Second International Renewable Energy Storage Conference November 2007 Bonn/Germany. Overview on current status of lithium-ion batteries

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1 Second International Renewable Energy Storage Conference November 2007 Bonn/Germany Overview on current status of lithium-ion batteries Andreas Jossen, Margret Wohlfahrt-Mehrens Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) Helmholtzstrasse 8, Ulm, Germany Contact: Overview Why is Lithium an interesting material for batteries? Principle of Li-Ion batteries Possible Material combinations Today s driving forces for Li-Battery development State of the art technologies Chances and risks of using large lithium batteries for stationary applications R&D required Lifetime, costs and economical aspects -2-

2 Why Lithium? Li Na Al Mn Zn Fe Cd Ni Pb Cu Ag Lithium is the material with the most negative voltage high cell voltage Potential vs hydrogen in V Li Na Mg Al Zn Fe Cd Ni Cu Ag Pb Lithium is the metal with the lowest density. high specific Energy Density in kg/l Why Lithium? Lithium is able to form a protection layer that allows the transport of Li-Ions Layer does not block current flow Li-Metal Li-Ion Electrolyte Layer protects electrode good lifetime is possible Lithium can be used for Batteries with high cell voltage and high specific energy Protection Layer protects Lithium for further dissolution (Solid electrolyte interface / SEI)

3 Possible Lithium Systems Li-Ionen Types of Lithium Batteries Li-Batteries Differentiation by anode material Systems with metallic Lithium: Li-Metal Systems with intercalated Lithium: Lithium-Ion Differentiation by electrolyte Liquid electrolyte: Li-Metalliquid Polymer electrolyte: Li-Metal- Polymer Flüssiger electrolyte: Li-Ionliquid Polymer electrolyte: Li-Ion- Polymer Button cells only France: Bolloré Preferred systems Cells available for cellphones, laptops, PDA, first larger cells -5- *E. J. Cairns, in Lithium Battery Technology, ed. by H. V. Venkatasetty, John Wiley & Sons (1984)

4 The Lithium-Ion System POSITIVE LiMO 2 Organic electrolyte NEGATIVE Carbon Oxygen Metal Ion (Co, Ni, Mn) Li + Li + Li +, LiC 6 Separator Passivating layer Li + Li + discharge e - charge Cell reactions: Discharged Charged Positive: LiCoO 2 Li 1-x CoO 2 + x Li + + x e - Negative: x Li + + C 6 (graphite) + x e - Li x C 6 Total reaction: LiCoO C 6 Li 0.4 CoO LiC 6 No Li metal in the cell. The electrolyte does not participate in the cell reaction. It constitutes only a vehicle for Li-Ion transfer. No excess of electrolyte is therefore required. Cell design of Li-Batteries Thin electrodes are necessary! Source: LTC-GAIA

5 Cell design of Li-Batteries Cylindrical cell Coffee bag cells Prismatic cells Cell design of Li-Batteries Electro Energy Inc. received 1.5 Mio US $ for developing of a bipolar Li-Battery Quelle: Nov

6 Battery System for Plug-In Hybrid Li-Ion Battery 63 cells (LiFePO 4 ) 200V / 35Ah (7 kwh) Battery-management with single cell voltage monitoring and chargeequalizing is required. Source: GAIA -11- High Energy Storage 500 energy density in Wh/l DLC Lead-acid NiCd NiMH -12- Redoxflow Li-Ionen specific energy in Wh/kg

7 Good Performance Achieved Energy Efficiency Li-Ion Cell: Saft MP HD High Power Type Temperature: 25 C Discharge time/ Charge time in h Lithium Batteries show an excellent energy efficiency. > 95% ( 2 h Rate) > 98% (10 h Rate) 120 Kapazität in % CN Cycle life test : DoD: 100% T: 25 C Rate: 1/2 h Lithium Batteries show a long cycle life cycles today 20 LiFePO 0 4 System Zyklenzahl Materials for Lithium-Ion-Batteries 5 5 LiCoO 2 Elektrolyte Potential vs. Li/Li+ in V Spannung gegen Li-Metall / V LiMn 2 O 4 MnO 2 LiNiO LiNiO 2 2 LiFePO 4 PTMA Li x V 3 O 8 Li 4 Ti 5 O 12 Kohle amorph V Systeme Positive 3-V Systeme 0 Li-Metall Graphit LiSi 0 Negative

8 New Cathode Materials 5V LiMn 1.5 (Co,Fe, Cr) 0,5 O 4 Potential vs. Li/Li+ 5V 4V 3V LiCoPO 4 Li 2 MnO 3 /1-xMO 2 LiNi 1/2 Mn 1/2 O 2 LiMn 1.5 Ni 0.5 O 4 LiCo 1/3 Ni 1/3 Mn 1/3 O 2 LiMnPO 4 LiMn 2 O 4 LiCoO2 Li(Ni,Co)O 2 LiFePO 4 Doped MnO 2 Cathode is limiting LiCoO 2 ~ 150 mah/g Graphite ~ 320 mah/g Cathode with higher capacity safety and lower costs necessary MnO 2 V 2 O Capacity [Ah/kg] New Anode Materials Potential vs. Li/Li + 1,5 V 1,0 V 0,5 V Li 4 Ti 5 O 12 nano TiO 2 Nano-Oxide Co 3 O 4 Li 2.6 Co 0.4 N Sn-alloys Graphite zero-strain without side reaction long lifetime safe high capacity high volume change Nano-composite!! Hard carbon Si/C composites; Si alloys Capacity [Ah/kg]

