Registration: European Humanoid Robot Summit 2025
Abstract:DTU in Denmark has developed 3D printed spiral solid oxide batteries (SOCs) with a power density exceeding 1 W/g, a weight reduction of 87% compared to traditional batteries, and stability under extreme conditions, reshaping energy applications in aerospace and deep space exploration, promoting zero-carbon flight and green hydrogen storage development.
Introduction:
The “zero-carbon transition” in the aerospace sector has always been hindered by a critical contradiction: energy devices need to be “powerful enough” but are often “too heavy.” Traditional lithium-ion batteries and planar solid oxide batteries (SOCs) either exceed weight limits or lack sufficient power, until the team at the Technical University of Denmark (DTU) restructured SOCs using “3D printing + Gyroid spiral structures,” finally bringing “aerospace-grade sustainable energy” from theory to practical testing.
1. Industry Pain Point: The “Weight-Power” Deadlock in Aerospace Sustainable Energy
The “zero-carbon dream” of commercial aviation and deep space exploration has been consistently hindered by the “weight of energy devices.” Let’s look at two shocking sets of data:
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If lithium-ion batteries were to replace 70 tons of aviation fuel in a commercial aircraft (of equivalent capacity), the total weight of the batteries would soar to 3,500 tons—equivalent to the empty weight of three Boeing 737s, making it impossible for the aircraft to take off;
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Traditional SOCs, while having higher energy density than lithium batteries, use a “planar stacking + metal support” design: metal components account for over 75%, resulting in significant weight, and due to the difference in thermal expansion coefficients between metal and ceramic, long-term use can lead to sealing failures and interlayer separation, requiring frequent maintenance even in fixed ground scenarios (like hospital power supply), let alone the extreme conditions of aerospace.
More critically, the core requirement for energy devices in aerospace is “high specific power” (output power per unit weight, unit: W/g)—traditional SOCs generally have specific power below 0.3 W/g, while the industry consensus is that “a breakthrough of 1 W/g is needed to meet aerospace demands.” This “deadlock” was only broken with the emergence of DTU’s 3D printed Gyroid SOC.
2. Technical Breakthrough: The “Dual-Drive” of 3D Printing + Gyroid Structure
DTU’s innovation is not a single technological upgrade but a synergistic innovation of “structural design + manufacturing process”—the core is integrating the “Gyroid structure from Triply Periodic Minimal Surface (TPMS)” into the all-ceramic SOC’s integrated design through 3D printing.
1. Gyroid Structure: The “Optimal Solution” from Nature to Engineering
The Gyroid structure is not designed out of thin air but is a “precise replication” of nature:
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In nature, the microscopic Gyroid channels in butterfly wings can achieve “mechanical support + airflow buffering + color refraction” functions within a thickness of 0.1mm;
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In engineering, Gyroid has been used in high-end heat exchangers—its periodically interwoven channels allow fluids (gases/liquids) to achieve maximum contact area with minimal resistance.
The DTU team is the first to apply Gyroid to SOCs, recognizing its three core advantages (corresponding to aerospace needs):
| Gyroid Structure Characteristics | Addressed SOC Pain Points | Aerospace Value |
|
High specific surface area (over 300% higher than planar) |
Insufficient electrochemical reaction interface, low power density |
Increases output power per unit weight |
|
Porosity of 60%-80% |
High proportion of metal components, overall heavy weight |
Reduces device weight, meets payload requirements |
|
Isotropic mechanical strength |
Ceramics are prone to brittle fracture, poor vibration resistance |
Withstands high-altitude vibrations and temperature fluctuations |
In simple terms: the Gyroid structure allows the SOC’s “reaction field” (specific surface area), “weight reduction design” (porosity), and “structural strength” to no longer contradict but support each other.
