Effects of cathode doping on 3D printed continuous carbon fiber structural battery composites by UV-assisted coextrusion deposition

Abstract

Structural battery composites are capable of significant system level mass and volume reductions not possible with separate battery and structural components by simultaneously carrying mechanical loads and storing electrical energy. The ability to 3D print lithium-ion structural batteries in arbitrary geometries would not only allow a flexible battery design but also facilitate its implementation as a structural component. This study presents a new 3D carbon fiber structural battery composite 3D printed by an ultraviolet (UV)-assisted coextrusion deposition method. With individual carbon fibers coated by solid polymer electrolyte (SPE) and dispersed within cathode doped matrix, energy storage is achieved in micro-battery cells at the fiber level within the 3D printed structural battery composite. The 3D printed structural battery composites with various complex geometries are demonstrated by successfully powering up LEDs. The SPE coating and cathode doping effect on microstructure, printability, mechanical and electrochemical properties are further characterized and investigated. A trade-off between printability and electrochemical performance is observed due to hindered curing by the doped cathode materials. The obtained electrochemical and mechanical performance is comparable to the carbon fiber based structural battery composites fabricated by conventional lay-up processes. These well demonstrate the great potentials of the proposed 3D printing method in rapidly fabricating functional structural battery composite components with complex geometries.

A multicell structural battery composite laminate

“…The second approach is to make a multifunctional composite material in which each constituent has inherent multifunctionality, that is, a multifunctional material 6 . Two types of such structural battery composite materials have emerged over the last decade 7–14 . The first type is a laminated device, in which one lamina constitutes a structural negative electrode and a structural positive electrode, separated by an electrically insulating separator ply 7–10 .…”

“…One such structural battery composite material concept studied here employs carbon fibers for mechanical performance and as electrode, and uses a lithium (Li) ion conductive two‐phase polymer electrolyte matrix for mechanical load transfer between fibers and for ion transport and electrical insulation between electrodes. The second type of structural battery composites is a micro‐battery material utilizing a unidirectional array of individually polymer electrolyte coated carbon fibers in a cathode doped polymer matrix 11–13 . Dong and co‐workers recently presented structural micro‐battery devices manufactured by a 3D‐printing technique 12,13 …”

“…The second type of structural battery composites is a micro‐battery material utilizing a unidirectional array of individually polymer electrolyte coated carbon fibers in a cathode doped polymer matrix 11–13 . Dong and co‐workers recently presented structural micro‐battery devices manufactured by a 3D‐printing technique 12,13 …”

“…Recently, Asp et al demonstrated a laminated structural battery composite cell, employing a structural battery electrolyte (SBE) 7 . Its multifunctional properties surpassed all previous structural battery materials reported in the literature 8–13 . The structural battery composite material had an energy density of 24 Wh kg −1 (relative the total mass of the cell) and an elastic modulus of 25 GPa.…”

“…To date, other attempts to make laminated structural batteries have resulted in significantly lower elastic modulus 8–10 . Pappas et al showed an increased longitudinal modulus for the 3D‐printed batteries, but with low cell capacity 13 …”