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A series of polyimides, which contain polyethylene glycol (PEG) segments with different molecular weight in the polymer chains, are synthesized through a facile one-pot method and characterized by Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy. The main part of polyimides is originated from trimellitic anhydride chloride (TMAC) and 4,4′-methylenedianiline, onto which PEG segments are introduced through an esterification reaction with TMAC. These obtained polyimides, which acquire excellent water solubility after being neutralized by triethylamine, are applied as water-soluble binders to silicon negative electrodes for lithium ion batteries, and significantly improve the electrochemical performance of silicon anodes. Specially, the PI-200 (polyimide copolymerized with PEG-200) based silicon electrode exhibits a high initial discharge capacity of 2989.7 mAh g −1 and remains about 2235.5 mAh g −1 after 200 cycles at the current density of 0.1 C (420 mA g −1 ). [ABSTRACT FROM AUTHOR]

Highly adhesive binders are developed to prolong the cycle life of silicon anodes and accelerate their practical application. A series of poly(N-methacryloyl-3,4-dihydroxy- l -phenylalanine) (PMDOPA) binders, containing ultra-high content of catechol groups, are synthesized through radical polymerization and applied to silicon anodes. The ultra-high content of catechol groups endows the PMDOPA binder superior adhesive strength compared to the carboxyl groups of the polyacrylic acid (PAA) binder. As the molecular weight increases, the flexibility, solvent resistance and adhesive strength of the PMDOPA binders are all enhanced, which effectively alleviates the electrode pulverization during long-term cycling and prolongs the cycle life of batteries. Especially, the PMDOPA-20 binder, which possesses the highest molecular weight of 208 kDa among all the PMDOPA samples, exhibits the longest cycle life of 665 cycles at the current density of 840 mA g−1, even though its molecular weight is lower than PAA. This work demonstrates that both the functional adhesive group and molecular weight are crucial for binder performance, which provides a valuable reference for the future development of high-performance binders. Image 1 • A series of binders containing ultra-high content of catechol groups are synthesized. • Silicon anode performance is improved as the binder molecular weight increases. • The silicon electrodes with catechol-based binders exhibit long cycle lives. • Both functional group and molecular weight are crucial for binder performance. [ABSTRACT FROM AUTHOR]

Highlights: A creative cooperative strategy involving silk fibroin/sericin is proposed for stabilizing high-performance flexible Li–S full batteries with a limited Li excess of 90% by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides. Such fabric Li–S full batteries offer high volumetric energy density (457.2 Wh L−1), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm). Lithium–sulfur batteries are highly appealing as high-energy power systems and hold great application prospects for flexible and wearable electronics. However, the easy formation of lithium dendrites, shuttle effect of dissolved polysulfides, random deposition of insulating lithium sulfides, and poor mechanical flexibility of both electrodes seriously restrict the utilization of lithium and stabilities of lithium and sulfur for practical applications. Herein, we present a cooperative strategy employing silk fibroin/sericin to stabilize flexible lithium–sulfur full batteries by simultaneously inhibiting lithium dendrites, adsorbing liquid polysulfides, and anchoring solid lithium sulfides. Benefiting from the abundant nitrogen- and oxygen-containing functional groups, the carbonized fibroin fabric serves as a lithiophilic fabric host for stabilizing the lithium anode, while the carbonized fibroin fabric and the extracted sericin are used as sulfiphilic hosts and adhesive binders, respectively, for stabilizing the sulfur cathode. Consequently, the assembled Li–S full battery provided a high areal capacity (5.6 mAh cm−2), limited lithium excess (90%), a high volumetric energy density (457.2 Wh L−1), high-capacity retention (99.8% per cycle), and remarkable bending capability (6000 flexing cycles at a small radius of 5 mm). [ABSTRACT FROM AUTHOR]

Using conductive binders, instead of the traditional binders and conductive additives, is an effective way to increase the specific capacity and long cycle life of the silicon (Si) anode. However, the rigid conductive binders of Si anodes tend to form cracks during the repetitive huge volume changes of Si. Here, a novel n-type conductive binder, multi-block polymer of poly(1-pyrenemethyl methacrylate) and polybutadiene (PPy- b -PB) was designed. The polybutadiene (PB) rubber was incorporated into the conductive binder by combining condensation and reversible addition-fragmentation chain transfer polymerization. With high initial coulombic efficiency of 77.9%, the PPy- b -PB/Si anode possesses high reversible capacity (2274 mAh g−1) and capacity retention (87.1%) at the rate of 0.2 C (0.84 A g−1) after 200 cycles. The superior cyclic performance of the PPy- b -PB can be ascribed to the PB rubber, which enhanced the reversible deformation ability, flexibility, and adhesion length scale of the binder, without with a negligible change of the charge-transfer resistance for the anode. The original structure and the preparation method of the multi-block conductive binder provide a new way to manufacture multifunctional binders. A n-type multi-block polymer PPy- b -PB of poly(1-pyrenemethyl methacrylate) (PPy) and polybutadiene (PB) was designed to enhance the reversible deformation ability, flexibility, and adhesion length scale of the conductive binder PPy. With high initial coulombic efficiency of 77.9%, the PPy- b -PB/Si anode possesses high reversible capacity (2274 mAh g−1) and capacity retention (87.1%) at the rate of 0.2 C (0.84 A g−1) after 200 cycles. Image 1 • A novel multi-block binder was prepared by Condensation and RAFT polymerization. • The binder was used as conductive binder for Si anodes in Li-ion batteries. • Reversible deformation ability of the binder was improved with polybutadiene. • High capacity and cycling stability of Si anode was achieved by using the binder. [ABSTRACT FROM AUTHOR]

Abstract Silicon is one of the most promising anode materials for the next-generation high energy density lithium-ion batteries as its superior specific capacity and ultralow lithiation/delithiation voltage. Whereas, silicon suffers massive volume change during cycling, resulting in drastic pulverization of active material and iterative growth of solid electrolyte interphase, largely limiting their widely applications. To address the challenge, water-soluble glycinamide modified PAA (PAA-GA) is synthesized through a facile and low-cost coupling method as a polymer binder to assemble silicon anode for alleviating its huge volume change. The carboxyl and double amide groups of the PAA-GA can form hydrogen bonds with the hydration layer of silicon, and meanwhile the double amide groups of PAA-GA can form double hydrogen bonds via interchain cohesion. These strong supramolecular interactions are reversible and can recover the dissociated bonds more efficiently upon the elimination of the mechanical stress. The PAA-GA-based silicon electrodes exhibit excellent cycling stability and high coulombic efficiency, demonstrating the PAA-GA binder being great potential in fabricating high energy density silicon anodes for next-generation lithium-ion batteries. Graphical abstract Image 1 Highlights • Glycinamide-based binder was synthesized via a facile coupling method. • Water-soluble binders were used for silicon anodes in lithium ion batteries. • A high capacity and good cyclestability were achieved by using the modified binder. [ABSTRACT FROM AUTHOR]