A joint study by TU Delft and Elysian Aircraft reveals a new role for batteries in aircraft structures—not only as an energy source but also as the key to lightweight design.

In conventional thinking, the high weight of batteries has been the biggest obstacle to electric aviation. But latest research shows that when batteries are properly integrated into the wing structure, high energy density lithium battery cells and advanced battery designs can become a core tool for structural weight reduction.

We have recently analyzed a research report (AIAA 2025–3470) jointly published by Delft University of Technology (TU Delft) and Elysian Aircraft. Focusing on the 90-seat electric aircraft Elysian E9X, the study systematically evaluates the impact of wing-integrated batteries on structural design. Below are the three major technological breakthroughs and commercial insights we have summarized.

Batteries Are No Longer a Burden: The Role of Wing-Integrated Batteries in Structural Weight Reduction

Weight Reduction Effect:

Compared with traditional fuselage-mounted battery configurations, the wing-integrated battery approach reduces wing structural weight by approximately 32%, demonstrating the potential of integrated battery systems in future electric aircraft design.

Bending Relief Mechanism:

The physical mass of batteries is distributed spanwise along the wing, effectively counteracting the upward bending moment of the wing during flight. This greatly reduces bending stress at the wing root and directly lowers the demand for structural reinforcement materials.

Composite Materials and Wide Wingbox Design Enable Lighter Electric Aircraft Structures

Great Potential of Composite Materials:

The study shows that using carbon fiber-reinforced polymer (CFRP) can further reduce wing mass by about 22% compared with conventional aluminum alloys.

Airfoil Thickness Optimization:

Appropriately increasing the thickness-to-chord ratio (t/c) at the wing root may slightly compromise aerodynamic performance, but the improved structural strength delivers a full-wing weight reduction of up to 8%.

Space Utilization: How Wide Wingbox Design Improves Battery Integration

Planning internal wing space is critical to accommodating more energy storage, especially when developing custom battery solutions for specific application requirements.

Balancing Battery Capacity and Structural Weight:

A wider wingbox structure (e.g., front and rear spars located at 5% and 65% of the chord length) provides approximately 39% more usable volume than a narrow wingbox.

This design not only integrates more battery cells but can even be lighter than narrow wingbox designs under given structural constraints.

Key Conclusion: The Future Role of Advanced Battery Suppliers

The realization of large electric aircraft (such as 90-seat models) no longer depends only on breakthroughs in battery energy density, but more on highly integrated design of batteries and wing structures.

Battery distribution has become an important design variable in aircraft aeroelastic optimization.

The mass distribution and installation location of batteries (e.g., coordination with landing gear span) significantly affect the overall structural mass and flight safety.

This means future battery suppliers for advanced mobility applications need to understand not only electrochemical performance, but also system integration requirements.

Closing Remarks:

Electric aircraft design is shifting from purely energy density-driven development toward integrated battery and structural design.

Batteries are no longer just an energy source — they are becoming an integrated part of future aircraft design.

Advanced battery cell technology and customized battery development capabilities will play an important role in enabling future integrated energy solutions.

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