Using Coal Waste to Power Lithium-Ion Battery Anodes

In 2020, NETL awarded X-MAT, a division of Semplastics, $1 million for a three-year project to develop polymer-derived ceramic composite anodes that use coal waste as the carbon source for lithium-ion battery anodes. The X-MAT research team has since turned that funding into some promising developments for the future of lithium-ion battery technology and sustainable energy.

According to NETL, an anode is one of two electrodes within a lithium-ion battery, typically consisting of graphite deposited on copper foil. The graphite represents a significant component of a lithium-ion battery’s overall weight and cost. Currently, it can be derived from natural graphite (mined as graphite) or synthetic graphite (derived from other hydrocarbons) and most of its cost (on the order of $10,000/ton) is due to processing temperature and time requirements, it was explained in a news release.

Benchmark Mineral Intelligence reports that "there are about 150 lb of graphite per electric vehicle and by 2035, it has been estimated that more than 150 new graphite mines would be required to meet projected demand." Since graphite makes up about 28% of the typical EV battery, the total amount of graphite needed would reach many millions of tons by 2035." Extensive energy, time, and resources would be needed to generate such an amount of graphite.

However, X-MAT’s new technology, which uses heat treating for coal- and polymer-derived ceramics as a substitute for graphite, can reduce both the processing time and temperature for anode materials, while also significantly increasing silicon loading. “Based on the results of our research and development funded by the Department of Energy’s National Energy Technology Laboratory, we believe that coal waste can play a major role in mitigating this shortfall and it is already being produced in the volumes that would be required,” explained a company spokesperson in the release.

The X-MAT research team has combined coal with the company’s proprietary silicon forming resin-based technology to create carbon for lithium-ion batteries, reported Joe Stoffa, NETL technology manager for the Carbon Ore Processing Program, in a press release. This anode material was independently tested in 18650 batteries, which are used in popular BEVs. Results from the first 18650 cells that were made using the coal and polymer-derived ceramic showed a retention capacity of 80% after 1,000 cycles of being fully charged and fully discharged, which demonstrated the promising cycle life capabilities of the new technology, according to the release.

“At the end of the project, the X-MAT anode material has demonstrated stability in the 18650 form factor and shows promise as a high silicon loaded carbon anode material with higher nominal voltage that could cost less than incumbents, while having a significant co-benefit through the utilization of coal waste,” Stoffa stated.

X-MAT CEO Bill Easter told Waste Advantage magazine: “The use of coal waste as a value-added material not only provides a domestic source for anodes but creates a new market for coal waste. We are grateful for the support of the Department of Energy and the NETL, who made this project possible. Our coal-based material can meet this demand in an eco-friendlier way and would lead to a domestic source for anode material, helping the U.S. reduce reliance on foreign countries for the critical materials needed to support the growing demand for electrification.”