Engineering materials that can store electrical energy in structural load paths can revolutionize lightweight design across transport modes. Stiff and strong batteries that use solid‐state ...electrolytes and resilient electrodes and separators are generally lacking. Herein, a structural battery composite with unprecedented multifunctional performance is demonstrated, featuring an energy density of 24 Wh kg−1 and an elastic modulus of 25 GPa and tensile strength exceeding 300 MPa. The structural battery is made from multifunctional constituents, where reinforcing carbon fibers (CFs) act as electrode and current collector. A structural electrolyte is used for load transfer and ion transport and a glass fiber fabric separates the CF electrode from an aluminum foil‐supported lithium–iron–phosphate positive electrode. Equipped with these materials, lighter electrical cars, aircraft, and consumer goods can be pursued.
Structural battery composites offer mass‐less energy storage for electrical vehicles and devices. Structural batteries are enabled by the recently discovered multifunctional properties of carbon fibers and the development of a structural electrolyte matrix material. The emergent multifunctional properties reach a level that allows lightweight vehicles and innovations across and beyond all transport modes.
Multifunctional materials facilitate lightweight and slender structural solutions for numerous applications. In transportation, construction materials that can act as a battery, and store electrical ...energy, will contribute to realization of highly energy efficient vehicles and aircraft. Herein, a multicell structural battery composite laminate, with three state‐of‐the‐art structural battery composite cells connected in series is demonstrated. The experimental results show that the capacity of the structural battery composite cells is only moderately affected by tensile loading up to 0.36% strain. The multicell structural battery laminate is made embedding the three connected structural battery composite cells between carbon fiber/glass fiber composite face sheets. Electrochemical performance of the multicell structural battery is demonstrated experimentally. High charge transfer resistance for the pack as well as the individual cells is reported. Mechanical performance of the structural battery laminate is estimated by classical laminate theory. Computed engineering in‐plane moduli for the multicell structural battery laminate are on par with conventional glass fiber composite multiaxial laminates.
Structural batteries offer lightweight solutions for electrical systems. With these materials, energy efficiency can be improved across transport modes. Herein, multifunctional durability of structural battery composite cells is proven for alternating electrochemical and tensile mechanical loads. Furthermore, a multicell structural battery laminate operating at 10.5 V is manufactured and its multifunctional performance characterized, experimentally and theoretically.
Grain Boundary Strengthening in High Mn Austenitic Steels Kang, Jee-Hyun; Duan, Shanghong; Kim, Sung-Joon ...
Metallurgical and materials transactions. A, Physical metallurgy and materials science,
05/2016, Letnik:
47, Številka:
5
Journal Article
Recenzirano
The Hall–Petch relationship is investigated to find the yield strengths of two high Mn austenitic steels. The Hall–Petch coefficient is found to depend on the overall C concentration and cooling ...rate, which suggests that the C concentration at the grain boundaries is an important factor. The pile-up model suggests that C raises the stress for the dislocation emission, while the ledge model predicts that C increases the density of ledges which act as dislocation sources.
Multifunctional materials offer a possibility to create lighter and more resource‐efficient products and thereby improve energy efficiency. Structural battery composites are one type of such a ...multifunctional material with potential to offer massless energy storage for electric vehicles and aircraft. Although such materials have been demonstrated, their performance level and consistency must be improved. Also, the cell dimensions need to be increased. Herein, a robust manufacturing procedure is developed and structural battery composite cells are repeatedly manufactured with double the multifunctional performance and size compared to state‐of‐the‐art structural battery cells. Furthermore, six structural battery cells are selected and laminated into a structural battery composite multicell demonstrator to showcase the technology. The multicell demonstrator performance is characterized for two different electrical configurations. The low variability in the multifunctional properties of the cells verifies the potential for upscaling offered by the proposed manufacture technique.
Abstract
Structural batteries are multifunctional composite materials that can carry mechanical load and store electrical energy. Their multifunctionality requires an ionically conductive and stiff ...electrolyte matrix material. For this purpose, a bi-continuous polymer electrolyte is used where a porous solid phase holds the structural integrity of the system, and a liquid phase, which occupies the pores, conducts lithium ions. To assess the porous structure, three-dimensional topology information is needed. Here we study the three-dimensional structure of the porous battery electrolyte material using combined focused ion beam and scanning electron microscopy and transfer into finite element models. Numerical analyses provide predictions of elastic modulus and ionic conductivity of the bi-continuous electrolyte material. Characterization of the three-dimensional structure also provides information on the diameter and volume distributions of the polymer and pores, as well as geodesic tortuosity.
Strontium silicate Sr2SiO4 undergoes a displacive phase transformation around 85°C. However, the steady state spectra involved in the process lacks investigation. In this paper, two kinds of ...Sr2SiO4:Eu2+ with and without Ba ions are synthesized. They are tested for XRD patterns and luminescent spectra at varying temperatures. The results show that Ba ions could effectively suppress the phase transition. For sample without Ba, temperature-dependent XRD patterns confirm the occurrence of phase transition and the emission peak positions at varying temperatures demonstrate a hysteresis behavior. The color of sample heated to 100°C under UV illumination is distinguishable from that unheated. This structure-sensitive behavior make Sr2SiO4:Eu2+ as potential thermochromic material.
•The displacive transition of Sr2SiO4:Eu2+ is confirmed by XRD and emission spectra.•Doping Ba ions could effectively suppress the phase transition.•A hysteresis trace of peak shift appears before and after the transition.•The thermal-sensitive behavior make Sr2SiO4:Eu2+ potential thermochromic material.
