Battery-Electric Vehicles (BEVs) are becoming the default transportation answer to cutting greenhouse gas emissions and getting off fossil fuels. The speed of their adoption is directly linked to one thing: how good the batteries are that power them. (Followed of course by constraints like the availability of chargers, the carbon footprint of the power used for charging, the ability of the grid to supply power, etc.)
Based on my current understanding of the issues:
PROS:
- Zero emissions — assuming renewable energy used for charging.
- Lower emissions — as the grid supplies for charging power become cleaner.
- Better air quality overall.
- Lower maintenance costs — electric motors are more durable, more efficient than internal combustion engines.
- Quieter in operation.
- Lower cost of operation — depending on the cost of electricity versus that of fossil fuels.
- Drive much like the internal combustion vehicles they replace.
- Increasingly better fit with the ‘car culture’ lifestyle.
CONS:
- The range issue — driver anxiety about how far they can go on a charge, which is not always predictable.
- Charging time — it can take hours to fully charge a battery, depending on the charger.
- Weather — temperatures can affect charging time and energy capacity/use.
- The weight penalty — batteries add significant weight to a vehicle reducing payload and consuming energy just to lug the battery around.
- Deterioration over time — as batteries age and are repeatedly recharged, they begin to lose energy storage capacity. This also affects resale value.
- Expense — batteries add significant up-front costs to a vehicle
- Resource intensive — the raw materials needed for batteries have supply constraints and impact the environment from extraction to production to disposal.
- Reinforces car culture.
A look at the list shows most of the cons are directly related to the characteristics of the battery. Improve those, and the cons get smaller.
HOW IT WORKS
Not to get too deep in the chemistry weeds, but a rechargeable battery is all about a reversible chemical reaction. Put electricity in to run it one way. Run it in the reverse direction to get electricity out. This U.S Department of Energy page has an animation showing how lithium ion batteries (the ones used in BEVs) work.
A battery is made up of an anode, cathode, separator, electrolyte, and two current collectors (positive and negative). The anode and cathode store the lithium. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the separator. The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector. The electrical current then flows from the current collector through a device being powered (cell phone, computer, etc.) to the negative current collector. The separator blocks the flow of electrons inside the battery.
While the battery is discharging and providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens: Lithium ions are released by the cathode and received by the anode.
There’s two more things to think about: Energy Density, and Power Density. The analogy used compares them to a swimming pool. A big pool can hold a lot of water (Energy Density). The bigger the drain pipe, the faster that pool can empty (Power Density). It’s basically about how much energy you can pack into a given sized battery, and how much power can be pulled out at a given rate.
BETTER BEVs THROUGH SULFUR
Because the power in a BEV battery comes from a chemical reaction, researchers are looking at how adding different chemicals to the mix can improve performance while reducing the cost of the batteries. Increasingly it looks like figuring out how to put sulfur to work can make a difference.
A news release from Drexel University back in February 2022 reported a breakthrough.
...Their discovery is a new way of producing and stabilizing a rare form of sulfur that functions in carbonate electrolyte — the energy-transport liquid used in commercial Li-ion batteries. This development would not only make sulfur batteries commercially viable, but they would have three times the capacity of Li-ion batteries and last more than 4,000 recharges – the equivalent of 10 years of use, which is also a substantial improvement.
emphasis added
It would also reduce the need for certain chemicals that are in critical supply: lithium, nickel, manganese, and cobalt.
What makes it interesting is that while they were working around some issues with sulfur and were trying to find a way to minimize one chemical reaction that’s a problem — sulfur getting bound in in polysulfide compounds — they accidentally managed something they weren’t looking for
"As we began the test, it started running beautifully – something we did not expect. In fact, we tested it over and over again – more than 100 times — to ensure we were really seeing what we thought we were seeing," Kalra said. "The sulfur cathode, which we suspected would cause the reaction to grind to a halt, actually performed amazingly well and it did so again and again without causing shuttling."
Upon further investigation, the team found that during the process of depositing sulfur on the carbon nanofiber surface — changing it from a gas to a solid — it crystallized in an unexpected way, forming a slight variation of the element, called monoclinic gamma-phase sulfur. This chemical phase of sulfur, which is not reactive with the carbonate electrolyte, had previously only been created at high temperatures in labs and has only been observed in nature in the extreme environment of oil wells.
The full paper on the Drexel team’s work is here, at Nature.
This April 2022 writeup from Big Think expands on the Drexel news and adds some additional perspective.
