Multifunctional Composites Research Articles

Electro-mechanical behavior of multi-functional glass fiber composites under dynamic Mode-I fracture loading

An experimental study was performed to investigate damage sensing and fracture toughness of multifunctional conductive glass fiber composites under dynamic mode-I fracture loading. Carbon nanotubes (CNTs) were dispersed within the epoxy matrix using a shear mixing and sonicating process. An electrostatic wet flocking process was used to reinforce milled short PAN-based carbon fibers onto each of the layers of glass fiber fabric along the thickness direction in the composites. These layers of flocked fabric were stacked, and a vacuum infusion process was employed to fabricate the composites. The parametric study consisted of two carbon fiber lengths (80 μm and 150 μm) and two fiber densities (1000 fibers/mm2 and 2000 fibers/mm2) and was performed to investigate the damage sensing capabilities of a three-dimensional conductive network generated through CNTs and carbon fibers. A double cantilever beam (DCB) configuration was considered, and a modified Hopkinson pressure bar setup along with a high-speed camera was used to investigate dynamic fracture toughness of the composites. The piezo-resistance response of the composites during dynamic fracture was measured using a modified system of four probes. For comparison, composites were also characterized for fracture toughness and piezo-resistance under quasi-static fracture loading conditions. The addition of short, milled PAN-based carbon fibers significantly increased the fracture toughness of glass/epoxy composites. The piezo-resistance response of the composites was easily correlated with instances of sudden crack growth during static fracture loading.

Biomass-derived porous carbon aerogels for effective solar thermal energy storage and atmospheric water harvesting

Solar-powered hydrated salt-based phase change materials have great potential in the field of solar building energy efficiency. However, hydrated salts suffer from leakage, subcooling and phase separation in practical applications. To address these problems, this study proposes a solution to encapsulate hydrated salt with biomass-derived carbon aerogel as a carrier, which can effectively mitigate the leakage, subcooling, and phase separation problems of hydrated salt without the need of additional modifiers. The composite phase change material exhibited high phase change enthalpy retention (92%), negligible supercooling (0.4 °C), and excellent photothermal conversion efficiency (91.5%). In addition, thanks to the rich porosity and superhydrophilicity of the carbon aerogel, a composite hygroscopic agent combined with lithium chloride was prepared for high-performance atmospheric water harvesting. The composite hygroscopic material has a moisture adsorption capacity of 2.1 g g−1 at 90% RH and can desorb more than 92.3% of the moisture by solar energy drive. The performance was stable after several adsorption-desorption cycles. The multifunctional composites based on biomass-derived carbon aerogels have excellent performance in solar thermal storage and atmospheric water harvesting, providing a new perspective on solar thermal utilization.

Scalable Fabrication of Lightweight, Heat‐Resistant, and Controllable Sizes Polyimide Hollow Microspheres

AbstractPolyimide hollow microspheres (PIHMs) possess lightweight and excellent thermal resistance, making them highly valuable for various applications in aerospace, catalysis, and irradiation. Co‐polymerized PIHMs (PIHMBMDs) are fabricated through powder foaming combined with a gradient heating strategy in this work. The diameter of PIHMBMDs ranged from 364 to 1230 µm, which can be designed by regulating the size of polyester ammonium salts (PEASs). The PIHMBMDs possess intact morphology with a breakage rate of 3%–10% and low bulk density with a density ranging from 28.3 to 62.9 kg m−3. Furthermore, PIHMBMDs exhibit excellent thermal properties with a 5% weight loss temperature and glass transition temperature of 525.0 and 282.5 °C, respectively, making it an ideal material for fabricating lightweight and high‐temperature‐resistant multifunctional composites. Moreover, the proposed method is simple, efficient, and easily scalable, which is suitable for industrial applications to manufacture large quantities of PIHMs.

Nickel-cobalt-TiO2 co-doped lignin based carbon nanofibers: Versatile integrated material for supercapacitor and microwave absorption

