CoEx is a novel co-extrusion printing technique allowing dissimilar materials to be deposited side by side at high speed. This technique can directly deposit an interdigitated structure as small as 1 µm in width with high aspect ratios. By changing the print head geometry, the relative thickness, width, and length of the deposited structure can easily be modified.

CoEx allows fine structures to be printed at high speed, and when applied to thick battery electrodes, it adds a new design dimension—e.g., 2- and 3-dimensional structures—that can be used to enhance energy and power performance. This innovative approach has the potential to help make high performance and affordable electric vehicles (EVs) a reality, PARC said.

PARC has already fabricated LiCoO₂ half cells using CoEx and measured improved energy and power. Performance modeling is also being conducted with different battery chemistries, including alkaline, Li_xMn₂O₄, LiCoO₂, Zn-air, and Ag-Zn. For example, the modeling of a CoEx structured cathode in a Li-ion battery resulted in a 10-20% improvement in energy density at the same power output. Applying the technique to anodes, additional improvements can be expected.

PARC will develop the inks and CoEx hardware required to fabricate thick high-energy and high-power CoEx cathode electrodes. ORNL will assist PARC with the matching anode development, anode and CoEx cathode coating at pilot scale, and electrochemical performance optimization in automotive-relevant lithium-ion pouch cells.

The bulk of this research will occur at the DOE Battery Manufacturing R&D Facility (BMF) at ORNL, which was designed in 2011 with these types of projects in mind. PARC will design a custom CoEx apparatus that will be integrated into one of the research coating lines at the BMF.

The PARC team is excited to start this collaboration with ORNL and Ford. CoEx has the potential to make higher capacity EV batteries possible through the creation of two and three dimensional structures which can enhance lithium-ion pathways in ultra-thick battery electrodes. Our goal is to fabricate EV pouch cells that are higher in energy and power than conventional, with a path towards a reduction in $/kWh costs for EVs.

—PARC CoEx technical lead Dr. Corie Cobb

PARC’s CoEx project is part of a portfolio of research within the PARC Energy Technology Program aimed at developing practical solutions to make clean and abundant energy available across a wide range of applications. This includes a focus on improving energy storage for EVs, consumer electronics, and electric grid support through better ways to make, monitor, and manage batteries. (Earlier post.)

By leveraging our deep background in printing, PARC has developed the CoEx printing process to enable higher performance solar cells, fuel cells and batteries. By applying CoEx to printed batteries, we can create optimal structures that boost power performance without compromising energy storage. It’s an efficient and a lower-cost approach that can be applied to the mass manufacturing of batteries.

—Dr. Scott Elrod, Vice President of PARC’s Hardware Systems Lab

The project is funded by the US Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy (EERE).