浒苔硫酸多糖基水凝胶的制备及在超级电容器领域的应用

Preparation of Ulva Polysaccharide-Based Hydrogel and Its Application in Supercapacitors

摘要: 随着可穿戴电子设备和能源可持续发展的日益增长，开发绿色环保、高性能且具备环境耐受性的柔性储能器件已成为当前研究的热点。优异的可拉伸性、形状适应性和良好的生物相容性使得水凝胶成为制备柔性可穿戴电子设备的理想材料。但单层网络型水凝胶所制备的超级电容器存在机械性能差和不稳定性等问题，构建多层网络状水凝胶或引入天然材料等措施，可有效解决上述缺点。浒苔多糖(SPEP)是从大型海藻浒苔中提取的一种具有刚性结构的水溶性酸性多糖，将其引入水凝胶中可增强水凝胶的机械性能。本实验采用热水浸提法制备SPEP，利用SPEP、丙烯酰胺、氯化锂和甘油通过一锅法制备聚丙烯酰胺/浒苔多糖/Li⁺/甘油(PAM/SPEP/Li⁺/Gly)水凝胶，并对其形貌、理化性质和各种性能进行测试。结果表明：通过改变SPEP、Li⁺和甘油的浓度可以调节水凝胶的性能，从而制备出满足于不同应用领域的水凝胶。通过添加SPEP、LiCl和Gly使水凝胶的机械、抗冻性能和所制备超级电容器的电化学性能有显著的提升。当SPEP、Li⁺和Gly浓度分别为1.12%、22%和7.6%时，水凝胶的综合性能最佳，拉伸强度和韧性分别为92 kPa和548 kj/m³，导电性为2.244 S/m，断裂伸长率为1019.22%。此外，以PAM/SPEP_1.12%/Li⁺_22%/Gly_7.6%水凝胶为电解质组装的超级电容器在500次折叠循环和10,000次循环充放电测试后，仍有较高的电容保持率。该电容器在−40℃和−80℃下仍分别保持79.1%和39.49%的比电容。PAM/SPEP_1.12%/Li⁺_22%/Gly_7.6%水凝胶的优异性能可以帮助超级电容器在低温环境下仍具有良好的比电容和可折叠性能，进一步提高了水凝胶电解质超级电容器在极端寒冷的环境中应用的可能。

Abstract: With the increasing demand for wearable electronic devices and sustainable energy development, the development of green, high-performance, and environmentally tolerant flexible energy storage devices has become a research hotspot. The excellent stretchability, shape adaptability, and good biocompatibility of hydrogels make them ideal materials for fabricating flexible wearable electronic devices. However, supercapacitors fabricated from single-network hydrogels often suffer from poor mechanical properties and instability. Constructing multi-network hydrogels or introducing natural materials can effectively address these drawbacks. Enteromorpha polysaccharides (SPEP), extracted from the large seaweed Sargassum, are water-soluble acidic polysaccharides with a rigid structure. Introducing SPEP into hydrogels can enhance their mechanical performance. In this experiment, SPEP was prepared using a hot water extraction method, and a one-pot synthesis approach was employed to fabricate polyacrylamide/SPEP/Li⁺/glycerol (PAM/SPEP/Li⁺/Gly) hydrogels using SPEP, acrylamide, lithium chloride, and glycerol. The morphology, physicochemical properties, and various performance metrics of the resulting hydrogels were subsequently characterized and evaluated. The results demonstrate that adjusting the concentrations of SPEP, Li⁺ and glycerol can effectively modulate the hydrogel’s properties, enabling the fabrication of hydrogels tailored for different applications. The incorporation of SPEP, LiCl and Gly significantly enhanced the mechanical properties, frost resistance and electrochemical performance of the resulting supercapacitors. At optimal concentrations of 1.12% SPEP, 22% Li⁺ and 7.6% Gly, the hydrogel exhibited superior comprehensive performance: tensile strength of 92 kPa, toughness of 548 kJ/m³, conductivity of 2.244 S/m, and fracture elongation of 1019.22%. Furthermore, supercapacitors assembled with the PAM/SPEP_1.12%/Li⁺_22%/Gly_7.6% hydrogel electrolyte maintained excellent capacitance retention after 500 folding cycles and 10,000 charge/discharge cycles. Remarkably, these devices retained 79.1% and 39.49% of their specific capacitance at −40˚C and −80˚C, respectively. The outstanding properties of the PAM/SPEP_1.12%/Li⁺_22%/Gly_7.6% hydrogel enable supercapacitors to maintain both high specific capacitance and foldability even under low-temperature conditions, significantly expanding the potential applications of hydrogel electrolyte-based supercapacitors in extreme cold environments.