2. 3D Printing: The “Key Springboard” for All-Ceramic Integrated Manufacturing
The manufacturing of traditional SOCs follows an “assembly logic”—first making planar electrodes and electrolytes, then using metal bolts for fixation and metal seals to prevent leakage, with assembly processes accounting for 40%; whereas DTU’s 3D printing follows an “integrated forming logic,” requiring only five steps for all-ceramic materials:
1) Ceramic Slurry Preparation:
Using yttria-stabilized zirconia (YSZ, a common electrolyte material for SOCs) as the base, adding nickel-based catalysts (anode) and lanthanum strontium cobalt oxide (LSCF, cathode) to ensure the slurry meets both 3D printing flowability and electrochemical activity;
2) Gyroid Model Slicing:
Based on the TPMS mathematical model, slicing software divides the Gyroid structure into printing paths with a thickness of 0.1mm, while reserving gas channels (hydrogen input for the anode, air input for the cathode);
3) Photopolymerization 3D Printing:
Using stereolithography (SLA) technology, the ceramic slurry is cured layer by layer to form a complete “electrode – electrolyte – channel” integrated framework;
4) Debinding and Sintering:
Debinding at 800℃ (removing organic binders), followed by sintering at 1400℃ for 4 hours to densify the ceramics (density over 98%, avoiding gas cross-leakage);
5) Current Collector Coating:
A thin silver layer is coated on the cathode surface (replacing traditional platinum collectors to reduce costs), completing the entire SOC preparation.
The core value of this process: it completely eliminates the metal bolts and seals of traditional SOCs, reducing weight by 75% and avoiding the “metal-ceramic interface degradation” issue—metal components in traditional SOCs can undergo diffusion reactions with ceramics at operating temperatures of 600-800℃, leading to a 30% performance degradation after 5000 hours, while the all-ceramic Gyroid SOC only experiences a 5% degradation over the same testing period.
3. Performance Testing: Breaking Through the “Core Indicators” of Aerospace Energy Devices
The DTU team published performance data in “Nature Energy,” directly targeting the “hard requirements” of aerospace, which we will analyze from three core dimensions:
1. Specific Power: First Breakthrough of 1 W/g, Reaching Aerospace Standards
| Type of Energy Device | Specific Power (W/g) | Weight (using MOXIE equipment as an example) | Can it meet aerospace demands? |
|
Traditional Lithium-Ion Battery |
0.01-0.02 |
Cannot be calculated (far exceeds payload) |
No |
|
Traditional Planar SOC |
0.2-0.3 |
6 tons |
No |
|
DTU Gyroid SOC |
1.05 |
800kg |
Yes |
It is important to note that the specific power of 1.05 W/g is not an “experimental theoretical value” but a stable output value under “fuel cell mode (700℃, hydrogen as fuel)”—after continuous operation for 1000 hours, the specific power only decreased by 2.3%, proving its long-term stability.
2. Extreme Condition Adaptability: Can Withstand “Aerospace-Level Tests”
The DTU team conducted three sets of “extreme tests,” with results far exceeding traditional SOCs:
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Temperature Shock Test: Rapidly increasing from room temperature (25℃) to 700℃ (SOC operating temperature), then rapidly decreasing to 25℃, cycling 50 times—traditional SOCs would experience interlayer cracking due to the thermal expansion differences between metal and ceramic, while the Gyroid SOC only showed minor surface stress lines, with no change in electrochemical performance;
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Mode Switching Test: Switching between “fuel cell mode (power generation)” and “electrolysis mode (hydrogen production)” every 30 minutes, totaling 1000 switches—traditional SOCs would see a 40% drop in hydrogen production efficiency after 500 switches due to the loss of active sites, while the Gyroid SOC only experienced an 8% drop;
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Vibration Test: Simulating the vibration environment during aircraft takeoff (frequency 20-2000Hz, acceleration 10g) for 2 hours—traditional SOCs would have metal bolts loosen, leading to gas leakage, while the Gyroid SOC’s integrated structure showed no loosening, maintaining over 99.5% gas tightness.
