The high work function of electrode materials inhibits the improvement of the performance of thermionic energy converters. Space charge effect and near-field heat transfer are also significant factors restricting the thermoelectric conversion capability. A micro-scale graphene-anode thermionic energy converter is proposed, in which a monolayer graphene sheet is placed on the substrate as the collector. The effects of both the space charge effect and the near-field heat transfer in the vacuum gap of the device are discussed based on Poisson's equation and the framework of fluctuation electrodynamics. Expressions for the power output density and efficiency of the system are derived. The systemic performance characteristics are comprehensively analyzed by optimizing main parameters. The results show that the electrode temperatures, current density, and energy fluxes in each portion are significantly regulated by the voltage output and the distance between the electrodes. There is a trade-off between the near-field heat transfer and the space charge effect so that the system can achieve optimum performance. The maximum values of the power output density and efficiency of the proposed system are, respectively, enhanced by 2.135% and 8.824% compared to those of the metal-thermionic energy converter. The optimal selection criteria of key parameters are determined, providing valuable guidance for actual operation.

电极材料的高功函数抑制了热离子能量转换器性能的提高。空间电荷效应和近场传热也是制约热电转换能力的重要因素。提出了一种微尺度石墨烯-阳极热离子能量转换器，其中将单层石墨烯片放置在基板上作为集电极。基于泊松方程和涨落电动力学框架，讨论了器件真空间隙中空间电荷效应和近场传热的影响。导出了系统功率输出密度和效率的表达式。通过优化主要参数，综合分析系统性能特点。结果表明，电极温度，每个部分的电流密度和能量通量受电压输出和电极之间的距离显着调节。在近场传热和空间电荷效应之间进行权衡，以使系统达到最佳性能。与金属-热离子能量转换器相比，该系统的功率输出密度和效率最大值分别提高了 2.135% 和 8.824%。确定了关键参数的最优选择标准，为实际操作提供了有价值的指导。与金属-热离子能量转换器相比，该系统的功率输出密度和效率最大值分别提高了 2.135% 和 8.824%。确定了关键参数的最优选择标准，为实际操作提供了有价值的指导。与金属-热离子能量转换器相比，该系统的功率输出密度和效率最大值分别提高了 2.135% 和 8.824%。确定了关键参数的最优选择标准，为实际操作提供了有价值的指导。