Electric‐Field‐Assisted Enhanced Electron Transfer to Boost Supercapacitor Negative Electrode Performance for a Fabricated Fe₇S₈/α‐FeOOH Nano‐Heterostructure

Abstract

nevertheless, they usually put undue emphasis on the capacity of the positive electrode, instead. There are few reports that discuss the negative electrode materials relatively. As a result, the capacity of the negative electrodes is much lower than that of the positive electrodes, and the capacity mismatch between the positive and negative electrodes is more serious. [6] As a matter of fact, similar to "cask effect," the capacity of the negative electrode is the shortest plank for supercapacitor, which decides how much energy capacity the supercapacitor can store. In other words, the way that can increase the capacity of the negative electrode materials, can remedy the low energy density deficiency of supercapacitor. [7] Looking at what predecessors have been developed for constructing the supercapacitor negative electrode, carbon and Fe-based materials are two major electrodes that can be utilized. [8][9][10] Due to the redox characteristic of Fe-based materials, it is believed to have the higher theoretical capacity compared with carbon materials that presents double layer capacitance characteristics. [11] To our disappointment, the poor electrical conductivity, which affects the efficiency of electronic transmission, resulted in low supercapacitor performance embodiment, far less than what was expected. [12,13] Therefore, how to improve the electrical conductivity to enhance the efficiency of electron transfer is the most important factor when designing and fabricating an Fe-based negative electrode material. [14] To address this challenge, one of the strategies is to fabricate composites with carbon materials. [4,15] On account of the excellent electrical conductivity of carbon materials, the Fe-based compand/carbon composites show good electrical conductivity. However, the low theoretical capacity of carbon materials limits the capacity promotion of Fe-based compand/ carbon composites. Another method is to rationally design a hierarchical nanostructure. [5,14,16,17] Core-shell structure is believed to be a good choice, where materials with good electrical conductivity are used as the core and materials with high theoretical capacity are used as the shell. [13,[18][19][20] Therefore, the good electrochemical performance has been ascribed to its unique structure, which endows the electrode with large specific area and facilitates the contact between the electrode and The shortcoming of Fe-based materials, their poor electron transfer efficiency, restricts their electrochemical performance severely. An electric field (E) is induced by an Fe 7 S 8 /α-FeOOH nano-heterostructure (SACF) via two simple immersion steps at room temperature. The charge transfer from α-FeOOH to Fe 7 S 8 spontaneously establishes an intrinsic electric field at the Fe 7 S 8 /α-FeOOH nano-heterostructure boundary. Additionally, the relationship between structure and property is investigated by structural characterization and density functional theory calculations that are used to explain the electron transfer mechanism and good wettabilit...

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