明胶基离子热电器件的设计与性能研究

离子热电器件具有热电势高、环境友好、柔性可拉伸等优点，有望实现可穿戴传感器的自供能需求。本论文以Gelatin-KCl-FeCN^4-/3-基离子热电凝胶器件为研究对象，围绕如何提高器件输出功率及能量的科学问题，系统地开展了高粗糙度三维Au/Cu电极提升器件短路电流，戊二醛交联提高器件服役温度区间和饱和开路电压，以及多层电极结构缩短热充电时间等研究工作，大幅提高了器件的瞬时功率和2h输出能量密度，并提出了离子热电品质因子参数来指导器件的设计与优化。

本文提出了通过增大电极粗糙度（RF）来提高离子热电器件的短路电流及瞬时功率的策略。利用刻蚀-还原-纳米金颗粒涂覆的方法，制备出粗糙度不同（RF = 134、272、386和459）的三维Au/Cu电极材料。当电极的RF值为459时，器件的归一化瞬时功率密度和2 h输出能量密度分别为8.9 mW m^-2 K^-2和80 J m^-2。相比于光滑Au/Cu电极（RF = 1），上述性能分别提高了6.5和4.6倍。这是由于电极粗糙度的提高降低了界面的电荷转移电阻，提高了器件的短路电流。本文首次揭示了凝胶材料相变温度点与器件服役上限温度的关联性。通过引入戊二醛（GTA）对明胶进行化学交联，形成稳定的C=N双键类共价键，提高了凝胶材料的热稳定性。当GTA的浓度和凝胶水含量值分别为0.8 mM和2.8时，器件的服役上限温度从30 ℃提高至44 ℃。器件的瞬时功率密度达到5.1 W m^-2，2 h输出能量密度达到198 J m^-2，相比于优化前的服役温度区间（21~30 ℃），上述性能分别提高了8.2和2.5倍。16个器件集成的可穿戴离子热电设备可以利用人体热能输出3.6 V电压和115 μW功率。本文提出多层电极结构缩短器件热充电时间并提升输出性能的策略。8层电极结构器件的归一化瞬时功率密度达到15.8 mW m^-2 K^-2，2 h输出能量密度达到403 J m^-2。相比于两层电极，上述性能分别提高了1.6和2倍。本文还推导了离子热电品质因子，该参数与材料的热电势、器件的介电常数及器件的服役温度区间成正比，与材料的热导率及器件的热充电时间成反比。

本论文系统研究了增大电极粗糙度、拓宽器件服役温度区间及多层电极结构设计等策略对Gelatin-KCl-FeCN^4-/3-基离子热电凝胶器件输出性能提升的影响，为优化离子热电凝胶器件的瞬时功率与输出能量提供了可行的技术途径，并验证了离子热电凝胶器件作为可穿戴自供能设备的可使用性。

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