The development of multifunctional composites is a challenging but necessary path for the miniaturization and integration of electronic products. Herein, versatile bimetal hydroxide (NiCo2(OH)6) nanowires coated on TiO2 modified lignin based carbon nanofibers (CNFs/TiO2@NiCo2(OH)6) have been prepared successfully by the method of electrospinning followed by hydrothermal treatment. The loading of NiCo2(OH)6, the doping of N, and the modification of TiO2 endow the CNFs/TiO2@NiCo2(OH)6 with multifunctional application in energy storage and microwave absorption (MA). The abundant pores and active sites result in an excellent electrochemical performance with a high specific capacitance of 752.47 F g−1 at 1 A g−1. More importantly, the assembled supercapacitor exhibits a maximum energy density of 60.64 Wh kg−1 and a superior stability of 90.2 % even after 4000 cycles at the current density of 10 A g−1. Moreover, considering the unique porous layered-structure as well as eminent electromagnetic matching properties, as-prepared composites display an excellent MA property, which possesses a minimum reflection loss (RLmin) of −46.48 dB and a maximum effective absorption bandwidth (EAB, RL < 10 dB) of 2 GHz (covering 47.62 % of X-band frequency). This work simultaneously delivers the potential application in the field of energy storage and MA.

Biomass composite based on metallized bamboo fiber for electromagnetic interference shielding, joule heating, and solar heating

The energy and environmental problems brought by petrochemical products promote the development of green and sustainable materials. Natural fiber reinforced plant-derived polylactic acid (PLA) is an attractive sustainable strategy. However, the lack of functionality largely limits its wider application. In this study, the most promising bamboo fiber (BF) whose versatility was realized by electroless plating (ELP) was selected as the reinforcing phase. By filling metallized BF(MBF) into PLA and then treating it by hot pressing, a low-cost, multifunctional MBF/PLA biomass composite(MBPC) was prepared. Results show that the ELP treatment of BF can not only significantly improve the thermal stability and mechanical properties of the composites but also endow it with excellent electromagnetic shielding, electro-thermal and photo-thermal conversion capabilities. Thereinto, the 70 wt%-MBPC has an electrical conductivity of 20.86 S/cm and an SE value of 45 dB in the X-band. The greater concern is the amazing electrothermal conversion performance, which can be heated rapidly at low voltage. Under the voltage of 3V, the temperature reaches 160 °C in about 50s. Besides, MBPC also possesses solar-driven heating, which can be rapidly heated to 75 °C under irradiation within 240s. This green and low-cost biomass multifunctional composite is expected to be used for electromagnetic shielding, energy conversion, and smart furniture, etc.

Multi-functional conductive cementitious composites including phase change materials (PCM) with snow/ice melting capability

ABSTRACT To remove snow/ice collected on surface of pavements is a must to prevent not only significant structural damages of infrastructures but also traffic accidents, however, today’s methods require higher labour and maintenance costs. Producing phase change materials (PCM)- and carbon fibre (CF)-incorporated multifunctional composites with melting snow/ice capability can be a cost effective alternative compared to mechanical methods and heating systems. In this study, the cementitious composites were produced adding 0, 2, 4, 6 and 8% PCM, by weight of the cement and 0.0, 0.1, 0.3% CF, by volume of the mixture. The composites were compared in means of ice melting performance and the damage resulted from freezing and thawing, applying two different simulations in a freeze–thaw cabinet: −10/+10°C and −20/+20°C. In addition, their compressive strength and consistency results were considered with their SEM analysis. As a result of the studies, the optimum CF ratio, which contributes the most to the melting ice performance of PCM-containing composites, was found to be 0.1% by volume. However, in freeze–thaw simulations, CFs increased the temperature amplitudes and PCMs were able to partially prevent this increase. While PCMs increased the workability of the composites and decreased their strength, CFs adversely affected both their workability and strength.

In situ growth of lanthanides-doped nanoparticles inside zeolites with enhanced upconversion emission for gallic acid detection

The combination of upconversion nanoparticles (UCNPs) with porous zeolites could enable the development of multifunctional composites and extend their optical applications in sensing, detection and biomedical monitoring. Herein, a series of high luminescent UCNPs@Zeolites nano-micro composites were constructed via the in situ growth strategy, by taking the low phonon-energy fluoride nanoparticles of NaLnF4 (Ln = Y, Gd) as doping hosts for Er3+/Yb3+, desilicated FAUY and ZSM-5 as the target zeolites. Benefiting from the formation of tightly combined interfaces between the UCNPs and the target zeolites that effectively passive the surface defects of UCNPs, three orders of magnitude of improved upconversion emission in maximum was obtained under 980 nm excitation through afterward heat treatment at 400 ℃. Moreover, the pre-exchange of Yb3+ into target zeolites before the in situ growth of UCNPs is another feasible approach to drastically improve the upconversion emission intensity of the UCNPs@Zeolites nano-micro composites. By taking NaGdF4:Yb,Er@DSZSM-5/HT as an example probe, the detection of GA was demonstrated and the detection ability of which is super than that of the corresponding bare NaGdF4:Yb,Er UCNPs. This research provided a universal approach to construct the UCNPs@Zeolites nano-micro composites with varied upconversion emission colors simply by choosing activator ions, which therefore indicates wide potential applications.

