Electron and Ion Conduction Network of Dry-Processed Electrodes: Influence of Morphology and Surface Energy of Carbon Additive

Lithium-ion batteries (LIBs) play a pivotal role in the electrified industry due to their high energy density, cost-effectiveness, and long lifespan. Especially, these characteristics make them suitable for electric vehicles (EVs). However, to successfully utilize LIBs as the main power source in EVs, improving the rate capability is highly significant, as it directly impacts fast-charging capabilities and power performance. Indeed, enhancing the rate capability of electrodes requires designing the microstructure to facilitate efficient electron and lithium-ion conduction even under high-rate operating conditions. In dry-processed electrodes, PTFE is used as a binder. During the electrode fabrication process, PTFE forms a fibril-like structure with more open pores, facilitating lithium-ion transport. However, since no solvent is used for electrode fabrication, uniform dispersion of the carbon additive is hard to achieve. Moreover, the fibril-like PTFE structure is disadvantageous for mechanically binding the carbon additive and constructing a robust electron percolation pathway. Consequently, these microstructural characteristics can hinder electron conduction in the dry-processed electrode, deteriorating the rate capability. Herein, we investigated the electron and lithium-ion conduction network of dry-processed electrodes with different types of carbon additive. Experimental results demonstrated that the morphology and surface energy of the carbon additive play a crucial role in determining the electron and lithium-ion conduction pathway in the dry-processed electrode. Finally, we correlated the rate capability of dry-processed electrodes with the conduction network using a digital twin-driven electrochemical modeling and simulation framework. We believe this basic research can provide a guide for the fabrication of high-performance dry-processed electrodes.