关键词: 超级电容器, 水系杂化电解质, 盐包水电解质, 宽电压窗口, 长循环寿命

Abstract:

Developing supercapacitors (SCs) with long cycling life and wide operative voltage window is a significant topic in the field of aqueous electrolytes. Although the design of water in salt (WIS) electrolytes has pushed the development of aqueous electrolytes to a new height, the WIS electrolytes with an operative voltage window of up to 2.5 V is still very scarce. Herein, in order to enrich the type of aqueous electrolyte with high operative voltage, tetramethylammonium trifluoromethanesulfonate (TMAOTf) based WIS electrolyte was used as a model to construct WIS based hybrid electrolyte with acetonitrile (ACN) co-solvent and LiTFSI co-solute. In view of the coordination effect of ACN and Li⁺ on free water in TMAOTf based WIS electrolyte, the TMA⁺-Li⁺-AWIS electrolyte has the electrochemical stabilization window of up to 3.35 V. Further coupled with the commercial YP-50F electrodes, TMA⁺-Li⁺-AWIS based SCs exhibited wide operative voltage window (2.5 V), long cycling life (45,000 cycles) and good low-temperature performance (99.99 % capacitance retention after 2000 cycles at -20 ^oC). The design of this hybrid electrolyte will enrich the types of aqueous hybrid electrolytes with long cycling life and wide operative voltage window.

Key words: Supercapacitor, Aqueous hybrid electrolyte, tetramethylammonium trifluoromethanesulfonate based water in salt electrolyte, Operative voltage window, Cycling life