oftentimes used. Please comment.
Author Response
R1-1: The manuscript is very nicely presented and the work provided could help the battery market and the researchers. The authors described a model able to visualize the role of the price fluctutation of the raw materials into the overall cost of the battery pack. This is clearly missing in nowadays model. It is a pioneer work because of course some points could be improved. However i recommend to be published as it is. Only few minor comments/questions come into my mind:
Response: Thank you for your review. We are glad that it has made an overall positive impression. Our responses to your questions are as follows.
R1-2: - line 157: "a prelithiation of the cathode is assumed". How is this prelithiation done from experimental point of view? I doubt that it is something done in industry....usually playing with the balancing is the first factor. Could you maybe make this point more clear?
Reponse: Thank you for your question. It has led us to reflect and decide to elaborate on the explanation within our manuscript. The issue we seek to address is the irreversible loss of lithium that occurs due to solid electrolyte interphase (SEI) formation during the initial battery charge process. Prelithiation involves adding lithium to the active lithium content of a lithium-ion battery and has been demonstrated as a way to compensate for capacity loss due to this process. We used work done by Holtstiege et al. as inspiration, the citation for which has now been added to our manuscript [1]. Experimentally, lithium can be added to either the cathode (using methods such as positive electrode additives or over-lithiated positive active materials) or anode (using methods such as thermal evaporation of lithium metal or use of a roll-to-roll electrochemical bath). Though not currently in industrial use, several of these methods show commercial promise and we thus assume that one or multiple will eventually be adopted industrially. The purpose of this assumption within the context of our model is to allow comparison of the maximum theoretical performance of various battery technologies. Despite this, we realize that it may also be desirable for users to compare battery technologies according solely to technological processes that are currently in use. Accordingly, we have now built a cell within our model (cell M15 within the “Cell Model” sheet) which contains an adjustable lithium loss percentage due to SEI formation. If the user wishes to examine the technologies assuming prelithiation, they are welcome to leave the cell with its default value of 0. If they want to simulate lithium loss, they are welcome to increase the value. For instance, assigning a value of 0.10 simulates a loss of 10% lithium.
R1-3: - sulfate-based precursors for transition metals is used in the model. Why such a choice? In the literature, mainly nitrate or acetate based precursors are oftentimes used. Please comment.
Reponse: It is true that literature sources do speak of nitrate or acetate based precursors for transition metals. However, our literature sources speak of nitrates and acetates specifically in the context of spray pyrolysis techniques, which are currently performed on a laboratory scale [2]. Our other sources speak primarily of sulfates when in the context of existing industrial scale production processes [3–5], and so we opted to consider sulfates within our work.
1. Holtstiege, F.; Bärmann, P.; Nölle, R.; Winter, M.; Placke, T. Pre-Lithiation Strategies for Rechargeable Energy Storage Technologies: Concepts, Promises and Challenges. Batteries 2018, 4, 4.
2. Fröhlich, K.; Legotin, E.; Bärhold, F.; Trifonova, A. New large-scale production route for synthesis of lithium nickel manganese cobalt oxide. J. Solid State Electrochem. 2017, 21, 3403–3410.
3. Dunn, J.B.; James, C.; Gaines, L.; Gallagher, K.; Dai, Q.; Kelly, J.C. Material and Energy Flows in the Production of Cathode and Anode Materials for Lithium Ion Batteries; 2015;
4. Nelson, P.A.; Gallagher, K.G.; Bloom, I.; Dees, D.W. Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles; 2011;
5. Olivetti, E.A.; Ceder, G.; Gaustad, G.G.; Fu, X. Lithium-Ion Battery Supply Chain Considerations: Analysis of Potential Bottlenecks in Critical Metals. Joule 2017, 1, 229–243.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this article, Wentker et al. demonstrated a well-elaborated model for the prediction of Lithium ion battery cost. This model is based on cathode active material and several chemistries, including Panasonic cells, are considered. The model is well-demonstrated and the results presented are very promising. I agree that this new approach guarantees attention and the paper will certainly be interesting for researchers, investigating lithium-ion batteries. However, in order to increase the article impact, the ageing electrode should be taking account since it is an important parameter in this kind of batteries. Instead of the model is focused on cathode materials, the electrolyte and separator material should be included
Author Response
R2-1: In this article, Wentker et al. demonstrated a well-elaborated model for the prediction of Lithium ion battery cost. This model is based on cathode active material and several chemistries, including Panasonic cells, are considered. The model is well-demonstrated and the results presented are very promising. I agree that this new approach guarantees attention and the paper will certainly be interesting for researchers, investigating lithium-ion batteries.
Response: Thank you for your review. We are glad that you find it well-demonstrated and promising. We will address your concerns below.
R2-2: However, in order to increase the article impact, the ageing electrode should be taking account since it is an important parameter in this kind of batteries.
Response: Thank you for your comment. Upon further review, we have decided that you are correct and that we should include modeling of ageing in the form of lithium loss due to solid electrolyte interphase (SEI) formation. Our model originally assumed prelithiation in order to compensate for this effect, and we have added an elaborated description of the reason for such an assumption to our manuscript. However, we have now added a cell to our model (cell M15 in the “Cell Model” sheet) that allows users to adjust the lithium loss due to SEI formation if they do not wish to make such an assumption. The value remains at a default value of 0, but can be modified, for instance, to 0.1 to simulate a 10% lithium loss.
R2-3: Instead of the model is focused on cathode materials, the electrolyte and separator material should be included.
Response: We agree that electrolyte and separator are essential components to any lithium-ion battery. Accordingly, we have included within our model the ability to modify electrolyte and separator density and cost as well as separator thickness and porosity. These parameters were included in order to make the simulation of the entire cell possible, which is a prerequisite for the comparison of the various cathode technologies. Considering the effects of using different materials for each component could also be interesting, and would make for a good future research project. We have also added the specific materials used in our model for electrolyte and separator, LiPF6 / EC-EMC (3:7) and Celgard 2320, respectively.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript addresses a topic which is of high importance for the community. Though it is more on the engineering, techno-economic modelling side, the information in the manuscript is essential for the community. It contains mostly novel data, is of high interest, comprehensive. As usual, the cost numbers mentioned in the manuscript are above industry standard. Typically, authors do not have access to the numbers negotiated by a car OEM. If the editors consider it as a valuable contribution they are free to forward my contact details to share some data. Otherwise, the manuscript is acceptable in the current state due to the available data for the public. The manuscript can be recommended for publication.Author Response
R3-1: The manuscript addresses a topic which is of high importance for the community. Though it is more on the engineering, techno-economic modelling side, the information in the manuscript is essential for the community. It contains mostly novel data, is of high interest, comprehensive. As usual, the cost numbers mentioned in the manuscript are above industry standard. Typically, authors do not have access to the numbers negotiated by a car OEM. If the editors consider it as a valuable contribution they are free to forward my contact details to share some data. Otherwise, the manuscript is acceptable in the current state due to the available data for the public. The manuscript can be recommended for publication.
Response: Thank you for your positive review. We are glad to hear that you find it interesting, comprehensive, and essential to the community. We also thank you for your generous offer of data sharing. If the editors would like to establish contact between us, we would be happy to collaborate further in order to improve the accuracy of our model data.
Author Response File: Author Response.pdf
