Improving high-energy lithium-ion batteries with carbon filler

Conductive carbon fillers in lithium-ion batteries allow high power output with reversible energy storage


Research News


WASHINGTON, November 10, 2020 — Lithium-ion batteries are the major rechargeable power source for many portable devices as well as electric vehicles, but their use is limited, because they do not provide high power output while simultaneously allowing reversible energy storage. Research reported in Applied Physics Reviews, by AIP Publishing, aims to offer a solution by showing how the inclusion of conductive fillers improves battery performance.

The optimum battery design involves thick electrode structures. This enhances the energy density, but the design suffers from poor lithium-ion transport, a key step in the functioning of these electrodes. Various improvement techniques have been tried, including building vertically aligned channels or creating pores of the proper size to facilitate transport of the lithium ions.

Another approach involves the use of fillers made of carbon that conduct electricity. This study considered three types of fillers: single-walled carbon nanotubes (SWCNTs), graphene nanosheets, and a substance known as Super P, a type of carbon black particles produced during oxidation of petroleum precursors. Super P is the most commonly used conductive filler in lithium-ion batteries.

The fillers were added to a type of electrode material known as NCM that contains nickel, cobalt, and manganese. The investigators examined the resulting composites with scanning electron microscopy. The Super P and NCM particles were found to be arranged in a point-to-point contact mode.

The SWCNTs were, however, wrapped around the NCM particles, forming a conductive coating. In addition, networks of interconnected SWCNTs were observed in the spaces between NCM particles. The graphene nanosheets were also wrapped around the NCM electrode particles but not as uniformly as the SWCNTs were.

The SWCNTs were found to be the best conductive filler for NCM electrodes.

“The measured conductivity is consistent with percolation theory … When an electrically conductive filler is added to an insulating matrix, significant increases in conductivity will occur once the first conducting pathway through the composite is formed,” said Guihua Yu, one of the authors.

Since percolation requires a complete pathway through the filler, a sufficient amount of conductive filler is needed. Therefore, the investigators considered various amounts of filler and found that combining NCM electrodes with as little as 0.16% by weight of SWCNT produced good electrical conductivity. Higher amounts of Super P and graphene were required to achieve these same results.

The investigators used several spectroscopic techniques, including Raman and X-ray absorption spectroscopy, to study the resulting composites.

“This is a collaborative effort from the Center for Mesoscale Transport Properties, an Energy Frontier Research Center supported by the U.S. Department of Energy Basic Energy Sciences program. Our findings suggest that the integration of SWCNTs into the NCM electrode facilitate ion and charge transfer. This will lead to higher electrochemical utilization, especially at high rates of discharge,” Yu said.


The article, “Unveiling the dimensionality effect of conductive fillers in thick battery electrodes for high-energy storage systems,” is authored by Zhengyu Ju, Xiao Zhang, Steven T. King, Calvin D. Quilty, Yue Zhu, Kenneth J. Takeuchi, Esther S. Takeuchi, David C. Bock, Lei Wang, Amy C. Marschilok, and Guihua Yu. The article will appear in Applied Physics Reviews on Nov. 10, 2020 (DOI: 10.1063/5.0024123). After that date, it can be accessed at THE JOURNAL

Applied Physics Reviews features articles on significant and current topics in experimental or theoretical research in applied physics, or in applications of physics to other branches of science and engineering. The journal publishes both original research on pioneering studies of broad interest to the applied physics community, and reviews on established or emerging areas of applied physics. See

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November 10, 2020 10:21 am

Yay! Carbon!

It doesn't add up...
November 10, 2020 10:44 am

High power output is one goal and improved re-charge characteristics, round trip efficiency (often more about inverters) and lifetime are others, but the real constraints on Li batteries are more about energy density and cost. In static applications (grid batteries) really cost and life are the main goals alongside round trip efficiency. But if you want kites that fly….

Beta Blocker
Reply to  It doesn't add up...
November 10, 2020 5:19 pm

Vanadium redox flow batteries are being touted by renewables advocates as the long term solution for supplying the grid-scale energy storage services needed to support the transition of US electric power generation away from coal, natural gas, and nuclear into mostly wind and solar. Would you have any perspectives to offer on this claim?

Reply to  Beta Blocker
November 10, 2020 9:45 pm

We know that a large one was tried in the King Island Renewable Energy Integration Project a decade ago but it failed prematurely and was replaced with a large bank of lead-acid cells.

Nick Schroeder
November 10, 2020 10:54 am

“…do not provide high power output while simultaneously allowing reversible energy storage.”

Guess my Honda hybrid didn’t get the memo.

November 10, 2020 11:19 am

Carbon is in there … it cannot be allowed to be used.

(maybe chicken feathers would be a suitable replacement).

Reply to  DonM
November 10, 2020 11:33 am

Don’t chicken feathers have carbon in them?

Reply to  DonM
November 10, 2020 11:38 am

Carbon usage?! Anathema!

Doc Chuck
November 10, 2020 11:44 am

What great news! Been wondering what I was going to do with an attic full of single walled carbon tubules. Elon, give me a call.