3. Electrolytic Hydrogen Production Efficiency: 10 Times Higher than Traditional, Balancing Storage Value
The “bidirectionality” of SOCs (power generation/electrolysis) is one of their core advantages—under electrolysis mode, they can convert electrical energy into hydrogen storage (green hydrogen). DTU’s tests show:
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The hydrogen production rate of traditional planar SOCs is about 0.1mL/(cm²・min) (700℃, 1.5V);
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The hydrogen production rate of the Gyroid SOC reaches 1.02mL/(cm²·min), which is ten times that of traditional SOCs—this is due to the Gyroid’s high specific surface area, which increases the number of “active sites” for the electrolysis reaction by three times, while the gas channel design reduces the diffusion resistance of hydrogen.
This feature allows the Gyroid SOC to serve not only as “aerospace power” but also as “deep space energy storage devices”—for example, in Mars exploration, using solar energy for power generation during the day, the Gyroid SOC can electrolyze CO₂ to produce oxygen (MOXIE mission goal), and at night, the stored oxygen and hydrogen can react to generate power, achieving an “energy-resource” cycle.
4. In-Depth Analysis of Advantages and Disadvantages: The “Key Threshold” from Laboratory to Industrialization
Every new technology has a gap between “ideal and reality,” and the Gyroid SOC is no exception. We objectively analyze the core issues in its commercialization path:
1. Core Advantages: Irreplaceable “Differentiated Value”
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Weight-Power Balance: The specific power of 1 W/g is currently the only one among all sustainable energy devices that can meet aerospace demands—even the fuel cell stacks in hydrogen fuel cell vehicles have a specific power of only about 0.5 W/g;
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Low Lifecycle Costs: Traditional SOCs require regular replacement of metal components (every 5000 hours), which accounts for 60% of total maintenance costs, while the Gyroid SOC’s all-ceramic structure has no easily damaged parts, with an expected lifespan of 20,000 hours, reducing maintenance costs by 80%;
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Multi-Scenario Adaptability: It can operate efficiently at 700℃ (aerospace power) and at 500℃ for hydrogen production (ground energy storage), unlike lithium batteries, which are significantly affected by temperature (performance drops by 50% at -20℃).
2. Challenges to Overcome: The “Industrialization Bottleneck”
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Engineering Solutions for Ceramic Brittleness: While the all-ceramic structure is resistant to vibration, its impact resistance remains weak—for instance, the instantaneous impact during aircraft landing (acceleration of 20g) could cause cracking in the Gyroid channels. The DTU team is currently testing “ceramic-carbon fiber composite slurries,” adding 10% carbon fiber to improve impact toughness by 30%;
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Scaling Control of 3D Printing Precision: In the laboratory, the size error of SLA printed Gyroid channels can be controlled within ±5μm, but ensuring consistent error across 100 printers during industrial mass production is challenging—if the channel size deviates by 10μm, it could lead to uneven gas distribution and a 15% drop in specific power. Currently, there is a need to develop an “online visual inspection system” to correct printing paths in real-time;
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Stability of Low-Cost Collectors: Currently, silver is used for collectors, which is cheaper than platinum, but silver is prone to sintering at 700℃ (particle size increases, conductivity drops by 20%). The team is developing a “silver-copper alloy coating” to suppress silver sintering through the dispersive effect of copper while maintaining high conductivity;
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High-Temperature Sealing Compatibility: In aerospace equipment, SOCs need to connect with hydrogen pipelines and cooling systems, and traditional metal seals are prone to failure at high temperatures—there is a need to develop “ceramic-metal transition joints” to address thermal expansion matching issues through gradient material design (gradually transitioning from ceramic to metal composition).
