Materials for Energy Storage Yang-Kook Sun Energy Storage and Conversion Materials Lab. http://energy.ce.to/ (FTC 1017) (02)2220-0524, (017)335-4074 yksun@hanyang.ac.kr

Grade Items Score Mild-term 100 Final-term Attendance 30 Presentation 합계 330

- Text 1) LITHIUM BATTERIES Science and Technology, G. -A. Nazri and G - Text 1) LITHIUM BATTERIES Science and Technology, G.-A. Nazri and G. Pistoia Eds. Kluwer Academic Pub., 2004 2) Lithium Secondary Batteries, 박정기, 홍릉과학출판사, 2010 3) J. of Electrochem. Soc.: http://www.ecsdl.org/JES 4) J. of Power Sources: http://www.sciencedirect.com/science/journal/03787753 5) Electrochimica Acta: http://www.sciencedirect.com/science/journal/00134686 6) Nature Materials: http://www.nature.com/nmat/index.html 7) Energy & Environmental Science: http://pubs.rsc.org/en/journals/journalissues/ee 8) J. of Amer. Chem. Soc.: http://pubs.acs.org/journal/jacsat 9) Chem. Mater.: http://pubs.acs.org/journal/cmatex 10) J. of Phy. Chem. C: http://pubs.acs.org/journal/jpccck 11) Adv. Mater.: http://onlinelibrary.wiley.com/doi/10.1002/adma.v20:21/issuetoc 12) J. Mater. Chem.: http://pubs.rsc.org/en/journals/journalissues/jm 13) Angewandte Chemie: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521- 3773 14) Adv. Ener. Mater.: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1614-6840 15) Electrochemistry Communications: http://www.sciencedirect.com/science/journal/13882481 16) Nat. Commun.: http://www.nature.com/ncomms/index.html 18) Nat. Chem.: http://www.nature.com/nchem/index.html 19) Nano Energ.: http://www.sciencedirect.com/science/journal/22112855

Electrochemical Concepts A battery is an electrochemical cell that converts the chemical energy of a reaction directly into electrical energy Chemical Energy Electrical Energy Electrochemical cells Anode : M Mn+ + ne- Cathode : X + ne- Xn- Overall : M + X Mn+ + Xn- Load Anode M Cathode X Separator Electrolyte e When a current of I amperes flows in the circuit for a time of t seconds, then the amount of charge Q transferred across any interface in the cell is equal to It coulombs. Number of moles Nm of the reactants M or X consumed by the passage of It coulombs is given by Nm = 𝐼𝑡 𝑛𝑁𝐴 𝑒 = 𝐼𝑡 𝑛𝐹 where n; # of electrons given up or accepted by M or X Q = It = nFNm : theoretical capacity Figure 1. Schematic of an electrochemical cell

Electrochemical Concepts 1F (faraday) = # of avogadro × charge of one electron = 6.023× 10 23 ×1.6× 10 −19 C=96485 C /equivalent = 26.8 Ah/equivalent Thermodynamics of Electrochemical Cells The driving force for an electrochemical cell to deliver electrical energy to an external circuit is the decrease in the standard free energy ∆Go of the cell reaction. Galvanic cell : ∆Go < 0 , Spontaneous reaction ∆Go = -nFEo, where N and F are, respectively, the # of electrons involved in the reaction and the Faraday constant. Eo is the difference between electrode potential of the cathode and anode and the equilibrium potential when all of the cell component are in their standard states; a positive value of Eo means that the cell reaction occurs spontaneously. Nernst equation at standard state 𝑬 = 𝑬 𝜽 − 𝑹𝑻 𝝂𝑭 𝒍𝒏 𝑎𝑀 𝑛 𝑎𝑋𝑛 𝑎𝑀 𝑎𝑋 𝑬 = 𝑬 𝜽 − 𝟎.𝟎𝟓𝟗𝟏 𝒏 𝒍𝒏 𝑎𝑀 𝑛 𝑎𝑋𝑛 𝑎𝑀 𝑎𝑋 + - - +

