In a move that could be a game-changer for the EV industry, Stellantis and Zeta Energy Corp are teaming up to develop next-generation electric vehicle batteries that have longer range, more power, charge 50% faster, and cost less than half.
Lithium-ion batteries have been the driving force of the electric vehicle (EV) revolution since Tesla introduced the Roadster to the world in 2008, which was powered by a 53kWh lithium-ion battery and had a range of approximately 245 miles (394 kilometers). The iconic Roadster nearly doubles the 1,140-mile (225-kilometer) range of General Motors' 1,140-mile (225-kilometer) EV.
Although the concept of lithium-sulfur (Li-S) batteries has been proposed as early as the 1960s, its practical application has been limited due to problems such as short life cycle and capacity loss caused by the unique "polysulfide shuttle effect" of lithium-sulfur (Li-S) batteries. When the battery is discharged, sulfur on the cathode side reacts with lithium to form lithium polysulfide, which diffuses through the electrolyte to the anode, leaving behind deposits. When charging, some polysulfides will migrate back to the cathode, but not all of them will migrate back to the anode, causing the battery's performance to degrade rapidly.
Texas-based Zeta, in partnership with global automotive giant Stellantis, believes it has solved the problem.
Recent advancements in materials technology and the development of barrier layers and coatings trap these polysulfides and prevent them from "shutting" between electrodes, effectively addressing the nasty premature aging effect.
The partnership could mean a leap forward in electric vehicle battery technology:
Lithium-sulfur batteries are much lighter than lithium-ion batteries. The energy per kilogram of lithium-ion batteries is generally between 150-250 watt hours (Wh/kg). Lithium-sulfur batteries can reach 400-600 Wh/kg.
Lithium-sulfur batteries can provide the same amount of power in a smaller package, which not only means longer range for electric vehicles (because the battery weight is 30-50% lighter), but also better handling and performance. The lighter, the better.
The companies also claim fast charging speeds are 50% faster than traditional lithium-ion battery packs. Lithium-sulfur batteries have a simpler chemical structure and do not rely on the slow diffusion of lithium ions into solid materials such as graphite in lithium-ion batteries. Instead, the reaction between lithium and sulfur occurs directly, faster and more directly. Additionally, they operate at a lower voltage, so they have less resistance when charging and absorb energy faster.
The bottom line is that the cost per kWh of lithium-sulfur batteries is expected to be less than half that of lithium-ion batteries.
Sulfur is abundant, and Zeta's lithium-sulfur batteries use waste materials such as methane and unrefined sulfur, which are sourced from various industries. In addition, they do away with expensive, hard-to-obtain materials such as cobalt, graphite, manganese or nickel, which lithium-ion batteries are also made from. Compared with existing battery technology, Zeta's approach can utilize local materials and use existing factories to assemble batteries, thereby reducing CO2 emissions.
They're also safer than lithium-ion batteries: Lithium-ion batteries have "sulfur" in their name, but that's not the same as the sulfur in gunpowder, matches, or fireworks. The sulfur in lithium-sulfur batteries is solid. The electrolyte in lithium-sulfur batteries is not as flammable as typical lithium-ion batteries. What causes battery fires is often the electrolyte. However, electric vehicle batteries are not without flaws, as using lithium metal anodes can pose risks such as dendrite formation, which can lead to short circuits.
But if you've ever seen an electric vehicle battery catch fire, you know how destructive it can be. When lithium-ion batteries "deflate" or explode, fire departments are often left waiting for the fire to extinguish itself. Puncture or thermal runaway (usually due to overcharging) can cause a chain reaction that generates large amounts of heat in lithium-ion batteries. Because the chemical reaction of sulfur is less exothermic, lithium-sulfur batteries are less prone to this condition. Without ingredients like cobalt and nickel to fuel combustion, lithium-sulfur batteries are considered safer than the batteries that power modern electric cars, laptops, cellphones and more.
Stellantis aims to launch lithium-sulfur electric vehicles by 2030, a collaboration that could redefine how we think about electric vehicles.