Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage
Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage
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DOI：
10.1021/acsami.2c04502
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发表时间：
2022-06-15
影响因子：
9.5
通讯作者：
Tsukruk, Vladimir V.
中科院分区：
文献类型：
--
作者：
Flouda, Paraskevi;Bukharina, Daria;Tsukruk, Vladimir V.
柔性且机械性能强的凝胶状电解质在电池和超级电容器中提供了增强的储能能力、多功能性和安全性。然而，离子传导和机械强度之间的权衡对于这些材料来说仍然是一个挑战。在此，我们提出在结构化的持久离子凝胶中引入离子型超支化聚合物将由于超支化聚合物的离子导电基团以及与离子液体的互补界面相互作用而导致离子传导和机械性能的增强。更具体地说，我们研究了具有羧酸盐端基和不同离子基团密度的咪唑鎓反离子的超支化聚合物对由共组装纤维素纳米纤维（CNF）和纤维素纳米晶体（CNC）作为离子液体浸渍的可持续开孔框架组成的离子凝胶性能的影响。超支化聚合物的加入通过利用聚合物与CNF/CNC“框架”之间的氢键，形成了高度互连的开孔、轻质且形状持久的材料。值得注意的是，这些材料的离子电导率提高了2倍，同时杨氏模量、拉伸强度和韧性提高了数倍，使其可与常见的增强纳米复合材料相媲美。此外，相应的薄膜凝胶超级电容器在反复弯曲时具有增强的电化学循环稳定性，在10000次循环后电容保持率为85%，这为开发同时具有导电性和柔性且性能持久的凝胶电解质提供了新的见解。
Flexible and mechanically robust gel-like electrolytes offer enhanced energy storage capabilities, versatility, and safety in batteries and supercapacitors. However, the trade-off between ion conduction and mechanical robustness remains a challenge for these materials. Here, we suggest that the introduction of ionic hyperbranched polymers in structured sustained ionogels will lead to both enhanced ion conduction and mechanical performance because of the hyperbranched polymers' ionically conductive groups and the complementary interfacial interactions with ionic liquids. More specifically, we investigate the effect of hyperbranched polymers with carboxylate terminal groups and imidazolium counterions with various ionic group densities on the properties of ionogels composed of coassembled cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) as sustainable open pore frame for ionic liquid immersion. The addition of hyperbranched polymers leads to the formation of highly interconnected openly porous, lightweight, and shape-persistent materials by harnessing hydrogen bonding between the polymers and the CNFs/CNCs "frame". Notably, these materials possess a 2-fold improvement in ionic conductivity combined with many-fold increase in Young's modulus, tensile strength, and toughness, making them comparable to common reinforced nanocomposite materials. Furthermore, the corresponding thin-film gel supercapacitors possess enhanced electrochemical cycling stability upon repeated bending with an 85% capacitance retention after 10 000 cycles, promising new insight in the development of simultaneously conductive and flexible gel electrolytes with sustained performance.