Supporting Information for. Long-Chain Polysulfide Retention at the Cathode of Li-S Batteries

Transcription

1 Supporting Information for Long-Chain Polysulfide Retention at the Cathode of Li-S Batteries Ethan P. Kamphaus and Perla B. Balbuena* Department of Chemical Engineering Texas A&M University, College Station, TX * S-1

2 Figure S1 Adsorption energies, structures, and Bader charges of Li 2 S 6 and Li 2 S 8 on graphene in presence of DME or DOL solvent, calculated by the DFT-D3 (BJ) approach. In each box, the simulation cell is shown along with some snapshots illustrating the PS/solvent/substrate interactions. Color code: C is grey, O red, H white, S yellow, and Li purple. Distances in Å and charges in units of e. Figure S2. Formation of closed and linear Li2S8 in gas phase (left) and continuum solvent (right) using B3PW91/6-311+G(d,f) and the PCM model with dielectric constants of THF and DMSO. S-2

3 Figure S3. DFT calculated structures of PS species in solvents (pure or mixtures). Top to bottom: Row 1: Li 2 S 6 in DME (left), Li 2 S 8 (closed) in DME (right). Row 2: Li 2 S 8 in DOL (left), and Li 2 S 8 linear in DOL (right). Row 3: Li 2 S 8 linear in DOL (left), and Li 2 S 8 closed in DOL/DME. Row 4: Li 2 S 8 linear in DOL/DME (left) and Li 2 S 6 in DOl/D2 (right). Row 5: Li 2 S 8 closed in DOL/D2 (left) and Li 2 S 8 linear in DOL/D2. S-3

4 0-0.1 Adsorption Energy (ev) DOL and DME DOL and D2 DOL or DME Li2S6 DME Li2S6 DOL Li2S8_4 DME Li2S8_4 DOL Li2S8_5 DME Li2S8_5 DOL Figure S4 Adsorption energies of Li 2 S 6 and Li 2 S 8 on graphene in mixtures of DME/DOL, DME/D2, or DOL/ DME solvents, calculated by the DFT-D3 (BJ) approach. The Li 2 S 8 _4 species has a closed structure and the Li 2 S 8 _5 has a linear structure. Figure S5 Simulation cells for Figures 2 (a and b), 3 (c and d), and 4 (e and f). Color code: C is grey, O red, H white, S yellow, and Li purple. S-4

5 Figure S6 Simulation cells for Figures 5 (a and b) and 6 (c and d). Color code: C is grey, O red, H white, S yellow, and Li purple. Figure S7 Simulation cells for Figures 7 (a and b) and 9 (c and d). Color code: Li: purple; S: yellow; Mn: mauve; O: red; H: white; C: grey. S-5

6 Figure S8 Simulation cells for Figure 10 (a and b). Color code: Li: purple; S: yellow; Mn: mauve; O: red; H: white; C: grey. Table S1. Size of substrate cells and surface areas Graphene 12.5 Length (Å) Graphene 10 Length (Å) Graphene 7.5 Length (Å) Graphene DOLDME Length (Å) Graphene DOL/D2 Length (Å) a a a a a b b b b b c 12.5 c c c 12.5 c 12.5 Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Graphene Mo Subs Length (Å) Graphene Mo Inter Length (Å) Graphene Mo inter small Length (Å) Graphene Mo2Sub Length (Å) Graphene Mo 2 subinter Length (Å) a a a 9.84 a a b b b 9.84 b b c 12.5 c 12.5 c 12.5 c 12.5 c 12.5 Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) MoS2 Length (Å) MoS2 111 Length (Å) MoS2 110 Length (Å) MnO2 Length (Å) Fe2O3 Length (Å) a a a a a b b b b b c 17.5 c c c c Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Surface Area (Å 2 ) Table S2. Number of solvent molecules employed in each simulation. Graphene 12.5 # of molecules Graphene 10 # of molecules Graphene 7.5 # of molecules Graphene DOLDME # of molecules Graphene DOL/D2 # of molecules DME 9 DME 6 DME 4 DME 6 DME 0 DOL 13 DOL 10 DOL 6 DOL 6 DOL 9 D2 3 Graphene Mo Subs # of molecules Graphene Mo Inter # of molecules Graphene Mo inter small # of molecules Graphene Mo2Sub # of molecules Graphene Mo 2 subinter # of molecules DME 9 DME 9 DME 4 DME 9 DME 9 DOL DOL 13 DOL 5 DOL DOL MoS2 # of molecules MoS2 111 # of molecules MoS2 110 # of molecules MnO2 # of molecules Fe2O3 # of molecules DME 8 DME 19 DME DME 10 DME 13 DOL 12 DOL DOL 23 DOL 14 DOL 20 Table S3. Densities of solvents S-6

