Thermoconformable, Flexible Lithium‐Ion Batteries

Abstract

This work introduces a scalable method for fabrication of flexible, thermoconformable lithium‐ion batteries, suitable for the interior of vehicles. Electrodes with a composite structure are fabricated by combining conventional granular slurries with a porous carbon nanotube fabric current collector and a solid gel polymer electrolyte. The composite structure reduces polarization at high current densities, for example, with 50% and 17% higher charge capacity at 1C in LTO/Li half cells than control samples and commercial electrodes, respectively. Introducing a gel‐polymer electrolyte increases cell durability, safety, and thermal stability. Cyclability test at of 1C shows a capacity retention as high as 91% after almost 400 cycles (average capacity fade of 0.025% cycle−1). Full cells operate from 0 to 60 °C without any additives. Cells stored for 30 min up to 90 °C suffer minor capacity degradation. The possibility to withstand high temperatures and significant flexural deformation enable subjecting these pouch cells to thermoconformable processes. A roof panel with four 25 cm2 pouch cells is demonstrated. Flammability test shows that the carbon nanotube fibers (CNTF)‐LFP/CNTF‐LTO cells have a 50% lower peak of heat release rate and a much smaller total heat released than control cells with metallic current collector and liquid electrolyte.

A Binder‐Free Nickel‐Rich Cathode Composite Utilizing Low‐Bundled Single‐Walled Carbon Nanotubes

“…[17] In addition, CNTs are mechanically strong and lightweight, making them useful for portable and flexible devices, where weight and flexibility are concerns such as wearable devices. [18][19][20][21] Li et al investigated binder-free electrodes with advantages such as flexibility and high energy density. [22] The authors employed a hierarchical configuration of electrode active materials with a network of single-walled carbon nanotubes (SWCNTs) as a support and reduced graphene oxide sheets as a conductive additive.…”

Processing of Composite Electrodes of Carbon Nanotube Fabrics and Inorganic Matrices via Rapid Joule Heating

“…Such morphology is particularly relevant in battery electrodes, where integrating two nanomaterials�a current collector and an electrochemically active material�into a single structure not only maximizes the stress/charge transfer between the building blocks but also eliminates the need for polymeric binders, additives, or metallic current collectors while enhancing battery performance. 23,24 The absence of a metallic foil current collector enables the fabrication of complex-shaped devices such as multifunctional structural batteries for vehicles 25 and thin, flexible, and stretchable batteries. 9,26 In our prior work, we showed that integrating an inorganic phase (namely, MoS 2 ) into a preformed network of CNTF gives a flexible hybrid electrode.…”