多级结构氮掺杂碳基一体化空气电极的可控制备及其可充锌-空气电池性能研究

The most significant challenges for investigating high performance rechargeable Zn-air batteries are designing excellent oxygen reduction reaction(ORR)/oxygen evolution reaction(OER) catalysts system and rational structures of air electrodes. In order to satisfy the needs of rechargeable Zn-air batteries for multi-function, such as high-efficient catalyzing, gas diffusion, current collecting and so on, this project is going to start with the structural design of electrodes and activity regulation of catalysts, and construct facile nitrogen doped carbon-based integral air electrodes with hierarchical structures by combining electrospinning, MgO template and chemical vapor deposition (CVD) methods. We will precisely optimize the CVD conditions to control the N species of carbon materials and regulate the catalytic function of N-doped carbon materials for ORR/OER. Based on these, transition metal hydroxides (TMHs) nanosheets will in-situ grow on the surface of N-doped carbon electrode using MgO as a self-sacrificed template to obtain enhanced OER catalytic performance. Then, the relationship between the structure and catalytic activity, and the promoting mechanism for mass transfer will be deeply investigated. We will further elucidated the synergistic effect of N-doped carbon and TMHs for promoting ORR/OER kinetics and cycling stability of Zn-air batteries. This project is very innovative in the structure building and preparation of air electrodes. It is expected that the guiding design principles and key techniques for fabricating integral air electrodes will be obtained to propel the practical applications of rechargeable Zn-air batteries forward.

设计优异的氧还原（ORR）/氧析出（OER）催化剂体系以及合理的空气电极结构是研发高性能可充锌-空气电池的重要难题。为满足可充锌-空气电池对高效催化、气体扩散、集流等功能的需求，本项目拟从电极的结构设计和催化剂的活性调控入手，结合静电纺丝、氧化镁模板以及化学气相沉积（CVD）法，实现多级结构氮掺杂碳基一体化空气电极的构建；通过CVD条件优化实现对碳材料可控氮掺杂和催化功能的调控；采用氧化镁牺牲模板法在氮掺杂碳电极表面原位生长过渡金属氢氧化物（TMHs）纳米片，实现OER催化增强；探索多级结构与ORR/OER催化活性的构效关系以及对传质过程的促进机制；明确氮掺杂碳与TMHs对促进ORR/OER动力学性能和提高锌-空气电池循环稳定性的协同影响机制。本项目在空气电极结构设计和制备方法上具有很好的创新性，预期获得高性能一体化空气电极的设计指导原则和关键制备技术，进而推动可充锌-空气电池的实际应用。

本项目围绕多级结构一体化电极的制备优化，研究其在电化学催化及储能领域中的应用，从微观结构方面揭示了多级结构对催化活性提升和能量密度提升的影响机制，构建了一系列能量存储和转化器件，主要研究结论如下：.（1）通过静电纺丝结合氢氧化镁模板来构筑具有垂直碳纳米片阵列的多级结构碳纤维基底，并将氧化镁模板原位转化为具有较好氧析出催化活性的镍铁氢氧化物。基于合理的设计，NiFe LDH@N-CNS@CNF电极与商业贵金属催化剂相比，具有良好的更低的ORR和OER催化过电位。组装的Zn-air电池在5 mA cm-2的电流密度下，稳定极化电位仅为0.85 V。.（2）以商用碳纤维布为基底，电沉积氢氧化镁作为模板，结合化学气相沉积技术制备出多级结构一体化碳载体，进而实现对纳米CoO的结合与锚定。高比表面积和多孔结构有利于催化剂表面活性位点与电解质的接触，促进反应物/产物的转移。集成的CoO@PCNAs@CC电极具有良好的ORR和OER催化性能。可充锌空气电池的最大功率密度可达152 mWcm-2。在5 mA cm-2的电流密度下，电池循环在超过200h后，仍可以保持0.96 V的电压差，超过600 h循环无明显的极化现象。.（3）发展了一种普适性氧化镁转化生长方法，分别以泡沫镍，不锈钢网以及柔性塑料薄膜为基底生长NiFe LDH垂直纳米片，在碱性条件下氧析出催化和响应薄膜致动领域均表现出较好的应用。.（4）在此项目的资助下还开展了不同结构碳涂层隔膜在锂硫电池中的应用研究，系统研究了不同维度涂层对电池性能的影响，揭示了零维碳涂层的结构优势。基于此结论，对零维碳进行空心化设计，获得了超低负载（0.025 mg cm-2）的涂层隔膜在0.2 C倍率下循环100次后，仍可获得747 mAh g-1的可逆容量。.本项目为多级结构碳及其复合材料的构建提出了一种新的构建思路，对于电催化，储能等领域研究具有推动意义。