在KOH活化的激光诱导石墨烯上沉积MnO_(2)用于柔性平面微型超级电容器

Deposition of MnO_(2)on KOH-activated laser-produced graphene for a flexible planar micro-supercapacitor

柔性超级电容器具有超高的功率密度和超长的循环寿命,结合其结构的灵活性、轻质和形状多样性的特点,在储能领域具有巨大的应用潜力。发展柔性超级电容器首先要解决柔性电极制备的难题。本研究通过激光直写技术结合KOH活化得到高柔性、高导电性的微孔石墨烯基底,即活化的激光诱导石墨烯(a-LIG),然后用电化学沉积法在其上沉积二氧化锰,成功开发出柔性a-LIG/MnO_(2)电极。在1 mol/L的Na_(2)SO_(4)电解质中,当电流密度为1 mA/cm^(2)时,复合a-LIG/MnO_(2)电极表现出304.61 mF/cm^(2)的高面积比电容。以a-LIG/MnO_(2)为阳极,a-LIG为阴极,PVA/H_(3)PO_(4)为凝胶电解质,组装了柔性非对称超级电容器,在功率密度为260.28μW/cm^(2)时其面积能量密度为2.61μWh/cm^(2),在电流密度为0.2 mA/cm^(2)时其面积比电容为18.82 mF/cm^(2),且5000次循环后电容保持率达到90.28%。此外,柔性a-LIG/MnO_(2)@a-LIG器件在弯曲状态下也表现出优异的电化学性能。这项工作为合理设计高性能的柔性超级电容器电极提供了一种简单和可扩展的方法,并可能为大规模制造平面柔性超级电容器提供新的途径。

The rapid development of flexible supercapacitors has been impeded by the difficulty of preparing flexible electrodes.We report the fabrication of a highly flexible and conductive microporous graphene-based substrate obtained by direct laser writing combined with KOH activation,which we call activated laser-produced graphene(a-LPG),which is then decorated with electrochemically deposited MnO_(2)to form a flexible a-LIG/MnO_(2)thin-film electrode.This hybrid electrode has a high areal capacitance of 304.61 mF/cm^(2)at a current density of 1 mA/cm^(2)in a 1 mol/L Na_(2)SO_(4)aqueous electrolyte.A flexible asymmetric supercapacitor with a-LIG/MnO_(2)as the anode,a-LIG as the cathode and PVA/H_(3)PO_(4)as a gel electrolyte was assembled,giving an areal energy density of 2.61μWh/cm^(2)at a power density of 260.28μW/cm^(2)and an ultra-high areal capacitance of 18.82 mF/cm^(2)at 0.2 mA/cm^(2),with 90.28%capacitance retained after 5000 cycles.It also has an excellent electrochemical performance even in the bent state.This work provides an easy and scalable method to design high-performance flexible supercapacitor electrodes and may open a new way for their large-scale fabrication.