9 Today's Driving Forces in Li-Battery development Mobile electronics (cellular phone, Laptop etc.) // < 100Wh very high specific energy, low cost, 2-3 years/200 cycles lifetime Hybrid Electric Vehicle (HEV) // 1 kwh high specific power, low cost, safety, >12 years lifetime@ shallow cycling Plug in Hybrid Electric Vehicle (PHEV) // 5-20 kwh medium specific power, high specific energy low cost, safety, > 12 years lifetime@ deep cycling (4000 cycles) Power and Energy of Li-Ion Batteries for different target applications Specific power in W/kg Spezifische Leistung in Wh/kg Li-Ion for HEV Li-Ion für HEV Li-Ion for powertools Li-Ion für Powertools NiMH Spezifische Energie in Wh/kg Li-Ion für E-Fahrräder Specific energy in Wh/kg Li-Ion for e-bikes / EV Li-Ion for mobile electr. Li-Ion für Geräte

10 Technology Trends for Mobile Electronics Increase off Cell capacity - New anode materials Si (Panasonic) based materials Sn (Sony) based materials - New Cathode Material to achieve higher cell voltage/higher capacity NCA (Panasonic, Sony) NMC (Sanyo) Voltage vs. Li/Li+ Increase of battery safety - Development of heat resistance layer (HRL) Ceramic coated anode or cathode Heat resistance polymer Ceramic coated Separator Lifetime is no critical factor The increase of cell capacity will reduce lifetime - 2 years calendar life cycles LiCoO 2 NMC NCA Graphite Sn. Si Capacity Additive for Shuttle-Process in Li-Ion Batteries as substitute for electronic charge equalization systems S + +e - S S S + +e

11 Technology Trends for Hybrid Electric Vehicles Increase in power - Increase of conductivity Coating of Active material with carbon - Increase of active area Smaller particles and nano size particles Increase in low temperature performance - New electrolytes - smaller particle size Increase in battery safety - New cathode materials (LiFePO 4 ) - New separator - Safer electrolyte Increase in Lifetime - Stable cathode (LiFePO 4 ) - Improved electrolyte - Optimized control strategy - Calendar life at high SOC maybe critical Voltage vs. Li/Li+ LiCoO 2 LiFePO 4 Graphite Lower voltage reduces electrolyte decomposition. Sn. Si Capacity -21- Li-Ion Batteries for Power Assist HEV Status: Comparison with FreedomCar targets Quelle: 2006 Annual progress report FreedomCar Group -22-

12 Requirements for Stationary Li-Batteries Increase of power low priority Increase of low temperature performance low priority Increase of battery safety important - New cathode materials (LiFePO 4 ) - New separator - Safer electrolyte Increase of Lifetime important - Increase in cycle life Zero strain anode? Gives low cell voltage! - Increase in calendar life at high state of charge Stable cathode (LiFePO 4 ) Improved electrolyte Optimized control strategy Voltage vs. Li/Li+ LiCoO 2 LiFePO 4 Li 4 Ti 5 O 12 Graphite Lower voltage reduces electrolyte decomposition. Sn. Si Capacity Long Life 2V Lithium Battery Long cycle life possible ( cycles +?) Long calendar lifetime at high state of charge (10 years +?) 2.5V 2V But - only 50% of energy - higher costs per Wh - more resources necessary - more cells necessary Source: Tsutomu Ohzuku, IMLB

13 Battery Safety The safety of Li-batteries can be critical. Million of batteries were recalled in the last 2 years. For large stationary systems safety is more critical. Must be solved by - new cathode materials - new electrolytes - Battery / cell design Thermal Stability of different Cathode Materials DSC /(mw/mg) Exo Li 0.2 Ni 0.8 Co 0.15 Al 0.05 O 2 Li 0.5 CoO 2 Li 0.15 Mn 2 O 4 Li 0.1 FePO 4 no exotherm reaction in charged state [ [ [ [4.1] Temperatur / C

14 A lithium-economy has some limitations Lithium Nickel Zinc battery technology Source: Meridian International Research The trouble with Lithium Global Lithium Reserve Base If Li batteries will enter automotive an stationary applications in relevant Market share we have to work on: - Recycling of Li from used batteries - Activating of Li resources - Developing of Li batteries with high cell voltage - Looking for none Li battery technologies Source: Meridian International Research

15 R&D in Li-Batteries Source: Namura-Report 2006 R&D required for large stationary Li-Batteries - Further improvement of intrinsic battery safety by use of new cathode materials and improved electrolytes and separators. - Cost reduction, by new cathode materials, improved engineering and finally mass production. - Development of Li-batteries that are optimized for stationary applications. Today most R&D is concentrated on mobile electronics and automotive applications. - Development of new, long-life generation of lithium batteries (2V types are maybe an option). - Control strategy for lithium ion batteries is totally different from that of other battery technologies. - Battery state determination methods for LiPFO 4 and other systems with flat discharge voltage curve

16 Summery Li-batteries show the highest specific energy (up to 200 Wh/kg) of available rechargeable battery systems. Today Li-batteries are market leader in portable power sources Li-batteries have a high technology potential for further improvement. Today >90% of battery R&D is done on Li-batteries. Upscaling of lithium batteries from 100 Wh storage to large stationary systems requires further R&D with the targets: - lower costs - improved battery safety - longer lifetime New Li-battery technologies optimized for stationary applications will show excellent performance, but some technologies will have higher specific costs. A Lithium economy is maybe limited by the available Li-resources. Lithium battery R&D in Europe low Worldwide no Li-battery R&D focus on stationary applications -31-