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The press release says "the researchers’ cells have demonstrated more than 1,200 cycles with low cell resistance." That's nice, but rising cell resistance is just one way the battery might cycle poorly over time.

Skimming the actual paper, I don't think they demonstrate 1200 cycles for any parameter. Eyeballing the graphs, it looks like they did charge/discharge testing for maybe 1200 hours (Figure 3a), but with really slow charge/discharge cycles of 10 hours each. Anyone publishing in this space would highlight 1200 cycles of stable cycling in the actual paper, if they had data to demonstrate it. They'd also show off faster cycles if high-rate performance looked good.

Looking at the data the authors did not present in the actual paper, I'm guessing that this battery doesn't handle rapid charge/discharge cycles well. (Their cycling test is at only 0.1C, paper claims "acceptable charge/discharge rates" but does not further quantify it... implication is "not a strength of this design.") It may not have great capacity retention either. I don't see any graphics specifically highlighting capacity retention vs. cycles. So at present I'd call this a solid research effort, but even if it could be commercialized immediately it's not clear that it would be a winner. The demonstrated charge/discharge rate is too slow to be practical for EVs or portable electronics. The demonstrated cycling stability is too low to be attractive for grid tied storage.

People who found this paper interesting may also be interested in this related publication about solid state sodium ion batteries that Goodenough was also involved with: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5269650/



I really wish they'd publish more of the limitations as well in the paper. I wonder how much of it got cut out in editing.

Publishing limitations and negative results that lead to dead ends can help other scientists when they attempt to replicate and improve on tech like this.


I agree that publishing negative results would help the whole enterprise of science, but the prisoner's dilemma is pretty clear. I would guess that the authors have been "trained" well enough by publication incentives that they didn't bother to highlight limitations even in their original manuscript. That kind of information shows up in the paper only by absences and implication; it's only informal chats with peers where people talk honestly and thoroughly about the negative results and limitations of their approaches. It's a shame that scientific publication ended up this way. It's one of the reasons I left research to write software.




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