Vehicle Battery R&D Progress and Future Plans Tien Q. Duong Office of Vehicle Technologies U.S. Department of Energy KSAE and IEA IA-HEV International Symposium on Electric Mobility and IA-HEV Task 1 Information Exchange Meeting 30 April 2015
Charter Objective Advance the development of batteries and other electrochemical energy storage devices to enable a large market penetration of electric drive vehicles. Target Applications 12V Start/Stop Power-Assist Hybrid Electric Vehicles (HEVs) Plug-in Hybrid Electric Vehicles (PHEVs) Battery Electric Vehicles (EVs) Drivers Energy security Greenhouse gas emissions reduction CAFE Standard 54.5 MPG for all light duty vehicles (effective 2025) 2
Vehicle Technologies Office: Battery R&D Activities Advanced Battery Materials Research (BMR) Applied Battery Research (ABR) Advanced Battery Development/USABC Novel Materials Advanced Models & Diagnostic Tools Cell Design and Optimization Prototype Development & Optimization Cycle Life Improvement & Cost Reduction Anodes (>600 mah/g) Cathodes (250+ mah/g) Electrolytes (>4.3 Volts) 4 10 mah cells Cell Targets 350 Wh/kg 750 Wh/l 1,000 C/3 cycles 250 Wh/kg 400 Wh/l 2,000 W/kg 0.5 1.0 Ah cells 5 40+ Ah cells 3
EDV Sales U.S. Electric Drive Vehicle Sales, by Technology (1999-2014) 700.000 600.000 500.000 400.000 Li-ion PHV/EV Li-ion HEV NiMH HEV Light-duty Trucks NiMH HEV Cars 300.000 200.000 100.000 - Year 2.65 GWh of Lithium-ion Batteries were installed in Electric Drive vehicles sold in the USA in 2014. 4
Future Battery R&D Advanced Battery Chemistries Extensive cost modeling has been conducted on advanced battery chemistries using the ANL BatPaC model. These are the best case projections: all chemistry problems solved, performance is not limiting, favorable system engineering assumptions, high volume manufacturing Projected Cost for a 100kWh Battery Pack USABC EV 45kWh use Source: ANL BatPaC 5
Advanced Battery Materials Research (BMR) Program Previously known as: Batteries for Advanced Transportation Technologies (BATT) Exploratory Technology Research (ETR) 10 Topic areas, 52 research projects Electrode modeling, diagnostics, cell analysis, silicon anodes, cathodes, liquid electrolytes, metallic lithium & solid electrolytes, sulfur electrodes, lithium air and sodium ion batteries. Participants include universities, national laboratories, and industry. Funding mechanisms: Annual Operating Plan (AOP) process via Lab Call for the national laboratories. Federal opportunity announcements (FOAs) for awards to universities and industries. 6
Fundamental advances in Si anodes Emphasis: Generate high-capacity reversible Si with good rate capability and cycle life Challenges: Large first-cycle irreversible loss 100 nm Low loading/areal capacity Large capacity fade Poor coulombic efficiency Inferior rate capability Approaches: Novel architectures: Nanotubes (NTs), Nanowires, core-shell structures, composites Si Nanotube: HRTEM Si pomegranate structures demonstrating exceptional stability over >500 cycles Functional coatings: Metals, oxide coatings, Li + and e - conducting ceramics, carbon based systems Binders: High strength and elastomeric polymers Electrolyte additives: VC, FEC Only 2 wt% PFM conductive binder needed to obtain stable capacity in SiO anodes Reactive molecular dynamics simulations of the lithiation of Si-core/SiO 2 -shell nanowires showing immediate lithiation of the SiO 2 shell without volume expansion, then lithiation of the Si core 7
Towards Commercialization of Si anode - SiNANOde TM Production process using battery grade graphite as direct substrate for Si nanowire growth Cost effective and high Si throughput Improves dispersion within slurry and drop in process Si-C conductivity improvement Tailored Si Weight % or anode specific capacity ~ 500-1600 mah/g High electrode loading (1.5g/cm 3 ) Good cycling performance up to 1,000 cycles SiNANOde TM material deforms to fill void areas in carbon anode material matrix SiNANOde TM material remains intact and fully functional after 100% DoD cycling Thin SEI formed on Si nanowires 8 8
Voltage vs. Li, V Advanced Cathodes Challenges: Limited by the cathode performance materials changed little over 20 years. Current cathodes are limited to 4.3V electrolyte oxidation at high voltages. Excess Li materials show promise but are not ready for prime time due to issues with voltage fade, high impedance, and low tap density. Discharged Li/TM Li/TM Discharged Hysteresis Li/TM Voltage Fade Charged Approach: Understand reactivity at voltages above 4.3V and design new materials 4.8 4.4 4 2-4.7V, RT, after 1 cycle 2-4.7V, RT, after 80 cycles Electrolytes to operate at high voltages Additives to form artificial coatings on cathodes Inorganic coatings to protect the cathode 3.6 3.2 2.8 Understand phase transformation in excess Li cathodes to design better materials. 2.4 2 0 0.4 0.8 1.2 1.6 2 Capacity, mah/cm 2 9
