Progress in lithium-sulfur batteries
Scientists from the University of Michigan, led by Professor Nicholas Kotov, have developed a lithium-sulfur battery capable of maintaining consistent performance over more than 1,000 charge-discharge cycles, thanks to a “bio-inspired battery membrane” made from recycled Kevlar fibers.
This innovation resolves the main weakness of lithium-sulfur batteries: rapid degradation. Indeed, these batteries have already been recognized for their potential to rival lithium-ion batteries but had issues that prevented their commercialization. Today, they are facing a technological breakthrough that could transform their evolution.
Lithium-sulfur batteries: a complex technology
Lithium-sulfur batteries have been the focus of studies for several years.
- 2013: Researchers from Stanford University developed a lithium-sulfur battery with significantly increased capacity, retaining 80% of its capacity after 300 charge-discharge cycles.
- 2017: Lithium-sulfur technology reached the next level. A CEA Tech institute manufactured a cylindrical format with encouraging performance.
- 2020: As we discussed, a team of Australian researchers from Monash University in Melbourne presented a solution to stabilize the cathode in lithium-sulfur batteries. However, further progress was needed to hope for industrialization.
Today, researchers at the University of Michigan claim to have developed a lithium-sulfur battery five times more efficient than lithium-ion batteries currently used for electric cars.
“Many lithium-sulfur battery models promise consistent performance over numerous cycles,” says Professor Nicholas Kotov.
However, to improve durability, compromises must often be made on energy density, charging speed, or safety. Thus, the goal of this American team is to develop a lithium-sulfur battery with a longer lifespan, without making compromises or generating additional costs.
Can lithium-sulfur batteries compete with lithium-ion?
If this research materializes, the electric car industry could be revolutionized!
Composed of a sulfur cathode and a lithium-metal anode, the lithium-sulfur battery stores five times more energy than a lithium-ion battery of the same mass. And it can be used for about 10 years, which corresponds to 1000 recharge cycles.
University of Michigan researchers have shown that the use of aramid nanofibers based on recycled Kevlar (similar to those used in bulletproof vests) does not alter other battery characteristics. They then retain the same capacities with an increased lifespan. This membrane has better thermal resistance than lithium-ion batteries.
Lithium-sulfur batteries therefore have superior capacities and advantages in terms of cost and durability. Cobalt is a strategic material, one of the primary metals found in lithium-ion batteries. It is relatively expensive since it comes from copper and nickel, whereas sulfur is more abundant on Earth than cobalt.
While waiting for lithium-sulfur batteries to hit the market, lithium-ion batteries remain the best technology for powering portable devices and vehicles.