‘Impossible’ anode-free EV battery promises 500+ mile range on single charge
Princeton research investigate factors that can help manufacture solid-state batteries at scale.
Research at the Andlinger Center for Energy and the Environment at Princeton University has found a new way to make ‘anode-free’ solid-state batteries that can overcome the limitations of lithium-ion batteries and potentially power electric aviation someday. Using these batteries, charge on laptops and phones will last longer, and electric vehicles can travel over 500 miles on a single charge, a press release said.
Lithium-ion batteries are a crucial component of our strategy to move away from fossil fuels and towards a clean energy economy. From small portable devices to grid-level energy storage, lithium-ion batteries are being used everywhere. However, as energy demand increases in the future, at their current energy storage densities, demand for storage solutions will outstrip lithium supplies, prompting the search for better batteries.
In their current form, too, lithium-ion batteries are prone to fire risks and thermal runaway. To overcome this, researchers are working with solid-state electrolytes, which can work across a wider range of temperatures, delivering safer and more efficient energy storage options.
Now, researchers at Princeton, as part of a US Department of Energy project, Mechano-Chemical Understanding of Solid Ion Conductors (MUSIC), are working to improve manufacturing processes so that solid-state batteries (SSBs) can be built at scale.
Building an anode-free SSB
A conventional battery design consists of two electrodes, the positive called the cathode and the negative referred to as the anode. Each electrode has a thin metal foil called the current collector that connects the battery to the circuit while the electrolyte separates them.
The flow of ions between the electrodes is important for the charging and discharging batteries. Previous research has shown that if the anode is removed, ions can still flow from the cathode to the current collector at the other during the charging process and allow the battery to function normally.
Building a battery without anode is cheaper and can help shrink the SSB‘s size while simplifying the manufacturing process. However, there must be good contact between the solid electrolyte and the current collector to do this.
Factors influencing good contact
Under the leadership of Kelsey Hatzell, an associate professor of mechanical and aerospace engineering, a team at Princeton University studied various factors that influence the flow of ions in the solid electrolyte and how evenly they are deposited on the current collector.
When researching whether applying external pressure improved performance, the team found that low pressure led to uneven plating of ions, causing hotspots and voids on the current collector. This uneven plating led to the formation of needle-like filaments that short-circuited the battery.
While applying higher pressures led to better ion plating, it also forced the electrolyte and current collector together, magnifying their imperfections and forming fractures.
The research team also investigated if applying a thin coating between the current collector and electrolyte improved ion plating outcomes. They tested various combinations of coatings, also called interlayers, and found that those made from carbon and silver nanoparticles performed the best.
Upon further investigation, the researchers found that the size of silver nanoparticles was instrumental in good plating. When silver nanoparticles with sizes of 200 nanometers were used, they formed spindle-like metal structures on the current collector, leading to battery failure over charging cycles.
On the other hand, when the nanoparticle size was 50 nanometers, the plating was denser and more uniform, and batteries generated a higher power output while also lasting longer.
Se Hwan Park, a researcher in the Hatzell lab who was involved in the work, said :
Only a few groups have investigated the actual processes that occur in these interlayers,
“Among other findings, we demonstrated that the stability of these systems is linked to the morphology of the metal as it plates and strips from the current collector.”
Hatzell in the press release, added:
The challenge will be getting from research to the real world in only a few years,
“Hopefully the work we’re doing now at MUSIC can underpin the development and deployment of these next-generation batteries at a meaningfully large scale.”
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