Sun Xinye, Deng Xinyue, Yin Shiqin, Tang Shengwei, Lv Li, Tang Wenxiang, Zhang Tao
School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
ACS Appl Mater Interfaces. 2025 Sep 4. doi: 10.1021/acsami.5c10283.
The rapid development of flexible electronics has intensified the demand for high-performance energy storage solutions. This research aims to enhance the performance of flexible supercapacitors under extreme temperatures through a lignin cross-linked poly(vinyl alcohol) (PVA) gel electrolyte. By incorporating lignin with PVA and using polyethylene glycol diglycidyl ether as a cross-linker, a hydrogel (PL, represents the mass ratio of lignin to PVA) with an enhanced three-dimensional network structure was constructed. Furthermore, the electrolyte's wide-temperature electrochemical behavior was optimized by incorporating -dimethylformamide (DMF) and lithium nitrate (LiNO). Results show that the PL0.3 hydrogel exhibits exceptional mechanical properties, with a tensile strength of 4.04 ± 0.16 MPa, an elongation at break of 520.08 ± 67.72%, and a compressive strength of up to 25 MPa. Notably, the PL0.3-D5H5Li2 (lignin at 0.3x PVA mass, DMF/HO = 5:5, and 2 mol/L LiNO) gel electrolyte exhibits superior temperature resilience, achieving a tensile strength of 1.24 MPa and elongation at break of 60.42% at -20 °C, and a tensile strength exceeding 1.41 MPa at 80 °C. Electrochemical tests reveal that at 2.0 V, the supercapacitor retains 95% Coulombic efficiency and nearly 100% capacitance retention after 8000 charge-discharge cycles. At -20 °C, it retains 83.5% of its room-temperature specific capacitance (64.58 F g), and after 2000 cycles at 80 °C, capacitance retention is 83%. These findings strongly support the application of flexible supercapacitors in wide-temperature conditions and suggest a promising future in high-performance energy storage systems.
柔性电子学的快速发展加剧了对高性能储能解决方案的需求。本研究旨在通过木质素交联聚（乙烯醇）（PVA）凝胶电解质提高柔性超级电容器在极端温度下的性能。通过将木质素与PVA混合并使用聚乙二醇二缩水甘油醚作为交联剂，构建了具有增强三维网络结构的水凝胶（PL，代表木质素与PVA的质量比）。此外，通过加入N，N-二甲基甲酰胺（DMF）和硝酸锂（LiNO₃）优化了电解质的宽温电化学行为。结果表明，PL0.3水凝胶具有优异的机械性能，拉伸强度为4.04±0.16MPa，断裂伸长率为520.08±67.72%，抗压强度高达25MPa。值得注意的是，PL0.3-D5H5Li2（木质素含量为0.3x PVA质量，DMF/H₂O = 5:5，以及2mol/L LiNO₃）凝胶电解质表现出卓越的温度适应性，在-20°C时拉伸强度为1.24MPa，断裂伸长率为60.42%，在80°C时拉伸强度超过1.41MPa。电化学测试表明，在2.0V时，超级电容器在8000次充放电循环后保持95%的库仑效率和近100%的电容保持率。在-20°C时，它保留了室温比电容（64.58F/g）的83.5%，在80°C下经过2000次循环后，电容保持率为83%。这些发现有力地支持了柔性超级电容器在宽温条件下的应用，并表明其在高性能储能系统中具有广阔的前景。
