电子科技大学：《材料设计与计算 Materials Design and Computation》课程教学资源（课件讲稿）MDC 06 Bulk calculations（2/2）

Energy Conversion and Energy Storage Materials >Structural stability and electrochemical property of electrode materials for Li-ion batteries >Interface stability in All-solid-state lithium-ion batteries >HER and OER >

Energy Conversion and Energy Storage Materials ➢ Structural stability and electrochemical property of electrode materials for Li-ion batteries ➢ Interface stability in All-solid-state lithium-ion batteries ➢ HER and OER ➢ ……

Lithium ion Batteries (LiBs) Current→ U,I Li must be more stable in cathode than anode Electrons Voltage Anode Separator/Electrolyte Cathode Electrodes must accomodate sufficient Li Capacity Electrons must be extractable from electrodes oc OLi 拳b 复Tri8ul Conductivity Materials Devices Battery Voltage x capacity Energy Anode Cathode Power 3C Industry Militark Ele ctrolyte

Materials Devices Battery 3C Power Anode Cathode Industry Military Electrolyte + = Lithium ion Batteries ( Lithium ion Batteries (LiBs) LiBs)

Electrode Structures Layered compounds LiMO, Spinal compounds LiM2O4 Olivine compounds LiMPO MO2slab The oxygen anions form a close- The oxygen framework is the same slightly distorted hcp anion packed fcc lattice; as that of LiMO2 layered structure. oxygen arrays with 12 Fe- cations located in the 6-coordinated M cations occupy the octahedral octahedral sites and 1/8 Li sites. octahedral crystal site. site but 1/4 of them are located in √ The LiOs octahedra are edge- The MO2 slabs and Li layers are the Li layer,leaving 1/4 of the sites shared while the FeOs octahedra stacked alternatively. in TM layer vacant. are corner-shared. Li ions occupy the tetrahedral sites LiOs and FeOs run parallel to the c in Li layer that share faces with the axis and alternate in b direction. empty octahedral sites in the The a-c planes containing Li are transition metal layer. bridged by PO4 tetrahedral

Electrode Structures Layered compounds LiMO2 Spinal compounds LiM2O4 Olivine compounds LiMPO4 ❖ The oxygen framework is the same as that of LiMO2 layered structure. ❖ M cations occupy the octahedral site but 1/4 of them are located in the Li layer, leaving 1/4 of the sites in TM layer vacant. ❖ Li ions occupy the tetrahedral sites in Li layer that share faces with the empty octahedral sites in the transition metal layer. ✓ slightly distorted hcp anion oxygen arrays with ½ Fe￾octahedral sites and 1/8 Li sites. ✓ The LiO6 octahedra are edge￾shared while the FeO6 octahedra are corner-shared. ✓ LiO6 and FeO6 run parallel to the c axis and alternate in b direction. ✓ The a–c planes containing Li are bridged by PO4 tetrahedral. • The oxygen anions form a close￾packed fcc lattice ; • cations located in the 6-coordinated octahedral crystal site. • The MO2 slabs and Li layers are stacked alternatively

Calculations on electrode materials LiTiO VF. +CoO,FeO A/o Graphene Ge Sn Si Lithium Graphite SWCNT 01000 2000300040005000 Capacity/mAh.g L Li First Principle Calculations Boltzman's constant M Electron Mass Phase diagram Electron Charge Interactions Planck Constant Light Velocity Experimental phenomena interpreting Diffusion

Calculations on electrode materials

Calculations on electrode materials Structural and chemical stabilities AEpper(phase,uM)=Eeg(Ceg(C,uM))-E(phase)-AnM'UM uLi(中)=2；-eφ， 2.5 231y GeS2 P2S 214y LiaPS4 LioGeRS122LiPS,+LiGeS 2.0 Stability Window LGPS LLGeSe 1.5 P LGPS 130V Li GeS GeS 117V LiP? PS GeS (A)a6eoA 1.0 Ge Li3Pr 093y P26 87 s Ge 0.561 Ge 0.5 045y LiGe LiP 028V LinGe (a) (b) (c) LitsGe4 0.0 0 400 800 1200 1600 Capacity(mAh g) Phase Equilibria

 Structural and chemical stabilities Calculations on electrode materials

Calculations on electrode materials The average intercalation voltage 4.5 Experimental rate~C/200 4.0 -E(LiyX）-(x2-x1)ELi边] 3.5 LiF+bulk Fe(GGA) (x2-x10e) 3.0 2.5 LiF+bulk Fe(Expt.E.Fit) 2.0 1.5 Computed discharge potentials 0.000.501.001.502.002.503.00 Conductivity u=D 9 KgT D=“KT=BKT x in Li FeF, a b D=-品rgoP (a) b)4 MD uuonon -6 7 D 03 AD. 8 0.5 101.5 2.0 0.51.01.52.02.53.03.5 1000/T(1/K) 1000/T(1/K)

 The average intercalation voltage  Conductivity Calculations on electrode materials 𝑫 = 𝐥𝐢𝐦 𝒕→∞ 𝟏 𝟐𝒅𝒕 𝒓 𝒕 − 𝒓 𝟎 𝟐

