Structural batteries
Also known as Structural battery composites, Multifunctional energy-storage composites, Structural power composites
A structural battery stores electrical energy while also carrying mechanical loads, for example in a composite panel whose carbon fibres act as electrodes. Laboratory cells have reported energy densities from about 30 to 187 Wh/kg, depending on design, electrolyte and mass basis, and high stiffness, but no complete vehicle or aircraft powered by a load-bearing battery structure has been demonstrated in the sources reviewed.
In plain language
A conventional battery is usually a separate component that a vehicle or device carries. A structural battery tries to make part of the structure itself store energy, so a panel might add stiffness and also act as part of a rechargeable cell. Carbon fibres can both reinforce a composite and conduct electricity, while coatings, a separator and an ion-conducting electrolyte provide the other battery functions.
The attraction is not simply high battery capacity. The combined material has to replace both a structural part and some battery mass that would otherwise be carried. Whether it does so depends on the whole design, including the energy, strength, stiffness, lifetime and support systems of the structural battery.
Technical explanation
In a 2024 peer-reviewed laboratory design, pristine carbon fibre served as the negative electrode and carbon fibre coated with lithium iron phosphate (LFP) served as the positive electrode. A thin cellulose separator prevented direct electrical contact while allowing lithium ions to move. The electrodes and separator were embedded in a structural battery electrolyte and cured into a rigid composite. The authors reported an energy density of 30 Wh/kg, an elastic modulus above 76 GPa parallel to the fibres, and stable cycling for up to 1,000 cycles at roughly 100% Coulombic efficiency. These are results for a laboratory cell and its material, measured under the conditions the authors describe.
This is one architecture, not the only meaning of the term. A 2025 peer-reviewed study used a full-cell model of a laminated design with carbon fibre negative electrodes and LFP particles on aluminium foil as the positive electrode. The model combines electrochemical and mechanical behaviour. It reproduces the general trend of measured voltage profiles at different charge rates, but it uses a simplified continuum representation of the positive electrode and some parameters fitted to voltage data. It is modelling evidence rather than a demonstrated product.
A separate 2025 peer-reviewed study reported an all-carbon-fibre cell with an NMC111 cathode, with 187 Wh/kg using a liquid electrolyte and 84 Wh/kg using a biphasic structural battery electrolyte. The publisher record does not state the mass basis for these figures, and the cell design differs from the 2024 LFP cell.
What the evidence says
Each statement is typed by the strength of its evidence and linked to the source that supports it.
Demonstrated Shown in a published experiment, test or shipping product.
In a 2024 peer-reviewed study, an all-carbon-fibre laboratory cell with pristine carbon fibre as the negative electrode and LFP-coated carbon fibre as the positive electrode reported an energy density of 30 Wh/kg, as stated in the abstract.
Sources: [1] · AbstractThe same 2024 laboratory cell reported an elastic modulus above 76 GPa parallel to the fibre direction, and stable cycling for up to 1,000 cycles at roughly 100% Coulombic efficiency. These are cell and material results and do not show constant capacity or retained structural properties over that cycling.
Sources: [1] · Abstract · medium confidenceA 2025 peer-reviewed study of an all-carbon-fibre structural battery with an NMC111 cathode reported 187 Wh/kg with a liquid electrolyte and 84 Wh/kg with a biphasic structural battery electrolyte. The publisher record does not state the mass basis for these figures.
Sources: [3] · Abstract · medium confidenceA 2025 peer-reviewed electro-chemo-mechanical model of a structural battery full cell captures the general trend of measured voltage profiles across a range of charge rates. It uses a simplified continuum representation of the positive electrode and some parameters fitted to voltage data, so agreement is described as general rather than quantitative.
Sources: [2] · Abstract · medium confidenceReported, unverified Stated by a company or team but not independently confirmed.
In June 2025, Chalmers reported that an ongoing study had achieved structural battery composites with an energy density of over 60 Wh/kg and an elastic modulus of over 100 GPa. The university did not identify a published paper or dataset for these figures.
Sources: [4] · Article text · low confidenceChalmers says there is still a lot of engineering work to be done before the cells move from small-scale lab manufacturing to large-scale production, and that the semi-solid electrolyte makes high power delivery challenging.
Sources: [5] · Article text · medium confidenceSpeculative An idea or possible use. Not evidence of anything.
Chalmers calculated that electric cars could drive up to 70% longer than today if they had competitive structural batteries. This is a conditional calculation, not an observed range increase.
