Antimony-based substances have good prospects as anode materials in sodium ion batteries (SIBs) due to their large hypothetical capacity. Unfortunately, the high volumetric growth and the limited ionic conduction in the electrolytic procedure prevent them from fulfilling their theoretical capacities.
Study: Sb chalcogenide nanodots confined to the carbon skeleton for stable sodium storage. Image credit: Blackboard / Shutterstock.com
In a study published in the journal Carbon, H2 / C heat reduction, selenization and sulfurization (SAS) of sodium stimogluconate resulted in Sb2Se3 @ C and Sb2S3 @ C nanodots with consistent diameters of 20.7 nm and 19 nm, respectively.
Antimony-based materials for sodium ion batteries
Many attempts have been made to investigate electrode substances suitable for sodium ion batteries (SIBs). Due to their increased capacities compared to intercalation-based anode materials, alloy and conversion-based electrode substances have gained popularity.
Antimony-based substances (Sb, SnSb, Sb2Se3, Sb2S3) are possible anode substances for sodium ion batteries that have unique electrolytic mechanisms and important hypothetical capabilities. Due to their large hypothetical specific capabilities, Sb2Se3 and Sb2S3 are especially attractive options.
Unfortunately, considerable volumetric growth and inadequate ion conduction in its electrochemical process are the two fundamental problems that cause rapid capacity degradation and poor speed performance at high current density.
Sb2Se3 and Sb2S3 are antimony-based chalcogenides with different anions, causing variations in composition and conduction. Studies on the influence of various anions on the volumetric growth of the electrode morphology, the ability to bind with sodium ions (Na +) in the charge / discharge phase and ionic conduction are of particular importance in the development of electrode components for sodium ions. batteries.
Since both substances have a rapid degradation of capacity and a low speed performance, the main objectives are considered to avoid the failure of the structure and to improve the conductance of the electrode.
Addressing the limitations of antimony-based materials
Overall, logical structural design and carbon encapsulation are excellent solutions to these critical problems. The use of nanoscale materials can reduce ion diffusion pathways and accelerate the exchange of electrons and Na + ions.
During the insertion / removal of sodium ions, composite carbon is advantageous for accelerating electron transport and improving structural integrity. As a result, a number of Sb2Se3 @ C and Sb2S3 @ C compounds for sodium ion batteries have been investigated.
To date, Sb2Se3, Sb2S3 rod-shaped nanowires and Sb2S3 @ PPy microchips have been documented. Although beneficial electrolytic performance has been achieved, the short cyclic life and extensive examination of the relationship between morphology and Na storage efficiency need further research.
It has been proposed that a suitable technique for obtaining an extended cyclic life is the construction of an interconnected conductive carbon frame outside the autonomous nanodots (ND).
Analysis techniques used in the study
Power X-ray diffraction (XRD) was used to describe the crystallographic features. The existence of sulfur or selenium-laden amorphous carbon was verified by Raman spectroscopy, and the amount of amorphous carbon was validated by thermogravimetric evaluation.
Transmission electron microscopy (TEM) imaging was used to indicate the unique morphological composition and particle size distribution. The electrolytic capacities of the two electrodes for sodium ion batteries were evaluated by galvanostatic charge / discharge experiments. Functional density theory (DFT) calculations were performed to further validate at the atomic level the kinetics of sodium ion storage.
Important discoveries
In this study, the team synthesized Sb2X3 (where X is Se or S) [email protected] from sodium stibogluconate using a complex pyrolytic technique and used them as anode components for sodium ion batteries. Nanodots with particle sizes of about 19 to 21 nanometers were enclosed in a conductive carbon frame loaded with selenium or sulfur.
Each Sb2Se3 and Sb2S3 nanodot was covered by a weakly graphitized interlaced carbon matrix, which was then bonded to generate a highly conductive frame.
The reversible capacity shown by the SB2Se3 [email protected] the electrode was about 316 mA h g-1 after 100 cycles at 100 mA g-1 and about 269 mA h g-1 after 200 cycles at 1 A g-1.
Extremely small nanodot architecture, limited shielding of the crosslinked carbon frame, superior electrical conductance, and hypothetical volumetric growth throughout recurrent alloying and conversion operations, all contributed to improved electrolytic performance.
Calculations of the functional theory of density revealed that Sb2Se3 [email protected] it has a lower sodium ion diffusion energy threshold, a stronger product-carbon bond, and more empty energy bands, which should result in stronger storage kinetics and speed performance.
Given the ease of manufacture, good performance, inexpensive cost, and excellent electrolytic performance, this research can pave the way for the development of enhanced multifunction electrodes with zero-dimensional three-dimensional Sb-based coordination compounds.
Reference
Yang, L., Liu, M., Xiang, Y., Deng, W., Zou, G., Hou, H. and Ji, X. (2022). Sb chalcogenide nanodots confined with a carbon backbone for stable sodium storage. Coal. Available at: https://doi.org/10.1016/j.carbon.2022.06.043
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