Abstract By increasing the number of functions a structure performs it is possible to save weight and volume on a systems level. Ion-insertion in carbon fibres (CFs) is a way to create multifunctional structures for energy storage, morphing, and strain-sensing. Previous studies have focussed on lithium- and sodium-insertion to create multifunctionality. However, with a larger ionic radius and a chemistry more amenable to insertion in polyacrylonitrile (PAN)-based CFs, potassium-insertion is a promising way forward. Here, a study is conducted to examine potassium-insertion in intermediate modulus PAN-based CFs for multifunctionality. Electrochemical cycling shows a maximum reversible capacity of 170 mAh/g, with ex-situ mechanical testing showing a small impact on the CFs’ mechanical properties post-cycling. Operando measurements show a maximum reversible CF expansion during potassium-insertion of 0.24%, and analytical modelling illustrates that such strains can generate significant deformations in a morphing structure. A voltage-strain coupling of 0.26 V/unit strain is also found. Results are compared with previous work on lithium- and sodium-insertion, with the conclusion that potassium-insertion is more promising than sodium-insertion, but less so than lithium-insertion for multifunctional structures.

中文翻译：

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在聚丙烯腈基碳纤维中插入钾，用于多功能储能、变形和应变传感

摘要 通过增加结构执行的功能数量，可以在系统级别上减轻重量和体积。碳纤维 (CF) 中的离子插入是一种创建多功能结构的方法，用于能量存储、变形和应变传感。以前的研究主要集中在插入锂和钠以创造多功能性。然而，由于更大的离子半径和更适合插入聚丙烯腈 (PAN) 基 CF 的化学物质，钾插入是一种很有前途的前进方式。在这里，进行了一项研究，以检查钾插入中等模量 PAN 基 CF 中的多功能性。电化学循环显示最大可逆容量为 170 mAh/g，非原位机械测试显示对循环后 CF 的机械性能影响很小。Operando 测量显示在钾插入期间最大可逆 CF 膨胀为 0.24%，分析模型表明这种应变可以在变形结构中产生显着变形。还发现了 0.26 V/单位应变的电压-应变耦合。结果与之前关于锂和钠插入的工作进行了比较，结论是钾插入比钠插入更有希望，但在多功能结构方面不如锂插入。