Nanobatteries Part 2 J Seminario, D Galvez, V Ponce, L Selis, C - PowerPoint PPT Presentation

Atomistic Classical and Quantum Simulations of Nanobatteries – Part 2 J Seminario, D Galvez, V Ponce, L Selis, C Roman, F Gallo, M Gamero Dept. of Chemical Engineering Dept. of Electrical & Computer Engineering Dept. of Materials Science & Engineering Cartagena, Colombia Texas A&M University ICTP School 6/1/2019

Pristine boxes: Li-metal & Li 9 N 2 Cl 3 solid- state electrolyte Li 9 N 2 Cl 3 (002) and (001) planes Interfacial box Li 9 N 2 Cl 3 (002) and (001) versus (001) Li-metal atoms on top highlighted. Li m (red) Li (purple) N (brown) Cl (green)

Crystal Structure after 15 Experimental (space group 225) ps of equilibration. cubic crystal structure of Li 9 N 2 Cl 3 . Li (purple), N (brown) Cl (light green) Energy per atom curve along the equilibration. -415.55 eV/atom -415.56 -415.57 t/ps -415.58 0 2 4 6 8 10 12 14

Experimental BCC (space group 225) crystal structure of Li-metal after 15 ps of AIMD equilibration Li (s) (red) Energy per atom (eV) curve along the equilibration -122.33 E/eV/atom -122.34 -122.35 t/ps -122.36 0 2 4 6 8 10 12 14

Li-metal trajectories & final Bader charges 0.08 0.06 0.04 0.02 q/e 0 0 10 20 30 40 50 60 -0.02 atom labels -0.04 -0.06

Experimental and AIMD lattice parameters (Å), and density (g/cm 3 ) for the Li metal crystal structure. Experimental (  = 0.5 fs, NPT ensemble) for Li 9 N 2 Cl 3 AIMD shows parameters averages a b c volume Method Density 10.53 10.53 10.53 1167 Experimental 0.53 9.96 11.38 10.91 1237 AIMD 0.50 5.41 8.07 3.61 5.99 Difference [%] 5.66 a b c volume Method Density 10.814 10.814 10.814 1264 Experimental 49 1.65 10.205 11.406 10.296 1198 AIMD 1.74 5.60 5.47 4.79 5.22 Difference [%] 5.45

Li 9 N 2 Cl 3 diffusion trajectories during 15 ps of AIMD with a  = 0.5 fs under NPT ensemble . (d) Atomic Bader charges after equilibration. N (brown) Cl (green) Li (purple). 1.00 0.50 0.00 0 20 40 60 80 100 Atom labels -0.50 -1.00 -1.50 -2.00 q/e -2.50

E p with ℰ = 0 @ 0 ps (yellow line) E p profile ℰ = 0.5 V/Å @ 0 ps (black line) Input potential (red line) E p profile @ 20 ps ℰ = 0.5 V/Å

AIMD Atomic density distributions at 0, 10, 20 ps

Charge evolution 1 q vs z-distance at 20 ps q/e 0 -1 Li (m) (red) -2 Li (violet) Cl (green) z/Å N (brown) -3 0 5 10 15 20 25

d 2 ( t ) ≡ MSD 𝑁 𝑂 1 2 𝑒 2 𝑢 = 𝑁𝑂 ෍ ෍ 𝑦 𝑜 𝜐 + 𝑢 − 𝑦 𝑜 𝜐 𝜐=1 𝑜=1 𝑒 2 (𝑢 𝐸(𝑢) = 1 ൯ 6 𝑢 𝑁 𝑂 1 2 𝐸 𝑢 = 6𝑁𝑂𝑢 ෍ ෍ 𝑦 𝑜 𝜐 + 𝑢 − 𝑦 𝑜 𝜐 𝜐=1 𝑜=1

Li-metal/SSE/Li-metal cell 8 Cl 6 MSD(t) /Å 2 Li(se) N MSD vs t, linear-scale 4 Li(s) 2 0 t/ps 0 5 10 15 20 10 Cl MSD (Å 2 ) Li(se) MSD vs t, log-scale N 5 Li(s) 0 0.001 0.01 0.1 t/ps 1 10 N (brown), Cl (green), Li (se) (purple) and Li (s) (red) Li(se) exploded MSD(t) 0.4 N MSD (Å 2 ) Cl Li(s) 0.2 0 t/ps 0.001 0.01 0.1 1 10 30 t-dependent diffusion D(t) D(t)/10 -7 cm 2 /s 20 Cl Li(se) N Li(s) 10 0 t/ps 0 5 10 15 20

5 Cl-Li cn 4.8 4.6 4.4 t/ps 0 2 4 6 8 10 12 14 16 18 20 N-Li cn 7.2 7 6.8 t/ps 6.6 0 2 4 6 8 10 12 14 16 18 20

Coordination number of Cl and N at the interphase during AIMD simulation 10 Cl (7) 10 5 5 N(82) 0 0 10 10 Cl(17) 5 5 N(84) 0 0 10 10 Cl(2) 5 5 N(89) 0 0 10 10 Cl(5) 5 5 N(85) 0 0 t/ps t/ps 0 5 10 0 5 10

