在石墨毡电极上无金属制备氮掺杂垂直石墨烯，增强高性能氧化还原液流电池的反应动力学和传质,Advanced Energy Materials

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在石墨毡电极上无金属制备氮掺杂垂直石墨烯，增强高性能氧化还原液流电池的反应动力学和传质
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2023-11-12 , DOI: 10.1002/aenm.202302521
Jincong Guo _{1,

2} , Lyuming Pan _{1,

2} , Jing Sun ₃ , Dongbo Wei _{1,

2} , Qiuxia Dai _{2,

4} , Junhui Xu _{2,

4} , Quanlong Li ₅ , Meisheng Han _{1,

2} , Lei Wei _{1,

2} , Tianshou Zhao _{1,

2}

Affiliation

石墨毡常用于氧化还原液流电池，但其低比表面积和较差的催化活性导致传质和反应动力学不理想。这里，通过无金属化学气相沉积方法在石墨毡上原位生长氮掺杂垂直石墨烯，由于大量暴露的高密度尖锐石墨烯边缘和氮掺杂，该石墨烯表现出高比表面积和显着的催化活性。多物理模拟表明，垂直纳米结构促进了钒离子到达电极/电解质界面的可及性，有效降低了活性物质的传质阻力。密度泛函理论计算证据表明，氮掺杂通过促进钒离子的吸附和氧化还原来帮助提高催化活性。因此，氮掺杂垂直石墨烯/石墨毡电极在200 mA cm ^-2下的能量效率为87.1% ，显着高于原始电极（65.9%）和空气氧化电极（73.1%），能量效率超过在300 mA cm ^-2下，1500次循环后的效率为80.2%，高峰值功率密度为1308.56 mW cm ^-2，优于之前报道的液流电池用碳纳米材料装饰电极。值得注意的是，合成过程仅涉及气相反应，无需金属催化剂，以避免析氢反应。这项工作为开发液流电池的高性能电极提供了一条令人兴奋的途径。

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Metal-free Fabrication of Nitrogen-doped Vertical Graphene on Graphite Felt Electrodes with Enhanced Reaction Kinetics and Mass Transport for High-performance Redox Flow Batteries

Graphite felt is commonly used in redox flow batteries, but the low specific surface area and poor catalytic activity cause unsatisfactory mass transfer and reaction kinetics. Here, nitrogen-doped vertical graphene is in-situ grown on graphite felt via a metal-free chemical vapor deposition method, which exhibits a high specific surface area and remarkable catalytic activity due to abundant exposed high-density sharp graphene edges and nitrogen doping. Multiphysical simulations reveal that the vertical-standing nanostructure promotes the accessibility of vanadium ions to electrode/electrolyte interfaces, effectively decreasing the mass transport resistance of active species. Density functional theory calculation evidence shows that nitrogen doping aids in the improvement of catalytic activity via boosting vanadium ions’ adsorption and redox. Consequently, the nitrogen-doped vertical graphene/graphite felt electrode shows an energy efficiency of 87.1% at 200 mA cm⁻², significantly higher than that of pristine (65.9%) and air-oxidize (73.1%) electrodes, an energy efficiency over 80.2% at 300 mA cm⁻² during 1500 cycles, and a high-peak power density of 1308.56 mW cm⁻², which are superior to previously reported carbon nanomaterial decorated electrodes for flow batteries. Significantly, the synthesis process only involves gas-phase reactions without metal catalysts to avoid hydrogen evolution reactions. This work provides an exciting pathway for developing high-performance electrodes for flow batteries.

更新日期：2023-11-12

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