Building A Better Battery… Using Plastic?

11:26 minutes

PolyJoule’s conductive polymer energy storage system illuminated at night.
PolyJoule’s conductive polymer energy storage system, deployed with its first customer in August 2021. Credit: PolyJoule

The lithium-ion battery in your cell phone, laptop, or electric car is a crucial component of the modern world. These batteries can charge quickly, and pack a lot of power into a small space. But they’re also expensive, require mining scarce lithium, and need to be handled carefully. 

Other battery technologies have issues as well. For example, the heavy lead-acid battery that starts your car is quite reliable—but lead has its own environmental and health costs. That’s why PolyJoule, a startup company based near Boston, is trying to create a new kind of battery, somewhere on the performance curve between those old lead-acid batteries and lithium-ion cells. Their technology relies not on a metal, but on polymer plastics. 

“Architecturally, it doesn’t differ from your traditional lithium-ion battery,” says Eli Paster, CEO of PolyJoule. “A plastic battery looks more or less like a conventional battery. It’s got an anode, it’s got a cathode, it’s got an electrolyte, and it’s encased in a typical battery form factor. Inside is where the magic happens.” Building the battery from polymers, Paster says, allows the company to avoid some of the environmental impact of metal-based batteries, while delivering a battery that is very safe and has a long lifetime. 

However, there’s a downside—the batteries can’t store as much charge per unit of volume as other technologies. That means the company’s polymer batteries need to be big. “We’re not going in[to] mobile applications, we won’t be going into cellphones anytime soon, we won’t be going into EVs,” says Paster. “We’re focused exclusively on grid-level stationary applications, where volumetric energy density is not the key driver.” Instead, he says, these polymer batteries will work great where what’s needed is safety, sustainability, long lifetime, and cost.

Paster joins Ira to talk about the polymer battery technology, and the road to developing large-scale grid-connected battery banks, a development that could be used to buffer fluctuations in the energy produced by renewable energy sources. 

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Segment Guests

Eli Paster

Eli Paster is the CEO of PolyJoule, based in Billerica, Massachusetts.

Segment Transcript

IRA FLATOW: This is Science Friday. I am Ira Flatow. That lithium ion battery in your cell phone, your laptop, your electric car, is a key part of our modern world– fast charging, compact size, high power. But it has downsides like costs, the need for careful handling, and careful temperature control. Too cold and it doesn’t work well. Too hot, it can catch on fire. That lead acid battery that starts your car is also a relic of the past and not ideal for large scale energy storage.

Well, a startup based in the Boston area is developing a battery it says might be able to replace those batteries with one that is not based on metals at all, but on a polymer, plastic, a plastic battery that may be a solution for storing electricity on a large scale from wind or solar power generation, or even right in your home. Eli Paster is CEO of PolyJoule, based in Billerica, Massachusetts. Welcome to Science Friday.

ELI PASTER: Thank you so much. Great to be on the show.

IRA FLATOW: Nice to have you. All right, what does a plastic battery look like?

ELI PASTER: A plastic battery looks, more or less, like a conventional battery. It’s got an anode. It’s got a cathode. It has electrolyte, and it’s encased in a typical battery form factor. The key differences are what are the active materials that actually store charge. So, architecturally, it doesn’t differ from your traditional lithium ion battery, but inside is where the magic happens.

IRA FLATOW: Let’s talk about that magic. What is inside?

ELI PASTER: Well, PolyJoule takes a bit of a contrarian approach to lithium ion or energy storage in general. We say, technology has been out there for decades. And it solved a whole bunch of problems. And when we look at grid level energy storage, it’s not hitting the right metrics. So safety is a key component when you look at utility, scale, energy storage. You want to think about energy storage as a multi-decade asset that is going to sit unattended, like a transmission line or like a utility pole. So that means it has to be ultra safe in wind, weather, temperatures, anything like that.

The second is sustainability. Lead acid, as an example, is a great success story in terms of recycling. I believe 99% of all lead acid batteries are recycled. And then the other side of it is, that other 1% poisons millions of children around the world per year. So if you have a battery chemistry that eventually is going to end up in landfills and reach into water supplies and soil supplies, you don’t have a long-term solution.

The last part is lifetime. People tend to still look at batteries as a consumable item. A lead acid battery will last three to five years. The best lithium ion batteries will last 7 to 10 years. A typical utility pole will last 30 years. And a hydroelectric plant with minor modifications will last 50 years. So we like to think about energy storage as having to be in the classification not of consumed batteries that can be discarded, but long-term capital assets that can add benefit to society.

IRA FLATOW: And so how does a plastic battery solve those problems?

ELI PASTER: There’s a couple of different ways that it solves it. First is from a material supply standpoint. So on one side, if you think about plastics from a feedstock perspective, you’re not dealing with mining. You’re not dealing with copper and cobalt and lithium and all of the other ecological disruptions. You’re dealing with a plastic supply chain that’s been well established for half a century.

The other side of it is, if you think about a plastic from an environmental standpoint, there’s two aspects which are great. Number one, it’s recyclable, right? You can take a plastic. You can reform it. You can add it into new plastics, and you can reuse it. The other side of it is that a plastic, by its very nature, when it is desensitized, it’s an inert material.

So a lot of the toxicity that comes from battery pollution actually comes from the metals that are in it. Not just lead as a metal but lithium, cobalt, copper, nickel, all of those metals, whether they’re in the parts per million or tens of kilograms, cause an environmental toxicity footprint. And by using plastics, basically, at the end of life, you’ve got an inert material.

IRA FLATOW: You hear stories about a lithium battery catching on fire or exploding if it somehow gets short circuited or punctured. What happens to a plastic battery?

