Lithium Sulphur Batteries With Twice The Energy Density May Be Used In Electric Airplanes

The ongoing wave of electric vehicles relies heavily on lithium-ion batteries. A major reason for this is the highest energy density that these batteries pack. Other battery technologies, however, are being worked upon and a recent one in the highlights is a lithium-sulphur battery pack. The claimed advantage on the same is so big that its viability is being tested for long range air flight.

Bye Aerospace is the firm behind the testing, having procured the said lithium-sulphur batteries from Oxis Energy of Abingdon, UK. Oxis Energy claims that the new batteries can greatly increase the available energy-per-weight ratio with their new batteries, in comparison with the regular lithium-ion batteries used in electric vehicles these days.

Better Energy Density

For the testing of the batteries, the two companies have initiated a joint one-year project. Theoretically, the individual cells on the Oxis batteries have been claimed to provide more than 500 watt-hours per kilogram. The number marks a monumental increase from what Bye Aerospace claimed for its own airplanes back in 2017, i.e. an energy density of 260 watt-hours per kilogram.

(Image: Bye Aerospace)

To put this into perspective, know that the batteries on the Tesla Model 3 mark an estimated 168 Wh/kg energy density. With more than quadruple the amount, the lithium-sulphur batteries by Oxis are a game-changer.

With more than twice the energy density than the previous batteries used by Bye Aerospace, the overall effect will result in an increase in the flying range by 50 to 100 percent. The main reason is the reduction in the number of battery cells to be used, thus reducing the weight that the total battery pack constitutes. Less weight, space for more battery cells, hence extended range.

Safety

An associated question, however, of battery safety arises in every battery comparison. Lithium sulphur batteries have been prone to overheating. Oxis claims to have overcome this hurdle, through a ¡°passivation layer¡± of ceramic lithium sulfide. The layer blocks the flow of electricity, thus preventing sudden discharge as well as any leakage that might lead to a drop in capacity overtime. In addition, Oxis claims to have used a non-flammable electrolyte for safety, marking the batteries safe enough for use in an electric airplane.

Lithium Sulphur Battery Pack (Image: Oxis Energy)

Near Future

Lithium sulphur batteries have another shortcoming in comparison with the lithium-ion ones. They have a shorter life due to the rapid degradation of the cathode during the charge-discharge cycle. Oxis aims to solve this problem within the next couple of years, targeting a battery life of at least 500 of such cycles to match the standards of current lithium-ion batteries.

Going forward, Oxis believes that the batteries will be at par to empower the electric aviation in various formats. This includes air taxis, commercial as well as regional aircraft. Hampson-Jones, the chief executive of Oxis says ¡°We believe this to be the first phase in the electrification of commercial aircraft and will ultimately form the basis for the electrification of air taxis, with the additional requirement for regional aircraft.¡±