Double-Morphology CoS₂ Anchored on N-Doped Multichannel Carbon Nanofibers as High-Performance Anode Materials for Na-Ion Batteries

Abstract

Na-ion batteries (NIBs) have attracted increasing attention given the fact that sodium is relatively more plentiful and affordable than lithium for sustainable and large-scale energy storage systems. However, the shortage of electrode materials with outstanding comprehensive properties has limited the practical implementations of NIBs. Among all the discovered anode materials, transition-metal sulfide has been proven as one of the most competitive and promising ones due to its excellent redox reversibility and relatively high theoretical capacity. In this study, double-morphology N-doped CoS/multichannel carbon nanofibers composites (CoS/MCNFs) are precisely designed, which overcome common issues such as the poor cycling life and inferior rate performance of CoS electrodes. The conductive 3D interconnected multichannel nanostructure of CoS/MCNFs provides efficient buffer zones for the release of mechanical stresses from Na ions intercalation/deintercalation. The synergy of the diverse structural features enables a robust frame and a rapid electrochemical reaction in CoS/MCNFs anode, resulting in an impressive long-term cycling life of 900 cycles with a capacity of 620 mAh g at 1 A g (86.4% theoretical capacity) and a surprisingly high-power output. The proposed design in this study provides a rational and novel thought for fabricating electrode materials.

Unraveling the Voltage Failure Mechanism in Metal Sulfide Anodes for Sodium Storage and Improving Their Long Cycle Life by Sulfur‐Doped Carbon Protection

“…The Co 1− x S/s‐C and bare Co 1− x S samples show similar Raman bands at around 185, 461, 499, and 662 cm −1 , corresponding to the E g , Tg (1) , Ag, and Tg (2) modes of the Co 1− x S crystal, respectively. [ 20 ] The characteristic peak position of Co 1− x S/s‐C is slightly redshifted because of the changed light frequency caused by the carbon component. Considering the equal contents of Co 3 S 4 and CoS 1.097 in Co 1− x S‐based samples, the proportion of carbon within the Co 1− x S/s‐C material is measured by TG tests in the air atmosphere and it is calculated to be ≈34.6 wt% based on the data of TG in Figure S8a,b, Supporting Information, following the reaction: 3 Co 1− x S (s) + 2 (1− x ) O 2 (g) = (1− x ) Co 3 O 4 (s) +3 S (g).…”

“…Considering the equal contents of Co 3 S 4 and CoS 1.097 in Co 1− x S‐based samples, the proportion of carbon within the Co 1− x S/s‐C material is measured by TG tests in the air atmosphere and it is calculated to be ≈34.6 wt% based on the data of TG in Figure S8a,b, Supporting Information, following the reaction: 3 Co 1− x S (s) + 2 (1− x ) O 2 (g) = (1− x ) Co 3 O 4 (s) +3 S (g). [ 20 ]…”

Double Morphology of Co9S8 Coated by N, S Co-doped Carbon as Efficient Anode Materials for Sodium-Ion Batteries

“…So far, most studies have also focused on designing novel carbon materials with heteroatom (N, P, S, B) doped, such as sandwich-like structures with N, S-doped RG O [33,34], nanoflower-like N-C/CoS 2 [35], Co 9 S 8 coated with N-doped carbon nanospheres [36,37], and N, S-doped nanofibers [38,39]. Carbon coating can not only enhance the conductivity of TMSs, but also remit the stress stemming from the volume expansion.…”

Synergistic Assembly of a CoS@NiFe/Ni Foam Heterostructure Electrocatalyst for Efficient Water Oxidation Catalysis at Large Current Densities

“…As shown in Figure c and Figure d, prominent peaks located at nearly 460 cm −1 can belong to Fe−O band, peaks around 545 cm −1 and 710 cm −1 can ascribe to Ni‐O, indicating the electrodeposited NiFe/NF is composed of NiFeO x . After CoS deposition, the Raman frequencies appeared at around 290 cm −1 and 416 cm −1 were assigned to Co−S, while peak around 670 cm −1 were related to Co−O bonds, further demonstrating the surface deposition of CoS film was partial cobalt‐oxide‐sulfide (Co−O−S), which has been suggested to optimize the covalence and the ionicity of the interactions between the electrode and electrolyte…”