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Super-dense lithium-sulfur battery gives electric plane a 230-mile range:
British company Oxis says it's developed safe, high-density lithium-sulfur battery chemistry and will supply Texas Aircraft Manufacturing with a 90-kWh, next-gen battery pack to power the eColt, an electric aircraft with a two hour, 230-mile range.
[...] In practice, they have had issues – notably with the old chestnut of dendrite formation, in which ion deposits on the anode grow into long spikes of conductive material that short circuit the cell and cause it to catch fire. The lithium-metal anodes also tend to degrade in less dangerous ways that eventually just make the batteries die.
In a piece written for IEEE Spectrum, Oxis head of battery development Mark Crittenden details how his team is addressing these problems with a thin layer of ceramic material at the anode, and it's resulting in high-energy cells with significantly longer lifespans than previous Li-S designs.
"Typical lithium-ion designs can hold from 100 to 265 Wh/kg, depending on the other performance characteristics for which it has been optimized, such as peak power or long life," writes Crittenden. "Oxis recently developed a prototype lithium-sulfur pouch cell that proved capable of 470 Wh/kg, and we expect to reach 500 Wh/kg within a year. And because the technology is still new and has room for improvement, it's not unreasonable to anticipate 600 Wh/kg by 2025."
Still needs work on the limited number of number of charge cycles.
(Score: 0) by Anonymous Coward on Friday August 21 2020, @11:10PM (3 children)
Let's ignore for a moment that range is limited, and accept that technology will improve with time. Batteries will store more energy per kg, last more cycles, recharge faster, be safer, etc, etc
This still leaves us with the not so small disadvantage of heavy batteries which don't get any lighter as they are "used up". Landing weight is an issue. Flight efficiency carrying extra weight is an issue.
What if the battery was designed as divided segments. Each segment is discharged in turn until the last segment remains. Further more, what if drained battery segments could be ditched, mid flight in a controlled manner. Some kind of automated para-foil recovery system that guides the drained battery safely to a pickup field for recovery and recharge. Maybe all at once on landing approach lightening the landing load to that of a comparable fuel powered aircraft. Maybe at designated points mid flight to reduce the trip flying weight. Or just after takeoff to dump the weight of the power used to get the plane off the ground up to flying altitude.
What if airports were equipped with a catapult system to eliminate the takeoff power requirements to begin with (something that could be done with today's fuel powered aircraft). Imagine a 747 getting slingshot into the air (gently and smoothly) at such a speed that it has enough momentum to gain considerable altitude before requiring it's own thrust to keep moving. This is not your average carrier deck catapult.
Electric flight may revolutionize aviation. It will look very different from the fuel driven aviation design that's been perfected up until now. We have to start looking at the problem in new ways.
(Score: 0) by Anonymous Coward on Friday August 21 2020, @11:28PM (1 child)
They could use tugs to tow airliners between the gate and the runway, but they don't. This involves a lot less trouble than trying to do a catapult launch, which exactly zero airliners or airports are designed for. Airliner engines are painfully inefficient on the ground.
It is against the law to drop uncontrolled objects from an aircraft, except under specific circumstances. Aircraft are never dropping their batteries. The military uses drop tanks, but they don't drop them over Los Angeles.
Weight in mid flight is basically not a factor at all. Weight at takeoff matters a lot.
Before electric aircraft can revolutionize aviation, they have to be revolutionized themselves, because batteries are not remotely competitive with jet fuel.
(Score: 2) by MostCynical on Friday August 21 2020, @11:37PM
. . you missed the qualifier: for now [stanford.edu]
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 0) by Anonymous Coward on Saturday August 22 2020, @12:10AM
Still within the box, from tfa, "...a 90-kWh, next-gen battery pack".
That is equivalent to about 120 horsepower for an hour (given high efficiency electric motors). Or 60 hp for 2 hours, which is what I expect they do to get the quoted range. Perhaps they use 120+ hp on takeoff for a few minutes?
This is not much of a plane at all, roughly comparable to the canonical Cessna trainers, here's a story on the latest version: https://www.aopa.org/community/flying-clubs/flying-club-newsletter/2017/november/19/aircraft-spotlight [aopa.org]