A Universal Aqueous Conductive Binder for Flexible Electrodes

Abstract

The development of wearable electronics has led to new requirements for flexible and high‐energy batteries. However, the conventional polyvinylidene fluoride binder fails in the manufacture of high‐loaded and thick battery electrodes owing to its insufficient adhesiveness and electronic insulation, let alone for flexible devices. Furthermore, organic processing is expensive and not eco‐friendly. Herein, the authors report a novel aqueous conductive binder made of carbon nanotubes interwoven in cellulose nanosheets, successfully satisfying the fabrication of flexible yet high‐strength electrodes for universal active materials of different sizes, morphologies, and negative‐to‐positive working potentials, with a high mass loading of up to ≈90 mg cm−2. The conductive binder has an ultrathin 2D‐reticular nanosheet structure that forms continuous conductive skeletons in electrodes to segregate and warp active particles via a robust “face‐to‐point” bonding mode, allowing the fabricated electrodes to have remarkable flexibility and excellent mechanical integrity even under various external forces and excessive electrolyte erosion. Flexible LCO cathodes with a mass loading of >30 mg cm−2 as a case study exhibit high mechanical strength (>20 MPa) and can easily achieve an ultrahigh areal capacity of 12.1 mAh cm−2. This cellulose‐based binder system is ideal for advanced high‐performance functional devices, especially for flexible and high‐energy batteries.

Frontiers and Structural Engineering for Building Flexible Zinc–Air Batteries

“…[151] Moreover, the binder may cover the active sites of the catalyst and leads to low catalytic activity. [152][153][154] Also, the powder catalysts coating on the flexible substrate would be easily immersed in the electrolyte, making it difficult to form a stable three-phase interface. Furthermore, the decomposition or swelling of the polymer binder during the cycle may also cause catalyst failure, leading to battery performance decay.…”

Synergistic Double Cross-Linked Dynamic Network of Epoxidized Natural Rubber/Glycinamide Modified Polyacrylic Acid for Silicon Anode in Lithium Ion Battery: High Peel Strength and Super Cycle Stability

“…The current commercial adhesive polyvinylidene fluoride (PVDF) cannot retain the integrity of Si during the lithium-ion deintercalation process for its weak van der Waals force. 14,15 More PVDF should be dissolved in N-methylpyrrolidone (NMP) which is toxic, so an aqueous binder should be developed for silicon anodes. 16 Some polymers with carboxyl (−COOH), amino (−NH 2 ), hydroxyl (−OH) and other active groups serve as adhesives, including poly(acrylic acid) (PAA), chitosan (CTS), carboxymethyl cellulose (CMC), etc.…”

“…Selecting a suitable binder can lead to an increase of the cycle stability of the battery. The current commercial adhesive polyvinylidene fluoride (PVDF) cannot retain the integrity of Si during the lithium-ion deintercalation process for its weak van der Waals force. , More PVDF should be dissolved in N -methylpyrrolidone (NMP) which is toxic, so an aqueous binder should be developed for silicon anodes …”

“…To further increase the cycle stability of silicon anodes, numerous researchers have proposed the concept of cross-linked polymer binders. A reverse inhibitory force can be exerted by the unique three-dimensional network structure of cross-linked polymers, while silicon expands. , However, rigid polymers cannot completely release the stress generated by silicon expansion due to their high stress and low strain, so the integrity of the electrode is difficult to maintain. , Accordingly, numerous researchers attempted to use highly elastic polymers to prepare the adhesive to increase its strain, so the adhesive is capable of suppressing the volume expansion of silicon while adapting to huge volume changes and maintaining the stable operation of the electrode . As early as 2006, Buqa et al.…”

Kirigami‐Based Flexible, High‐Performance Piezoelectric/Triboelectric Hybrid Nanogenerator for Mechanical Energy Harvesting and Multifunctional Self‐Powered Sensing

“…For these devices, the flexibility of electrodes is a major challenge that must be resolved. [ 34–37 ] The existing flexible electrode devices remain subjected to constraints on adaptability and compatibility due to their relatively complex process of production and high production costs. [ 38–41 ] In recent years, there have been plenty of studies where the kirigami‐based electrode is used to produce flexible electrodes due to various advantages like cheap affordability, ease of production, excellent shape adaptability, and biological compatibility.…”