Interspersing Partially Oxidized V₂C Nanosheets and Carbon Nanotubes toward Multifunctional Polysulfide Barriers for High-Performance Lithium-Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries have attracted much attention attributed to their high theoretical energy density, whereas the parasitic shuttling behavior of lithium polysulfides (LiPS) hinders this technology from yielding practically competitive performance. Targeting this critical challenge, we develop an advanced polysulfide barrier by modifying the conventional separator with CNTs-interspersed V2C/V2O5 nanosheets to alleviate the shuttle effect. The partial oxidization of V2C MXene constructs the V2C/V2O5 composite with V2O5 nanoparticles uniformly dispersed on few-layered V2C nanosheets, which synergistically and concurrently improves the sulfur confinement and redox reaction kinetics. Moreover, the interstacking between the 1D CNTs and the 2D V2C/V2O5 not only prevents the agglomeration of nanosheets for efficient exposure of active interfaces but also constructs a robust conductive network for fast charge and mass transfers. The Li–S cells with V2C/V2O5/CNTs-modified separator realize a high initial capacity (1240.4 mAh g–1 at 0.2 C), decent capacity retention (82.6% over 500 cycles), and favorable areal capacity (5.9 mAh cm–2) at a raised sulfur loading (6.0 mg cm–2). This work affords a unique multifunctional separator design toward durable and efficient sulfur electrochemistry, holding great promise for improving the electrochemical properties of Li–S batteries.

Recent advances in MXenes: beyond Ti-only systems

“…104–107 The non-Ti MXenes were doped/intercalated and formed composites with other materials to modulate their properties. 108,109 V 2 CT x exhibited intrinsic ferromagnetism with a magnetic moment of 0.013 emu g −1 , which is close to the values reported for La-doped Ti 3 C 2 , 110 thus exhibiting the potential to be used in spintronic applications. 111 Using DFT computations, Luo et al predicted the magnetic moment of Zr 3 C 2 MXene and Hf 3 C 2 MXenes as 1.69 μ B per cell and 1.40 μ B per cell, respectively.…”

A stepwise oxidation strategy for the synthesis of amorphous V2O5@V2CTxnanohybrid cathodes toward high-performance aqueous Zn-ion batteries

“…3h-k), there are three pairs of peaks appearing in the range of 510-527 eV aer discharging to 0.2 V and charging to 1.4 V, which correspond to V 2+ (513.6 and 521.5 eV), V 3+ (514.9 and 522.4 eV), and V 4+ (516.7 and 523.8 eV). 25,37 The peak intensity of V 4+ dominates in the cathodes at the 1st discharge to 0.2 V and charge to 1.4 V states, indicating a reversible V 4+ /V 3+ redox reaction in the potential window of 0.2-1.4 V. When charged to 1.6 and 1.8 V, the V 5+ peak appears and dominates, while the V 2+ and V 3+ peaks disappear and the intensity of the V 4+ peak decreases signicantly, demonstrating the transition of VO 2 (M) to higher valence vanadium oxide. The possible chemical reaction formula during the long charging platform is summarized as: 38,39 This journal is © The Royal Society of Chemistry 2023…”

Transition Metal Compounds Family for Li–S Batteries: The DFT‐Guide for Suppressing Polysulfides Shuttle

“…The rate capacity for the Li 2 S in the polysulfides catalytic conversion reaction is a critical index to measure the cycling performance of LSBs. Herein, Sun et al [187] proposed a strategy for synergistic interaction between active Li 2 S and Fe 3 C electrocatalysts to achieve rapid and continuous conversion in sulfur intermediates, thereby substantially boosting the electrochemical [148] TiC (100), [176] V 2 C (002), [167] Cr 3 C 2 (110), [177] V 8 C 7 (400), [168] Fe 3 C (031), [170] Ni 3 C (002), [178] NbC (200), [183] Mo 2 C (100), [149] and W 2 C (001) [176] surface. d) Comparisons of binding energies between Li 2 S n (n = 1, 2, 4, 6, and 8)/S 8 and common TMCcs (All comparisons are used for objective evaluation only).…”