The battery Bottleneck for the E-mobility?

Transcription

1 Workshop of the The Dutch Royal Institute of Engineers The battery Bottleneck for the E-mobility? Prof. Dr. rer. nat. Dirk Uwe Sauer Electrochemical Energy Conversion and Storage Systems Group Institute for Power Electronics and Electrical Drives (ISEA) RWTH Aachen University Why electrification of vehicles? 1. Limited resources oil is limited and can get very expensive as seen in Climate change CO 2 emissions must be reduced worldwide by 7% until 25 (in Germany by 9%) World-wide CO 2 emissions world This is, what the world is currently doing No. 2

2 Why electrification of vehicles? 1. Limited resources oil is limited and can get very expensive as seen in Climate change CO 2 emissions must be reduced worldwide by 7% until 25 (in Germany by 9%) Quelle: Powerlight Corporation Electricity is available in the long-run in almost unlimited quantities from renewable energy sources, nuclear power plants, or fossil power plants with carbon capture! Quelle: K. Puchas, LEA Oststeiermark Quelle: GtV e.v. No. 3 Land requirement for bio fuels vs. electricity for mobility Harvest from bio mass of 2 nd generation (BTL) expected: 6, km/ha/year Harvest from photovoltaics in Germany: 1,, km/ha/year Assumptions: Solar energy in Germany 1 kwh/m 2 /a, photovoltaics with 1% efficiency, land use factor 1/3, vehicle energy consumption 2 kwh / 1 km, efficiency grid & vehicle 6% 16x more driving with electricity from PV compared with bio fuels No. 4

3 Energy efficiency fuel cell vs. electric vehcile Starting point: electrical power (from CO 2 -free sources) Quelle: ATZ online usable energy with fuel cell vehicles: 25 3% Quelle: minispace.com usable energy with electric vehicles: 7 75% Energy needs for fuel cell vehicles with clean hydrogen is 2.5 x higher compared with electric vehicles No. 5 Electric- and hybrid electric vehicles are under construction - everywhere Quelle: Volvo Quelle: Daimler Quelle: Think Quelle: Daimler Quelle: minispace.com Quelle: Tesla Motors No. 6

4 Electrification concepts for passenger cars Hybrid electric vehicle (HEV) Storage capacity approx. 1 kwh, charging only during driving, fuel reduction max. 2% Plug-in Hybrid electric vehicle (PHEV) Storage capacity 5 1 kwh, charging from the grid, 3 to 5 km electrical driving range, full driving range with conventional engine or fuel cell, driving with empty battery possible Electric vehicle (EV) Storage capacity 15 4 kwh, charging from the grid, 1 to 3 km electrical driving range No. 7 Gravimetric power density vs. energy density (power and energy density of specific products taken from data sheets and measurements) 1, Specific Power, W/kg at Cell Level 1, 1, SuperCap Blei spiral wound Blei NiCd Li-Ion Very High Power Li-Ion High Power NiMH NaNiCl 2 Zebra LiM-Polymer Specific Energy, Wh/kg at Cell Level Li-Ion High Energy Quelle Ragone Plot: Saft No. 8

5 The lithium ion system ( Rocking Chair ) discharging LiMO 2 R e - e - graphite oxygen Li + LiC 6 m Metal ion graphite separator Li + Li + Graphik: Saft POSITIVE elektrolyte & separator NEGATIVE Main technologies in the focus for lithium-ion batteries Li-ion liquid cathode material anode material Good lifetime, high safety risk Highest safety risk, good electrical performance Short lifetime, safety better compared with Co & Ni Popular mixed material with optimum of different features High variability of mixed materials (e.g. additional Al) 3.3 V material, cheap & safe, lower energy density LiCoO 2 LiNiO 2 LiMn 2 O 4 LiCo 1/3 Ni 1/3 Mn 1/3 O 2 LiCo x Ni y Mn z O 2 LiFePO 4 Hard Carbon LiC 6 Graphit LiC 6 Titanat Li 4 Ti 5 O 12 Silizium Li 22 Si V material, low number of full cycles 3.7 V material, expensive good cycle lifetime (EV) 2.2 V Material, safe, low energy density 3.7 V material, high energy denstiy, under investigation No. 1

6 Lithium-ion batteries Performance of different materials Potential in mv vs. Li / Li Quelle: ZSW Ulm LiMn 2 O 4 Li(Ni,Co,Mn)O 2 only cathode material LiFePO Li(Ni,Co)O 2 LiCoO spezifische Kapazität [mah/g] No. 11 Important technology innovations under development Improved energy density by 5 Volt cathode materials e.g. LiCoPO 4 Advantage: high potential, high safety disadvantage: costs of cobalt, sufficient cycle lifetimes not confirmed Silicon anode materials (LiSi 5 ) Advantage: theo. 11x higher energy density of the anode compared with graphite Disadvantage: high volume expansiun, severe lifetime problems Quelle: Stanford University Silicon Nano Wires Energy densities up to a maximum of 3 Wh/kg might be possible No. 12

