Electric cars: batteries of fuel cells? Piercarlo Mustarelli Department of Chemistry University of Pavia
Summary The electric transportation paradox Batteries and fuel cells at a glance State-of-the-art and roadmaps (Li batteries, polymer fuel cells) Critical issues Perspectives and conclusions
The electric transportation paradox Almost linear development! Many quantum jumps! Volta s pile (1799)
Relevance of electric transportation Global EV Outlook 2016, International Energy Agency, Paris 2DS: 2 Scenario (decarbonization) 6DS: 6 Scenario (current policies) Transport includes BEV, PHEV and FCEV)
The electric market (excluding FCEVs) China: 170000 electrical buses already circulating (2016) Paris Agreement: 100 million EVs in 2030 Global EV Outlook 2016, International Energy Agency, Paris
Batteries and fuel cells at a glance Fuel cells (Polymer, PEMFCs) Batteries (lead/acid, NiMh, lithium*) Energy conversion (chemical into electrical) Energy storage * Many chemistries are possible
The Ragone s plot: a useful chart Li/air Li/S
A preliminary comparison (people perception) Li-ion batteries PEMFCs PROS Good power density Good energy density PROS Green (?) High energy density CONS Charging time/rate Safety Materials disposal CONS Low power density Hydrogen storage Catalysts cost
Li batteries state-of-the-art and roadmap Global EV Outlook 2016, International Energy Agency, Paris Costs roadmap US DOE target: 125 $/kwh 2022 (10% every year reduction from 2016 to 2022) GM: <100 $/kwh 2022 Tesla: 100 $/kwh 2020
Battery roadmap (NEDO, 2009) At present, 265 Wh/Kg)
How to improve Li (ion, metal) battery energy density LiNi 0.5 Mn 1.5 O 4 Tarascon, Armand, Nature 2001 ZnO, nano-silicon, etc.
However D. Howell, U.S. DOE, 2012
Electric Vehicles Supply Equipments (EVSE) Global EV Outlook 2016, International Energy Agency, Paris
PEMFCs state-of-the-art and roadmap US Drive report 2013 (DOE sponsored)
PEMFCs costs: where can we work? Platinum is not the main concern! Costs for large-scale production are rapidly asymptotic! B.D. James, DOE Hydrogen and Fuel Cells Program Review, 2016
Batteries vs. fuel cells: on-the-road-comparison Model Year Cost (USD) Toyota Mirai Hyundai Tucson FC Honda Clarity FC Nissan Leaf Tesla S (75 kwh) Combined fuel economy (Km/L eq )** Range (Km) Fuel cost/year (USD) Sales 2016 58500 28.05 502 1250 2850 2017 599* 20.40 426 1700 n.a. 2017 369* 28.90 589 1250 n.a. 2012-2016 20000 48.98 172*** 600 250000 2016 69500 42.97 401 700 >100000 * Leasing (amount per month) ** Km per litre of gasoline (US EPA, October 2016) *** 2016 model, 30 kwh battery EV 0.1-0.3 Wh/Km
Critical issues: batteries Charge speed (30 claimed fast charge at 80%*) Safety Weight (about 1 Kg/km) Lithium? Tesla s Supercharger network, 350 sites, Feb. 2017 * Practical 50% in 20 (with possibly battery damage), Tesla s web site
Critical issues: fuel cells Low overall efficiency* (25%, EV s typical >40%) Low ORR efficiency (new catalysts required) High costs of vehicles and fuel No infrastructures Hydrogen refueling stations (2016) US: 23 (20 California) Japan: 80 Germany: 35 Typical cost: 1-2 $million each NREL Technical Report 2012 * Green Car Reports, 4 May 2017
Perspectives Maybe optimistic! Source: California Air Resource Board
Improving batteries Li-ion chemistries Anode: Intermetallics nanophase metal oxides tailored SEI Electrolyte (separator): High-voltage Polymer/ceramics Non-flammable Cathode High-voltage Tailored surfaces 2-electrons materials New chemistries Fraunhofer claimed 1000 km range in the medium term thanks to a new battery concept (EMBATT project, May 2017)
Improving PEMFCs More efficient catalysts (N-doped graphene, iron based) Cheaper proton-conducting membranes New fuels (bio-alcohols, ammonia?) VERY light materials for hydrogen-storage, working near r.t., to substitute compressed H 2.
Conclusions Batteries are expected to win during the next decades chiefly for 2- wheelers and small cars* Fuel cells are expected to dominate the high-energy automotive sector (trucks, buses, maybe mini-vans) * however, recharging at home with PV plants is unlike. In contrast, high-energy electric cars (e.g. Tesla 100) could work as electric buffers (storage systems) during the night to integrate the PV work.