Just to follow up, since I was curious to do a bit of searching:<p>* Wikipedia&#x27;s article [1] mentions two other startups working on sodium-ion batteries. Faradion apparently has a 150 Wh&#x2F;kg sodium-ion battery [2]. According to the Wikipedia article, &quot;These cells can be completely drained (to zero charge) without damaging the active materials. They can be stored and shipped safely.&quot;<p>* A Physics Today article entitled &quot;Surprising stability for sodium-ion batteries&quot; [3] summarizes a Brookhaven National Laboratory that despite an expected worse performance for Na vs Li, (with a tin anode), they found that &quot;after that initial damage, subsequent desodiation and nine further charging–discharging cycles produced no further fractures: The expansion and shrinkage were reversible and produced a minimal decrease in charge capacity.&quot;<p>* While searching I found an interesting paper on a NA-SO2 formulation &quot;A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte&quot; [4] which has great numbers (discharge capacity similar to LiFe), but seems like one of those battery formulations that never make it out into the real world.<p>That&#x27;s as far as my passing curiousity took it, but if anyone works in the field, it&#x27;d be interesting to hear their thoughts.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Sodium-ion_battery" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Sodium-ion_battery</a><p>[2] <a href="http:&#x2F;&#x2F;cen.acs.org&#x2F;articles&#x2F;93&#x2F;i29&#x2F;Challenging-Lithium-Ion-Batteries-New.html" rel="nofollow">http:&#x2F;&#x2F;cen.acs.org&#x2F;articles&#x2F;93&#x2F;i29&#x2F;Challenging-Lithium-Ion-B...</a><p>[3] <a href="http:&#x2F;&#x2F;scitation.aip.org&#x2F;content&#x2F;aip&#x2F;magazine&#x2F;physicstoday&#x2F;news&#x2F;10.1063&#x2F;PT.5.7184" rel="nofollow">http:&#x2F;&#x2F;scitation.aip.org&#x2F;content&#x2F;aip&#x2F;magazine&#x2F;physicstoday&#x2F;n...</a><p>[4] <a href="http:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pmc&#x2F;articles&#x2F;PMC4525335&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pmc&#x2F;articles&#x2F;PMC4525335&#x2F;</a>