Electrochemical Concepts Polarization Losses in Electrochemical Cells When a current I is passed through the cell, part of energy is lost as waste heat due to polarization losses in the cell (three types); 1) activation polarization, 2) concentration polarization, and 3) ohmic polarization. Activation polarization is related to the kinetics of electrode reactions Concentration polarization is related to the concentration differences of the reactants and products at the electrode surfaces and in the bulk as a result of mass transfer Ohmic polarization, usually referred to as internal IR drop, is related to the internal impedance of the cell, which is sum of the ionic resistance of electrolyte and the electronic resistance of the electrodes Figure 2. Variation of cell voltage with operating current illustrating polarization losses

OPERATING PARAMETERS in Batteries Capacity, Ah, is the total quantity of charge that the battery may deliver in discharge. Gravimetric Specific capacity, Ah/g, is the total quantity of charge that the battery may deliver in discharge per weight. Volumetric Capacity density, Ah/cm3, is the total quantity of charge that the battery may deliver in discharge per volume. Gravimetric Energy Density, Wh/kg, is the energy that the battery can deliver per weight. Volumetric Energy density Wh/cm3, is energy that the battery can deliver per volume. - The practical values, that include total weight or volume (electrodes, electrolyte, case, current collector, separators, etc) are usually 1/4 of the theoretical ones. For instance in the case of the lead acid battery, the theoretical value is 171 Wh/ kg while the practical value decreases to about 40 Wh/kg

History of Batteries

Mg + 2MnO2 + H2O → Mn2O3 + Mg(OH)2 Table 1. Major Primary Battery systems Cell Voltage Capacity Battery Anode Cathode Cell Reaction (V) (Ah/Kg)a Leclanche Zn MnO2 Zn + 2MnO2 → ZnO∙Mn2O3 1.6 224 Magnesium Mg Mg + 2MnO2 + H2O → Mn2O3 + Mg(OH)2 2.8 271 Alkaline MnO2 Zn + 2MnO2 → ZnO + MnO3 1.5 Mercury HgO Zn + HgO → ZnO + Hg 1.34 190 Zinc-air O2 Zn + 0.5O2 → ZnO 1.65 658 Li-SO2 Li SO2 2Li + 2SO2 → Li2S2O4 3.1 379 Li-MnO2 Li + MnO2 → LiMnO2 286 a Based only on active cathode and anode materials

History of Batteries 1990s~ 1980s~ 1970s~ 1899 1859 · Lithium-ion Battery (3.6V) 1980s~ · Ni-MH Battery (1.2V) 1970s~ Ni-Cd, 1973 · Lithium Battery · Early 1970s: Nickel hydrogen battery · 1955: Common alkaline battery · 1903: Ni-Fe battery (EDISON) 1899 · Ni-Cd Battery (1.2V) · 1887: Zinc-carbon cell – the first dry cell · 1866: Leclanche Cell · 1860s: Gravity Cell 1859 · Lead-acid Cell: the first rechargeable battery (1.2V) · 1844: Grove Cell · 1836: Daniell Cell · 1800: Voltaic Pile

Cd + 2NiOOH + 2H2O → 2Ni(OH)2 + Cd(OH)2 Table 2. Major Secondary Battery Systems Battery Anode Cathode Cell Reaction Cell Voltage (V) Capacity (Ah/kg)a Lend-acid Pb PbO2 Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O 2.1 120 Nickel-cadmium Cd NiOOH Cd + 2NiOOH + 2H2O → 2Ni(OH)2 + Cd(OH)2 1.35 181 Nickel-hydrogen H2 H2 + 2NiOOH → 2Ni(OH)2 1.5 289 Nickel-metal hydride MH MH + NiOOH → M + Ni(OH)2 206 Lithium-ion Li Li0.5CoO2 0.5Li + Li0.5CoO2 → LiCoO2 3.7 137 a Based only on active cathode and anode materials.

Reactions in the solid state: Gaston Planté and the lead-acid battery (1859): The first rechargeable system PbSO4 4 H+ Pb PbO2 SO42- H2SO4 / H2O v + _ I/A H2O- PbO2(s) + 4H+ + SO42- + 2e-     PbSO4(s) + 2H2O DE = 2,0 V Pb(s) + SO42-  PbSO4 + 2e- ● Usable batteries for thermal vehicles ● Industrial batteries (network support, heavy traction) Its cost (100 €/kWh) Low energy and specific power (25-35 Wh/Kg; 60-120Wh/l) Reduced cyclability and calendar life, weak in temperature Reactions in the solid state: ● Breaking of chemical bonds at both electrodes 12

