Prototypes for electric airplanes have been in testing for years, but the tech has not been practically implemented because of the lack of a suitable power source. With the limitations of the current battery technology, airplanes would need to carry thousands of kilograms of batteries, making it impossible for the aircraft to take off, let alone cover long distances.
This is about to change soon as scientists at Oxis Energy in England have successfully completed flight trials for an all-electric aircraft. This was made possible by lithium-sulfur batteries, the next step in battery technology that is extremely lightweight and provides more than twice the energy capacity of typical lithium-ion batteries.
These batteries were able to provide the required power and durability for aviation and were also proven to be safe enough for practical use. This new technology has been a long time coming, but now the first set of flight trials have been completed.
However, just like lithium-ion batteries, lithium-sulfur batteries tend to degrade over time as well. To make sure that the battery can perform at a high level over many discharge cycles, the scientists coated the lithium-metal anode with a thin layers of ceramic to prevent degradation.
This allows the lithium ions to pass through without any hindrance and incorporate into the lithium bulk metal underneath.
Besides working on the battery anode to improve longevity, Oxis is also working on improving the cathode to increase power and energy density. While lithium-sulfur batteries already provide more than twice the capacity of their lithium-ion counterparts, the company hopes to reach new limits by 2021, and even further beyond in 2025.
If you are interested in technical details for how lithium-sulfur batteries work, head to this link for more comprehensive details.