Silicon has attracted ever-increasing attention as a high-capacity anode material in Li-ion batteries owing to its extremely high theoretical capacity. However, practical application of silicon anodes is seriously hindered by its fast capacity fading as a result of huge volume changes during the charge/discharge process. Here, an interpenetrated gel polymer binder for high-performance silicon anodes is created through in-situ crosslinking of water-soluble poly(acrylic acid) (PAA) and polyvinyl alcohol (PVA) precursors. This gel polymer binder with deformable polymer network and strong adhesion on silicon particles can effectively accommodate the large volume change of silicon anodes upon lithiation/delithiation, leading to an excellent cycling stability and high Coulombic efficiency even at high current densities. Moreover, high areal capacity of ∼4.3 mAh/cm2 is achieved based on the silicon anode using the gel PAA–PVA polymer binder with a high mass loading. In view of simplicity in using the water soluble gel polymer binder, it is believed that this novel binder has a great potential to be used for high capacity silicon anodes in next generation Li-ion batteries, as well as for other electrode materials with large volume change during cycling.

Interpenetrated Gel Polymer Binder for High Performance Silicon Anodes in Lithium-Ion Batteries

In conventional polymer materials, mechanical performance is traditionally engineered via material structure, using motifs such as polymer molecular weight, polymer branching, or copolymer-block design1. Here, by means of a model system of 4-arm poly(ethylene glycol) hydrogels crosslinked with multiple, kinetically distinct dynamic metal-ligand coordinate complexes, we show that polymer materials with decoupled spatial structure and mechanical performance can be designed. By tuning the relative concentration of two types of metal-ligand crosslinks, we demonstrate control over the material’s mechanical hierarchy of energy-dissipating modes under dynamic mechanical loading, and therefore the ability to engineer a priori the viscoelastic properties of these materials by controlling the types of crosslinks rather than by modifying the polymer itself. This strategy to decouple material mechanics from structure may inform the design of soft materials for use in complex mechanical environments.

Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics

Transparent, Mechanically Strong, Extremely Tough, Self-Recoverable, Healable Supramolecular Elastomers Facilely Fabricated via Dynamic Hard Domains Design for Multifunctional Applications

We designed and synthesized a colorless transparent glassy polyurethane assembled using low-molecular-weight oligomers carrying a large number of loosely packed weak hydrogen bonds (H-bonds), which has a glass transition temperature (Tg ) up to 36.8 °C and behaves unprecedentedly robust stiffness with a tensile Young's modulus of 1.56±0.03 GPa. Fast room-temperature self-healing was observed in this polymer network: the broken glassy polyurethane (GPU) specimen can recover to a tensile strength up 7.74±0.76 MPa after healing for as little as 10 min, which is prominent compared to reported room-temperature self-healing polymers. The high density of loose-packed hydrogen bonds can reversibly dissociate/associate below Tg of GPU (that is secondary relaxation), which enables the reconfiguration of the damaged network in the fractured interfaces, despite the extremely slow diffusion dynamics of molecular chains under room temperature. This GPU shows potential application as an optical lens.

A Fast Room-Temperature Self-Healing Glassy Polyurethane.

Recent advances of wearable and flexible piezoresistivity pressure sensor devices and its future prospects

Self-healing polymers with microphase-separated structure are plagued with inferior self-healing efficiency at room temperature due to a lack of dynamic interactions in hard domains. Herein, we des...

Notch-Insensitive, Ultrastretchable, Efficient Self-Healing Supramolecular Polymers Constructed from Multiphase Active Hydrogen Bonds for Electronic Applications

Advanced rechargeable lithium-based batteries have a profound effect on our global society and polymer materials are one of the key components of these batteries. The key roles of polymers applied in battery technology are presented in terms of binders, package coatings, separators, and electrolytes. However, the loathsomely structural changes during repeated charge/discharge processes result in the mechanical fracture problems of polymers inside batteries, which significantly reduce the cycling lifetimes. The use of intrinsic self-healing polymers as substitutes is one of the most favored strategies for reviving lithium-based batteries since self-healing polymers spontaneously eliminate the mechanical cracks or damages and result in greatly enhanced electrochemical performances. In this review, we first introduce the advances and working mechanism of intrinsic self-healing polymers. Then, we discuss the opportunities and challenges in the development of advanced lithium-based batteries with Si, Li-metal, S electrodes, and polymer electrolytes, respectively, and summarize the up-to-date key progress in intrinsic self-healing polymers for solving the above-mentioned challenges. Finally, we propose some designing principles of desired intrinsic self-healing polymers from the perspectives of basic structures, ionic conductivities, mechanical properties, chemical interactions, and the self-healing capabilities.

Intrinsic self-healing polymers for advanced lithium-based batteries: Advances and strategies

Solid-state polymer electrolytes (SPEs) with superior self-healing capacity are urgently required for next-generation flexible energy storage devices Herein, a highly stretchable (extensibility > 4000% and stress > 130 kPa), non-flammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte (SHSPE) was prepared based on the combination of a poly(HFBM-co-SBMA) network, imidazole-based ionic liquid (EMI–TFSI) and LiTFSI The incorporation of the imidazole cation and fluorine atom contributed to the formation of supramolecular bonds (ion–dipole interactions) inside the electrolyte framework, thus endowing SHSPE with prominent self-healing ability (recovery time 200 g) The as-assembled Li/SHSPE3/LiFePO4 battery delivered a high discharge capacity of 1448 mA h g−1 at 02C, and its capacity retention ratio reached 82% after 100 cycles with a coulombic efficiency of 97% In particular, the mechanical properties and conductivity of SHSPE3 could fully recover after repeated damage, conferring the derived soft-pack battery excellent anti-fatigue capability The use of intrinsic self-healing principles in the field of SPEs provides new insight for developing reliable and safe flexible electronic devices

Highly stretchable, non-flammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte for stable and safe flexible lithium batteries

Peng Chen

Papers

Notch-Insensitive, Ultrastretchable, Efficient Self-Healing Supramolecular Polymers Constructed from Multiphase Active Hydrogen Bonds for Electronic Applications

Intrinsic self-healing polymers for advanced lithium-based batteries: Advances and strategies

Highly stretchable, non-flammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte for stable and safe flexible lithium batteries