Self-buffered pH at carbon surfaces in aqueous supercapacitors
Self-buffered pH at carbon surfaces in aqueous supercapacitors
复制标题
DOI：
10.1016/j.carbon.2017.12.101
复制
发表时间：
2018-04
期刊：
影响因子：
10.9
通讯作者：
Adam Ślesiński;C. Matei-Ghimbeu;K. Fic;F. Béguin;E. Frąckowiak
中科院分区：
文献类型：
--
作者：
Adam Ślesiński;C. Matei-Ghimbeu;K. Fic;F. Béguin;E. Frąckowiak
本文提出了一种独特的策略，旨在扩大工作在中性水溶液中的超级电容器的工作电压范围。深入分析碳/电解液界面形成的平衡，有可能达到1.8GV，在循环过程中具有良好的可逆性。为了达到这一目的，我们考虑了碳电极表面的施主-受主性质。实现了电极材料的控制氧化和氨吸附的耦合，以调整最佳的平衡条件。碳的硝酸氧化导致形成促进氨吸附的电化学活性酸性中心。氨水的修饰会在电容器体系中引入自控的pH梯度，并在电极上形成保护层，从而导致较高的溶剂分解过电位。这反过来又允许电容器在更高的电压下运行。此外，这种配置不需要物理分离离子(如离子交换膜)来减慢它们的混合速度，并提高了设备的功率密度。
This paper presents a unique strategy aiming at extending the operational voltage range in supercapacitor working in the neutral aqueous electrolyte. In-depth analysis of the equilibria formed at the carbon/electrolyte interface gives the possibility to reach 1.8 V with excellent reversibility during cycling. To reach the goal, the donor - acceptor nature of carbon electrode surface has been taken into consideration. Controlled oxidation of electrode materials coupled with ammonia adsorption have been realized in order to adjust the optimal equilibrium conditions. Nitric acid oxidation of carbon leads to the formation of electrochemically active acidic sites promoting adsorption of ammonia. Modification with ammonia results in the introduction of self-controlled pH gradient within the capacitor system and formation of protective layer on electrodes, responsible for higher overpotentials of solvent decomposition. This, in turn, allows capacitor operation at higher voltages. Furthermore, this configuration eliminates the need for physical separation of ions (such as an ion-exchange membrane) to decelerate their mixing and improves the power density of the device.