3D-Printed Diamond Electrode Boosts Flow Battery Output 52%

A New Twist on Grid Storage, Not EV Batteries

A team of researchers at the University of Waterloo has built a 3D-printed electrode that improves the performance of redox flow batteries by as much as 52%, a development aimed squarely at the challenge of storing large amounts of wind and solar power rather than at improving the batteries inside electric vehicles 17. The distinction matters because the word "battery" in a headline can easily be read as a leap forward for EVs, when the underlying technology addresses a fundamentally different engineering problem: how to hold electricity safely and cheaply for hours at grid scale, then release it when renewable generation drops off 713.

Led by chemical engineering professor Dr. Maxime van der Heijden, the research team drew on structures found in nature to redesign the electrode at the heart of a redox flow battery (RFB), a storage technology that behaves very differently from the lithium-ion cells found in phones, laptops and cars 713. The study, published in the Journal of Energy Storage, describes the fabrication and testing of porous carbon electrodes built using triply periodic minimal surface (TPMS) geometries — repeating three-dimensional shapes that visually resemble natural patterns 813.

How the Electrode Was Built and Tested

The researchers used a digital light-processing 3D printer to produce several candidate electrode geometries, including gyroid, diamond, IWP and cubic structures, then heat-treated the printed parts to convert them into electrically conductive carbon electrodes 814. Because conventional manufacturing methods struggle to create such intricate internal architectures, 3D printing gave the team far more control over how liquid electrolyte moves through the material and reaches the reactive surfaces where energy-storing chemical reactions occur 715.

Among the geometries tested, the "diamond" design proved most effective, delivering what the university and multiple outlets described as a 52% increase in performance 11314. The primary study itself is more circumspect about that figure, framing the diamond structure's advantage in terms of enhanced mass transport and low hydraulic resistance rather than restating the 52% figure directly, which leaves some ambiguity about exactly which metric — current density, mass-transport efficiency, or another composite measure — the widely cited number refers to 8.

Testing proceeded in stages. The team first evaluated the printed electrodes in single-electrolyte flow cells using an organic redox couple chosen for its fast reaction kinetics, allowing researchers to isolate the effects of electrode geometry on pressure drop, surface area and electrochemical behavior without chemistry-related complications getting in the way 89. They also found that increasing porosity improved electrolyte flow even as it reduced surface area, a trade-off that can actually help when the electrolyte itself reacts quickly but conducts ions poorly 8.

A representative 3D-printed gyroid electrode was then installed in a working vanadium redox flow battery (VRFB) as a proof of concept, achieving a voltage efficiency of 76% at a current density of 50 mA/cm² 8. Compared with a commercial carbon-felt electrode, the printed structure showed comparable ohmic resistance and favorable flow characteristics, though its lower electrochemical surface area limited the current densities it could reach — a meaningful engineering limitation given that power density directly affects the size and cost of a battery stack 8.

Why Flow Batteries Suit the Grid, Not Cars

Redox flow batteries work by storing charge in liquid electrolytes held in external tanks rather than in solid electrode materials 71315. Pumps circulate the electrolytes through a reactor stack where oxidation and reduction reactions charge and discharge the system. Because energy capacity is essentially a function of tank size, while power output depends on the stack, flow batteries can decouple energy and power in a way lithium-ion systems cannot — a feature repeatedly cited across the flow-battery literature as their central advantage for stationary storage 91012.

That architecture is a poor fit for vehicles, which demand compact, lightweight, energy-dense batteries capable of rapid charging. Flow batteries require tanks, pumps and plumbing, and their energy density trails lithium-ion by a wide margin — reviews put flow-battery specific energy in the range of tens of watt-hours per liter compared with well over a hundred for lithium-ion chemistries 12. A recent review of vanadium flow-battery materials makes the point explicitly, noting that RFBs show their greatest advantage in grid-scale stationary storage rather than in electric vehicles or small portable devices 11.

That is precisely why flow batteries are typically described as complementary to, rather than competitors with, lithium-ion technology: lithium-ion suits high-power, compact applications, while flow batteries suit long-duration, large-volume storage tied to renewable generation and grid stability 712.

The Safety Argument, and Its Limits

Much of the appeal of redox flow batteries comes from their use of water-based electrolytes, which sidesteps the flammability risks associated with the organic electrolytes in many lithium-ion systems 71315. The U.S. Department of Energy's Sandia National Laboratories has similarly noted that flow batteries can be significantly safer than other electrochemical storage technologies, a quality increasingly valued as utilities push toward longer-duration, less-flammable storage options 10.

That safety advantage stems from the underlying chemistry and system design, not from 3D printing itself. Vanadium flow batteries still involve pumps, membranes and acidic electrolyte, and typically operate with round-trip efficiencies in the 70–85% range, alongside real risks like electrolyte leakage or imbalance 1216. The electrode innovation described here should be understood as a refinement that could make an already comparatively safe technology perform better, not as a claim that 3D printing makes energy storage inherently safe 7.

Broader Context: An Industry Already Betting on Storage Diversity

The Waterloo work lands amid a broader wave of grid-storage activity. Capital Power recently commissioned a 120-MW battery storage system in Ontario alongside a 50-MW project, underscoring how utilities are rapidly scaling up battery deployments to firm up renewable generation 3. Elsewhere, U.S. researchers are testing high-speed flywheels designed for decades-long grid storage, while solid-state battery development continues to draw attention as a potential long-term shift for both vehicles and stationary storage 45. Even residential and off-grid users are expanding battery capacity, as seen in one case where a builder pushed a home system to 65.5 kWh of storage with dozens more solar panels still to come 6. Together, these developments illustrate an energy-storage landscape diversifying across chemistries and mechanical approaches, of which flow batteries and their electrode designs are just one piece 2.

Remaining Questions and Caveats

Several qualifications temper the 52% headline figure. It is not clear from public materials whether the number reflects power density, current density, or another specific measure, and the primary study's abstract does not restate it directly 8. The strongest full-cell demonstration used a gyroid electrode rather than the top-performing diamond design, meaning the marquee statistic and the working-battery test are related but not identical experiments 8. The printed electrodes also underperformed commercial carbon felt on achievable current density due to reduced surface area, a limitation the researchers acknowledge needs further work 814.

Scaling remains an open question as well. Digital light-processing printing can produce intricate geometries unreachable by conventional manufacturing, but commercial-scale batteries require electrode material in large, consistent, affordable quantities — precisely the challenge the Waterloo team flags for future research, alongside increasing surface area and refining design tools 71314. Broader structural challenges facing vanadium flow batteries, including high capital costs, expensive membranes, limited vanadium solubility and electrolyte price volatility, remain unresolved industry-wide issues that this electrode advance does not directly address 11161718.

The Bottom Line

The Waterloo team has demonstrated that engineering the internal architecture of a flow-battery electrode — treating it almost like a fluid-dynamics problem rather than a fixed slab of carbon felt — can meaningfully improve how efficiently electrolyte moves and reacts inside the cell 78. The diamond geometry's 52% performance gain, and the successful operation of a printed electrode inside a working vanadium flow battery, represent a genuine proof of concept for making renewable-energy storage more efficient and inherently safer 11314. It is not, however, evidence of a breakthrough for EV batteries, nor proof that flow batteries are now ready for widespread commercial deployment; it is one incremental but notable step toward making a technology already suited to the grid work better at the job it was designed for 79.