Predicting the electrical conductivity of short carbon fiber/graphene nanoplatelet/polymer composites

The current work examines the effect of graphene nanoplatelet (GNP) additives upon the electrical conductivity of short carbon fiber (SCF)-reinforced polymer multifunctional composites. GNPs and SCFs are randomly dispersed into the representative volume element of the composite. A multi-step physics-based approach is developed to determine the effective electrical conductivity of SCF/GNP/polymer composites. Outcomes of the current work are compared with the available experimental data and other numerical results to verify its accuracy. Changes in the volume fraction and geometry of multi-scale reinforcements, interphase characteristics, barrier height, nanofiller tunneling distance and fiber material property are considered to reflect the influence of microstructures on the electrical conducing behavior of SCF/GNP/polymer multifunctional composites. It is found that the electrical conductivity of the multifunctional composite enhances by the increase of volume fraction and aspect ratio of GNP as well as the reduction of its thickness. Moreover, the multifunctional composite shows a higher electrical conductivity with the increase of fiber aspect ratio. The electrical conductivity of the SCF/GNP-reinforced composite depends on the interphase such that its value increases by the increase of interphase thickness. The developed method can be adopted to provide useful guidelines for the design and optimization of multifunctional composites filled by hybrid reinforcements.

Thermal, Morphological and Mechanical Properties of Multifunctional Composites Based on Biodegradable Polymers/Bentonite Clay: A Review.

The extensive use of non-biodegradable plastic products has resulted in significant environmental problems caused by their accumulation in landfills and their proliferation into water bodies. Biodegradable polymers offer a potential solution to mitigate these issues through the utilization of renewable resources which are abundantly available and biodegradable, making them environmentally friendly. However, biodegradable polymers face challenges such as relatively low mechanical strength and thermal resistance, relatively inferior gas barrier properties, low processability, and economic viability. To overcome these limitations, researchers are investigating the incorporation of nanofillers, specifically bentonite clay, into biodegradable polymeric matrices. Bentonite clay is an aluminum phyllosilicate with interesting properties such as a high cation exchange capacity, a large surface area, and environmental compatibility. However, achieving complete dispersion of nanoclays in polymeric matrices remains a challenge due to these materials' hydrophilic and hydrophobic nature. Several methods are employed to prepare polymer-clay nanocomposites, including solution casting, melt extrusion, spraying, inkjet printing, and electrospinning. Biodegradable polymeric nanocomposites are versatile and promising in various industrial applications such as electromagnetic shielding, energy storage, electronics, and flexible electronics. Additionally, combining bentonite clay with other fillers such as graphene can significantly reduce production costs compared to the exclusive use of carbon nanotubes or metallic fillers in the matrix. This work reviews the development of bentonite clay-based composites with biodegradable polymers for multifunctional applications. The composition, structure, preparation methods, and characterization techniques of these nanocomposites are discussed, along with the challenges and future directions in this field.

Spiderweb-inspired fabrication of 3D MXene hybrid filler with multilayer and multiscale features for multifunctional polydimethylsiloxane composites

Polymer-based composite with high thermal conductivity and excellent fire safety is urgently desired and required in the field of thermal management of advanced electronic devices. In this study, inspired by the structure of a spiderweb, we reported a polymer composite with three-dimensional (3D) interconnected spiderweb-like structures by assembling adsorption of transition metal carbides/nitrides (MXene) and diethylenetriaminepenta(methylene-phosphonic acid) coordinated cobalt ions complex. In this composite, MXene combined with the coordination complex forms a 3D network structure with multi-layer/-scale features, which enables high cross-plane thermal conductivity (∼0.59 K w-1m−1) and excellent flame retardancy, especially including effective inhibition of toxic CO and asphyxiating CO2 production. Notably, the 3D MXene networks embedded in the polymer matrix impart the composite with an intelligent damage detection function that is able to detect the depth of cracks. This bioinspired strategy provides a promising approach to creating high-performance polymer-based composites.

