Cobalt Nanoparticles Loaded on MXene for Li‐S Batteries: Anchoring Polysulfides and Accelerating Redox Reactions

Abstract

Catalysis is regarded as an effective strategy to fundamentally increase sulfur utilization, accelerating the kinetics of the transformation between lithium polysulfides (LiPSs) and lithium sulfide (Li2S) on a substrate. However, the intermodulation of catalysts and sulfur species is elusive, which is limited to the comprehensive analysis of electrochemical performance in the dynamic reaction process. Herein, cobalt nanoparticles loaded on MXene nanosheets (Co/Ti2C) are selected as sulfur hosts and the representative catalyst. By combining ex situ electrochemical results and interfacial structural chemical monitoring, the catalysis process of Co/Ti2C toward LiPSs conversion is revealed, and the outstanding performance originates from the optimization of chemical adsorption, catalytic activity, and lithium‐ion transfer behaviors, which is based on electronic/ion modulation and sufficient interfaces among catalysts and electrolyte. This work can guide the construction of electronic modulation at triple‐phase interface catalysis to overcome the shuttle effect and facilitate sulfur redox kinetics in Li‐S batteries.

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

“…[2] However, the polysulfides shuttle effect during charge and discharge, the sluggish LiPSs redox kinetics, and uncontrollable deposition of Li 2 S 2 /Li 2 S become the key factors to limit commercial application of LSBs. [3] Based on the above considerations, researchers have made tremendous efforts in designing functionalized sulfur hosts, [4] separator modification, [5] modulating electrolyte composition, [6] and Li metal anode protection for a long time. [7] It is noted that it is not enough to address these issues from someone side through improving electrical conductivity of the electrode materials, energy band structure, chemical binding toward LiPSs, along with the Li + diffusion rate on its surface.…”

“…[ 2 ] However, the polysulfides shuttle effect during charge and discharge, the sluggish LiPSs redox kinetics, and uncontrollable deposition of Li 2 S 2 /Li 2 S become the key factors to limit commercial application of LSBs. [ 3 ]…”

Amide (n, π*) Transitions Enabled Clusteroluminescence in Solid‐State Carbon Dots

“…XRD and FT‐IR characterization results indicate that APTES is chemically bonded to the surface of the carbon core via –CONH formed by the amino group of APTES and carboxyl groups of CDs, and the shell of CDs is rich with Si−O−Si network due to hydrolysis and condensation of the silane molecules, and this can effectively passivate the amides and hinder their interaction (Figures S19 and S20, Supporting Information). [ 48,49 ] The optical characterizations demonstrate that the Si‐CDs aqueous solution still shows blue emission (Figure S21), while the Si‐CDs solid exhibits excitation‐independent emission peaks at 608 nm with a redshift of 38 nm compared to that of D‐CDs (Figure 3f). The UV–vis diffuse reflectance spectrum (UV‐DRS) of Si‐CDs displays a new absorption peak appearing at 517 nm, and the band gap was calculated to be 2.15 eV, which is narrower than that of D‐CDs (2.26 eV).…”

Recent advances in modified commercial separators for lithium–sulfur batteries

“…152 MXenes are also highly compatible with other materials that can provide functionality, such as increased electrocatalytic ability and faster Li-ion diffusion via ionic channels. Gu et al 29 added Co nanoparticles to MXenes to improve polysulde conversion kinetics. As shown in Fig.…”

“…Among the candidates for next-generation batteries, lithium-sulfur batteries (LSBs) are especially promising for their high theoretical capacity, natural abundance, and safety. 29,30 LSBs have a theoretical energy density of 2600 W h kg −1 and a specic capacity of 1675 mA h g −1 for a sulfur cathode, 31,32 which is around 5 times higher than that of LIBs (150-220 W h kg −1 and 150-200 mA h g −1 ). 33,34 We do not extensively describe the redox mechanism and battery operation of LSBs because such principles have been described in great detail in more general reviews by Li et al, 35 Zhao et al, 36 Yin et al, 37 and Wild et al 38 The components and construction of an LSB have been excellently summarized by Manthiram et al 39 Briey, as shown in Fig.…”