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Researchers at the Technical University of Denmark (DTU) have developed a new type of solid oxide cell (SOC) that combines low weight with high power output.
Published in Nature Energy, the design addresses long-standing barriers that have kept fuel cells from being practical in aerospace and space exploration. According to TechXplore, the project was led by Professor Vincenzo Esposito of DTU Energy and Senior Researcher Venkata Karthik Nadimpalli of DTU Construct, together with colleagues from both departments. Their work reimagines SOCs through gyroid geometry, a form of triply periodic minimal surface (TPMS).
This geometry is mathematically optimized to maximize surface area within a given volume while remaining lightweight and mechanically stable. It occurs in natural structures such as butterfly wings and is also used in engineering, including heat exchangers where efficient flow and robustness are essential.
Breaking weight barriers in fuel cells
Conventional SOCs are typically built as flat stacks that rely on metal parts for sealing and electrical connections. These components often account for more than 75% of the system’s weight, creating a significant barrier in applications where every kilogram matters, such as aviation.
The scale of the challenge is illustrated by batteries: replacing the 70 t of jet fuel carried by a commercial aircraft with Li-ion batteries of equivalent energy would require about 3,500 t, making flight impossible. Traditional SOCs face a similar limitation because of their heavy construction.
To move past this constraint, the DTU team used 3D printing to produced a fully ceramic, monolithic SOC that eliminates both metal supports and fragile seals. The new fabrication method reduces production to 5 steps, compared with the dozens required by conventional stacks, and results in a single-piece device the team calls the Monolithic Gyroidal Solid Oxide Cell, or “Monolith.”
Tests of the Monolith showed that it delivers more than 1 W per gram of weight. According to the researchers, this marks the first time an SOC has reached such a power-to-weight ratio. Nadimpalli explains that achieving this level of performance is a prerequisite if electricity-based conversion technologies such as batteries and fuel cells are to become viable in aerospace.
Beyond aerospace, fuel cells already play important roles in other sectors. They power hydrogen vehicles and ships, provide backup electricity for hospitals and data centers, and serve as storage systems that help stabilize renewable grids. Their value lies in versatility, since they can operate both as generators and as electrolyzers that produce hydrogen. In electrolysis mode, the DTU design generated hydrogen at nearly 10× the rate of conventional SOCs.
The Monolith was repeatedly cycled between fuel cell and electrolysis operation and exposed to temperature shifts of 100 °C. The device maintained performance without delamination or structural failure. Esposito notes that this resilience is crucial for systems intended to function in demanding environments.
Space exploration is one area where such durability could be particularly significant. NASA’s Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE), which produces O₂ from the CO₂-rich Martian atmosphere, currently relies on SOC stacks weighing more than 6 t. The DTU team estimates that a system based on their design could achieve comparable performance at about 800 kg, a reduction that would substantially ease launch requirements.
The researchers also highlight that the method of construction is as important as the performance itself. Conventional SOC stacks are complex to assemble, requiring many steps and a mix of materials that degrade over time. The monolithic ceramic approach removes metals and seals, simplifying production while potentially extending long-term reliability.
Although the prototype already represents a major departure from established designs, the team sees further opportunities to improve it. They point to thinner electrolytes as a way to reduce weight, less expensive current collectors such as Ag or Ni as alternatives to Pt, and more compact geometries as a means of increasing efficiency.
3D printing ceramic fuel cells
3D printing makes ceramic fuel cells cheaper to produce and easier to design with shapes that improve efficiency. It also reduces material waste while creating stronger, more durable cells.
Researchers from the Catalonia Institute for Energy Research and the Catalan Institution for Research and Advanced Studies used ceramic 3D printing to make a new type of solid oxide fuel cell (SOFC) that is lighter and more efficient than conventional versions. Using stereolithography (SLA), they printed both flat and corrugated membranes made of yttria-stabilized zirconia (YSZ) and added electrodes to complete the cells.
The corrugated design increased the surface area by 57% (3.15 cm² compared to 2.00 cm²) and delivered 60% more capacity than standard SOFCs. The cells also worked in reverse as electrolysis cells (SOECs), producing hydrogen or syngas while showing stable performance with very little degradation over time.
At Skolkovo Institute of Science and Technology (Skoltech), researchers used a low-cost micro-stereolithography setup with a standard office projector to 3D print complex ceramic structures for solid oxide fuel cells (SOFCs). They combined scandia-stabilized zirconia (6ScSZ) and yttria-stabilized zirconia (8YSZ) into a hierarchical lattice structure that cannot be produced with traditional methods.
This lattice enhanced ionic conductivity, which is key to maximizing fuel cell efficiency. The team fabricated “green” ceramic parts via UV curing, then consolidated them through optimized burning and sintering, successfully demonstrating a novel, inexpensive route to producing high-performance SOFC components.
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Featured image shows 3D printed fuel cells. Image via DTU / Nature Energy.