Fabrication of rigid polyimide foams with good mechanical and thermal properties

Rigid polyimide foams (PIFs) were successfully fabricated through thermal foaming of polyester ammonium salt precursors (PEASs) with the addition of a pararosaniline base (PA) as a crosslinker. These foams exhibited good mechanical properties and thermal resistance. The construction of crosslinked structure derived from PA could improve melt viscosity and provide cell walls with sufficient strength to prevent shrinkage, which was conducive to elevating compressive properties. PIFBMP-2 (i.e., repeating unit was 2) exhibited optimal compressive strength of 1.76 and 1.25 MPa at room temperature (RT) and 200 °C, which were increased by 6.6 and 7.9 times compared to PIFBM (0.17 MPa (RT) and 0.11 MPa (200 °C)). Furthermore, a relationship between compressive strength and density was established, showing that the compressive strength is proportional to 2.34 and 2.13 powers of density at RT and 200 °C, respectively. Moreover, PIFs owned excellent thermal properties, the 5% weight loss temperature was higher than 458.9 °C in a nitrogen (N2) atmosphere, and the glass transition temperature was up to 291.3 °C. Additionally, the thermal conductivities of the rigid polyimide foams (PIFs) ranged from 0.058 to 0.094 W m−1 K−1, which makes them highly suitable for potential applications in the fabrication of high-temperature resistant multifunctional composites, particularly in aerospace, defense, and transportation industries.

Anchoring and catalyzing polysulfides by rGO/MoS2/C modified separator in lithium–sulfur batteries

Effective adsorption and catalysis are vital in developing high-efficient and stable lithium-sulfur (Li–S) batteries. Here, a coral-like porous composite containing molybdenum sulfide (rGO/MoS2/C) as interlayer on the separator to mitigate polysulfide shuttling. Since the rGO/MoS2/C composite exhibits promising electrolyte wetting properties with a large specific surface area, which can be fully utilized for the adsorption of lithium polysulfides (LiPSs). In addition, the molybdenum sulfide active site can effectively bind to and catalyze the conversion of LiPSs, further preventing the penetration of LiPSs. As a result, the assembled device shows excellent cycle stability with a low capacity decay of 0.022% per cycle over 1000 cycles (2.0C). In addition, the device still preserves a decent cycle ability even at low electrolyte and high sulfur loading conditions. This work presents a feasible strategy to anchor and accelerate the conversion of LiPSs by designing multifunctional transition metal sulfide composites with high adsorption properties and catalytic activity to achieve stable cycle of Li–S batteries.

In-situ synthesis of copper phytate-hierarchically porous MOF-199 hybrid in wood towards multifunctional flame-retardant wood composite

The modern society pays growing attention on global environmental issues, public safety, and individual health, which highlights the necessity of exploring sustainable, energy-saving, flame-retardant, and anti-mildew materials for building applications. Herein, by in-situ preparing copper phytate-hierarchically porous MOF-199 hybrid (PCuM) in natural wood (W) via simple phytate induced defect engineering strategy, we reported a multifunctional low fire-hazard wood composite (PCuM-W). The phytate anion not only acted as a modulator to generate hierarchical porosity in MOF-199, but also offered high flame retardancy due to its six phosphorus groups. The copper phytate anchored on the cell wall exhibited charring and graphitizing effects and enhanced the flame retardancy and smoke suppression performance of wood. By pyrolysis, a hierarchically porous MOF-199-derived carbon formed and offered a considerably enhanced catalytic activity towards the conversion of CO. With a weight percent gain of only 13.5%, the fire growth index, total smoke production, and maximum CO production rate of PCuM-W were 74.2%, 85.4%, and 33.3% lower than that of W, respectively, showing outstanding fire-hazard-reducing efficiency that surpassed most of its counterparts. Furthermore, due to the hierarchical porosity and antimicrobial property of PCuM, PCuM-W showed excellent moisture-buffering ability and mildew resistance. This work brings guidelines for fabricating hierarchically porous MOFs to realize multifunctional materials via phytate induced defect engineering.

