MoSe₂‐Covered N,P‐Doped Carbon Nanosheets as a Long‐Life and High‐Rate Anode Material for Sodium‐Ion Batteries

Abstract

MoSe 2 grown on N,P-co-doped carbon nanosheets is synthesized by a solvothermal reaction followed with a high-temperature calcination. This composite has an interlayer spacing of MoSe 2 expanded to facilitate sodiumion diffusion, MoSe 2 immobilized on carbon nanosheets to improve chargetransfer kinetics, and N and P incorporated into carbon to enhance its interaction with active species upon cycling. These features greatly improve the electrochemical performance of this composite, as compared to all the controls. It presents a specific capacity of 378 mAh g −1 after 1000 cycles at 0.5 A g −1 , corresponding to 87% of the capacity at the second cycle. Ex situ Raman spectra and high-resolution transmission electron microscopy images confirm that it is element Se, rather than MoSe 2 , formed after the charging process. The interaction of the active species with modified carbon is simulated using density functional theory to explain this excellent stability. The superior rate capability, where the capacity at 15 A g −1 equals ≈55% of that at 0.5 A g −1 , could be associated with the significant contribution of pseudocapacitance. By pairing with homemade Na 3 V 2 (PO 4 ) 3 /C, this composite also exhibits excellent performances in full cells.

TiO2‐Coated Interlayer‐Expanded MoSe2/Phosphorus‐Doped Carbon Nanospheres for Ultrafast and Ultralong Cycling Sodium Storage

“…As displayed in Figure 5A, all the CV curves have similar peak shapes except for the corresponding shift during Na + insertion/extraction processes. [11,49,50] As shown in Figure 5C, 86.2% of the total capacity is attributed to the capacitive contribution at a scan rate of MoSe 2 /P-C electrode ( Figure S7A, Supporting Information) and the decreasing charge-transfer resistance upon cycling ( Figure S7B, Supporting Information). Generally, b = 0.5 indicates a diffusion-controlled process, and b = 1.0 represents capacitive-contributed charge storage.…”

“…[45,46] These results indicate the successful coating of the anatase TiO 2 phase. [11,47] The C 1s spectrum ( Figure 3F) could be divided into three peaks, which are located at 284.3, 285.1, and 285.7 eV, corresponding to sp 2 C, sp 3 C, and CP bonds, respectively. [11,47] The C 1s spectrum ( Figure 3F) could be divided into three peaks, which are located at 284.3, 285.1, and 285.7 eV, corresponding to sp 2 C, sp 3 C, and CP bonds, respectively.…”

“…[5][6][7] For these reasons, numerous effort including development of appropriate anode materials has been taken to satisfy the demands of decent specific capacity, long cycle life, and excellent rate performance for stationary energy storage. [11][12][13][14][15] Unfortunately, it still suffers from rapid cycling capacity degradation caused by large volume change and slow kinetics during the sodiation/desodiation process. [11][12][13][14][15] Unfortunately, it still suffers from rapid cycling capacity degradation caused by large volume change and slow kinetics during the sodiation/desodiation process.…”

Solubility‐Parameter‐Guided Solvent Selection to Initiate Ostwald Ripening for Interior Space‐Tunable Structures with Architecture‐Dependent Electrochemical Performance

“…[22] Theg alvanostatic dischargecharge profiles indicate that the initial discharge capacity of MoSe 2 HSs at the current density of 100 mA g À1 is 710.3 mAh g À1 with initial Coulombic efficiency( CE) as high as 91.25 %, which is markedly higher than those of MoSe 2 yolk-shell-II (84.97 %) and solid spheres (80.62 %; Figure S20). [22] Theg alvanostatic dischargecharge profiles indicate that the initial discharge capacity of MoSe 2 HSs at the current density of 100 mA g À1 is 710.3 mAh g À1 with initial Coulombic efficiency( CE) as high as 91.25 %, which is markedly higher than those of MoSe 2 yolk-shell-II (84.97 %) and solid spheres (80.62 %; Figure S20).…”

Recent Research on Strategies to Improve Ion Conduction in Alkali Metal‐Ion Batteries

“…Figure shows some recent experimental synthesis strategies. The solvothermal method followed by calcination is a common method for synthesizing the above metal oxide/sulfide and carbon composites ,. Figure a depicts this typical process.…”