Metallic Mo₂C Quantum Dots Confined in Functional Carbon Nanofiber Films toward Efficient Sodium Storage: Heterogeneous Interface Engineering and Charge-Storage Mechanism

Abstract

Sodium ion capacitors (SICs) have drawn enormous interest due to their cost efficiency, superb power/energy densities, and long-span service life. Nevertheless, the imbalance of two involved electrodes in both kinetics and stability, mainly originating from battery-type anodes, restricts their practical application. Herein, we first propose a heterointerface engineering strategy to design a flexible self-supporting hybrid film anode, where metallic Mo 2 C quantum dots (QDs, ∼41.1 wt %) selfencapsulated in N-doped carbon nanofibers (N-CNFs) thanks to the interfacial interactions, toward advanced SICs. The synergistic effect of structural/compositional merits is highlighted with the induced interface coupling Mo−N−C toward enhanced electrochemical kinetics/stability and reinforced electrode structural integrity. The accelerating mechanism of electron migration at the heterogeneous interfaces is unveiled with density functional theory calculations. The obtained Mo 2 C QDs@N-CNFs film electrode is rendered with a competitive capacity of ∼160.9 mAh g −1 at 5.0 A g −1 , robust pseudocapacitive contribution, and long-duration cycling stability. Besides, the Mo 2 C QDs@N-CNFs-based SICs exhibit exceptional electrochemical properties. More significantly, the in-depth insights into the unique Na + -(de)intercalation mechanism of Mo 2 C QDs@N-CNFs are rationally proposed with in situ X-ray diffraction and electrochemical techniques. This promises the enormous potential of our designed carbon-matrix-confined Mo 2 C QDs nanohybrid for SICs and beyond.

Internal and External Cultivation Design of Zero‐Strain Columbite‐Structured MNb2O6 toward Lithium‐Ion Capacitors as Competitive Anodes

“…Clearly, the representative D‐band (1365 cm −1 ) and G‐band (1580 cm −1 ) originating from carbon materials appear for the five counterparts. [ 30 ] The carbon contents in MNb 2 O 6 (M = Co, Zn, Mn, Mg and Ca) are all less than 2 wt.%, as estimated from thermalgravimetric (TG) plots (Figure S6, Supporting Information). Notably, the well‐distributed carbon network, to a certain extent, favors the enhanced electronic transport in the MNb 2 O 6 (M = Co, Zn, Mn, Mg and Ca) specimens.…”

Soybean protein-derived N, O co-doped porous carbon sheets for supercapacitor applications

“…The I-band is typically related to sp 2 -sp 3 bonds, disordered graphitic lattices, and the presence of polyenes, while the peak in the D 00 -band corresponds to disordered graphitic structures. 30,31 The peak intensity ratio of the D-band to G-band (I D /I G ) can be utilized to identify the graphitization degree of the carbon materials. 5,32 In this study, the I D /I G values are above 1.30 indicating that all the carbon materials exhibit disordered phases, which are in accordance with the XRD results.…”

Diffusion mechanism and electrochemical investigation of 1T phase Al–MoS2@rGO nano-composite as a high-performance anode for sodium-ion batteries

“…At present, the SIB anode materials based on alloying and conversion are widely used because of their high theoretical capacity [21,22]. On the other hand, the insertion based materials provide excellent cycle life, but with a low specific capacity in SIBs [23].…”