Simple ultrasonic integration of shapeable, rebuildable, and multifunctional MIL-53(Fe)@cellulose composite for remediation of aqueous contaminants

Metal-organic frames (MOFs) have been recognized as one of the best candidates in the remediation of aqueous contaminants, while the fragile powder shape restricts the practical implementation. In this work, a shapeable, rebuildable, and multifunctional MOF composite (MIL-53@CF) was prepared from MIL-53 (Fe) and cellulose fiber (CF) using a simple ultrasonic method for adsorption and photocatalytic degradation of organic pollutants in wastewater. The results showed MIL-53(Fe) crystals were uniformly growth on CF surfaces and bonded with surface nanofibrils of CF through physical crosslinking and hydrogen bonding. Because of the high bonding strength, the MIL-53@CF composite exhibited an excellent compressive strength (3.53 MPa). More importantly, the MIL-53@CF composite was rebuildable through mechanical destruction followed by re-ultrasonication, suggesting the excellent reusability of MIL-53@CF for water remediation. The MIL-53@CF composite also had high adsorption capacities for methyl orange (884.6 mg·g−1), methylene blue (198.3 mg·g−1), and tetracycline (106.4 mg·g−1). MIL-53@CF composite could degrade TC through photocatalysis. The photocatalytic degradation mechanism was attributed to the Fe(II)/Fe(III) transform cycle reaction of MIL-53 crystal located on MIL-53@CF. Furthermore, the mechanical property and remoldability of MIL-53@CF composite increased its practicability. Comprehensively, MIL-53@CF composite provided a possible strategy to practically apply MOF in the remediation of aqueous contaminants.

Residual Strain and Nanostructural Effects during Drying of Nanocellulose/Clay Nanosheet Hybrids: Synchrotron X-ray Scattering Results.

Cellulose nanofibrils (CNF) with 2D silicate nanoplatelet reinforcement readily form multifunctional composites by vacuum-assisted self-assembly from hydrocolloidal mixtures. The final nanostructure is formed during drying. The crystalline nature of CNF and montmorillonite (MTM) made it possible to use synchrotron X-ray scattering (WAXS, SAXS) to monitor structural development during drying from water and from ethanol. Nanostructural changes in the CNF and MTM crystals were investigated. Changes in the out-of-plane orientation of CNF and MTM were determined. Residual drying strains previously predicted from theory were confirmed in both cellulose and MTM platelets due to capillary forces. The formation of tactoid platelet stacks could be followed. We propose that after filtration, the constituent nanoparticles in the swollen, solid gel already have a "fixed" location, although self-assembly and ordering processes take place during drying.

Electrospun polyvinyl alcohol/Withania somnifera extract nanofibers incorporating tadalafil-loaded nanoparticles for diabetic ulcers.

Background: Impaired inflammation and vascularization are common reasons for delayed diabetic wound healing. Nanoparticles (NPs)-in-nanofiberscomposites can manage diabetic wounds. A multifunctional scaffold was developed based on tadalafil (TDF)-loaded NPs incorporated into polyvinyl alcohol/Withania somnifera extract nanofibers. Materials & methods: TDF-loaded NPs were prepared and fully characterized in terms of their physicochemical properties. Extract of ashwagandha was prepared and a blend composed of TDF-loaded NPs, herbal extract and polyvinyl alcohol was used to prepare the whole composite. Results: The whole composite exhibited improved wound closure in a diabetic rat model in terms of reduced inflammation and enhanced angiogenesis. Conclusion: Results suggest that this multifunctional composite could serve as a promising diabetic wound dressing.

Fe‐doped MoS2@AuNPs Grown on Carbon Cloth for Efficient SERS Detection and Photo/photo‐Fenton Degradation of Fungicides

AbstractA composite CC/Fe−MoS2@Au composed of gold nanoparticles in‐situ grown on Fe‐doped MoS2 anchored on carbon cloth (CC) was prepared for SERS detection and photo/photo‐Fenton degradation of fungi pesticides. Flower‐like MoS2 grown on CC provides large surface area for in‐situ reduction and immobilization of AuNPs, generating high SERS enhancement effect. Fe‐doping improves MoS2’s SERS activity and photocatalysis and endows the composite with Fenton degradation ability due to the coexistence of Fe3+/Fe2+ confirmed by XPS. Owing to their synergy, the CC/Fe−MoS2@Au can achieve the SERS detection of fungicide crystal violet (CV) and malachite green (MG) with detection limits of 0.1 nM and 10 nM, respectively. The CC endows it flexibility for fungicide sensing on irregular surface, such as fish skin with a LOD of 10−7 M for MG. The composite displayed multimode degradation ability for fungicides: 70 % of 10−5 M CV could be degraded after 75 min photocatalytic degradation by CC/Fe−MoS2@Au under natural light, while it increases to 85 % in the presence of H2O2 through a photo‐Fenton reaction. The synergy mechanism of these components for fungicide degradation were discussed. Such flexible multifunctional composite has great value in SERS analysis, environmental monitoring and remediation.

