基于电催化剂和赝电容材料耦合的“内部复合”化学电源构筑及性能研究

With the rapid development of new energy vehicles, electrochemical power sources with high specific energy and power are urgently required. Hybrid electrochemical power sources (HEPSs), which come from the integrating complementary characteristics of polymer electrolyte membrane fuel cells and supercapacitors, can be an alternative approach to the goal of high specific energy and power. A HEPS can be achieved by hybridization at either the devices or the materials level, which is also known as external and internal hybrids, respectively. External hybrids have been primarily based on simply connecting two or more separate devices into a larger system through an external circuitry. Thus, additional modules are needed, which increase the size, weight, cost and failure rate of the system. Therefore, internal hybrids, which are based on coupling of electrocatalyst and pseudocapacitive material, are adopted in this project proposal. The key factors affecting the performance of internal hybrids include, i) the insufficient contact between the pseudocapacitive material and the polymer electrolyte, ii) the high transport resistance of the reactants and products due to the introduction of the pseudocapacitive material, iii) the complicated electrochemical mechanism derived from the coupling of electrocatalytic reaction and energy storage process in one electrode. Thereby, it is proposed to construct ordered structured electrodes by supporting Pt catalyst on polyaniline nanowire arrays, which are doped by Nafion ionomers. On one hand, it can significantly extend the electrochemical interface between polyaniline and polymer electrolyte by the Nafion ionomers doping. On the other hand, the ordered structured electrodes can greatly reduce transport resistances. The electrode reaction kinetics and the coupling mechanisms of electrocatalytic reaction and energy storage process are explored by combining electrochemical testing, in situ spectroscopy and theoretical calculation, and consequently guide the optimization of the HEPS performance. This project is to create a new methodology and theoretical basis for developing next generation electrochemical power sources with high specific energy and power.

随着新能源汽车的发展，兼具高比能量和高比功率的双高化学电源需求迫切。聚合物电解质膜燃料电池比能量高，超级电容器比功率高，结合两者优势的复合化学电源可实现双高目标，传统“外部电路复合”化学电源存在体积大、质量重、成本和故障率高的问题，本项目拟构建基于电催化剂和赝电容材料耦合的“内部复合”化学电源。项目难点有：赝电容材料和聚电解质接触不充分；赝电容材料阻碍电极中反应物和反应产物的传输；电催化反应与储能过程在同一电极上发生，机理复杂。拟解决方法如下：对赝电容材料聚苯胺纳米线阵列进行Nafion聚离子掺杂，然后担载Pt催化剂构筑有序化电极，其中Nafion聚离子掺杂可扩展聚苯胺/聚电解质界面，电极有序化可强化物质传输；结合电化学测试、原位谱学表征和理论计算，探究电极反应动力学过程和电催化-储能耦合机理，指导复合化学电源性能优化。本项目将为新一代双高化学电源开发提供新的方法学和理论依据。

兼具高比能量和高比功率的“双高”化学电源在军用和民用领域有重要作用。常见化学电源中聚合物电解质膜燃料电池比能量高、比功率低；而超级电容器则相反，比功率高、比能量低，目前还没有单一化学电源兼具“双高”特性。本项目结合聚合物电解质膜燃料电池和超级电容器优势，构筑了基于赝电容材料和电催化剂耦合的“内部复合”化学电源，兼具“双高”特性。.本项目主要进行了以下两部分工作：（1）针对赝电容材料和聚合物电解质接触不充分的问题，制备了Nafion掺杂聚苯胺材料和Nafion掺杂聚苯胺/氧化石墨烯复合材料，通过调变Nafion掺杂量，研究了聚苯胺/Nafion界面的兼容性机制，以此来扩展聚苯胺/聚电解质的电化学界面，以上述材料为电极材料构筑了基于Nafion膜的柔性超级电容器，比电容达到309.0 F g−1，接近液态电解质中测试得到的376.6 F g−1，且循环稳定性良好。（2）在上述工作基础上，通过冷冻干燥法，制备了两种有序大孔骨架结构的双功能电极：还原氧化石墨烯/Nafon/Pt电极和还原氧化石墨烯/Nafion掺杂聚苯胺/Pt电极，其中还原氧化石墨烯和Nafion掺杂聚苯胺为电容材料，Pt为电催化剂。通过系统电化学测试和原位光谱表征，研究了双功能电极中电催化-储能耦合机理，并基于双功能电极组装了“内部复合”化学电源。测试得到复合化学电源比能量为12.7 kWh kg−1，接近聚合物电解质膜燃料电池的比能量（13.5 kWh kg−1）；复合化学电源比功率为26.2 kW kg−1，接近超级电容器的比功率，远高于聚合物电解质膜燃料电池的23.9 kW kg−1，成功实现“双高”目标。.本项目制备了多种电极材料，并构筑了两种新能源器件，其中构筑的“内部复合”化学电源兼具高比能量和高比功率，为新一代化学电源开发提供新的方法学和理论依据，应用前景广阔。

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