\”Firmness and flexibility, stability and change\” double dot dynamic crosslinking booster multifunctional aqueous gel electrolyte Synthesis

The flexible supercapacitors typically have higher power density, rapid charge-discharge capacity and longer cycle life, obtained much attention in terms of energizing wearable devices, implantable devices. Aqueous gel electrolyte its unique flexibility, good processability and environmental friendliness, has become an important material can withstand constructed deformable, and a flexible super capacitor is resistant to physical damage. However, a small molecule or an inorganic electrolyte is introduced directly into the hydrogel polymer network formed in the electrolyte, mechanical strength, processability, self-healing, etc. ionic conductivity and electrochemical stability greatly reduced. Based polymer composition, structure and design supramolecular driving force, the hydrogel polymer network is introduced synergy between dynamic and strong covalent molecular interactions, while embedded to produce specific functional binding site with the electrolyte is more than a means to solve key scientific and technological issues. , Xiamen University Materials Professor Dai Zong team Yuan Hui Cong Associate Professor led boric acid ester polymer research at borate design and ester functional polymer controlled / predictable advances have been achieved in terms of assembly series ( Journal of the American Chemical Society , 2018,140: 7629-7636; ACS Applied Materials & Interfaces , 2017, 9: 14700-14708; Composites Part A: Applied Science and Manufacturing , 2020, 130: 105751). Based on these preliminary studies, the team recently From the small molecule crosslinker and rigid flexible water-soluble polymer, In a double covalent bond dynamic crosslinking points in the polymer slip network implemented ingenious structure and properties \”firmness and flexibility, stability and change\” multifunctional synthetic polymer hydrogel electrolyte boronate . This \”sliding-type polymer network\” design strategy is simple. Using two flexible water-soluble polymer (polyethylene imine (PEI), polyvinyl alcohol (PVA)) Rigid with small molecules (4-formylphenyl boronic acid (Bn)) reaction to form an imine bond, a double bond boronate dynamic crosslinking point (Figure 1a). The main structural features include: (1) bond breaking and re-engagement dynamic key may be performed in an aqueous environment and at room temperature; (2) rigidly connected to Bn on the hydrophilic polymer chains by covalent bonds two dynamic, such that the cross-linking \”bridge\” may be slid between a flexible chain, the purpose of stability and change; crosslink density (3) having a controllable polymer network, and to ensure that the hydrogen bonds between water molecules and segments. The resulting PEI-PVA-Bn hydrogel only has good workability, plasticity (Fig. IB), also exhibits better mechanical strength (up to 59.5 kPa) and drawability (up to 1400%, not broken ) (FIG. 1c, d). If the integrity of the crosslinked polymer network reflects the dynamic crosslinking double point \”stability\”, the self-healing properties of the hydrogel is crosslinked to show a double dynamic point \”change.\” Because of the highly dynamic and reversible imine bond boronic ester bond, the aqueous gel at room temperature will have an excellent self-healing ability. By OF rheological, optical microscopy, and mechanical testing macro photograph presents the angles hydrogel fast, efficient automatic self-healing, 100% fastest within 2 min strain self-healing efficiency (FIG. 1e, f).

Such hydrogels more electrolytes exhibited high \”inclusive\”, author LiCl, NaCl, KCl, etc. is introduced into the ionic liquid AMC PEI-PVA-Bn hydrogel construct a series of aqueous gel electrolyte (ionic conductivity up to 21.49 mS cm ^-1 ). 1HNMR utilization system characterized answered Cause \”inclusive\” in this generation (FIG. 2): forming a strong binding force between the electrolyte and the nitrogen atom of the imine bond, and PEI. PEI-PVA-Bn aqueous gel electrolyte exhibits not only higher machineMechanical properties (strength up to 34.6 kPa, the maximum elongation at break of 1223%), but also have high self-healing capability (up to 94.3% within 2 min of the efficiency of self-healing strain). On using PEI-PVA-Bn-LiCl aqueous gel electrolyte and the electrode assembly MWCNTs sandwich type flexible supercapacitor. Such a device can be stably operated at 1.4 V of the potential window, along with up to 16.7 mF cm ^-2 The area ratio of the capacitance, 10, 000 retention capacitance charging and discharging cycle was 86%, and exhibited good resistance to bending deformation ability, good bending properties before and after the electrical stability of the devices (FIG. 3). In summary, this study presents a rigid small molecular construct containing a double sliding-type polymer network dynamically crosslinking point as crosslinking agent, the design principle is simple, easy to quantify and having adaptability for preparing more electrolytes, for design of high-performance gel electrolyte and the aqueous energy storage device having a flexible inspiration. The paper was published in \”ACS Applied Materials & Interfaces\” , entitled \”Design of SlidablePolymer Networks: A Rational Strategy to Stretchable, Rapid Self-Healing Hydrogel Electrolytes for Flexible Supercapacitors\”, the first The author is , Xiamen University Graduate School of material Master Liu Jun, Professor Dai Zong Yuan and Hui Cong Associate Professor co-corresponding author for the paper. Document link: https: //doi.org/10.1021/acsami.0c03224