Thermodynamics of lithium ion batteries Hans J. Seifert Institute - PowerPoint PPT Presentation

Thermodynamics of lithium ion batteries Hans J. Seifert Institute for Applied Materials – Applied Materials Physics (IAM-AWP) KIT – University of the State of Baden-Wuerttemberg and www.kit.edu National Research Center of the Helmholtz Association

- SPP1473, Scientific Aims - Materials - Thermodynamics, - Phase Diagrams, - Kinetics Micro- and Nanomaterials Crystal structures, Electrochemical Crystal chemistry, performance Microstructure, and safety of Reactivity cells / batteries

Li-Fe-P-O System Kang and Ceder (2009)

Li-Fe-P-O System Ong et al. (2008)

Li-Fe-P-O System Dodd et al. (2006)

Li-Mn-O System Detailed phase relationships in the subsystem LiMn 2 O 4 - Li 4 Mn 5 O 12 – Li 2 Mn 4 O 9 (Yonemura et al. 2004).

Li-Mn-O System Temperature-Composition Ratio Section in the Li-Mn-O System p(O 2 )=0.21 atm 60 [1999Pau] Paulsen and Dahn, Chem. Mater ., 11, 3065-3079, 1999

Lithium Ion Battery discharging charging material of anode oxidized / material of anode reduced / material of cathode reduced material of cathode oxidized

Li-Mn-O System

Li-Mn-O System R. Huggins, Advanced Batteries

Heat generation rates Sources of heat generation: 1. The “reversible” heat released (or absorbed) by the chemical reaction of the cell 2. The “irreversible” heat generation by ohmic resistance and polarisation 3. The heat generation by “side reactions”, i.e. parasitic/corrosion reactions and “chemical shorts” S. Hallaj, H. Maleki, J.S. Hong, J.R. Selman, J. Power Source 83, p.1-8 (1999)

C p, eff measurement on a 40Ah pouch cell U = 4,1V U = 3,0V

Separation of reversible and irreversible parts J.R. Selman, S. Hallaj , J. Power Source 97-98, p.726-732 (2001)

Enthalpy of Drop Solution of Li 1+x Mn 2-x O 4- δ 755°C 0.525 Li-Mn-O Temperature-Composition Ratio Section Samples prepared using a modified Pechini method • The homogeneity range of the spinel phase determined using thermogravimmetric analysis at • po 2 =0.2 atm Li-rich boundary of the homogeneity range Li 1+x Mn 2-x O 4 should be refined

Li-Mn-O System Section in the Li-Mn-O phase diagram (Thackeray et al., 1995).

Li-Mn-O System, sample preparation 69

Li-Mn-O System  Decomposition of LiMn 2 O 4 in air  Samples heat treated at 15 hours and quenched in liquid nitrogen 70

In-situ technique “entropymetry” Entropy as a function of Li concentration Open circuit voltage as a in LiMn 2 O 4 function of Li concentration in LiMn 2 O 4 Note: Half cells measured Yazami et al. in Lithium Ion Rechargeable Batteries, WILEY-VCH (2010)

2 nd kind phase diagram in the Li-Mn-O system Luo and Martin, 2007 Paulsen and Dahn, 1999 Li-Mn-O System Yonemura et al. 2004

German Research Foundation, Priority Program 1473, Materials with New Design for Improved Lithium Ion Batteries - WeNDeLIB Battery Properties Thermodynamics and Kinetics Oxygen partial pressure, Thermal runaway Gibbs free energies of reactions Voltage, potential Chemical potentials (of lithium) Capacity, energy- and Phase diagrams, power density Gibbs free energies Stability of compounds in Life time battery; Materials constitution Formation of SEI; Relative Power- and materials thermochemical stabilities of loss during first materials for electrodes and charge cycle electrolyte

Relationships Thermodynamics and Electrochemistry Total change in enthalpy and entropy between two electrode compositions x 1 and x 2 :    x 2 E ( x , T )      x 2 0 S F    x 1  T  x x 1    x 2 E ( x , T )        x 2 0 H F E ( x , T ) T dx    x 1 0   T x x 1 x    y , 0 y 1 … and with normalization  x max    1 E ( y , T )      1 0 S F dy    0 T   y 0    1 Thermodynamic functions of E ( y , T )        1 0 H F E ( y , T ) T dy   active materials are needed  0 0 T   y 0

Battery technology spider chart (USABC) for electrical vehicles (EV) Specific Power Discharge: 300 W/kg Operating temperature: Specific Energy at C/3: -40 to +50°C 150 Wh/kg Selling price at Power density: 10k/Jahr: 150$/kWh 460 W/l Calendar life: Energy density at C/3: 10 years 230 Wh/l Cycle life at 80% DOD: 1000 Cycles Sources: (1) D. Howell, Energy Storage Research and Development, Annual Progress Report 2006 (Washington, D.C.: Office of FreedomCAR and Vehicle Technologies, U.S. Department of Energy, 2007) (2) FreedomCAR and Fuel Partnership and United States Advanced Battery Consortium (USABC), Electrochemical Energy Storage Technical Team Technology Development Roadmap (Southfield, MI: USCAR, 2006)

M Winter, J. O. Besenhard, Chem. uns. Zeit 33, p. 320-332 (1999)

