Random Copolymer Hydrogel as Elastic Binder for the SiO_x Microparticle Anode in Lithium-Ion Batteries

Abstract

Silicon suboxides (SiO x ) have been widely concerned as a practical anode material for the next-generation lithium-ion batteries due to their relatively high theoretical capacity and lower volume change compared to silicon (Si). Nevertheless, traditional binder poly­(vinylidene difluoride) (PVDF) still cannot hold the integrity of the SiO x particle due to its weak van der Waals force. Herein, a copolymer binder for SiO x microparticles is synthesized through a facile method of free radical polymerization between acrylamide (AM) and acrylic acid (AA). By adjusting the mass ratio of the AM/AA monomer, the copolymer binder can generate a covalent–noncovalent network with superior elastic properties from the synergistic effect. During electrochemical testing, the SiO x anode with the optimal copolymer binder (AM/AA = 3:1) delivered a reversible capacity of 734 mAh g–1 (two times that of commercial graphite) at 0.5C after 300 cycles. Thus, this work developed a green and effective strategy for synthesizing a water-soluble binder for Si-based anodes.

Body Armor-Inspired Double-Wrapped Binder with High Energy Dispersion for a Stable SiOx Anode

“…Materials Characterizations, Mechanical Characterizations and Electrochemical Measurements were performed according to the method reported in our previous work. 23 ■ ASSOCIATED CONTENT * sı Supporting Information…”

“…To further promote the commercialization of SiO x anodes, numerous efforts have been devoted to designing ingenious nanostructures, tailoring the component in a solid electrolyte interface (SEI) layer , and exploring electrolyte additives. , Besides, developing a more advanced binder has also been deemed to be an auspicious strategy due to the merits of convenience, high efficiency, and cost-effectiveness. − As is well known, proper mechanical properties are crucial for a binder to maintain the cycling stability of Si-based anodes . It is widely accepted that a polymer binder’s intrinsic molecular configuration, and intramolecular and intermolecular interactions highly determine the mechanical property of the binder. , Generally, because of the intrinsic hard polymer backbone or covalent 3D network cross-linked configuration, a stiff binder is short of sufficient toughness to endure the structural damage caused by repeated volume change. , In comparison with the stiff binder, an elastic binder consisting of a soft polymer chain or flexible interaction could adapt to the huge volume expansion and contraction of SiO x particles .…”

Rational design of SiOx based anode materials for next generation lithium-ion batteries

“…After 50 cycles, no significant electrode cracking was observed, and 1025 mA h g −1 was still achievable after 250 cycles under 500 mA g −1 . Similarly, Weng et al 190 utilized free radical polymerization of acrylamide and acrylic acid to produce covalent–noncovalent networks with exceptional elasticity. The presence of carboxyl and amide groups within the network of a material enables the formation of hydrogen bonds.…”

Research progress of robust binders with superior mechanical properties for high-performance silicon-based lithium-ion batteries

“…126 Copyright 2020, Nature communication. And some self-healing binders by hydrogen bonding, 128 Copyright 2018, Small, metal ion coordination bonds, 119 Copyright 2021, Advance science, host-guest interaction, 129 Copyright 2017, Nature and other dynamic covalent bonds, 54,130 Copyright 2018, Wiley Online Library, Copyright 2020, Wiley Online Library. Fig.…”

“…(j) Load-displacement curves of the films of different binders. (k) Elastic modulus and hardness of different binders 119. Copyright 2022, American Chemical Society.…”