An Affordable, Sustainable New Battery Technology

Andrew Corselli

Atin Pramanik, a postdoctoral associate in Ajayan’s lab, examines the battery prototype. (Image: Jeff Fitlow/Rice University)

As global demand for electric vehicles and renewable energy storage surges, so does the need for affordable and sustainable battery technologies. A new study led by researchers from the Department of Materials Science and NanoEngineering at Rice University, along with collaborators from Baylor University and the Indian Institute of Science Education and Research Thiruvananthapuram, has introduced an innovative solution that could impact electrochemical energy storage technologies. The research was recently published in the journal Advanced Functional Materials.

Using an oil and gas industry’s byproduct, the team worked with uniquely shaped carbon materials — tiny cones and discs — with a pure graphitic structure. These unusual forms produced via scalable pyrolysis of hydrocarbons could help address a long-standing challenge for anodes in battery research: how to store energy with elements like sodium and potassium, which are far cheaper and more widely available than lithium.

“For years, we’ve known that sodium and potassium are attractive alternatives to lithium,” said Corresponding Author Pulickel Ajayan, Benjamin M. and Mary Greenwood Anderson Professor of Engineering at Rice. “But the challenge has always been finding carbon-based anode materials that can store these larger ions efficiently.”

Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor of Engineering at Rice. (Image: Jeff Fitlow/Rice University)

Traditional lithium-ion batteries rely on graphite as an anode material. However, the same graphite structure fails when it comes to sodium or potassium. Their atoms are simply too big and interactions too complex to slide in and out of graphite’s tightly packed layers.

But by rethinking the shape of the carbon at the microscopic level, the team found a workaround. The cone and disc structures offer curvature and spacing that welcome sodium and potassium ions without the need for chemical doping (the process of intentionally adding small amounts of specific atoms or molecules to change its properties) or other artificial modifications.

Here is an exclusive Tech Briefs interview, edited for length and clarity, with First Author Atin Pramanik, Postdoctoral Associate in Ajayan’s lab.

Tech Briefs: What was the biggest technical challenge you faced while developing this energy storage method?

Pramanik: In this particular work, we used graphitic carbon because that material was synthesized from oil and natural gas byproducts. That material is very cheap; we just throw it in the field or somewhere, but it's not environmentally friendly. And from that material, we synthesized unique carbon — graphitic carbon — that is very morphable, and that is used for sodium-ion batteries.

So, these days, the biggest thing is lithium technologies being commercialized. But traditional lithium is not well distributed throughout the world. The price of the lithium is a couple of times higher than the sodium, but, fortunately, sodium is distributed uniformly throughout the world.

So, let’s say a researcher is trying to make commercialized sodium-ion batteries for practical use — not just research. One particular thing I would like to mention is that graphitic carbon is very good for lithium and battery anode materials that are currently commercialized. But the graphite is not good for sodium because there is a layer spacing, and the lithium can move very quickly between the layers, but sodium cannot because sodium’s size is much larger than lithium. So, ours is a unique morphology where the sodium can integrate in the graphitic structure. That's the good thing actually; that is the thing we just developed.

Tech Briefs: How does it differ from prior renewable energy storage methods?

Pramanik: There are three, four, or maybe five maximum. In our study, graphitic carbon shows very high reversible sodium-ion battery performance. So, this is completely unique compared to the previously reported works.

Tech Briefs: Do you have any set plans or further research, work, etc.? If not, what are your next steps?

Pramanik: We are doing a follow up based on this work. So, we just published a part of the work for longer cycling, etc., just to get it commercialized.

Tech Briefs: Is there anything else you'd like to add that I didn't touch upon?

Pramanik: The most unique thing here is the material development, because this material is very cheap. As I said in the beginning, this was derived from the oil and natural gas derived byproduct. So, it's very cheap, and you can make it on a kilogram scale — and can actually scale it even more. That’s a very unique thing.

So, I would say this material is sustainable because from waste material, you are making a usable product. So, that's the most important thing. Also, we've got very sustainable battery performance as well. That's another unique thing.