Manufacturing Thick Structured Electrodes Using Acoustophoresis

Finding ways to improve the energy and power densities of current lithium-ion batteries (LIBs) is crucial to improving the performance of electric vehicles (EVs). Commercial LIBs are constructed with planar electrodes wherein their performance can be optimized for energy or power but not both simultaneously. An approach to mitigate these trade-offs is to manufacture electrodes with more controlled structure and engineered porosity to enable rapid ion transport through thick electrodes at higher discharge rates and current densities.^1,2 For example, structured electrodes (SEs) with line patterns have demonstrated a > 10% increase in fast charge behavior and energy density over their planar electrode counterparts.^1-3 However, manufacturing line-patterned SEs over large areas remains a challenge with current processing methods available to the battery community. To solve this challenge, we have developed a new manufacturing approach for creating line-patterned SEs using principles of acoustophoresis. Acoustophoresis uses acoustic forces to rapidly assemble particles in a fluid medium on a micron scale and is independent of material chemistry. Using conventional LIB slurries with carbon black, polyvinylidene fluoride, N-methyl-2-pyrrolidone, and LiNi_0.6Mn_0.2Co_0.2O₂ (NMC-622), we demonstrate how acoustophoresis enables the rapid fabrication and assembly of thick line-patterned SEs. Initial electrochemical results with graphite and NMC-622 in a 2032 coin cell show a 10 - 140% improvement in specific discharge capacity at C/2 - 2C.

References
1. C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164 (7), A1339-A1241 (2017).
2. N. Dunlap et al., J. Power Sources, 537, 231464 (2022).
3. Y. Zhang et al., J. Mater. Chem. A, 22, (2023).

Acknowledgement
This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office (AMO) Award Number DE-EE0009112. The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. This work was partially carried out at the Materials Engineering Research Facility (MERF) at Argonne National Laboratory, which is supported by the DOE, Office of Energy Efficiency and Renewable Energy, and the Vehicle Technologies Office, under the Contract No. DE-AC02-06CH11357. The MERF synthesized size-specific NMC-622 for the project.