Lithium-ion (Li-ion) batteries are the solution of choice for most energy storage applications, including smartphones, electric vehicles, and battery energy storage systems. But the dominance of Li-ion batteries may be in question soon, as their safety and high costs have come under scrutiny, with many scientists looking for a substitute. At the moment, American scientists have made excellent strides in potassium-ion (K-ion) battery research, an important field due to potassium’s cheaper cost and higher count in the earth’s crust.
Potassium comprises about 2.09% of earth’s crust and is the seventh most abundant element in it. The element has lower manufacturing and material costs compared to lithium. According to Rensselaer Polytechnic Institute, high-capacity batteries with potassium metal anodes can deliver performance on par with Li-ion batteries in energy density by both weight and volume.
But K-ion batteries and Li-ion batteries alike face the problem of dendrite growth. As Li-ion batteries go through charge/discharge cycles, Li-ions scatter across the battery anode. Over time, these accumulations will begin to form dendrites, crystalline, branch-like extensions of lithium ions. When the dendrites grow past a certain length, they can pierce the polymer membrane separating the anode and cathode, causing the battery to short and catch fire. As potassium has higher thermodynamic activity than does lithium, its melting point is also lower, at 68 degrees Celsius, making it highly flammable and explosive. Safety is therefore of upmost importance when handling potassium.
In response, researchers from Rensselaer developed a self-healing technology for batteries. This technology will allow batteries to automatically clear the dendrite formed on the anode after overnight charging, thus preventing dendrite overgrowth. The research team indicated that the technology works by precision-managing the temperature inside the battery under controlled circumstances. Once the temperature reaches an optimal point that’s high enough to stimulate the dissipation of dendrites and low enough to prevent potassium metal from melting, K-ions will move away from their original deposits, in turn solving the dendrite problem.
A suitable analogy for this process, offered by Nikhil Koratkar, professor of mechanical, aerospace, and nuclear engineering at Rensselaer, would be piles of snow on a sunny day after a blizzard. The snow piles get smaller and smaller as the wind blows and sun shines, until all that’s left is the flat ground. According to Koratkar, when not in use, the battery can begin a process of self-healing through localized resistive heating, as controlled by a battery management system.
The team believes this process is key to the successful commercialization of inexpensive and long-lasting K-ion batteries.
Then again, this isn’t the first time the team demoed a self-healing mechanism in batteries. The researchers discovered back in 2018 that it’s possible to smooth out dendrites in Li-ion batteries by raising the internal temperature. As well as applying the process to K-ion batteries, the team is pairing it with battery management software to prevent the wear and tear on battery health due to rapid overheating.