ELI PASTER: Nothing happens, actually. So we actually, we short circuit ourselves all the time, and they recover 100%. Short circuits, punctured with a nail, heated up, throw the kitchen sink at it, it’s still a very safe, ultra safe battery.

IRA FLATOW: OK, there’s got to be a downside to everything, right? So what’s the weakness of a plastic battery?

ELI PASTER: Absolutely. What’s the catch? The catch is, we’re five times less energy dense than a lithium ion system. So we’re not going in mobile applications. We won’t be going into cell phones anytime soon. We won’t be going into EVs. We’re focused exclusively on grid level stationary applications where volumetric energy density is not the key driver. The key driver is safety, sustainability, long lifetime, and cost.

IRA FLATOW: And so, for cities looking to back up or store their electricity from their wind or solar generation, you have a lot of room. So you could put a lot of batteries of this size in there that are not as efficient as lithium.

ELI PASTER: That’s right. And think about– this is where safety comes into it. So take one of the hardest cities to do business in– New York City, right? And New York City, obviously, hates anything that is flammable anywhere. If you have an ultra safe battery, you can throw small units in 10% of the population’s empty cupboards and accomplish the same amount of energy as throwing a massive battery installation outside of New York. That safety enables you to either go with a distributed version or go with a centralized version in a cheaper piece of land where footprint is not an issue.

IRA FLATOW: So you’re saying this battery would also work, for example, in my basement? There’s enough room for this?

ELI PASTER: Oh, absolutely. Think of it as for an equivalent single family household, it would be about the size of 1 and 1/2 large refrigerators. That would give you a full day of backup.

IRA FLATOW: OK, you mentioned the need for long life. How long does it last? And what happens then?

ELI PASTER: The honest answer is, we’re not really sure how long our batteries last. A year ago, we said 12,000 cycles. This year, we’re saying 20,000 cycles. But real world cycle life testing takes physical time. So it’s quite possible that we’re going to be at 30,000 cycles in a year from now. But from a capital and depreciation standpoint, we call a battery a two to three-decade battery. And after that, the energy and power landscape is going to be different in 30 years from now. So it may be time for an upgrade.

IRA FLATOW: I would think so. If you can get it to last two to decades, I think you’ve done pretty well.

ELI PASTER: We hope so.

IRA FLATOW: So what’s the time frame here? Are you still in testing phase? Would it be rolled out at any time? Do you have customers?

ELI PASTER: So there’s multiple valleys of death for energy storage startups. You start with a cell chemistry. You move to a prototype. You have to get your first commercial customer. You have to scale up that prototype. Those are probably the first five valleys of death. PolyJoule passed those a year and a half ago.

So we produced 20,000 cells. We’ve integrated them into energy storage systems. We are revenue-generating. We have eight months of field trial for grid connected energy storage. The next three valleys of death are scale up by 10, scale up by 10, and scale up by 10. And that’s our next three years of development.

IRA FLATOW: Now there is a need for this for grid storage, right? We’re talking about creating a new grid, people going more electric, uniting cars and solar power and wind, especially when the sun doesn’t shine, right, storing up excess energy for when you can use it and smooth out the grid. This is that kind of solution.

ELI PASTER: That’s absolutely right. And there are two sides to it. One part of it is all of the hoopla about energy storage right now is focused on decarbonizing the transportation sector. If you look at the global emissions from transportation, it’s about 14% to 15% of total CO2 emissions. If you look at the electricity, heat generation, and industrial sector, add those categories up, and it’s about 45% to 46% of global emissions.

So there’s an enormous amount of– I don’t want to call it low hanging fruit because it’s not trivial. But there’s an enormous opportunity to decarbonize some of the largest polluting sectors. And energy storage can be considered a force multiplier for renewables and the intermittency of renewables.

If you have the sun, which only signs six to eight hours a day, and you have the wind, which blows intermittently, but you have both of those renewables paired with energy storage, you’ve gone from 50% capacity utilization to 75% or 100% capacity utilization. That’s part one.

Part two is the economic effects of introducing renewables to the grid. As you add more wind and as you add more solar, those opportunities can be thought of as volatile power generation assets. And what that volatility actually means, it’s like the stock market. There’s a supply and demand for electricity that is traded on a real-time market. And if there’s not enough sun or there’s not enough wind, the price of electricity is going to be more volatile. Battery smooth out that price volatility over the long-term and enable renewables.

IRA FLATOW: All right, let me give you my blank check question here because I’m sure there’s stuff you’d like to continue to do research on. And if I gave you a blank check and you had an unlimited budget, how would you spend it? What are the problems that still remain? What are the challenges that you’re looking into?

ELI PASTER: The short answer is, from a macro perspective, we would like to scale up to dislodge Goliath. And by Goliath, I mean that 95% of energy storage today is lithium ion battery chemistry. There’s a bunch of historical reasons for it. But most of it has to do with price. And most of it has to do with availability. We believe in two years from now, if we scale up by a factor of 100, we’ll be cost competitive with lithium ion.

But scaling up is a non-trivial application from a manufacturing and supply chain and execution standpoint. And we essentially want the opportunity to dislodge the Samsungs of the world, the Teslas of the world, the LG Chem of the world that have this 30 years of R&D, 30 years of financial backing, with an inferior chemistry that is unsafe, that is not sustainable, and doesn’t last for that 30-year utility level lifetime that we’re looking for.

IRA FLATOW: All right, we will look forward to seeing your batteries. Eli Paster, CEO of the battery startup PolyJoule, based in Billerica, Massachusetts. Thank you for taking time to be with us today.

ELI PASTER: Thank you so much.

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