7 Bulk Densities used g/cm3 DME DOL 1.06 DME/DOL (1:1 mol) approx. (1:1 w) 0.95 DOL/D2 (1:1 weight) 1.45 Table S4. MD simulation times Experiment Title time (ps) MoS2 (110) Li2S6 DME 2.89 MoS2 (110) Li2S8 Linear DME 5.86 MoS2 (110) Li2S8 Linear DOL 6.34 MoS2 (111) Li2S6 DME 5.74 Mo interstitial Li2S8 Linear DOL 9.18 Mo interstitial Li2S6 DOL 9.18 Mo substituted Li2S8 Closed DOL 9.54 Mo Subsituted Li2S8 Linear DME Mo substituted closed Li2S8 and S8 ring alt configuration 7.38 Mo subsituted closed Li2S8 & S8 ring DME 6.54 Mo interstital S8 DOL 2.28 Mo Substituted S8 DOL 2.33 Mo subsistuted S8 DME 3.27 MnO2 DME S MnO2 DOL S MnO2 Li2S6 DME 1.64 MnO2 Li2S6 DOL 1.53 MnO2 Li2S8 Linear DME 2.95 MnO2 Li2S8 Linear DOL 3.46 MnO2 Li2S8 Closed DME 3.63 MnO2 Li2S8 Closed DOL 2.77 MnO2 S8 DOL 1 Li 2.72 MnO2 S8 DME 3 Li 3.11 MnO2 S8 DME 2 LI 2.83 MnO2 S8 DME 1 Li 4.07 Fe203 S8 DOL 1.58 Fe203 S8 DME 1.78 Fe203 Li2S8 Linear DME 1.82 Fe203 Li2S8 Closed DME 1.80 Fe2O3 Li2S6 DME 1.74 Fe2O3 DOL 3 Li 1.68 Fe2O3 S8 DOL 2 Li 0.67 Fe2O3 S8 DoL 1 Li 1.34 Fe2O3 S8 DME 3 Li 1.55 Fe2O3 S8 DME 2 Li 1.85 Fe2O3 S8 DME 1 Li 2.10 Table S5. Binding energies of the Mo atoms to the graphene substrate. Binding energies Simulation (ev) 1 Mo substituted Mo interstitial Mo Substituted S-7

8 Table S6. a) Raw data for Figure Å Li2S6 DME Li2S6 DOL Li2S84 Closed DME Li2S8 Closed DOL Li2S8 Linear DME Li2S8 Linear DOL Å Li2S6 DME Li2S6 DOL Li2S84 Closed DME Li2S8 Closed DOL Li2S8 Linear DME Li2S8 Linear DOL Å Li2S6 DME Li2S6 DOL Li2S84 Closed DME Li2S8 Closed DOL Li2S8 Linear DME Li2S8 Linear DOL Table S6. b) Raw data for Figure 8. MnO2 (001) plane Li2S6 DME Li2S6 DOL Li2S8 Closed DME Li2S8 Closed DOL Li2S8 Linear DME LI2S8 Linear DOL Table S6. c) Raw data for Figure 11. S-8

9 Fe2O3 (0001) Li2S6 DME Li2S6 DOL Li2S8 Closed DME Li2S8 Closed DOL Li2S8 Linear DME LI2S8 Linear DOL Table S6. d) Raw data for Figure S4. Figure S2 DOL or DME Li2S6 DME Li2S6 DOL Li2S8 Closed DME Li2S8 Closed DOL Li2S8 Linear DME LI2S8 Linear DOL DOL and DME Li2S6 DME and DOL Li2S6 DME and DOL Li2S8 Closed DME and DOL Li2S8 Closed DME and DOL Li2S8 Linear DME and DOL Li2S8 Linear DME and DOL DOL and D2 Li2S6 DOL and D Li2S6 DOL and D Li2S8 Closed DOL and D Li2S8 Closed DOL and D Li2S8 Linear DOL and D Li2S8 Linear DOL and D S-9