What appears to be the big deal is that these Lithium-Sulfur batteries (betteries?) have these advantages:
- Three times the energy density of a lithium battery — the same power for less weight, or more power at the same weight
- Use fewer critical and expensive elements
- Is more environmentally friendly regarding what it does use
- Has a much longer useful life cycle time before it begins to degrade.
A 2023 press release from Argonne National Laboratory is optimistic about these developments. They’ve also been investigating how to overcome the issues with using sulfur in batteries.
To further study the redox-active layer, the team conducted experiments at the 17-BMbeamline of Argonne’s Advanced Photon Source (APS), a DOE Office of Science user facility. The data gathered from exposing cells with this layer to X-ray beams allowed the team to ascertain the interlayer’s benefits.
The data confirmed that a redox-active interlayer can reduce shuttling, reduce detrimental reactions within the battery and increase the battery’s capacity to hold more charge and last for more cycles. “These results demonstrate that a redox-active interlayer could have a huge impact on Li-S battery development,” said Wenqian Xu, a beamline scientist at APS. “We’re one step closer to seeing this technology in our everyday lives.”
Going forward, the team wants to evaluate the growth potential of the redox-active interlayer technology. “We want to try to make it much thinner, much lighter,” Guiliang Xu said.
The paper describing their work is here: Development of high-energy non-aqueous lithium-sulfur batteries via redox-active interlayer strategy
Out of the labs, into the Streets
A March 2023 report by Katie Fehrenbacher in GreenBiz says commercial development efforts to come up up with some form of lithium-sulfur batteries are already underway.
[Celina] Mikolajczak’s company Lyten — an 8-year-old startup based in San Jose, California — can manufacture a crumpled form of graphene that it says is great at essentially holding the sulfur together in the battery while also acting as a conductor. The company says it’s seen promising results in its trials, and Mikolajczak told GreenBiz in an interview that she expects Lyten to be able to develop "a respectable battery cell" in about a year. It won’t be in high volumes, but early customers will be able to use it, she said. Lyten plans to sell the batteries to automakers and manufacturers of drones and flying vehicles.
Note that it’s going to take a while to scale these batteries up to where they can power BEVs — probably years if not longer. Working out all the wrinkles in turning research into a mass-produced product is going to be a challenge all by itself.
GreenBiz reports Argonne National Laboratories is looking for private sector partners to get the technology out of the labs and into use. Inflation Reduction Act funding is one of the ways this work is moving forward. It’s not just a U.S. effort either.
The U.S. of course isn’t the only place where researchers are trying to unlock the lithium-sulfur code. The European Union funded the LISA project, which just concluded, and looked at developing innovations around lithium-sulfur battery cell design.
Korean giant LG, through its energy arm LG Energy Solution, has said it plans to try to commercialize a lithium-sulfur battery in 2025. A German startup called Theion says on its website that it’s also trying to bring a lithium-sulfur battery to market soon.
One More Thing
The article at Big Think hints at further developments down the road that might replace the need for lithium.
But that isn’t the end of this discovery. The team at Drexel are already looking into using this breakthrough to make sodium-sulfur batteries. By removing the need for lithium, they can make batteries even more eco-friendly and eliminate a massive supply chain bottleneck, ensuring EV adoption can continue at the breakneck speeds carmakers are planning for.
This accidental discovery at Drexel is set to revolutionize the world’s power usage and help humanity transition toward a cleaner, carbon-neutral society. Let’s just hope the team at Drexel can get this technology out of the lab and into our hands soon.
A few caveats. As noted, it’s going to take an unknown amount of time before this technology turns up in BEVs. There’s no discussion in this as to whether or not these batteries could be charged faster either, or how long it would take to fully charge a higher capacity battery either. If you could go a week or longer on a single charge, that might not be such big deal.
There’s also how important these batteries could be in banking excess power from renewables, or protecting the energy reserves in microgrids. There’s a lot that will only come into view once this technology comes into full use.
There’s also non-technical hurdles that might pop up. A Republican administration combined with a Republican Congress would slash the funding that is making this possible. They’d likely throw up regulatory hurdles. The Wall Street interests and others who have invested heavily in lithium battery production and its supply chain would likely attempt to obstruct adoption of this technology, as would the Fossil Fuel industry. And Cthulhu only knows what kind of conspiracy theories would pop up.
But let’s deal with that as it comes. This is potentially great news at a time when we can really use it — and when the need for this technology is so important.