da Silva Débora A C, Paulista Neto Antenor J, Pascon Aline M, Fileti Eudes E, Fonseca Leonardo R C, Zanin Hudson G
Center for Innovation on New Energies, Advanced Energy Storage Division, Carbon Sci-Tech Labs, University of Campinas, School of Electrical and Computer Engineering, Av. Albert Einstein 400, Campinas, SP 13083-852, Brazil.
Institute of Science and Technology of the Federal University of São Paulo, 12247-014, São José dos Campos, SP, Brazil.
Phys Chem Chem Phys. 2020 Feb 19;22(7):3906-3913. doi: 10.1039/c9cp06495h.
We report here density functional theory calculations and molecular dynamics atomistic simulations to determine the total capacitance of graphene-modified supercapacitors. The contributions of quantum capacitance to the total capacitance for boron-, sulfur-, and fluorine-doped graphene electrodes, as well as vacancy-modified electrodes, were examined. All the doped electrodes presented significant variations in quantum capacitance (ranging from 0 to ∼200 μF cm-2) due to changes in the electronic structure of pristine graphene. The graphene-modified supercapacitors show any appreciable effect on double-layer capacitance being virtually the same for all the devices investigated. The total differential capacitance was found to be limited by the quantum capacitance, and for all the systems, it is lower than the quantum capacitance over the entire voltage window. We found that the total capacitance can be optimized by considering an adequate modification to each electrode in the supercapacitor. In addition, we found that an asymmetric supercapacitor assembled with different doped electrodes, i.e. an F doped negative electrode and an N doped positive electrode, is the best choice for a supercapacitor since this combination results in better capacitance over the entire potential window.
我们在此报告密度泛函理论计算和分子动力学原子模拟，以确定石墨烯修饰超级电容器的总电容。研究了硼、硫和氟掺杂石墨烯电极以及空位修饰电极的量子电容对总电容的贡献。由于原始石墨烯电子结构的变化，所有掺杂电极的量子电容都有显著变化（范围从0到约200 μF cm-2）。石墨烯修饰的超级电容器对双层电容没有明显影响，在所研究的所有器件中双层电容几乎相同。发现总微分电容受量子电容限制，并且对于所有系统，在整个电压窗口内它都低于量子电容。我们发现，通过对超级电容器中的每个电极进行适当修饰，可以优化总电容。此外，我们发现，用不同掺杂电极组装的不对称超级电容器，即F掺杂负极和N掺杂正极，是超级电容器的最佳选择，因为这种组合在整个电位窗口内具有更好的电容。
