The impact of laser-scribing carbon-based supercapacitor electrodes
The impact of laser-scribing carbon-based supercapacitor electrodes
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DOI：
10.1016/j.apsadv.2022.100262
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发表时间：
2022-08
影响因子：
6.2
通讯作者：
M. Baptista;G. Gáspár;K. Wijayantha;K. Lobato
中科院分区：
文献类型：
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作者：
M. Baptista;G. Gáspár;K. Wijayantha;K. Lobato
在高度多孔的碳电极中，大部分孔可能无法进入电解质，这转化为较低的比电容。这在高电流密度下更加突出。为了避免这种情况，可以打开通道以增强离子扩散。在这项工作中，使用脉冲激光创建离子通道。在两组碳基超级电容器电极上施加九组激光划线参数（脉冲能量密度和光斑间距）：K条手工涂覆电极（“K”）和丝网印刷电极（“SP”）。轮廓仪和扫描电子显微镜显示，在激光划片之前，后者已经有几个孔和沟槽，而前者是致密的薄膜。在硫酸钠中的电化学测量表明激光刻划的SP电极的倍率性能的改善，即能量密度随着功率密度的增加而降低的倍率降低高达50%。对于激光刻划的K电极，Ragone图的斜率仅降低约。在最佳条件下的20%。然而，对于两组电极，观察到负面的权衡：激光处理的电极似乎具有较低的比电容。这可能是由激光钻孔中的碎片截留引起的，这可能导致活性质量的高估。此外，X射线光电子能谱分析表明，这也可以通过氧官能度的降低及其对电极润湿性的影响来解释。另一方面，对于在有机电解质（乙腈中的高氯酸四丁基铵）中测试的电极，对于激光刻划的电极，在2A/g下的比电容高出高达66%，并且即使在2.8kW/kg下也实现了13 Wh/kg的能量密度。
In highly porous carbon electrodes, a large fraction of pores can be inaccessible to the electrolyte, which translates into lower specific capacitances. This is accentuated at high current densities. To circumvent this, channels can be opened to enhance ionic diffusion. In this work, ionic channels were created using a pulsed laser. Nine sets of laser-scribing parameters (pulse fluence and spot spacing) were applied on two sets of carbon-based supercapacitor electrodes: K-bar hand-coated electrodes (“K”) and screen-printed electrodes (“SP”). Profilometry and scanning electron microscopy revealed that, before laser-scribing, the latter already had several holes and trenches, whilst the former were compact films. Electrochemical measurements in Na2SO4indicate improvements in the rate capability of the laser-scribed SP electrodes, namely an up to 50% reduction of the rate at which energy density decreases as power densities increase. For laser-scribed K electrodes, the slope of the Ragone plot only decreased by ca. 20% in the best set of conditions. However, for both sets of electrodes, a negative trade-off is observed: laser processed electrodes seem to have a lower specific capacitance. This might be caused by the entrapment of debris in the laser-drilled holes, which could lead to the overestimation of the active mass. Moreover, X-ray Photoelectron Spectroscopy analysis suggests that this may also be explained by the decrease in the oxygen functionalities and by its impact on the electrodes’ wettability. On the other hand, for electrodes tested in an organic electrolyte (tetrabutylammonium perchlorate in acetonitrile), the specific capacitance at 2 A/g was up to 66% higher for laser-scribed electrodes and an energy density of 13 Wh/kg was achieved even at 2.8 kW/kg.