Supplemental Information

Utilizing a metal as a sulfur host for high performance Li-S batteries

Xiao-Chen Liu,a, † Sophia P. Zhou,a, † Miao Liu,b Gui-Liang Xu,c Xiao-Dong Zhou,d Ling Huang,e

Shi-Gang Sun,e Khalil Amine, c, f, g,* and Fu-Sheng Ke a*

aCollege of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.

bEnergy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

cChemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass

Avenue, Lemont, Illinois 60439, United States.

dDepartment of Chemical Engineering, Institute of Materials Research and Innovation,

University of Louisiana at Lafayette, Lafayette, LA 70504, USA.

eState Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry,

College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.

fMaterials Science and Engineering, Stanford University, Stanford, CA 94305, USA

g Institute for Research & Medical Consultations, Imam Abdulrahman Bin Faisal

University, Po Box 1982, 31441, Saudi Arabia

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Density functional theory calculations

We employed density functional theory (DFT) calculations to investigate the formation energy

and reaction dynamics in the Mo-Li-S system. The Vienna ab initio software package (VASP)

was employed. The projector augmented-wave (PAW) method was used to describe the

wavefunctions near the core, and the generalized gradient approximation (GGA) within the

Perdew–Burke–Ernzerhof (PBE) parameterization was employed as the electron exchange–

correlation function. A Mo slab with Mo (110) facets was used to simulate the Mo particle

surface, as the (110) surface is the most stable and covers ~45% of the surface area of Mo

particles. The surface slab consists of a 4 × 4 unit cell in the in-plane direction to supply enough

area for the Li-S molecule to diffuse, rotate, and relax, so that the interaction between the Mo

surface and Li-S molecule can be isolated. There are six layers of Mo in the vertical direction to

prevent the interaction of the two (110) surfaces. For formation energy calculations, the Brillouin

zone sampling of 2 × 2 × 1 is adopted to provide good accuracy. We used ab initio molecular

dynamics to mimic the formation of the Mo-Li-S bindings; the Li-S and Mo were initially placed

apart with a distance of 3.5 Å. Room temperature was selected for all the systems to relax for

500 steps. An energy minimization at 0 K was carried out thereafter to obtain accurate ground

energies for all the systems. We used a DFT-D2 method in all the calculations to include the

intra-molecule van der Waals forces as they play an important role in S-anchoring materials.

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Fig. S1 (a) SEM image and (b) particle size distribution of Mo powder.

Fig. S2 (a) SEM image of the Mo-80S composite. (b-d) XEDS mapping of Mo, S, and color overlay of S vs Mo.

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Fig. S3 Selected voltage profiles of (a) Mo-60S, (b) carbon-60S, and (c) Mo-80S composite electrodes at a rate of 0.1 C. (d) Selected voltage profiles of Mo-80S electrode at 5.0 C. The first cycles was run at 0.1 C, corresponding to an activation cycle.

Fig. S4 (a) Selected voltage profiles and (b) Specific capacity versus cycle number of Mo electrode at current density of 50 mA g-1.

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Fig. S5 (a) Initial LSV and (b) stabilized CV curves of Mo and carbon electrodes in 1.0 M LiTFSI and Li2S6 DME/DOL (1:1, vol.) electrolyte at scan rate of 0.1 mV s-1.

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