3D-Printed Interpenetrated Electrode Architecture for Enhanced Ion Diffusion in Next-Generation Electrochemical Energy Storage Devices

The architectural design of electrodes offers significant potential for next-generation electrochemical energy storage devices (EESDs) by enhancing surface area, thickness, and active material mass loading, while maintaining efficient ion diffusion through optimized electrode tortuosity. However, conventional thick electrodes increase ion diffusion length and create larger ion concentration gradients, which limit reaction kinetics. In this presentation, we demonstrate a strategy for constructing interpenetrated structures that shorten ion diffusion paths and reduce ion concentration inhomogeneity. This free-standing device structure avoids short-circuiting without the need for a separator. The feature size and density of the interpenetrated units can be adjusted during 3D printing to balance surface area and ion diffusion.

Starting with a 3D-printed interpenetrated polymer substrate, we metallize it to enhance conductivity. This substrate supports two individually addressable electrodes, enabling selective electrodeposition of energy storage materials. Using a Zn/MnO₂ battery as a model system, the interpenetrated device outperforms conventional separate electrode configurations, improving volumetric energy density by 221% and exhibiting a higher capacity retention rate of 49% compared to 35% at temperatures from 20 to 0 °C. Additionally, we demonstrate the viability of this interpenetrated design in alkaline water splitting (AWS), providing a large ion-accessible surface area and efficient gas diffusion channels. This architecture significantly reduces the interelectrode distance, lowering ion-diffusion length and solution resistance. Overall, our 3D-printed design introduces a novel EESD architecture with broad applications for Li-ion and Na-ion batteries, supercapacitors, and beyond.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA2734. The IM tracking number is 1109886.