Stellantis and Zeta Energy develop lithium-sulphur batteries for electric cars

Stellantis is partnering with Zeta Energy to develop a cheaper, more efficient and more sustainable alternative to NMC (nickel, manganese and cobalt) lithium-ion batteries: lithium-sulphur batteries.

Batteries remain one of the biggest challenges facing today’s electric cars. It is not simply a matter of their high cost, but a combination of environmental, technical and geopolitical factors.

Why lithium-sulphur?

Lithium-sulphur batteries could address or reduce many of these issues. They could be even more affordable than LFP (lithium iron phosphate) batteries - which continue to gain popularity - while offering gravimetric energy density (more energy per unit of weight) and volumetric energy density equal to or higher than current NMC lithium-ion batteries.

Put simply, sulphur batteries can provide the same usable energy as lithium-ion batteries while weighing less. This could lead to electric vehicles with greater range, lower weight - improving both dynamic performance and efficiency - and reduced costs.

“Lithium-sulphur batteries could cost less than half as much per kWh compared with lithium-ion batteries,” says Stellantis. They also promise charging times up to 50% shorter, as well as greater sustainability because sulphur is a widely available material.

Do lithium-sulphur batteries have drawbacks?

If lithium-sulphur batteries can deliver higher energy density at a lower cost, it is reasonable to ask why they are not already used in electric cars. The reality is that several hurdles still need to be overcome.

Their cycle life, for instance, is shorter than that of lithium-ion batteries. They also present technological challenges involving the stability of sulphur-based cathodes, electrolyte compatibility and safety, including the formation of lithium dendrites and electrolyte degradation.

This is where the partnership between Stellantis and Zeta Energy comes in. Zeta Energy specialises in developing and producing this technology.

Production

Stellantis and Zeta Energy also state that producing lithium-sulphur batteries will not require new gigafactories. Existing facilities can be used instead, supported by a short and entirely local supply chain concentrated in Europe and North America.

In addition to sulphur, “these batteries are produced using waste materials and methane, with CO₂ (carbon dioxide) emissions significantly lower than those of any technology currently available”.

“Our collaboration with Zeta Energy is another step forward in advancing our electrification strategy. We are working to deliver sustainable, safe and affordable vehicles.”

Ned Curic, Stellantis Chief Engineering and Technology Officer

When will they arrive?

The collaboration between Stellantis and Zeta Energy covers two stages: development, pre-production and planning for future manufacturing.

It will still be several years before Stellantis electric models fitted with these lithium-sulphur batteries appear. Both companies are targeting 2030 for the start of their use in electric vehicles.