W. Jungner (1909): The Ni-Cd batteries and its its derivatives Ni-Fe, Ni-Zn, and Ni-H2 Cd: 1.2 V Fe; 1.4 V Zn: 1.7 V H2: 1.3 V Cd Long calendar life High power Good cycling behaviour Waldemat Junger has invented the Ni-Cd battery in 1899 and try to replace Cd by Fe, therefore here is found thath there has been too much H2 gasing so he decided to abandon (although he had several patents). it and Edison took over in 1901 wit Performances 45-60 Wh/kg 170 W/kg 2000 cycles Weak specific energy Important self-discharge Cadmium toxicity

1975: the Nickel-Metal hydride battery: Two insertion reactions "LaNi5H6" + 6H+ + 6e- "LaNi5" High Volume energy (310 Wh/L) Good cyclability High power rate Cost of materials Energy density (80Wh/kg) 1997, Toyota Prius Performances 80 Wh/kg 200-1350 W/kg 1000 cycles

Large energy densities How to increase the energy density of rechargeable Batteries ??? From H+ to Li+ ENERGY Energy density (Wh/kg) = Capacity (Ah/kg) x V (volts) Requires aqueous media Limited to 1.2 V (Water stability) Reacts with water Organic electrolytes Lightest metal (6.9 g) Most reducing metal - 3.04V vs. ENH Large energy densities ENERGY CAPACITY (Volts) 0.8 0.4 1.2 1.4 1.0 0.2 0.6 Number of e- exchanged POTENTIAL ENERGY

Comparison of Energy Density Why Li-ion ? Comparison of Energy Density Lead Acid Ni-Cd Ni-MH LiB LiPB

Market for LIB

Why Li-ion ? Market trend: Mobile IT → EV or ESS LIBs Market for Auto Market for LIBs LIBs Market for Auto

Development of Ni-rich cathode is indispensable !! LIBs Market for automobile The market will exponentially increase in the future. In 2019, based on the number of car, BEV market is only 16%. However, based on energy, BEV market will be 57%. 333 NCM widely used in Evs with driving range of around 100 miles, to increase driving range, we should develop high capacity Ni-rich cathode materials. Development of Ni-rich cathode is indispensable !!

LIB Energy Density History -. Higher voltage cut-off -. Metal alloy NE Map of energy density for cylindrical LIB (18650) 98 → 185 Wh/kg 220 → 620 Wh/L ? The 1st LIB was introduced in the market by SONY (1991) For last 20yrs, energy density of LIB has been increased only 2~3times Changing the negative material from H/G to Graphite Improving the high voltage stability of positive materials Optimizing cell design to maximize the packing density - 3 -

Chem. Energy Electrical Energy Principle of Lithium Batteries charge e- Chem. Energy Electrical Energy Charge Discharge charger e- discharge cathode anode discharge Li+ charge Oxygen Metal Atom Lithium Carbon - 16 -

Lithium-Ion Battery Charge Electrolyte Cu Current Collector AL Current Collector Graphite LiMO2 SEI SEI

Lithium-Ion Battery Discharge Electrolyte Cu Current Collector AL Current Collector Graphite LiMO2 SEI SEI

Cost analysis of materials and battery Material cost Battery cost Cathode Separator Anode Electrolyte Case Others Material Depreciation Labor Ownership Profit

Four Key Materials for Li-ion Batteries Requirement Cathode ∙ LiCoO2 ∙ High Energy ∙ LiNiCoMnO2 ∙ Low Cost ∙ LiFePO4 ∙ Safety ∙ Li1+xNiCoMnO2 Anode ∙ Graphite ∙ High Energy ∙ Hard carbon / Soft carbon ∙ Low Cost ∙ Li4Ti5O12 ∙ Fast Charge ∙ Si, Sn, etc Separator ∙ PE / PP ∙ Low Thermal Shrinkage ∙ Nonwoven ∙ High Mechanical Strength ∙ Ceramic Coated ∙ Low Cost Electrolyte ∙ Organic Solvent (EC, EMC, DME, DEC, etc.) ∙ Less Flammable ∙ Li Salt ∙ Low Cost (LiPF6, LiBF4, LiBOB, etc.)

Electrochemical Concepts Eoc Eop Current / A Cell Voltage / V Ohmic polarization Activation polarization Concentration polarization