Engineers at BU are figuring out how to make better, more sustainable batteries—a technology that is essential for clean energy
We know that to have a green future, the entire world needs to shift from fossil fuel–generated power to renewable energy. And as countries agree on tripling solar and wind capacity, there are still major hurdles in the plan: one is that existing batteries aren’t good enough.
The idea of storing energy for later use is old, but in order to move society toward clean energy, scientists and engineers are experimenting with the fundamental elements of batteries, finding better ways to source raw materials, and even testing more outlandish energy storage ideas—like electricity-conducting ceramics. Experts agree that batteries will be a vital resource to ensure power is always on tap, no matter when energy is collected from renewable sources—whether in very sunny months or in cloudy rainy seasons.
It’s projected that the US will have over a billion battery-powered electric vehicles on the road by 2050, most of which use lithium-ion batteries, the same kind as in laptops, phones, and other electronics. This will make the demand for battery minerals and metals higher than ever before. But is our current technology enough to power the future, and is it truly sustainable?
“If we look at really transitioning to electric vehicles, and to renewables that need more grid-level storage, we won’t be able to get there with just lithium ion,” says Emily Ryan, a Boston University College of Engineering associate professor of mechanical engineering. She studies alternative materials for constructing batteries. Mining current raw materials, like lithium and cobalt, can cause major environmental hazards and unsafe working conditions, and right now there’s no reliable way to recycle batteries once they’re spent, creating a waste nightmare.
Emily Ryan, an ENG associate professor of mechanical engineering, studies how batteries degrade in order to build more stable, powerful versions. Photo by Dana J. Quigley
“Batteries are a lot more complex than they seem, because they have all these impacts beyond where you’re using them,” says Benjamin Sovacool, director of BU’s Institute for Global Sustainability. “Truly sustainable solutions integrate mining, the design of batteries, all the way into waste.”
The future of batteries impacts us all—the materials they use, where the metals are sourced and mined, how they’re disposed of and reused. And all of the decisions and scientific discoveries made now will impact our future—like, how much greenhouse gas emissions will be averted by charging a car instead of filling the tank with gas? The race to better batteries is one that can change everything.
Reinventing Battery Architecture
Whether it’s in a phone, a plastic toy, or connected to a giant solar array, every battery’s purpose remains the same: store electricity until it’s ready to be used. And in all batteries, no matter the size or strength, there’s a delicate combination of chemistry and electrical engineering at play. Ryan and others at BU are figuring out how to improve the design of current batteries—for instance by swapping out the active layers of metal and adding different elements to make an old idea new again.
In her lab, Ryan uses complex computer models to test alternative battery materials, like lithium metal instead of lithium ion. According to Ryan, lithium-metal batteries, which use solid lithium metal as the anode (positive side), could have substantially higher energy density than lithium-ion batteries, which use a graphite anode. So, you can store more energy in the same size battery.
This video shows how lithium-ion batteries, which power everything from laptops to electric cars, charge and discharge. The cathode, on the left side, stores lithium and releases the ions when charging—so the ion particles move left to right. The anode, on the right side, releases ions when the battery is in use—so the ions move right to left. The separator in the middle keeps the negatively and positively charged electrons from touching. Video courtesy of US Department of Energy
“If we started using lithium-metal batteries in your cell phone, instead of charging it every day, you would charge it once a week. Or in a car with the same size battery as we have now, you might get 600 miles instead of 300 miles,” says Ryan, associate director of BU’s Institute for Global Sustainability. That also means a much smaller battery could be used to provide the same capacity as we have today (about a 300-mile range), so less materials would have to be sourced.
But lithium metal is far from perfect. It’s highly reactive and unstable, causing tree-like structures, called dendrites, to form as the battery goes through charging and discharging cycles. (All batteries get dendrites, but they’re more common in lithium metal.) Dendrites degrade the battery life and cause it to short-circuit. Ryan and her team, along with researchers at the Hebrew University of Jerusalem in Israel, are researching the root cause of dendrites by analyzing the interfaces of the material and the chemistry at play. Through a joint National Science Foundation-Israel Binational Science Foundation grant, they’re studying the chemical-physical processes occurring during battery operation with the aim of making things more stable. Ryan also tests other materials to figure out how to make batteries nonflammable, since fires are an all-too-common issue for e-scooters and other battery-powered devices.
“We know right now we are not on a sustainable path, so I think it’s on us to try and come up with solutions to help us get to a more sustainable energy generation and energy use,” Ryan says.
"We know right now we are not on a sustainable path, so I think it is on us to try and come up with solutions to help us get to a more sustainable energy generation and energy use."