The microwave absorption and anti-corrosion performance of flaky FeSiCr powder coated by silane film

A silane film was prepared on the surface of flaky FeSiCr powder by sol-gel method. The phase and morphology of the samples were observed by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM), and the valence state and chemical composition of the elements were determined by X-ray Photoelectron Spectroscopy (XPS). The results showed that the observed images of homogeneous silane films confirm the successful preparation of lamellar FeSiCr@PFOTMS composites. The electromagnetic parameters measurement results showed that the complex permittivity of the samples is substantially reduced and the complex permeability changes little, then the balance of electromagnetic parameters is improved and the impedance matching is optimized. When PFOTMS is added in amounts up to 2 mL, the FeSiCr@PFOTMS composites showed the best microwave energy absorption and corrosion resistance. The minimum reflection loss value of the sample reached –32.22 dB at 2.16 GHz. The electrochemical test results showed that the open circuit corrosion potential of FeSiCr@PFOTMS composites with 2 mL PFOTMS increased from –0.217 V to 0.031 V, and the corrosion voltage increased from –0.215 V to 0.028 V. These results provide ideas for the preparation of multifunctional composites with both excellent microwave absorption properties and corrosion resistance in practical applications.

Design and characterization of a novel supported epoxy film adhesive reinforced by Ti3C2Tx MXene nanoparticles

Film adhesives made from epoxy resin are typically used in different industries including transportation and aerospace to attach aluminum substrates together. These film adhesives offer a series of advantages including ease of application and handling, control over the adhesive thickness, minimal waste and uniform product as compared to other forms of adhesive like paste adhesives. Here, we try to improve the mechanical and thermal properties of these adhesives as well as to address poor ductility and weak fracture toughness of cured epoxy as major disadvantages. We used two dimensional (2D) Ti3C2Tx nanoparticles (NPs) which is the most well-known member of the emerging MXene family. MXenes a recent class of 2D transition metal carbides, nitrides and carbonitrides, have attracted many attentions since they were synthesized in 2011.The particular structural and functional characteristics of MXenes make them good candidate for multifunctional composites. The addition of inorganic MXene NPs to epoxy matrix at 1 phr accompanied by phenolic resin (novolac type) improves the tensile strength, modulus, and toughness of the adhesive by 16.49%, 43.51%, and 17.19%, respectively. Using MXene NP-containing epoxy film adhesives for attaching aluminum pieces together, we realized that the presence of MXene increases the single-lap shear strength and T-peel strength by 32.69% and 37.94%, respectively.in addition, the thermal stability of the MXene NP-containing film adhesives was improved, as indicated by 10.51% increase in the initial degradation temperature.

Climate impact and energy use of structural battery composites in electrical vehicles—a comparative prospective life cycle assessment

PurposeStructural battery composites (SBCs) are multifunctional carbon fibre composites that can be used as structural elements in battery electric vehicles to store energy. By decreasing the weight of the vehicle, energy consumption in the use phase can be reduced, something that could be counteracted by the energy-intensive carbon fibre production. The purpose of this study is to shed light on such life-cycle considerations.MethodProspective life cycle assessment is used to compare the future cradle-to-grave climate impact and energy use of SBCs in battery electric vehicles to conventional metals and lithium-ion batteries. Additionally, the influences from different technology development routes, primarily related to the carbon fibre production, are assessed. The functional unit is the roof, hood, and doors of a battery electric vehicle with maintained flexural stiffness used for 200,000 km. To capture the multifunctionality of the material, the lithium-ion battery is also included in the functional unit.Results and discussionResults show that SBCs have a large potential to decrease the life cycle climate impact and energy use of battery electric vehicles, especially following routes focusing on decreasing the use of fossil resources, both for raw materials and as energy sources. The comparative assessment of multifunctional or recycled materials to conventional materials introduces several methodological challenges, such as defining the functional unit and choice of allocation approach for distributing burdens and benefits between life cycles in recycling. This study illustrates the importance of using both the cut-off and end-of-life recycling allocation approaches to capture extremes and to not provide biased results. This study also highlights the importance of considering the ease of repairability in comparative studies, as damages to car parts made from SBCs are likely more difficult to repair than those made from conventional materials.ConclusionsSBCs have the potential to reduce the life cycle climate impact and energy use for most scenarios compared to conventional materials. Three main methodological challenges were found: the comparison to a material with a well-established recycling system throughout its life cycle, the need for expanding the system boundaries to include the lithium-ion battery, and the difference in repairability of SBCs compared to the conventional material.