That overhyped Na-Cl2 battery

Original post at Twitter here

News: new battery could mean six times the range in an electric car! 🙌

Press release: six times the electrode capacity compared to lithium-ion batteries 👍

Paper (in Nature): …normalised to the mass of a carbon coating on a Ni foam electrode 🤔

Don’t get me wrong, I find the chemistry interesting, but this is a good example of misleading scicomm starting with questionable reporting in the paper itself. The <5 mg/cm2 carbon isn’t the active material, the ~150 mg/cm2 SOCl2/AlCl3 electrolyte is…

If we want to compare this fairly, it should be done on the basis of actual redox active materials. However, even assuming Cl2 as the active material, theoretically this is ~760 mAh/g(Cl2)

Excerpt from the news article

And it’s not that this not-very-appropriate comparison is just in the press release, it’s heavily implied in the SI too. I’m surprised to find this Nature of all places (or perhaps I shouldn’t be) - we have known this is not a fair practice since at least the Li-air heyday.

Table from the Nature paper

Maybe it can be argued that because the active material is actually liquid/dissolved it is hard to compare on the same basis. In which case maybe a comparison of mAh/cm3 would be better… but if only I could find the thickness of the Ni foam…

I could get a little cynical about the practical prospects or whether it can be fairly called a Na/Cl2 battery at all but I won’t. I’ll rather just encourage researchers, reviewers, editors to be a bit more careful about reporting numbers like these…

comments powered by Disqus