7 Actual main R&D topics for Li-ion batteries Li-ion liquid Separators Electrolyte General: very expensive component in Li-ion cells Multi-layer separator with a melting layer ( turns to high resistance at overheating) Ceramic separator minimizes the risk of short circuits at high temperatures standard LiMn 2 O 4 Shut-Down Separion Electrolyte and binders are major components with regard to deep temperature performance and lifetime. standard LIBOB Polymere Ionic liquids Electrolyte: EC, PC, DMC, DEC, EMC salts: LiPF 6, LiCF 3 SO 3, LiN(CF 3 SO 2 ) 2 Additives Higher security safe, low conductivity at room temperature Possible electrolyte for 5 Volt cells No. 13 Different cell concepts Round cells Long years of experience with cell design High lifetime expectations Cooling difficult Coffee bag cells Very good cooling properties High energy density Tightness of foils still in question Prismatic cells Simple system design Combines several advantages of round cells and coffee-bag cells No. 14

8 Discharge characteristic of Li-Ion High Power batteries 4,1 4. 4, 3,9 3,8 Saft high power cell Saft high power cell cell voltage [V] Voltage (V) 3,7 3, ,5 3,4 3,3 3,2 3,1 3. 3, 2,9 2,8 2,7 2, , Capacity (Ah) capacity [Ah] 1/3 C ½C 1C=15A 2C 3.33C 1C 19C D/3 D/2 1 D = 15 A 2D 5A 15A 285A No. 15 Electrical performance (cell level) high energy high power Power density 2 4 W/kg 2 4 W/kg Energy density Wh/kg 8 1 Wh/kg Efficiency ~ 95% ~ 9% Self discharge < 5%/month (25 C) < 5%/month (25 C) Cycle lifetime up to 5 full cycles 1 6 (3.3% DOD) Energy (Wh) E n e r g y ( W h ) 1 Quelle: Saft Storage duration (Years) Calendar life assessment at 4 C and 1 % SOC Energy (Wh) Energy ( W h ) 1 5 Quelle: Saft Cycle number Cycle life assessment at 2 C at 8 % DOD cycle No. 16

9 Ageing effects by cycling NiMH-batteries Grid expansion during emplacement of hydrogen leads to mechanical stress and thereby destroys crystals of metal alloy volumeexpansion: LaNi LaNi approx. 2% 5 5H6 2 cycles 1 cycles 5 cycles hydrogen absorption No. 17 There is a lot of additional battery cycle lifetime to support grid stability or doing energy trading! Life time as a function of cycle depth (Generally similar for lithium-ion-, NiMH- and lead-acid batteries; absolute numbers varying depending on the product) 1 6 Zyklen cycles Äquivalente equivalent full Vollzyklen cycles number Zyklenzahl of cycles years 1 years 1 cycle/day 55 years with on cycle per day Δ SOC [%] different products and technologies No. 18

10 Quelle: Boston Consulting Group, 29 No. 19 Quelle: Boston Consulting Group, 29 No. 2

11 Cost development of consumer cells of the type 1865 (standard cell e.g. used in battery packs of laptops) spec. energy [Wh/kg], energy density [Wh/l] energy density specific energy specific costs costs [US$ / Wh] Source: Institute of Information Technology, AABC 24, San Francisco No. 21 Most important battery manufacturers of lithium-ion consumer batteries (type 1865 cell) Battery manufacturer Country Production in million cells Sanyo Japan 588 Samsung Korea 386 Sony Japan 359 Panasonic Japan 237 LG Chem Korea ca. 2 source: Institute Information Technology, data for 27 No. 22

12 Main tracks of current R&D activities on Li-ion batteries Maximising safety and reliability Reduction of costs by material selection and economcy of scale Transferring life cycle results from the lab to the field Improving the usable DOD while maintaining the lfietime Optimisation of system technology (mainly costs) Improving the energy density Consolidation of the technology and preparing for mass production is in the focus. Improving of energy density improves the market penetration only slightly. No. 23 Products are available on the market Specific Power, W/kg at Cell Level 1, 1, 1, SuperCap Blei spiral wound Blei Saft VHP 6 Ah NiCd Li-Ion Very High Power NiMH NaNiCl 2 Zebra GAIA LiFePO 4 LiTeC HP 6 Ah Li-Ion High Power GAIA HE 6 Ah LiM-Polymer Specific Energy, Wh/kg at Cell Level GS Yuasa LEV 5 A123 Saft VL M Kokam Coffee Bag Li-Ion High Energy E- One Moli Quelle Ragone Plot: Saft No. 24