Calculations on electrode materials E=0.50eV 1.01 E=0.88eV Diffusion and its barriers Site 2 Site 3 △E=0.02eV 0.0 Site 1 △E=0.49eV Higher中/ Nominal oxidation potential Lower u “ 中-5V/: Overpotential 4=-5eV Cathode Low Hu Oxidation potential Interphase Structure and Electrochemical stability of Intrinsic Extended Electrochemica Electrochemical Window Electrode/electrolyte interfaces Window Solid Inter electrolyte Reduction potential Anode 中=0V/ High u phase =0eV

 Diffusion and its barriers Calculations on electrode materials  Structure and Electrochemical stability of Electrode/electrolyte interfaces

PHYSICAL REVIEW B 82.075122 (2010) Methodologies Hybrid density functional calculations of redox potentials and formation energies of transition metal compounds V.L.Chevrier.S.P.Ong.R.Armiento.M.K.Y.Chan.and G.Ceder HSE06 is as successful as GGA+U in predicting Jahn-Teller Depurtment of Muterials Science and Engineering.Massachusetts Institute of Technology.Cambridge,02139.USA (Received 12 February 2010:revised manuscript received 18 July 2010:published 12 August 2010) distortions,magnetic moments,and charge localization. TABLE I.Values of the (parameters in electron volt,adapted (a)GGA+U (b)HSE06 from Ref.3. HSE06 consistently predicts more accurate geometries than Olivine Layered Spinel both GGA and GGA+U Mn 4.5 48 Fe 4.3 HSE06 and GGA+U with a linear response U yield similar Co 5.7 5.1 Ni 61 6.4 accuracies for Li intercalation potentials. Isosurfaces of the change in charge density upon lithiation of Relative error of the optimized volumes compared NiPO4 to LiNiPO4 to experiment for the lithiated phases Average Li intercalation potentials vs.Li/Li,in volts 15 GGA● GGA GGA+U HSE06 Expt. 0.6 GGA-⊙ GGA+U LiCoO: 3.38 3.85 4.51 4.1 GGA+U△ 10 HSE06 LiNiO2 3.08 3.92 4.14 3.9 0.2 HSE06日 LiTiS, 1.91 (1.91) 206 21 0 回 LixTixO 1.05 (1.05) 1.19 1.3 LiMn2O 3.37 4.04 425 4.1 0.2 LiMnPO 2.99 4.01 3.87 4.1 04 LiFePO 2.84 3.47 3.33 3.5 LiCoPO 3.62 4.63 4.57 4.8 0,6 LiNiPO 4.15 5.00 541 53 0.8 Mean 2.93 3.54 3.70 3.69 -1 MAE 0.76 0.15 0.19 10 -1.2 Delithiation to LiTiO. L甜 LiNiPO is unstable upon delithiation,leading to a larger error in average intercalation potential. Mean absolute error

Methodologies ✓ HSE06 is as successful as GGA+U in predicting Jahn-Teller distortions, magnetic moments, and charge localization. ✓ HSE06 consistently predicts more accurate geometries than both GGA and GGA+U. ✓ HSE06 and GGA+U with a linear response U yield similar accuracies for Li intercalation potentials. Isosurfaces of the change in charge density upon lithiation of NiPO4 to LiNiPO4 Average Li intercalation potentials vs. Li/Li+ in volts Relative error of the optimized volumes compared to experiment for the lithiated phases

ZnCo2O is a promising candidate as the anode material of LIBs,and one can expect a total capacity corresponding to The Structural 7.0-8.33 mol of recyclable Li per mole of ZnCo2. Stability of Spinel However,the high capacity drops extensively in discharge- ZnCo2O4 as an charge cycles in practical experiments. Electrode Material ZnCo204+8Lit 8e-Zn+2Co +4Li2O (1) for Lithium-ion Zn+Lit+e←→LiZn (2) Batteries Zn+Li20←→ZnO+2Lit+2e (3) 2Co+2Li20←→2Co0+4Lit+4e (4) 2Co0+2/3Li20←→2/3Co3O4+4/3Lit+4/3e (5) SCIENTIFIC REPORTS|6:36717|DOI:10.1038/srep36717

The Structural Stability of Spinel ZnCo2O4 as an Electrode Material for Lithium-ion Batteries  ZnCo2O4 is a promising candidate as the anode material of LIBs, and one can expect a total capacity corresponding to 7.0 - 8.33 mol of recyclable Li per mole of ZnCo2O4 .  However, the high capacity drops extensively in discharge￾charge cycles in practical experiments

Structural and Electronic Properties 7r尚f bie品spinel 0 (b)Tetragonal spinel Relative Space group Magnetism energy (eV) Lattice constants(A) Fd3m(C) NFM 0 a=b=c=8.164(8.10) ⊙p 141/amd (T) FM +2.30 a=5.893.b=5.920, c=8.592 texs! ZnCoO:Nonmagnetic cubic spinel b M=o 12 (a (b) Total DOS VBM:Co-3d and O-2p orbitals; 0 Zn Co Eg=2.22 eV CBM:Co-3d states; 8 VBM shows a flat dispersion,leading to 6 heavy holes with large effective masses and a poor p-type conductivity. -2 elecmic十ekwe Energy (eV)

Structural and Electronic Properties ZnCo2O4 : Nonmagnetic cubic spinel VBM: Co-3d and O-2p orbitals; CBM: Co-3d states; VBM shows a flat dispersion, leading to heavy holes with large effective masses and a poor p-type conductivity