Promising Trade‐Offs Between Energy Storage and Load Bearing in Carbon Nanofibers as Structural Energy Storage Devices

Abstract

Structural energy storage materials refer to a broad category of multifunctional materials which can simultaneously provide load bearing and energy storage to achieve weight reduction in weight-sensitive applications. Reliable and satisfactory performance in each function, load bearing or energy storage, requires peculiar material design with potential trade-offs between them. Here, the trade-offs between functionalities in an emerging class of nanomaterials, carbon nanofibers (CNFs), are unraveled. The CNFs are fabricated by emulsion and coaxial electrospinning and activated by KOH at different activation conditions. The effect of activation on supercapacitor performance is analyzed using two electrode test cells with aqueous electrolyte. Porous CNFs show promising energy storage capacity (191.3 F g −1 and excellent cyclic stability) and load-bearing capability (σ f > 0.55 ± 0.15 GPa and E > 27.4 ± 2.6 GPa). While activation enhances surface area and capacitance, it introduces flaws in the material, such as nanopores, reducing mechanical properties. It is found that moderate activation can lead to dramatic improvement in capacitance (by >300%), at a rather moderate loss in strength (<17%). The gain in specific surface area and capacitance in CNFs is many times those observed in bulk carbon structures, such as carbon fibers, indicating that activation is mainly effective near the free surfaces and for low-dimensional materials.

A Structural Battery and its Multifunctional Performance

“…Here, the electrical energy storage is integrated in the structural material of the vehicle—via multifunctional materials coined as “structural battery composites or structural power composites.” [ 5–8 ] Electrical energy storage in structural load paths has been shown to offer large mass savings for cars, aircraft, consumer electronics, etc. [ 9–15 ] Due to their multifunctionality, structural battery composites are often referred to as “mass‐less energy storage” and have the potential to revolutionize the future design of electric vehicles and devices.…”

“…[5][6][7][8] Electrical energy storage in structural load paths has been shown to offer large mass savings for cars, aircraft, consumer electronics, etc. [9][10][11][12][13][14][15] Due to their multifunctionality, structural battery composites are often referred to as "mass-less energy storage" and have the potential to revolutionize the future design of electric vehicles and devices.…”

Extended 2,2′-Bipyrroles: New Monomers for Conjugated Polymers with Tailored Processability

“…Arguably, the most extensively studied conducting polymers are polyacetylenes (PA), polyaniline (PANI), polypyrrole (PPy), and polythiophenes (PTh). However, the latter polymers, PPy and PTh, have attracted the attention of many groups due to their outstanding properties as energy storage devices [21] or highly conductive materials [22].…”

Designing Structural Electrochemical Energy Storage Systems: A Perspective on the Role of Device Chemistry

“…CFs may be electrochemically active themselves, or act as framework and current collector for a multifunctional matrix packed around them. EDLCs are particularly attractive, since the energy storage process is entirely physical, depending only on the interface between electrode and electrolyte ( Figures 2A,B ) ( Li et al, 2010 ; Qian et al, 2013a ; Shirshova et al, 2013a ; Qian et al, 2013b ; Javaid et al, 2014 ; Shirshova et al, 2014 ; Westover et al, 2014 ; Greenhalgh et al, 2015 ; Javaid et al, 2016 ; Senokos et al, 2016 ; Kwon et al, 2017 ; Senokos et al, 2017 ; Shen and Zhou, 2017 ; Xu and Zhang, 2017 ; Li et al, 2018a ; Chen et al, 2018 ; Javaid et al, 2018 ; Javaid and Irfan, 2018 ; Muralidharan et al, 2018 ; Senokos et al, 2018 ; Aderyani et al, 2019 ; Flouda et al, 2019a ; Chen et al, 2019 ; Patel et al, 2019 ; Reece et al, 2019 ; Patel et al, 2020b ; Rana et al, 2020 ; Reece et al, 2020 ; Sun et al, 2020 ; Sánchez-Romate et al, 2021 ; Subhani et al, 2021 ; Xu et al, 2021 ). The central advantage for SESDs, is that there is little or no change in volume, and no (re)dissolution of material, associated with the electrochemical process, minimizing stresses, and simplifying the structural design, whilst ensuring an excellent cycle life.…”