November 10, 2020 11:52 am

Carbon-based batteries. Carbon-based babies. A temperature signal that precedes carbon dioxide emission, then rises and falls with other factors. Decarbonize?

November 10, 2020 12:18 pm

Okay EV armchair experts, I have a few simple questions.

1) What happens when an EV drives in a partly flooded street?
1b) What happens when a cheap Chinese EV drives through a partly flooded street? (They’re coming you know.)
1c) What happens to first responders when they approach a wrecked, cheap Chinese EV in a partly flooded street?
2) What will the repair bills look like on EVs, i.e. for the long-term buyers who don’t fall into the rapid turnover category of owners?
2b) What will be the diagnostic charge just to look initially at these high voltage EVs by qualified electro-mechanics?
3) What will happen when the low income buyers of used cars come up against the used EV market? Is there a cliff on costs?

Reply to  ResourceGuy
November 11, 2020 2:35 am

nothing happens to an EV in a part flooded street. The battery units are sealed: it keeps driving.

EVs may be safer, this argues:

EVs have a lot less parts to wear/go wrong, so the total cost of ownership is lower than an ICe.

Reply to  griff
November 12, 2020 9:10 am

So what if the battery pack is sealed. You still have to get the power from the battery to the motor.
Are you being paid to make yourself look stupid?

As to the seal, what happens to it in an accident?

The motor for an ICE car will last longer than your battery and cost half as much to replace when it wears out.

The claim that cost of ownership is less for electrics is only true due to massive government subsidies.

Reply to  griff
November 12, 2020 3:21 pm

Cost is not determined simply by number of parts. And how are you counting the number of parts in a battery composed of thousands of cells?

Reply to  griff
November 13, 2020 1:02 pm

“EVs have a lot less parts to wear/go wrong, so the total cost of ownership is lower than an ICe”

Utterly false.

Unfortunately, while people point at single engines and bemoan the parts, they totally ignore the many circuits and circuit boards necessary for EVs. All it takes is one part failing out of the thousands on any circuit board to disable an EV or cause danger to the occupants.

As well as the many parts for each motor, brake system, flywheels along with the miles of wiring required. Wiring that will develop shorts as time and vibration take their toll.

mike macray
Reply to  griff
November 15, 2020 2:18 pm

…”The battery units are sealed: it keeps driving.”

and the Titanic was unsinkable.. ..fortunately!

November 10, 2020 1:08 pm

“Super P, a type of carbon black particles produced during oxidation of petroleum precursors. Super P is the most commonly used conductive filler in lithium-ion batteries.”

You can’t make lithium batteries without burning oil. You can’t charge them, either.

Rud Istvan
November 10, 2020 1:08 pm

There are three flies in this research ointment.
1. SWCNT, unlike MWCNT, are very expensive and difficult to produce.
2. SWCNT have three chiralities, only one of which is conducting. There is no know way sort that useful 1/3 out.
3. Where power density is needed, a simple supercap addition can solve the problem—a ‘batcap’. For hybrids and EV autos, this was shown years ago with the Chevy Volt at Argonne National Lab in Chicagoland. The supercaps were the then standard Maxwells. And, the cost size, and weight of the batcap all come down. Reason not commercial is the EV batteries got so big (range anxiety) that power density is provided by mere bulk.

November 10, 2020 1:20 pm

You can’t have carbon free energy systems by using carbon. So this technology will be illegal by 2050 according to Joe Biden. Sorry.

Carl Friis-Hansen
November 10, 2020 1:24 pm

If reverse power, I assume “engine” breaking is implied, then why not incorporate a large capacitor to take the brunt?

Chris Hanley
November 10, 2020 2:25 pm

Terrific, battery-powered hand tools, garden tools etc. are very safe and convenient.
But they have limitations and powering small vehicles on short runs is about it for the foreseeable future, let alone a nation:
“The annual output of Tesla’s Gigafactory, the world’s largest battery factory, could store three minutes’ worth of annual U.S. electricity demand. It would require 1,000 years of production to make enough batteries for two days’ worth of U.S. electricity demand. Meanwhile, 50–100 pounds of materials are mined, moved, and processed for every pound of battery produced”.

November 10, 2020 4:32 pm

“Researchers found the added carbon caused difficult to control temperature increases in the batteries.”

it’s a joke sorry I couldn’t help it

Curious George
November 10, 2020 5:45 pm

Not the best written article. “The optimum battery design involves thick electrode structures. This enhances the energy density[why?], but the design suffers from poor lithium-ion transport[are lithium ions transported inside the electrodes?].”

November 10, 2020 11:55 pm

Two molecules always seem to stand out as having remarkable properties for life and utility in the natural world.


Robert of Texas
Reply to  ThinkingScientist
November 11, 2020 5:51 am

You forgot Beer. The Beer molecule is essential to my life.

Reply to  Robert of Texas
November 11, 2020 5:00 pm

Beer has food value, but food has no Beer value!

(Beer is proof that God exists and wants us to be happy.)

Reply to  Richmond
November 13, 2020 2:13 pm

Paging Ben Frankin, eh?

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