Carbon fibres are extensively used for their high specific mechanical properties. Exploiting their high axial stiffness and strength, they are employed to reinforce polymer matrix materials in ...advanced composites. However, carbon fibres are not isotropic. Data of the elastic properties in the other directions of the fibres are still largely unknown. Furthermore, standardised methods to characterise these properties are lacking. In the present work, we propose a methodology to determine the transverse and shear moduli of single carbon fibres. An experimental procedure is developed to fabricate high-quality, flat fibre cross-sections in both longitudinal and transverse directions using Focused Ion Beam, which gives full control of the specimen geometry. Indentation modulus on those surfaces are obtained using both Atomic Force Microscopy (AFM) and nanoindentation tests. Hysteresis was found to occur in the nanoindentation tests. The hysteresis response was due to nano-buckling and reversible shear deformation of the carbon crystals. For this reason, indentation tests using AFM is recommended. From the AFM indentation tests the transverse and shear moduli of three different carbon fibres (IMS65, T800 and M60J) are successfully determined.
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Here we demonstrate carbon fibers with tailorable multifunctional properties for energy storage composites. Carbon fibers made from the same precursor but with different processing tensions are ...investigated. The applied tension during the stabilization/oxidation stage of fiber manufacturing determines the microstructure and the resulting mechanical and electrochemical performance. Understanding of the interconnected effects enables tailoring of fibers to function as electrodes in structural battery composites. The study reveals that both amorphous and crystalline phases affect the electrochemical capacity, as higher capacity is achieved by larger d-spacing as well as higher void content. Further, the study confirms the trade-off between high tensile strength and high electrochemical capacity that needs to be taken into consideration when designing multifunctional carbon fibers.
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The structural battery composite is a recently successfully developed multifunctional lithium-ion battery. It is safer and capable to carry mechanical load compared to commercially available liquid ...electrolyte batteries. This makes it possible to apply the structural batteries to replace parts of the structural components in a system and thus reduce the weight of the whole system. The structural battery composite uses carbon fibre, an excellent lightweight material, as the anode material and uses a semi-solid structural battery electrolyte (SBE) material. The entire battery behaves as a solid material. The overall mechanical properties of the structural battery composite material are excellent due to the reinforcement of the carbon fibres and the mechanically robust SBE matrix.In this thesis, first of all, a multifunctional structural battery composite is manufactured. The structural battery composite uses the lithium storage capacity of carbon fibre for the first time and therefore, has an energy density of 24 Wh/kg and an elastic modulus of 25 GPa. Secondly, characterisation methods were developed for a number of important components in the structural battery composite. This includes precise measurements of transverse and shear moduli on micron-scale carbon fibres, the effect of lithiation on the carbon fibre anode mechanical properties, and 3D reconstruction and simulation of the SBE. For the pristine carbon fibres, focused ion beam combined with scanning electron microscopy (FIB/SEM) was used to accurately mill flat surfaces in different orientations on the carbon fibres, followed by indentation test using atomic force microscopy, and nanoindentation. The elastic hysteresis of the carbon fibres was observed in the experiments. For the first time, the moduli in the transverse and shear directions were derived in conjunction with an accurate orthotropic mechanical model. For the study of lithiation effects on the carbon fibre anode, the focus is on volume expansion and modulus changes. The volume expansion was obtained by analysis of SEM and optical micrographs. By using the protection of hydrophobic ionic liquids, the samples were successfully transferred into a vacuum environment in the SEM and subjected to transverse compression experiments. The transverse modulus of the carbon fibres is found to be doubled after lithiation. Finally, the microstructure of the SBE was reconstructed in 3D. The geodesic tortuosity of the SBE was found to be approximately 1.8. Meanwhile, the elastic modulus and ionic conductivity of the SBE were experimentally measured and simulated. In terms of elastic modulus, the results were consistent, and in terms of ionic conductivity, the simulated result overestimated the measured result.
In this paper, electrode laminae consisting of carbon fibres embedded in structural battery electrolyte (CF-SBE electrodes) are characterized with respect to their multifunctional (i.e. combined ...electrochemical and mechanical) performance utilizing experimental and numerical techniques. The studied material is made from commercially available polyacrylonitrile (PAN)-based carbon fibres and a porous SBE matrix/electrolyte, which is composed of two continuous phases: a solid polymer skeleton (vinyl ester-based) and a Li-salt containing liquid electrolyte. Experimental and numerical studies are performed on CF-SBE electrode half-cells, whereby a coupled electro-chemo-mechanical finite element model is exploited. Results show that, similar to traditional batteries, electrode thickness, transport properties of the electrolyte and applied current significantly affect electrochemical performance. For example, increasing the electrode thickness of the studied CF-SBE electrode from 50 μm to 200 μm results in a reduction in specific capacity of approximately 70/95% for an applied current of 30/120 mA g−1 of fibres, respectively. Further, Li-insertion induced longitudinal expansion of carbon fibre electrodes are video microscopically recorded during charge/discharge conditions. In liquid electrolyte the total/reversible longitudinal expansion are found to be 0.85/0.8% while for the CF-SBE electrode the reversible expansion is found to be 0.6%. The fibre expansion in the CF-SBE electrode gives rise to residual strains which is demonstrated numerically. We expect that the utilized computational framework and experimental data open a route to develop high-performing, both mechanically and electrochemically, carbon fibre based battery electrode laminae for future lightweight structural components with energy storage ability.
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•Carbon fibre electrodes embedded in structural battery electrolyte are studied experimentally and theoretically.•Effects of electrode lamina thickness on electrochemical performance are measured.•Li-insertion induced longitudinal expansion of carbon fibre electrodes is measured in situ during electrochemical cycling.•A previously developed coupled electro-chemo-mechanical finite element model is validated based on experimental data.
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