In their review article entitled "Alkali and alkaline earth metals in liquid salts for supercapattery", Croft, Chen, and their coauthors give a critical overview over supercapattery systems based on alkali and alkaline earth metals with molten salts/ionic liquids as electrolytes. Booth sides of the devices as well as electrolyte-electrode interactions are critically addressed. Overall, I enjoyed very much reading this manuscript. Unlike other reviews in related fields, it is not just an example-after-example article but also gives a certainly critical overview over the field with clear scientific wording. The article follows a clear structure and deals with a topic of great importance. To judge weather or not the journal of RSC sustainable is a suitable platform for the publication of this article I will leave to the editors. In my opinion, the particular focus on sustainability is rather weak and in my opinion, this paper would be more suitable for a journal with a stronger focus on electrochemical energy storage. I would like to mention the following points for the authors which should be carefully addressed before possible publication:

1) The statement "The best performance of a supercapattery depends mainly
on the optimal coupling of electrode materials and electrolytes to utilise effectively the potential windows and charge capacities of both electrodes..." in the introduction is absolutely crucial for the supercapattery technology. If needs more critical explanation how, for instance, a mass balancing is correctly done. It should be clarified, that the devices can only be as good in terms of energy and power as their worst part is. This otherwise really nice article needs a bit more overall assessment of the electochemical engineering approaches in the introduction.

2) I do also find the first sentence in chapter 1 misleading. Electrode materials and electrodes should always be developed together, not one after the other.

3) In the subheadings of chapter 1 it is sometimes "Li-based" and other times "sodium-based". This should be more uniform. Minor point.

4) I see a major drawback in the non-uniformity of the figures. The style of writing and also of figures quite much changes between chapters 1 and 2. In chapter 1 figures are rather elegant but minimalistic in chapter 2. This makes no good impression. In chapter 1 also many figures are repeatedly showing similar chemical structures. This makes no sense.

5) Authors often refer to the properties of ILs to be able to "combing capacitive and Nernstian charge storage". I think that we do not yet know enough about especially the "capacitive" storage mechanism of ILs. There are still fundamental novel insights about their structures formed at interfaces and I do also think that there are other and new energy storage terms in ILs which are neither faradic nor capacitive. While probably less critical for the battery side, I would recommend a little chapter about recent insights into the use of ILs in supercapacitors.

I have carefully checked the response of the authors to my initial comments and find them satisfactory. As the initially submitted version, also the revised manuscript is a nice piece of work. If the editors are of the opinion that it falls within the scope of the journal I can recommend publication in the present form.