5. Application Scenarios: Beyond Aerospace, Driving “Decarbonization Across Multiple Fields”
The value of the Gyroid SOC extends far beyond “aerospace”; its “high specific power + high electrolysis efficiency” characteristics can drive transformations in several hard-to-decarbonize sectors:
1. Aerospace: From “Auxiliary Power” to “Main Power”
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Commercial Aircraft APU Systems: Current auxiliary power units (APUs) in aircraft, responsible for ground power and air conditioning, rely on fuel; if replaced with Gyroid SOCs (weighing only 50kg, compared to 150kg for traditional APUs), ground carbon emissions could be reduced by 80%;
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Long-Endurance Drones: A reconnaissance drone currently powered by lithium batteries lasts 4 hours; if equipped with “Gyroid SOC + hydrogen tanks” (total weight equivalent to lithium batteries), endurance could be extended to 24 hours, meeting long-distance reconnaissance needs;
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Deep Space Exploration: Beyond the MOXIE mission, future lunar bases could use Gyroid SOCs for their “oxygen-power cycle systems”—weighing only 1/8 of traditional devices, significantly reducing rocket launch costs (current launch costs are about $10,000/kg, saving $520 million for 800kg compared to 6 tons).
2. Ground Energy Storage: Accelerating “Green Hydrogen to Replace Fossil Fuels”
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Wind/Solar Energy Storage: Current wind energy curtailment rates are about 15%; if Gyroid SOCs are used to convert excess electricity into green hydrogen (hydrogen production efficiency of 90%, compared to 75% for traditional electrolyzers), it could enhance the absorption rate of renewable energy;
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Distributed Energy Stations: In remote mining areas, using “solar + Gyroid SOC” to produce hydrogen, then powering mining equipment with hydrogen fuel cells instead of diesel generators, reducing carbon emissions in mining areas.
3. Industrial Decarbonization: Addressing the “Energy Pain Points of High-Energy-Consumption Industries”
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Steel Industry: Current steel production uses coke to reduce iron ore, accounting for 15% of total industrial emissions; if hydrogen is produced using Gyroid SOCs (low-cost green hydrogen) to replace coke as a reducing agent, it could achieve “zero-carbon steelmaking”;
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Ammonia Synthesis: Traditional ammonia synthesis requires high temperature and pressure (400℃, 20MPa), which is energy-intensive; if Gyroid SOCs are used to directly electrolyze nitrogen and water at 700℃ to produce ammonia, energy consumption could be reduced by 30%, while using green electricity to drive “green ammonia” production.
6. Technical Insights: The “Collaborative Innovation Logic” of Sustainable Energy Devices
The reason DTU’s Gyroid SOC can break through is fundamentally due to stepping out of the traditional thinking of “single material optimization” or “single process improvement” and instead pursuing a collaborative innovation path of “structural design – material selection – manufacturing process”:
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Using Gyroid structure (design) to solve the contradictions of “specific surface area – weight – strength”;
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Using all-ceramic materials (materials) to address the issues of “high-temperature stability – interface degradation”;
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Using 3D printing (process) to tackle the challenges of “integrated manufacturing – complex structure forming.”
This logic has implications for the development of all sustainable energy devices—for example, the “silicon-based anode” in lithium batteries, if combined with TPMS structural design, could solve the silicon anode expansion problem while enhancing conductivity; similarly, the “proton exchange membrane” in hydrogen fuel cells could improve proton conduction efficiency if made with a porous structure using 3D printing.
Conclusion: The Distance from “Laboratory Breakthrough” to “Industry Transformation”
DTU’s 3D printed Gyroid SOC has provided a clear path for “zero-carbon energy in aerospace”—it is not “future technology” but a technology that has been validated through practical testing and has industrialization potential. Of course, transitioning from an 800kg laboratory sample to a 100kg aerospace-grade product will require 3-5 years of engineering iteration, but it is undeniable that as “structural innovation” begins to dominate the development of energy devices, the “weight-power-cost” deadlock of sustainable energy is being broken one by one. In the future, we may see: passenger aircraft powered by Gyroid SOC achieving “zero-carbon flight”; Gyroid SOCs in Mars bases continuously producing oxygen to support human habitation— and all of this began with the Gyroid structure model in the DTU team’s laboratory today.
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