Study Shows Low-Cost Desktop Resin 3D Printing Used to Create Battery Electrodes

Researchers at Eindhoven University of Technology and the University of Waterloo have demonstrated that standard entry-level resin 3D printers can produce functional carbon battery components. Using an off-the-shelf SLA printer valued at approximately $350, the team printed complex polymer structures and converted them into conductive carbon electrodes for redox flow batteries through high-temperature carbonisation.

The study highlights how mathematically derived internal geometries, such as triply periodic minimal surface (TPMS) designs, can address fluid flow bottlenecks that limit conventional commercial battery materials.

Evaluating Printed Geometries and High-Temperature Carbonisation

To fabricate the electrodes, the research team printed four distinct architectures using a desktop stereolithography setup, maintaining a uniform 70% open porosity and 1 mm repeating unit size across the designs. The resin models were subsequently baked at 1,000°C in a specialised furnace. This thermal conversion process, known as pyrolysis, drove off non-carbon elements, raising the atomic carbon content of the structures from 71.5% to 94.2% while making them electrically conductive.

Among the shapes evaluated—which included cubic and diamond lattices—the diamond geometry offered the best overall performance among the 3D-printed samples. Flow modelling revealed that the diamond structure distributed liquid electrolyte far more evenly than the cubic grid, achieving a flow variation coefficient of 1.01 compared to 1.43 for the cubic option. Additionally, the diamond shape yielded 1.47 times the surface area of the cubic grid and recorded the lowest electrical resistance of the printed geometries.

When compared to traditional carbon felt electrodes, the 3D-printed TPMS structures demonstrated significantly reduced hydraulic resistance. At a liquid flow speed of 10 cm per second, the printed electrodes generated pressure drops between 14 and 80 kPa per metre, whereas conventional carbon felt registered a pressure drop of 745 kPa per metre. Reducing this flow resistance directly decreases the pumping energy required to operate flow battery systems.

Surface Area and Chemical Tradeoffs

Despite the improved fluid dynamics, printed electrodes face physical limitations regarding microscopic surface area. Gas adsorption tests revealed that commercial carbon felt possesses roughly ten times more surface area per unit volume than the printed lattice structures. In practical cell testing with a vanadium redox flow battery, the printed electrode assembly achieved 76% voltage efficiency and 71% coulombic efficiency at 50 mA/cm².

Tests on gyroid geometries at varying porosities (50%, 70%, and 90%) showed that higher porosity provided superior mass transfer at higher flow rates, even with lower total surface area. These findings suggest that 3D-printed geometries are particularly suitable for fast-reacting liquid chemistries where fluid movement is the primary bottleneck.

What This Means for South African Makers

For South African researchers, engineering students, and energy storage innovators, this methodology demonstrates how low-cost desktop resin printing can participate in advanced material development. While specialised high-temperature furnaces are required for the 1,000°C carbonisation step, the initial shaping of complex microstructures can be handled on entry-level SLA printers available locally.

As interest in municipal grid-scale storage, off-grid solar backup, and custom battery systems grows across South Africa, accessible prototyping methods allow local labs and makers to experiment with functional carbon structures without investing in industrial additive manufacturing hardware.

DC3D’s Take

This research offers a clear example of using standard SLA hardware for functional engineering experiments rather than purely aesthetic prints. The ability to generate complex TPMS geometries on a basic resin printer confirms the versatility of light-cured photopolymers as precursor materials for carbon structures.

However, practical challenges remain. Thermal shrinkage during pyrolysis alters final part dimensions, and rigid carbon lattices can compress delicate internal battery membranes during assembly. For local experimenters, SLA printing provides a viable pathway for prototyping geometry, but scaling to full working cells requires careful handling of shrinkage allowances and post-processing steps.