LMR-NMC LMR-NMC NCA Voltage Fade in LMR-NMC Necessitates Compromise LMR-NMC: Still the best option 990 LMR-NMC, 2-4.7 V Wh/Kg oxide 880 770 660 NCA, 2-4.25 V Optimized LMR-NMC, 2-4.6 V LMR-NMC, 2-4.30 V 4.70 4.25 4.25 Voltage vs. Graphite NMC, 2-4.25 V 550 0 5 10 15 20 Cycle Number Source: ANL BatPaC LMR-NMC, with no voltage fade, has the same energy density as NCA but is less expensive. 10
Li Metal Anode Opportunity Dramatic increases in specific and volumetric energies possible. Objectives Key technical hurdle is to prevent the gradual loss of lithium and impede dendrite formation while providing adequate power. This will be addressed through: Improved understanding of the chemical and physical processes that consume lithium at the electrode-electrolyte interface Electrolyte additives to prevent dendritic Li growth Engineered barrier materials, solid or liquid electrolytes, to stabilize the anode-electrolyte interface Before cycling (with SEI layer) 10 cycles Evolution of an SEI Layer on Cycling of a Metallic Lithium Electrode (scale bars represent 100 microns) Source: ORNL 11
Li Metal Anode (2) BlueCar Electric Vehicles with Lithium Metal Battery Started in 2011, currently over 2,000 BlueCar vehicles available for rental from Autolib one-way car sharing in Paris. Technology is based on Li 0 /PEO/LiFePO 4 operating at 60 /80 C Batteries (30 kwh) are currently manufactured in: Boucherville, Montreal Brittany, France Demonstrated 3,000 cycles when discharged to 50% DOD Energy density: 100 Wh/kg 12
Li Metal Anode (3) Approach Study the use of Cesium salts and organic additives to typical carbonate solvents to impede dendrite formation (PNNL). Apply interfacial layers between lithium metal and electrolyte to stabilize the lithium surface upon cycling (Stanford University). Source: Stanford University, SLAC Stable lithium metal cycling enabled by interconnected carbon hollow spheres. (a) Fabrication process (b) SEM images. (c) Cycling performance of lithium metal with (solid) and without (open) hollow carbon coating at different current densities 13
Solid Electrolytes Barriers Not all are stable against lithium Have relatively poor ionic conductivity Exhibit inherently very large interfacial impedance Brittle and difficult to fabricate Approach Perform mechanical studies through state-of-the-art nano-indentation techniques to probe the surface properties of the solid electrolyte and the changes occurring to lithium (ORNL, UTK, UM). Develop composite electrolytes (polymer and ceramic electrolytes) investigate lithium ion transport at the interface to study the effective ionic conductivity achievable for the composite membrane (ORNL). Identify the relation of defect types that could impact the current density limit in Garnet-based electrolytes (UM). Computationally and experimentally study the interfacial structureimpedance relationship in Garnet-based electrolytes to design new materials (U Maryland). 14
Solid Electrolytes: Interfacial Impedance Li metal Porous cathode Focus: Quantify impedance at the interface of SIC and liquid electrolyte Single Ion Conductor (SIC) Organic electrolyte Custom cell to extract interfacial impedance Source: LBNL Ohara glass LICGC 15
High Interfacial Impedance: Potential Show Stopper LiPF6 in EC/DEC Typical Li-ion resistance High impedance not a function of concentration or nature of electrolyte Typical electrode is highly porous: Large area for ion transfer From: Ohara data sheet Ceramic separators have lower area: Impedance caused by area difference? 1 6 Source: LBNL 16
Summary Vehicle Technology Office continues to work closely with USABC, Industry, Academia and the National Laboratories to advance battery technologies. Advanced Battery Materials Research (BMR) Program underwent a recent name change Previously known as BATT, ETR Name better reflects the materials focus of the program 10 Topic areas 52 Research projects Annual Merit Review Meeting Crystal Gateway Marriott, Crystal City, VA June 9-11, 2015 Showcase 35 oral presentations of the BMR program 17
Thank you for your attention! 18