13 What follows from costs and performance of lithium-ion batteries? Batteries are expensive 15 kwh/1km x 3 /kwh = 4,5 /1km (selling price to the car manufacturer, after (!) cost reduction) Batteries for electric vehicles cost as much as the total remaining car Costs for a small to medium size vehicle (all parts and manufacturing) are in the order of 5, /vehicle Lithium-ion batteries achieve many more cycles than typically used, but the battery will die even without cycling after a certain time No. 25 Why long-ranging full electric vehicle are not economic for the mass market. An example. Size of the battery for 2 km full electric driving: approx. 3 kwh (ranges from 24 kwh for very efficient small vehicles to 4 kwh) Costs for battery purchase (selling from battery manufacturer to car manufacturer): approx. 3 x 3 = 9, Selling price to the user: approx 9, x 1,8 = 16,2 for the battery only Weight at 1 Wh/kg 3 kg Battery dies after 1 to 15 years anyway, even if it wouldn t be used at all.. Average usage of vehicles in Germany: 37 km/day 8% of the battery dies unused. A full electric vehicle as a mass product remains a short ranging vehicle. 1 km full electric driving range seems to be an appropriate sizing. No. 26

14 Fast charging and exchangeable battery concepts try to make the full electric vehicle a one-by-one replacement of today s conventional vehicles. This is nonsense from an economical and from an ecological point of view. No. 27 Electrification concepts for passenger cars Hybrid electric vehicle (HEV) Storage capacity approx. 1 kwh, charging only during driving, fuel reduction max. 2% Plug-in Hybrid electric vehicle (PHEV) Storage capacity 5 1 kwh, charging from the grid, 3 to 5 km electrical driving range, full driving range with conventional engine or fuel cell, driving with empty battery possible Electric vehicle (EV) Storage capacity 15 4 kwh, charging from the grid, 1 to 3 km electrical driving range No. 28

15 Topology of hybrid- (HEV) and Plug-in hybrid vehciles (PHEV) Parallel hybrid Series hybrid (incl. range extender) Clutch 1 Transmission Electric motor Clutch 2 Power electronics IC engine e.g. study Mercedes Vision S 5 Plug-in-Hybrid Photo: Photo: Generator Battery Power electronics IC engine Tank Battery Tank z.b. Opel Ampera Electric motor Transmission Graphik: Dr. Kube, Volkswagen Konzernforschung, 27 No. 29 Statistical Driving Behaviour 1 Stop Stop 3 Stop 2 Single trips Single trips (GER) km 95 % of single trips shorter than 42 km Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung No. 3

16 Statistical Driving Behaviour 1 Stop Single trips (GER) Day trips (GER) km 95 % of single trips shorter than 42 km 95 % of day trips shorter than 15 km Stop 3 Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung Stop 2 Single trips Day trip No. 31 Statistical Driving Behaviour 1 Stop Stop VMT, day trips (GER) km Stop 3 VMT: Vehicle miles travelled Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung 95 % of single trips shorter than 42 km 95 % of day trips shorter than 15 km 5 % of VMT can be driven with a battery for 8 km Single trips Day trip No. 32

17 Statistical Driving Behaviour 1 Stop % VMT, single trips (GER) VMT, day trips (GER) km Stop 3 VMT: Vehicle miles travelled Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung Stop 2 Single trips Day trip 95 % of single trips shorter than 42 km 95 % of day trips shorter than 15 km 5 % of VMT can be driven with a battery for 8 km Recharging after every single trip increases fuel substitution by 23 % No. 33 All-electric operation fraction of PHEVs All-electric operation fraction Recharging over night (GER) All-electric range in km Stop 3 Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung Stop 1 Stop 2 PHEV-35: fuel substitution of 5 % (same as EV-8) PHEV-5: Over night charging sufficient for 6 % of VMT (and more than 7 % of days for pure electric driving) No. 34

18 All-electric operation fraction of PHEVs All-electric operation fraction % Recharging after every trip (GER) Recharging over night (GER) All-electric range in km Stop 3 Data source: Mobilität in Deutschland, Bundesministerium für Verkehr, Bau und Stadtentwicklung Stop 1 Stop 2 PHEV-35: fuel substitution of 5 % (same as EV-8) PHEV-5: Over night charging sufficient for 6 % of VMT (and more than 7 % of days for pure electric driving) Recharging after every trip increases fuel substitution by 17 % No. 35 Sizing of the battery of Plug-in hybrids very high fuel saving potential with small battery 1% All-electric operation fraction 8% 68% 6% 45% 4% 2% % Recharging after every trip (GER) Recharging over night (GER) Recharging over night (USA) 2 3 km All-electric range in km No. 36

19 Electro mobility concepts need to be intelligent : Full electric vehicles for short distances ( second family car, urban delivery, craftsmen, etc.) or expensive upper class cars where costs are not a major issue, or for user with a very high daily mileage Plug-in hybrid electric vehciles is the replacement technology for today s universal cars with a high degree of fuel substitution No. 37 Workshop of the The Dutch Royal Institute of Engineers The battery Bottleneck for the E-mobility? Prof. Dr. rer. nat. Dirk Uwe Sauer sr@isea.rwth-aachen.de Electrochemical Energy Conversion and Storage Systems Group Institute for Power Electronics and Electrical Drives (ISEA) RWTH Aachen University