(64e) Development of Coal-Derived Graphites for Lithium-Ion Batteries

Graphite is one of several critical minerals that are used in lithium-ion batteries. As the demand for rechargeable batteries increases, especially with the rising demand for electric vehicles, the demand for the raw materials also increases. In the United States, there is much interest in developing a domestic supply of graphite to reduce the reliance on other countries. Due to the lack of graphite mines in the U.S., the focus has been put on the production of synthetic graphite from domestic feedstocks. One feedstock being investigated is coal because of its high carbon content and abundance in the United States.

In this project, several coal-derived graphites were synthesized from anthracite, bituminous coals, and coal pitches. Extensive characterization was done on each coal-derived graphite. This includes XRD, Raman spectroscopy, BET surface area and SEM images. With the physical properties well characterized, the electrochemical performance of each coal-derived graphite was investigated and compared to a commercial MesoCarbon, Microbead (MCMB) graphite. To do this, coin cells (CR2032) were constructed with lithium metal as the counter electrode. Low-rate SEI formation, pseudo-equilibrium open circuit voltage (POCV) cycling, and entropic coefficient tests were completed.1-3 Using the POCV data, the Multi-Species, Multi-Reaction (MSMR) model has been applied to several of the coal-derived graphites to probe the thermodynamics of lithium intercalation in each material.

Selected coal-derived graphites made from a medium volatile bituminous coal and an anthracite coal were made into single layer pouch cells. These cells were also compared to a commercial MesoCarbon, MicroBead (MCMB) graphite. The graphite synthesized from the medium volatile bituminous coal has shown superior capacity retention with 90% retention after 800 cycles with testing still ongoing. Our study demonstrates that coal has the potential to be the key to establishing a domestic supply of graphite for lithium-ion batteries.

References:

1. A. Paul et al., Journal of The Electrochemical Society, 171, 039001 (2024)

2. A. Paul et al., ECS Advances, 3, 042501 (2024)

3. A. Paul et al., Journal of The Electrochemical Society, 171, 103505 (2024)