Interfacial “Double-Terminal Binding Sites” Catalysts Synergistically Boosting the Electrocatalytic Li2S Redox for Durable Lithium–Sulfur Batteries

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium–sulfur (Li–S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li–S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li–S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g–1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm–2 even in challenging conditions with a high sulfur loading (10.7 mg cm–2) and lean electrolyte environments (5.8 μL mg–1). The DTB site strategy offers valuable insights into the development of high-performance Li–S batteries.


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Figure S1.a) Schematic illustrations of the shuttle effect in a typical Li-S battery.b)The importance of functional sites in a typical Li-S battery.

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Figure S3.a-c) SEM images of Zn/Co-MOF.

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Figure S4.a,b) SEM images of Co@NC, c) TEM image, and d) high-resolution TEM

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Figure S5.a,b) SEM images of Co 0.85 Se@NC, c) TEM image, and d) high-resolution TEM image of Co 0.85 Se@NC, e) IFFT lattice image of the selected area of Co 0.85 Se@NC (Inset: lattice distance profiles of the area in red).

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Figure S7.a) TEM-EDX element mapping of the Co@NC, b) EDS spectrum of

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Figure S8.a) TEM-EDX element mapping of the Co 0.85 Se@NC, b) EDS spectrum of Co 0.85 Se@NC.

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Figure S9.a) Nitrogen adsorption-desorption isotherm, and b) pore size distributions

Figure S13 .
Figure S13.a) High-resolution XPS plots of Co 2p of Co@NC before and after adsorption of Li 2 S 6 .b) High-resolution XPS plots of Co 2p of Co 0.85 Se@NC before and after adsorption of Li 2 S 6 .c) High-resolution XPS plots of Se 3d of Co 0.85 Se@NC before and after adsorption of Li 2 S 6 .

Figure S14 .
Figure S14.TGA curves of C/S composite at a heating rate of 10 o C min -1 under Ar atmosphere.

Figure S15 .
Figure S15.Digital photos of the modified separator.a,b) the front and back, and c-e) under various mechanical stresses.

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Figure S16.a,b) SEM images of the Side-view of the modified separator.

Figure S18 .
Figure S18.The DME/DOL electrolyte contact angle shots of the PP, Co@NC-PP, Co 0.85 Se@NC-PP, and Co/Co 0.85 Se@NC-PP.

Figure S19 .
Figure S19.CV profiles of Li-S cells with a) Blank PP, b) Co@NC-modified, c)

Figure S20 .
Figure S20.Charge/discharge profiles of Li-S cells with different separators under

Figure S21 .
Figure S21.The digital images of Co/Co 0.85 Se@NC-PP before and after cycling.

Figure S22 .
Figure S22.SEM images of Co@NC, Co 0.85 Se@NC, and Co/Co 0.85 Se@NC modified separators after cycling.

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Figure S23.a) SEM image, b) TEM images, c) High-resolution TEM image, and d) SAED pattern of Co/Co 0.85 Se@NC after cycling.

Figure S24 .
Figure S24.Top view and side view of optimized structures of a,b) Co@NC, c,d)

Figure S25 .
Figure S25.The optimized adsorption structures of b) Li 2 S 4 , c) Li 2 S 6 , d) Li 2 S 8 on the

Figure S27 .
Figure S27.Two-electrons reaction equations of Li-S batteries.

Figure S28 .
Figure S28.Visualized images of a) pure Li 2 S 6 solution and Li 2 S 6 solutions after

Figure S29 .
Figure S29.Polysulfides permeation tests and corresponding UV-Vis absorption spectra in the right compartment of the H-typed glass cells with a,b) blank separator, and c,d) Co/Co 0.85 Se@NC-modified separator.

Figure S30 .
Figure S30.Self-discharge test of Li-S cells with a) blank separator, and c)

Figure S31 .
Figure S31.CV profiles of the Li 2 S 6 symmetric cells assembled using a) three catalysts,

Figure S32 .
Figure S32.Current vs. time curve for potentiostatic discharge at 2.05 V on a) Co@NC,

Figure S33 .
Figure S33.Charge/discharge profiles of Li-S cell with Co/Co 0.85 Se@NC-modified

Figure S34 .
Figure S34.Cell performance comparison between our Li-S cells with DTB sites modified separator and previously reported Li-S cells.

Figure S35 .
Figure S35.SEM images of SEI morphology on the surface of lithium anode in Li-S

Table S1 .
BET and Pore Volume of the samples.

Table S2 .
Comparison of electrochemical performance of Co/Co 0.85 Se@NC for Li-S batteries with present state-of-the-art catalyst materials.