Yin Xiao-Ting, You En-Ming, Zhou Ru-Yu, Zhu Li-Hong, Wang Wei-Wei, Li Kai-Xuan, Wu De-Yin, Gu Yu, Li Jian-Feng, Mao Bing-Wei, Yan Jia-Wei
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
School of Ocean Information Engineering, Fujian Provincial Key Laboratory of Oceanic Information Perception and Intelligent Processing, Jimei University, Xiamen, China.
Nat Commun. 2024 Jul 4;15(1):5624. doi: 10.1038/s41467-024-49973-9.
Graphene has been extensively utilized as an electrode material for nonaqueous electrochemical capacitors. However, a comprehensive understanding of the charging mechanism and ion arrangement at the graphene/electrolyte interface remain elusive. Herein, a gap-enhanced Raman spectroscopic strategy is designed to characterize the dynamic interfacial process of graphene with an adjustable number of layers, which is based on synergistic enhancement of localized surface plasmons from shell-isolated nanoparticles and a metal substrate. By employing such a strategy combined with complementary characterization techniques, we study the potential-dependent configuration of adsorbed ions and capacitance curves for graphene based on the number of layers. As the number of layers increases, the properties of graphene transform from a metalloid nature to graphite-like behavior. The charging mechanism shifts from co-ion desorption in single-layer graphene to ion exchange domination in few-layer graphene. The increase in area specific capacitance from 64 to 145 µF cm is attributed to the influence on ion packing, thereby impacting the electrochemical performance. Furthermore, the potential-dependent coordination structure of lithium bis(fluorosulfonyl) imide in tetraglyme ([Li(G4)][FSI]) at graphene/electrolyte interface is revealed. This work adds to the understanding of graphene interfaces with distinct properties, offering insights for optimization of electrochemical capacitors.
石墨烯已被广泛用作非水电化学电容器的电极材料。然而，对石墨烯/电解质界面处的充电机制和离子排列的全面理解仍然难以捉摸。在此，设计了一种间隙增强拉曼光谱策略，以表征具有可调节层数的石墨烯的动态界面过程，该策略基于壳层隔离纳米颗粒和金属基底的局域表面等离子体的协同增强。通过采用这种策略并结合互补的表征技术，我们基于层数研究了石墨烯吸附离子的电位依赖性构型和电容曲线。随着层数的增加，石墨烯的性质从类金属性质转变为类石墨行为。充电机制从单层石墨烯中的共离子解吸转变为少层石墨烯中的离子交换主导。面积比电容从64增加到145 μF/cm归因于对离子堆积的影响，从而影响电化学性能。此外，还揭示了双（氟磺酰）亚胺锂在石墨烯/电解质界面处的电位依赖性配位结构。这项工作有助于理解具有不同性质的石墨烯界面，为优化电化学电容器提供了见解。
