A High‐Efficiency Mo₂C Electrocatalyst Promoting the Polysulfide Redox Kinetics for Na–S Batteries

Abstract

of RT Na-S batteries. First, S cathode is the intrinsic electronic insulator (5 × 10 −30 S cm −1 ), which leads to large polarization and low sulfur utilization. [3] Second, the enormous volume change (170%) during sodiation and desodiation cause the pulverization of S cathode, resulting in a continuous decline of capacity. [4] Third, the dissolution of the sodium polysulfide intermediates (NaPSs) results in severe shuttle effect and sluggish reaction kinetics. [5] To address these limitations, some rational strategies have been proposed to improve the electrochemical performance of S cathode. Developing nanostructured carbon hosts with different pore structures, [4,6] heteroatoms (e.g., B, N, O, P, S), [7] singleatom and metal clusters (e.g., Co, Cu, Ni), [8] optimizing the electrolyte composition to reduce the dissolution of NaPSs and modifying the separator to block the diffusion of NaPSs have been proved to be effective methods to boost the cycling performance of RT Na-S. [2b,9] However, these strategies do not fundamentally solve the intractable issue of NaPSs dissolution. Hiking up the transformation rate of intermediate NaPSs toward Na 2 S 2 /Na 2 S via effective catalysts is foremost.Catalytic transformation of NaPSs by polar hosts (e.g., oxides, nitrides, sulfides, selenides, etc.) is the most powerful approach to improve the electrochemical performance of sulfur cathodes. [7a,10] For example, Xue et al. prepared hollow CoS 2 as a polar catalyst for RT Na-S, which could promote the transformation of NaPSs and inhibit the dissolution, displaying a high capacity of 349 mAh g −1 at 3 C and long cycling life over 800 cycles. [11] Cao et al. combined the high electrical Room-temperature sodium-sulfur (RT Na-S) batteries, as promising nextgeneration energy storage candidates, are drawing more and more attention due to the high energy density and abundant elements reserved in the earth. However, the native downsides of RT Na-S batteries (i.e., enormous volume changes, the polysulfide shuttle, and the insulation and low reactivity of S) impede their further application. To conquer these challenges, hierarchical porous hollow carbon polyhedrons embedded with uniform Mo 2 C nanoparticles are designed deliberately as the host for S. The micro-and mesoporous hollow carbon indeed dramatically enhances the reactivity of the S cathodes and accommodates the volume changes. Meanwhile, the highly conductive dispersed Mo 2 C has a strong chemical adsorption to polysulfides and catalyzes the transformation of polysulfides, which can effectively inhibit the dissolution of polysulfides and accelerate the reaction kinetics. Thus, the as-prepared S cathode can display a high reversible capacity (1098 mAh g −1 at 0.2 A g −1 after 120 cycles) and superior rate performance (483 mAh g −1 at 10.0 A g −1 ). This work provides a new method to boost the performance of RT Na-S batteries.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202200479.

Single-Atom Yttrium Engineering Janus Electrode for Rechargeable Na–S Batteries

“…Figure S49 shows that a light-emitting diode (LED) displaying a pattern of “THU” was lighted by two series-connected Na–S pouch cells. The spider chart showed the device performances consisting of Y SAs/NC-S||Y SAs/NC-Na in comparison with some state-of-the-art Na–S systems (Figure g). ,, Overall, the great advantage of the Y SAs/NC-S||Y SAs/NC-Na full cell showed the potential of the rare-earth metal SACs for advanced energy storage devices in the future.…”

In situ implanting MnO nanoparticles into carbon nanorod-assembled microspheres enables performance-enhanced room-temperature Na–S batteries

“…It reveals the amorphous nature of S confined within the nanopores of the MnO@NACM. 22 Such a case has been widely discovered in other studies of S cathode materials for Na-ion storage. 23,24 Raman spectroscopy was utilized to further analyze the micro/nanostructures of the samples.…”

Room‐Temperature Sodium–Sulfur Batteries: Rules for Catalyst Selection and Electrode Design

“…In addition, the apparent Na + diffusion coefficient in both the S/MoN@CNFs|Na/MoN@CNFs and S/CNFs|Na cells was analyzed by the GITT test, as shown in Figures S24 and S25, Supporting Information. Based on Fick's second law, [63,64] the schematic of the calculation of diffusion coefficient was schematically illustrated (Figure S26, Supporting Information). It is obvious that the Na + diffusion coefficient of the S/MoN@CNFs|Na/MoN@CNFs is much larger than that of the S/CNFs|Na during the whole discharge and charge process, suggesting rapider reaction kinetics of the S/MoN@CNFs|Na/MoN@CNFs full cell (Figure 6h and Figure S27, Supporting Information).…”