An All Carbon Fiber-Based Structural Battery

Here a structural battery composite made from thin carbon fiber reinforced polymer composite electrodes is discussed. The negative electrode consists of this layer of carbon fibers in a spread tow. The positive electrode, the cathode, consists of lithium iron phosphate (LFP) coated onto carbon fibers, again in a spread tow. The electrodes are typically 30 micrometer thick [1]. The electrodes are set apart by an electrically insulating, ionically conductive, separator. Here we use, e.g., glass fiber and cellulose based separators. The stacked layers are impregnated by a bicontinuous structural battery electrolyte, where a glassy polymer provides mechanical load transfer between fibers, and electrodes, and a liquid electrolyte facilitates Li-ion migration between the electrodes. The multifunctional performance of the structural battery composites exceeds a specific energy density of 30 Wh/kg at a tensile modulus of 60 GPa for the strucutral battery composite cell.

This paper presents recent progress in carbon fiber based structural battery composites. In particular, the coupled electro-chemo-mechanical processes and their effect on the strucutral battery composite material and its constituents will be discussed. During electrochemical cycling, the elastic properties of the electrode materials, i.e., carbon fiber and lithium iron phosphate, swells/shrinks and undergoes changes in elastic moduli [2]. These changes to the composite’s constituents give rise to high internal stresses that may cause damage to the structural battery electrolyte or the fibers and thereby affect the multifunctional performance of the structural battery composite [3]. To conclude the presentation, routes towards imporoved multifunctional performance as well as damage tolerant structural battery composites is discussed.


References
[1] Siraj M.S., et al. Advancing Structural Battery Composites: Robust Manufacturing for Enhanced and Consistent Multifunctional Performance. Adv. Energy Sustainability Res. 4: 2300109, 2023.
[2] Duan S., et al. Effect of lithiation on the elastic moduli of carbon fibres, Carbon. 185: 234-241, 2021.
[3] Larsson C., Larsson F., Xu J., Runesson K., Asp L.E. Effects of lithium insertion induced swelling of a structural battery negative electrode. Compos. Sci. Technol. 244: 110299, 2023.
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