Optimized Co–S bonds energy and confinement effect of hollow MXene@CoS2/NC for enhanced sodium storage kinetics and stability

Facile Construction of Nano-Dimensional Bi Encapsulated in N-Doped Porous Carbon Frameworks for High-Performance Sodium-Ion Hybrid Capacitors

“…Meanwhile, with the cycle going on, the slopes of straight line increase gradually and tend to be stable, revealing the faster ion diffusion rate of the electrode. The results suggest that the Bi@NPC-850-U electrode has fast electrochemical reaction kinetics, rapid electrons/ions transmission pathways, and structure stability. , The galvanostatic intermittent titration technique was used to measure and to comprehend the sodium-ion transport behaviors in the Bi@NPC composites. The corresponding curves were obtained in the third cycle at a current pulse of 0.1 A g –1 for 10 min with a rest for 30 min to reach a quasi-equilibrium potential (Figure a).…”

Prussian Blue Analogue-Derived Fe-Doped CoS2 Nanoparticles Confined in Bayberry-like N-Doped Carbon Spheres as Anodes for Sodium-Ion Batteries

“…Notably, the reversible capacity of the Fe-CoS 2 /NC-3 electrode at 0.2 A g −1 and 5 A g −1 was about 2.1 and 3.6 times higher than those for CoS 2 /NC, respectively. Additionally, the superior rate capability of the Fe-CoS 2 /NC-3 electrode can be further illustrated by a comparison with that of some recently reported CoS 2 -based anodes such as a CoS 2 /C micropolyhedron composite entangled in a carbon-nanotube base network (CoS 2 -C/CNT) [ 44 ], CoS 2 nanoparticles embedded in N-doped carbon nanosheets (CoS 2 /CN) [ 67 ], CuS@CoS 2 double shelled nanoboxes (CuS@CoS 2 DSNBs) [ 20 ], CoS 2 nanoparticles embedded in N-doped carbon grown on MXene nanosheets (MXene@CoS 2 /CN) [ 29 ], Ti 3 C 2 MXene/CoS 2 @N-doped porous carbon (f-Ti 3 C 4 /CoS 2 /NPC) [ 68 ], and SnS 2 -CoS 2 @C core-shell nanocubes (SCS@C) [ 69 ], as shown in Figure 4 d. The long-term cycling stabilities of the Fe-CoS 2 /NC-3, CoS 2 /NC, Fe-CoS 2 /NC-1, Fe-CoS 2 /NC-2, and Fe-CoS 2 /NC-4 electrodes were also evaluated at 1 A g −1 , as shown in Figure 4 e. For the Fe-CoS 2 /NC-3 electrode, the capacity decayed from 850 mA h g −1 to 673 mA h g −1 at the second cycle, and gradually stabilized at 621 mA h g −1 over 400 cycles with a CE approaching 100%, showing a retention of 92.2% to the second cycle, suggesting the good stability of the Fe-CoS 2 /NC-3 electrode during the cycling process. In contrast, the CoS 2 /NC, Fe-CoS 2 /NC-1, Fe-CoS 2 /NC-2, and Fe-CoS 2 /NC-4 electrodes displayed relatively poor cycling stabilities, which only retained lower values of 313, 352, 432, and 382 mA h g −1 over 400 cycles with a retention of 83.9%, 74.3%, 74.1, and 67.5% compared to the second cycle, respectively.…”

“…In another work, Dong and co-workers illustrated the preparation of a Prussian blue analogue (PBA) Mn 3 [Co(CN 6 )] 2 ·9H 2 O derived bimetallic sulfide MnS-CoS 2 -NC@NC with a hollow nanocubic structure through a simple one-step calcination, delivering a capacity of 609 and 561 mA h g −1 at 0.2 and 5 A g −1 , respectively [ 28 ]. More recently, Feng’s group reported the preparation of metal–organic framework (MOF) derived CoS 2 nanoparticles embedded in N-doped carbon on Ti 3 C 2 T x MXene nanosheets, achieving a capacity of 355 mA h g −1 at 5 A g −1 after 5000 cycles [ 29 ]. Zhao et al reported the fabrication of CoS 2 nanoparticles on three-dimensional N-doped carbon, which displayed a capacity of 341 mA h g −1 after 1000 cycles at 1 A g −1 [ 30 ].…”

Bismuth−Antimony Alloy Embedded in Carbon Matrix for Ultra-Stable Sodium Storage

“…Another two weaker peaks at 162.7 and 157.4 eV are ascribed to metallic Bi 4f 5/2 and Bi 4f 7/2 , confirming that Bi mainly exists in the oxidized state on the surface of Bi 1 Sb 1 @C [ 5 , 24 ]. As displayed in Figure 2 e and Figure S6 , the N 2 adsorption–desorption isotherm curves exhibit the Brunnauer–Emmett–Teller (BET) apparent surface area of 43.6, 48.6, 59.6, 34.9, 43.7, and 7.3 m 2 g −1 for Bi@C, Bi 3 Sb 1 @C, Bi 1 Sb 1 @C, Bi 2 Sb 3 @C, Bi 1 Sb 3 @C, and Sb@C, respectively, which is conducive to enlarging the interface between the electrolyte and electrode and enhancing of the ions/electrons transport rate [ 25 , 26 ]. Figure 2 f and Figure S7 show that the pore-size distribution of these samples is mainly concentrated around 4 and 300 nm, which allows infiltration of sodium ions and electrolytes.…”