Shape-morphing carbon fiber composite using electrochemical actuation

Abstract

Structures that are capable of changing shape can increase efficiency in many applications, but are often heavy and maintenance intensive. To reduce the mass and mechanical complexity solid-state morphing materials are desirable but are typically nonstructural and problematic to control. Here we present an electrically controlled solid-state morphing composite material that is lightweight and has a stiffness higher than aluminum. It is capable of producing large deformations and holding them with no additional power, albeit at low rates. The material is manufactured from commercial carbon fibers and a structural battery electrolyte, and uses lithium-ion insertion to produce shape changes at low voltages. A proof-of-concept material in a cantilever setup is used to show morphing, and analytical modeling shows good correlation with experimental observations. The concept presented shows considerable promise and paves the way for stiff, solid-state morphing materials.

A Structural Battery and its Multifunctional Performance

“…First, the fiber volume fraction in the negative electrode is lower than desired and limited by the manufacturing method and can probably be improved significantly using, e.g., a vacuum‐infusion manufacturing method. [ 25 ] Second, due to the manual process, the CFs in the negative electrode are not ideally straight, which again may be remedied using fixtures to hold the spread tow fiber bundles during manufacturing. Finally, the stiff carbon fiber electrode constitutes only a part of the total laminate thickness, which is shown in the micrograph of the structural battery composite with the Whatman GF/A separator shown in Figure 2a.…”

Grasping with kirigami shells

“…The requirement of an additional, tethered support system and challenges with miniaturization also occur in cable-driven actuation (21). Alternatively, soft grippers may be actuated by the deformation of stimuliresponsive materials (22), which can deform in response to light (23), temperature (24), electric (25), magnetic (26), and chemical (27) stimuli. These materials may pave the way to multiscale, untethered grasping; however, stimuli-responsive materials often sacrifice response speed and precision.…”

Experimental and computational characterization of carbon fibre based structural battery electrode laminae

“…This type of material can be used in lithium-ion (Li-ion) based structural batteries, i.e. batteries with mechanical load-bearing capability [1,2,[4][5][6][7][8][12][13][14][15], in electrochemical actuators [16], or in energy harvesting and strain sensing composites [17][18][19]. Due to the multifunctional character of such material, it offers a promising material choice for innovative future design of electric vehicles [6] and devices (e.g.…”

“…Moreover, the ion conductivity of the SBE is in the order of 10 − 4 S cm − 1 [21,22], whereas the conductivity of conventional liquid electrolytes is significantly higher, typically in the order of 10 − 2 S cm − 1 [37] at room temperature. In addition, the carbon fibres undergo significant expansion when lithiated [16,38]. This means that the geometric and topological characteristics of the cell, i.e.…”