British company Oxis Energy says its high-capacity lithium-sulfur battery can hold five times as much energy per pound as lithium-ion batteries and is expected to significantly increase the range of electric aircraft. The world is looking for a true source of electric aviation energy, but so far the existing lithium-ion batteries are so heavy that short trips are uneconomical.
For electric aviation, the energy density of batteries is key, and leading commercial lithium-ion batteries can still store only about 250Wh/kg (i.e. the Tesla 2170 battery used in the Tesla Model 3), and new chemical batteries with higher density while remaining reliable and safe are the dream of the next generation of aviation operators.
In this case, looking backwards may be an option: lithium-sulfur batteries have been around since the 1960s and have long been known for their relatively high energy densities and low costs, but what is disappointing is cycle life. Lithium polysulfide is very easy to dissolve in the electrolytes used in batteries, which means that the cathode eventually melts over time.
Oxis says it has developed a safe, non-flammable electrolyte that preserves lithium metal for longer while providing an energy density of more than 500Wh/kg, which can still be shown to be safe in the event of punctures and perforations, with a service life of about 250 charging cycles. The company believes it could extend its life cycle to 500 cycles in the next few years of technological development, which is the life of many lithium-ion batteries today.
Oxis has struck a partnership with Bye Aerospace, a Colorado-based company that specializes in electric and solar aircraft, to increase flight time for future aircraft by 50 to 100 percent. If successful, the battery is likely to attract interest from large aircraft companies.
Oxis is preparing to build manufacturing plants in Brazil and Wales and hopes its batteries will match electric buses on Brazil’s busy public transport.