Li-Cu-Fe-O System  Thermodynamic N. Saunders, I. Ansara (Ed), Cost 507, calculations based on the Report,1994,168–169 CALPHAD method B. Hallstedt,L.J. Gauckler CALPHAD, 2003, 27:177-191 – predict battery K. Chang, B. Hallstedt, CALPHAD, 2011, 35:160-164 performance equilibrium voltages (OCV) plateau capacities  Database development for the Li-Cu-Fe-O System – The Cu-Fe-O ternary system assessed by Khvan et al. – First calculated phase diagrams in the Li-Cu-O system addressed in present work

Isothermal calorimetric measurements on a 16 mAh Lithium ion coin cell Discharge parameters: - Method: constant current (CC) - U min = 2.75 V I = 16 mA → 1C-rate - Charge parameters: - Method: constant current, constant voltage (CCCV) - U max = 4.25 V Isothermal Battery Calorimeter (IBC) I = 16 mA → 1C-rate - - I min = 1.6 mA Cell type: coin cell LIR 2016, Conrad energy (commercial) Capacity: 20  5 mAh; Working voltage: 3.6 V

Isothermal calorimetric measurements on a 16 mAh Lithium ion coin cell Temperature T env = 40 °C Temperature T env = 20 °C Charge (16 mA) Discharge (16 mA) Charge (16 mA) Discharge (16 mA) 15 15 Current [mA] 10 Current [mA] 10 5 5 0 0 -5 -5 -10 -10 -15 -15 4,25 4,25 4,00 4,00 Voltage [V] Voltage [V] 3,75 3,75 3,50 3,50 3,25 3,25 3,00 3,00 2,75 2,75 10 10 8 8 Heat [mW] Heat [mW] 6 6 4 4 2 2 0 0 0 2500 5000 7500 10000 12500 0 2500 5000 7500 10000 12500 Time [s] Time [s]

Accelerating Rate Calorimeter (ARC) ARC provides an adiabatic environment in which a sample may be studied under conditions of negligible heat loss heat of reaction: total heat generated: EV ARC: Ø: 25cm h: 50cm ES ARC: Ø: 10cm h: 10cm

Thermodynamics of electrochemical reactions electrochemical reaction Thermal Runaway Gibbs-Helmholtz equation entropic change of electrochem. reaction cell catch fire reversible heat start of thermal runaway S. Tobishima, J.Yamaki, J. Power Source 81-82, p. 882–886 (1999) A.K. Shukla, T.P. Kumar, Current Sci. 94, p. 314-331 (2008)

Enthalpy of Drop Solution of Li 1+x Mn 2-x O 4- δ Sodium Molybdate, 700°C AlexSys 1000, SETARAM High Temperature Calvet Calorimeter

Enthalpy of Drop Solution of Li 1+x Mn 2-x O 4- δ Sample Number DROP 1 DROP 2 DROP 3 DROP 4 DROP 5 DROP 6 DROP 7 DROP 8 08. Mai 08. Mai 08. Mai 08. Mai 08. Mai 09. Mai 09. Mai 09. Mai Date Mass pellet (mg) 6,00 5,14 6,10 6,62 4,85 5,35 4,83 5,59 T(room) (°C) 23,90 24,10 24,20 24,10 24,20 24,50 24,30 24,20 T(cal.) (°C) 700,40 700,40 700,40 700,40 700,40 700,40 700,40 700,40 Formula weight (g/mol) 180,815 180,815 180,815 180,815 180,815 180,815 180,815 180,815 Moles of LiMn2O4 (mol) 0,0000332 0,0000284 0,0000337 0,0000366 0,0000268 0,0000296 0,0000267 0,0000309 Peak Area [µV.s] 1832,4170 1538,5640 1765,6030 1910,2030 1402,3320 1544,6110 1397,2290 1611,2630 Calibration factor from Al 2 O 3 calibration[J/µV.s] 0,00462077 0,00462077 0,00462077 0,00462077 0,00462077 0,00462077 0,00462077 0,00462077 Measured Heat Effect (kJ/mol) 255,1652 250,0926 241,8308 241,0849 241,5781 241,2203 241,6957 240,8258 Accepted Measurement 0 0 1 1 1 1 1 1

2 nd kind phase diagram in the Li-Mn-O system Luo and Martin, 2007 Paulsen and Dahn, 1999 Li-Mn-O System Yonemura et al. 2004

Li-Mn-O System Chemical potential diagram in the Li-Mn-O system (Tsuji et al. 2005). What to do next: (1) Evaluation; (2) Solution phase modeling; (3) Thermodynamic optimization

Li-Mn-O System Experimental Potential Diagram for Stoichiometric LiMn 2 O 4 86 [2005Tsu] Tsuji et al., J. Chem. Phys. Solids , 66, 283-287, 2005

Li-Mn-O System Critically Evaluated Potential Diagram for Stoichiometric LiMn 2 O 4 87

Temperature-Composition Ratio and Potential Diagrams Li-Mn-O System  LiMn 2 O 4 composition is a vertical line in the temperature-composition ratio diagram  p(O 2 )=0.21 atm is a horizontal line in the potential diagram 88

Potential diagram at constant Li/Mn ratio Li-Mn-O System p(O 2 )=0.21 atm Li/Mn ratio for LiMn 2 O 4 LiMn 2 O 4 ↔ zLi 2 MnO 3 + Li 1-2z Mn 2-z O 4-3z-y (tet) + (y/2)O 2 Li 1-2z Mn 2-z O 4-3z-y (tet) ↔ LiMnO 2 +(1/3) Mn 3 O 4 + {(1/3)-(y/2)}O 2 [1999 Pau] Chem. Mater., 11 (1999), 3065-3079. 89 [2005 Tsu] J. Phys. Chem ., Solids. 66 (2005), 283-287.