A team from the Carnegie Mellon University has developed a new way to produce 3D printed battery electrodes that create a 3D microlattice structure with controlled porosity.
Due to the nature of the manufacturing process, the design of 3D printed electrodes is currently limited to just a few possible architectures. The internal geometry that currently produces the best porous electrodes through additive manufacturing is called interdigitated geometry, where metal prongs interlocked with the lithium shuttling between the two sides.
By 3D printing the microlattice structure, the researchers vastly improved the capacity and charge-discharge rates for lithium-ion batteries. Overall, the new structure led to a fourfold increase in specific capacity and a two-fold increase in areal capacity when compared to a solid block electrode.
“In the case of lithium-ion batteries, the electrodes with porous architectures can lead to higher charge capacities,” Rahul Panat, an associate professor of mechanical engineering at Carnegie Mellon University, said in a statement. “This is because such architectures allow the lithium to penetrate through the electrode volume leading to very high electrode utilization, and thereby higher energy storage capacity.
“In normal batteries, 30 to 50 percent of the total electrode volume is unutilized,” he added. “Our method overcomes this issue by using 3D printing where we create a microlattice electrode architecture that allows the efficient transport of lithium through the entire electrode, which also increases the battery charging rates.”
The electrodes also retained their complex 3D lattice structures after 40 electrochemical cycles, meaning the batteries have a high capacity for the weight or the same capacity at a vastly reduced weight.
The new method creates porous microlattice architectures while leveraging the existing capabilities of an Aerosol Jet 3D printing system, which allows researchers to print planar sensors and other electronics on a micro-scale.
Previously, 3D printed batteries were limited to extrusion-based printing, where a wire of material is extruded from a nozzle to create continuous structures, including interdigitated structures.
However, the new method will allow researchers to 3D print the battery electrodes by rapidly assembling individual droplets one-by-one into three-dimensional structures that result in structures with complex geometries impossible to fabricate using typical extrusion methods.
“Because these droplets are separated from each other, we can create these new complex geometries,” Panat said. “If this was a single stream of material, as is in the case of extrusion printing, we wouldn’t be able to make them. This is a new thing. I don’t believe anybody until now has used 3D printing to create these kinds of complex structures.”
The new method could lead to geometrically optimized 3D configurations for electrochemical energy storage and could be transitioned to industrial applications in the next two to three years. It could be beneficial in a number of fields, including consumer electronics, medical devices and aerospace. The research could also integrate with biomedical electronic devices where miniaturized batteries are necessary.
The study was published in Additive Manufacturing.