Oxis Energy, of Abingdon, UK, says it has a battery based on lithium-sulfur chemistry that can greatly increase the ratio of watt-hours per kilogram, and do so in a product that’s safe enough for use even in an electric airplane. Specifically, a plane built by Bye Aerospace, in Englewood, Colo., whose founder, George Bye, described the project in this 2017 article for IEEE Spectrum. From a report: The two companies said in a statement that they were beginning a one-year joint project to demonstrate feasibility. They said the Oxis battery would provide “in excess” of 500 Wh/kg, a number which appears to apply to the individual cells, rather than the battery pack, with all its packaging, power electronics, and other paraphernalia. That per-cell figure may be compared directly to the “record-breaking energy density of 260 watt-hours per kilogram” that Bye cited for the batteries his planes were using in 2017.
This per-cell reduction will cut the total system weight in half, enough to extend flying range by 50 to 100 percent, at least in the small planes Bye Aerospace has specialized in so far. If lithium-sulfur wins the day, bigger planes may well follow. […] One reason why lithium-sulfur batteries have been on the sidelines for so long is their short life, due to degradation of the cathode during the charge-discharge cycle. Oxis expects its batteries will be able to last for 500 such cycles within the next two years. That’s about par for the course for today’s lithium-ion batteries. Another reason is safety: Lithium-sulfur batteries have been prone to overheating. Oxis says its design incorporates a ceramic lithium sulfide as a “passivation layer,” which blocks the flow of electricity — both to prevent sudden discharge and the more insidious leakage that can cause a lithium-ion battery to slowly lose capacity even while just sitting on a shelf. Oxis also uses a non-flammable electrolyte.
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