Li 9 N 2 Cl 3 /Li interface atomic density profiles along z

Nano-battery model: Li-metal/Li 9 N 2 Cl 3 /NMC Ab-Initio MD model to study an take parameters of interfacial behavior Anode/Electrolyte 1 AIMD DFT PBE, τ = 0.5 fs, t AIMD = 50 ps, E cutoff = 40 Ry ( λ cutoff = 0.5 Å), ℰ = 0.75 V/Å ML classifier is trained with data obtained from AIMD to develop a full Nano-battery model considering: ℰ = 0.75 V/Å Bader charge analysis Atoms neighborhood in an sphere with r = 5 Å / 3 Li types are recognized Li (i) 1 Li (i) # atoms Li (s) Li-ions 15 15 25 # atoms # atoms Cl e N 10 10 Li-ions Li(s) 15 Li (s) 5 5 Li(s) Cl N 0 5 0 0 index z (Å) 10.14 × 11.41 × 22.41 Å index index 30 60 90 0 10 20 14 19 24 22 24 26 2 Nanobattery MD model is developed using parameters from Ab-Initio MD simulation Li-metal Anode – Reax potential Li (i) – ML and LJ potential LAMMPS: MD, NVT, τ = 0.01 fs, t MD = 1.2 ns, ℰ = 0.75 V/Å, ML algorithm every 1 fs Anode: Li 145 Electrolyte – MEAM and LJ potential 21.62 × 21.62 × 106 Å Electrolyte: Li 365 N 78 Cl 114 Other interactions – LJ potential Charge evolution of a Li traveling from Li-metal/Li 9 N 2 Cl 3 /NMC Cathode: Ni 53 Mn 8 C 8 O 136 Li 62 electrolyte through the interphase to the anode. 1 q 0.8 0.6 0.4 0.2 z / Å 0 20 25 30 Interphase Li Cl Li m Li (i) N Anode Electrolyte

Nano-battery model: Li-metal/Li 9 N 2 Cl 3 /NMC BCC Li Amorphous 0 ps 60 Lithiation due to an ℰ = 0.75 V/Å Amorphous BCC Li 500 ps 50 Polyhedral template matching algorithm is used to identify crystallographic structures. 40 Li-metal anode shows two clear phases during lithiation: BCC/Amorphous 30 % Amorphous BCC Li 15 1 ns Li-Li (0 ns) Li-Li (0.5 ns) 20 Li-Li (1 ns) 10 Li-Li (1.5 ns) 10 Amorphous BCC Li 5 1.5 ns 0 0 ns 0.5 ns 1 ns 1.5 ns 0 ps 200 ps 400 ps 600 ps 0 Other FCC HCP BCC ICO SC 1 2 3 4 5

Nano-battery model: Li-metal/Li 9 N 2 Cl 3 /NMC 240 Total Li(anode) Li(s) Li(i) 220 # of Li 200 180 160 140 Lithiation due to an ℰ = 0.75 V/Å t/ns 120 0 0.5 1 1.5 3200 Å 3 3000 2800 2600 420 # of Li 2400 400 2200 t/ns 2000 380 t/ns 0 0.2 0.4 0.6 0.8 1 1.2 1.4 360 0 0.5 1 1.5

Nano-battery model: Li-metal/Li 9 N 2 Cl 3 /NMC Trajectory of a Li-ion through the electrolyte (5 ps) Cl 110 Cl 105 Cl 61 Cl 47 Cl 67 Cl 96 Cl 60 Cl 111 Cl 66 Cl 65 N 478 N 522 N 507 N 487 Cl 31 N 521 N 488 N 516 N 486 25 Displacement / Å 20 15 10 5 0 time / ps Cl 47 Cl 67 0 1 2 3 4 5 Cl 60 Cl 66 Distance / Å Cl 111 Cl 110 Cl 105 Cl 65 Cl 96 Cl 61 Cl 31 Cl 65 Cl 47 Cl 67 Cl 96 Cl 111 Cl 61 Cl 105 Cl 66 Cl 110 Cl 60 N 488 Distance / Å N 486 N 487 N 522 N 516 N 521 N 522 N 507 N 487 Cl 31 N 521 N 478 N 516 N 486 N 488 N 507 N 478 Distance / Å NN Li-ion time / ps

Nano-battery model: Li-metal/Li 9 N 2 Cl 3 /NMC Trajectory of a Li-ion through the electrolyte (5 ps)

Conclusions ▪ Li closest to interface shows major diffusion (B) ▪ new bonds with N and Cl of the SSE (B) ▪ SSE shows stability at the interface with Li-metal (B) ▪ Initial reactions on the SSE(002) plane (of Li 9 N 2 Cl 3 ) (NE) ▪ Reactions don't modify crystallographic structure of electrolyte (B) ▪ Li (s) density increases at both interfaces, (001) and (002) (NE) ▪ Major density change at (002) interface due to negative N and Cl (NE) ▪ N and Cl have 3-4 Li NNs at the beginning of the simulation (NE) ▪ To complete 7-8 Li NNs of Li 9 N 2 Cl 3 , N and Cl take Li (s) from anode ▪ Li (s) diffusion anode to electrolyte at (001) lower than at (002) (NE) ▪ Because Cl and N already have at least 7 Li at the Li 9 N 2 Cl 3 (001) no need to take Li (s) from the anode. (NE)

Conclusions ▪ Li-BCC structure changes into HCP (E) ▪ But BCC and HCP energies difference ≤ 10 meV ▪ Thus, @ 300 K (26 meV), transitions are highly possible (E) ▪ but not necessarily due to the electric field. ▪ (001) better than (002) of SSE to reduce deformation of anode (NE) ▪ No new phase formed due to interfacial interactions (B) ▪ no expected, if we extend the simulation times based on MSD trends and charge stability. (B) ▪ Li 9 N 2 Cl 3 remains very stable in contact with Li-metal (B) ▪ Theory correctly model metallic-insulator interface (B)