Abstract:

It is urgent to develop transparent electrochemical energy storage devices such as transparent supercapacitors for wearable and portable electronic devices. The carbonized leaf vein is composed of a continuous carbon fiber network, which has the advantages of very good transparency, good conductivity and light weight. In this paper, we used carbonized leaf vein network as current collector to directly grow Ni/Co-based metal organic frameworks (MOFs) by using a solvothermal method. The continuous carbon fiber network of carbonized leaf vein can provide pathways for continuous electron and ion transportation. The mixed metal centers in Ni/Co-MOF are beneficial to provide more electrochemical sites for charge storage. The prepared transparent carbonized leaf vein network@Ni/Co-MOF electrode exhibited a high areal capacity of 1.15F/cm² at a current density of 1mA/cm². In addition, its capacity retention rate after 1000 cycles was 105.4%, indicating a good cycle stability. The transparent asymmetric transparent supercapacitor was assembled by carbonized leaf vein@Ni/Co MOFs and carbonized leaf vein@activated carbon, which achieved an areal capacitance of 0.47F/cm² and an areal energy density of 0.61W·h/cm² in a wide potential range of 0—1.6V and at a current density of 1mA/cm². Moreover, the supercapacitor exhibited a good cycling stability with an areal capacitance retention rate of 93.6% after 300 cycles. The method presented here provides a new way for the preparation of transparent functional devices such as sensors, optoelectronic devices, solar cells and lithium-ion batteries.

Key words: electrochemistry, metal organic frameworks, powders, carbonized leaf vein network, transparent supercapacitor

摘要：

可穿戴和便携式电子设备迫切需要发展透明超级电容器等电化学储能器件。炭化树叶叶脉由连续的碳纤维网络构成，具有非常好的透明性，且兼具导电性好和质量轻的优点。本文以炭化菩提树叶叶脉网络为集流体，通过溶剂热法在其上原位生长了Ni/Co混合金属-有机框架材料（Ni/Co-MOF）。炭化叶脉的连续碳纤维网络有利于电子连续传输及电解液的输运；Ni/Co-MOF中混合金属中心有利于提供更多的电化学位点存储电荷。所制备的炭化叶脉网络@Ni/Co-MOF透明电极在1mA/cm²电流密度下表现出1.15F/cm²的高面积容量，经过1000次循环后，容量保持率为105.4%，仍具有良好的循环稳定性。以炭化叶脉网络@Ni/Co-MOF和炭化叶脉网络@活性炭组装成非对称透明超级电容器，在1.6V的大电势窗口、1mA/cm²的电流密度下，得到的面积容量为0.47F/cm²、面积能量密度为0.61W·h/cm²；并具有良好的循环稳定性，在循环300圈后，容量保持率为93.6%。炭化叶脉网络@MOF材料的方法将为制备透明功能器件如传感器、光电器件、太阳电池和锂离子电池等应用提供了新途径。

关键词: 电化学, 金属-有机框架, 粉体, 炭化叶脉网络, 透明超级电容器