Abstract

Surface modification of graphene and activated carbon through heat treatment has been used to increase the materials' electrical and optical properties for lithium-ion capacitor (LIC) applications. The surface modification techniques employed in this study emphasize introduction of an acidic group and a small number of lactonic and phenolic groups on graphite and activated carbon to facilitate their dispersion in aqueous media. In this research, lithium dispersion at high temperatures, the surface properties of the materials, and their electrochemical and optical properties are assessed. These include lithium dispersion and covalent attachment of functional groups. The effects of these surface modifications on the performance characteristics of dispersed nanocomposites were evaluated through several techniques (XRD, SEM, TEM, cyclic voltammetry, Mott-Schottky, BET, BJH, T-plot, pore size distribution, Boehm titration, and chronoamperometry). Especially, the highest oxidation peak corresponding to current value appeared at 0.0056 mA/cm² current density and the lowest reduction peak value marked at 0.0002 mA/cm², when the Li-G sample used to the FTO surface. The electrochemical stability of cathode materials was tested by 10 recycling tests, which the peak current drop decreased the peak profile became stable. The Li-dispersed graphite and activated carbon had synergistically upgraded electrochemical activity and superior cycling stability that were demonstrated in LIC. This research presented herein offers a promising route for the rational design of Li amounts and stable electrochemical reaction in LIC working mechanism.

1. Highlights

2. Surface modification with the introduction of an acidic group and a small number of lactonic and phenolic groups on graphite and activated carbon

3. Lithium dispersion at high temperatures for the lithium amounts expansion for the cyclic stability

4. The electrochemical stability of cathode materials with stable peak profile

5. The rational design of Li amounts and stable electrochemical reaction in LIC working mechanism

摘要

通过热处理对石墨烯和活性炭进行表面改性已被用于提高锂离子电容器 (LIC) 应用中材料的电学和光学性能。本研究中采用的表面改性技术强调在石墨和活性炭上引入酸性基团和少量内酯基和酚基，以促进它们在水性介质中的分散。在这项研究中，评估了高温下的锂分散、材料的表面特性以及它们的电化学和光学特性。这些包括锂分散和官能团的共价连接。通过多种技术（XRD、SEM、TEM、循环伏安法、Mott-Schottky、BET、BJH、T-plot、孔径分布、Boehm 滴定法和计时电流法）。特别是电流值对应的最高氧化峰出现在0.0056 mA/cm当Li-G样品用于FTO表面时，²电流密度和最低还原峰值标记为0.0002 mA/cm ^{2 。}正极材料的电化学稳定性通过10次循环测试，峰值电流下降减小，峰值曲线趋于稳定。分散锂的石墨和活性炭具有协同升级的电化学活性和优异的循环稳定性，这在 LIC 中得到了证明。本文提出的这项研究为在 LIC 工作机制中合理设计锂量和稳定电化学反应提供了一条有前景的途径。

1. 强调

2. 通过在石墨和活性炭上引入酸性基团和少量内酯基和酚基进行表面改性

3. 高温下锂分散，锂量膨胀，循环稳定性

4. 具有稳定峰形的正极材料的电化学稳定性

5. LIC工作机理中锂量的合理设计和电化学反应的稳定