Understanding the Effects of Electrode Formulation on the Mechanical Strength of Composite Electrodes for Flexible Batteries

Abstract

Flexible lithium-ion batteries are necessary for powering the next generation of wearable electronic devices. In most designs, the mechanical flexibility of the battery is improved by reducing the thickness of the active layers, which in turn reduces the areal capacity and energy density of the battery. The performance of a battery depends on the electrode composition, and in most flexible batteries, standard electrode formulation is used, which is not suitable for flexing. Even with considerable efforts made toward the development of flexible lithium-ion batteries, the formulation of the electrodes has received very little attention. In this study, we investigate the relation between the electrode formulation and the mechanical strength of the electrodes. Peel and drag tests are used to compare the adhesion and cohesion strength of the electrodes. The strength of an electrode is sensitive to the particle size and the choice of polymeric binder. By optimizing the electrode composition, we were able to fabricate a high areal capacity (∼2 mAh/cm) flexible lithium-ion battery with conventional metal-based current collectors that shows superior electrochemical and mechanical performance in comparison to that of batteries with standard composition.

Electrode Composite for Flexible Zinc–Manganese Dioxide Batteries through In Situ Polymerization of Polymer Hydrogel

“…Overall, protocols to measure the adhesion and cohesion strength of composite battery electrodes are not standardized. As a result, researches adopted and modified various mechanical testing methods . For example, Gaikwad et al used the modified peel test and drag test as tools to investigate the effect of the electrode formulation on the mechanical strength of the electrodes .…”

“…As a result, researches adopted and modified various mechanical testing methods . For example, Gaikwad et al used the modified peel test and drag test as tools to investigate the effect of the electrode formulation on the mechanical strength of the electrodes . These testing methods could be used to further study the effect of changing the electrode composition on the mechanical strength of the electrodes fabricated through in situ polymerization of PVA/PAA.…”

Issues and Challenges Facing Flexible Lithium‐Ion Batteries for Practical Application

“…In comparison to nonbent site, a severe contact loss of active materials was observed in the bent site, showing significant capacity fading (Figure g,h). The crack and delamination of electrodes could generate partially isolated particles, which eventually give rise to poor electron transfer and ionic transport kinetics with uneven current distribution . When this phenomenon is continued, it may trigger the safety issues such as Li plating and thermal runaway under the flammable organic electrolyte .…”

“…The crack and delamination of electrodes could generate partially isolated particles, which eventually give rise to poor electron transfer and ionic transport kinetics with uneven current distribution. [76,77] When this phenomenon is continued, it may trigger the safety issues such as Li plating and thermal runaway under the flammable organic electrolyte. [78] These safety issues of the flexible LIBs should be considered more strictly with respect to their broader applications such as wearable electronics and implantable medical devices.…”

Iron Phosphate Coated Flexible Carbon Nanotube Fabric as a Multifunctional Cathode for Na‐Ion Batteries

“…Many future energy‐storage devices will not only need to boost powerful energy capacities, but also be flexible, lightweight, and mechanically compatible with the human body's motions to allow for their integration into wearable technologies . Flexibility can be achieved by replacing rigid cell packaging with flexible pouches and by utilizing mechanically robust current collectors, electrodes, and separators . The fabrication process of electrodes in conventional nonflexible batteries requires the casting of a slurry, which has highly variable mechanical properties that depend on thickness, porosity, and the quantity of binder and carbon additive .…”