Sources: [5] · Article text · low confidenceLimitations and open problems
- The demonstrated results are laboratory cells and material samples. The sources reviewed do not show a complete vehicle or aircraft whose primary load-bearing structure also provides its operating battery pack.
- Energy density per unit mass does not establish that a finished product is lighter. Protection, wiring, power electronics, support structure and repair provisions all add mass, and the whole-product result is unknown.
- The reported figures come from different cell designs and electrolytes, and the mass basis is not always stated. The 30 Wh/kg, 84 Wh/kg, 187 Wh/kg and the university's over 60 Wh/kg figures should not be treated as interchangeable.
- Ageing, fatigue, impact, damage and repair under mechanical load while the cell is charged and discharged are not addressed in the sources reviewed. The modelling does not demonstrate fatigue life or product operation.
- How a damaged load-bearing cell behaves under crash, puncture, fire or thermal runaway, and how it can be isolated, is not addressed in the sources reviewed. Recycling integrated fibres, resin, electrolyte and battery-active materials is also not addressed in them.
- Chalmers states that high power delivery is challenging with the semi-solid electrolyte used in its 2024 design, and that substantial engineering work is needed before cells move from small-scale lab manufacturing to large-scale production.
Possible future uses
Ideas, not predictions. None of these has been demonstrated.
- Vehicle body panels that store energy for the vehicle while also carrying structural loads. The 2024 Advanced Materials abstract suggests such batteries could replace structural vehicle parts and reduce the number of conventional batteries. This is a proposed application, not a demonstrated vehicle.
Product concepts: Structural battery drone frame
Timeline
- 10 Sept 2024Advanced Materials publishes the all-carbon-fibre LFP structural battery paper reporting 30 Wh/kg and a modulus above 76 GPa along the fibre direction. Sources: [1]
- 19 Sept 2024Chalmers publishes an explainer reporting a calculation that electric cars could drive up to 70% longer if they had competitive structural batteries. Sources: [5]
- 19 May 2025npj Computational Materials publishes an electro-chemo-mechanical model of structural battery composite full cells, calibrated against experimental voltage profiles. Sources: [2]
- 24 Jun 2025Chalmers reports ongoing-study figures of over 60 Wh/kg and over 100 GPa elastic modulus. The news report does not name the underlying publication. Sources: [4]
- Sept 2025Composites Part B: Engineering publishes a carbon-fibre structural battery with an NMC111 cathode, reporting 187 Wh/kg with liquid electrolyte and 84 Wh/kg with a structural battery electrolyte. Sources: [3]
Futures this could help bring about
Glossary
- Anode / negative electrode
- The electrode at which oxidation occurs during discharge. In the cited structural cells, carbon fibres serve this role.
- Coulombic efficiency
- The charge recovered divided by the charge supplied in a cycle. A high value does not, by itself, show that capacity or structural properties were retained.
- Elastic modulus
- A measure of stiffness under elastic deformation. The cited value is directional, measured along the carbon-fibre direction.
- Structural battery electrolyte
- An electrolyte designed to conduct ions while also contributing to the mechanical load-bearing properties of the composite.
Sources
- peer reviewed paper
Unveiling the Multifunctional Carbon Fiber Structural Battery
Richa Chaudhary, Johanna Xu, Zhenyuan Xia et al.. Advanced Materials, 10 Sept 2024. DOI: 10.1002/adma.202409725. Accessed 21 Oct 2026. - peer reviewed paper
Electro-chemo-mechanical modelling of structural battery composite full cells
Carl Larsson, Fredrik Larsson, Johanna Xu et al.. npj Computational Materials, 19 May 2025. DOI: 10.1038/s41524-025-01646-x. Accessed 21 Oct 2026. - peer reviewed paper
High-energy cathode in carbon fibre structural battery
Richa Chaudhary, Nur Ayu Afira Sutrisnoh, Kwok Kiong Chan et al.. Composites Part B: Engineering, Sept 2025. DOI: 10.1016/j.compositesb.2025.112629. Accessed 21 Oct 2026. - university press release
Structural Batteries from Chalmers Highlighted by the World Economic Forum
Chalmers University of Technology, 24 Jun 2025. Accessed 21 Oct 2026. - university press release
World's strongest battery paves way for light, energy-efficient vehicles
Chalmers University of Technology, 19 Sept 2024. Accessed 21 Oct 2026.
Revision history
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