An Overview of Current U.S. DOE Hybrid Electric Systems R&D Activities

EVS28 KINTEX, Korea, May 3-6, 2015 An Overview of Current U.S. DOE Hybrid Electric Systems R&D Activities David Howell 1 1 Vehicle Technologies Program, EE-2G, U.S. Department of Energy 1000 Independence Avenue, SW, Washington, DC 20585, USA E-mail: David.Howell@ee.doe.gov Abstract Electric and hybrid vehicle technologies are critical to attaining the long-term U.S. objectives of energy independence and its associated benefits. The U.S. has actively supported the development of cleaner, more efficient automotive technologies over the long term. Further impetus for these efforts comes from several legislative mandates including parts of the 1975 Energy Policy and Conservation Act and its successive Acts. Over time, the U.S. has adopted specific strategies and policy initiatives to meet the goals set by such mandates. Accordingly, the U.S. Department of Energy (DOE), through its Vehicle Technologies Office (VTO) has supported the development and deployment of advanced vehicle technologies with electric drive systems often in close partnership with industry. This paper provides an overview of the current market adoption of HEV and EV vehicles in the U.S. and the associated VTO R&D and Deployment initiatives for accelerating their commercialization. It also highlights the many significant research breakthroughs resulting from R&D in the hybrid vehicle systems areas of research (with special emphasis on the advanced automotive battery research activities) funded directly or via collaboration by VTO. Keywords: EV, Energy Storage, HEV, R&D, Batteries 1 Introduction This paper provides an overview of the Fiscal Years (FYs) 2014 2015 Hybrid and Electric Systems (HES) R&D activities with special emphasis on its advanced automotive battery research funded by the Vehicles Technologies Office (VTO) of the U.S. Department of Energy (DOE). VTO spearheads the R&D needed for a new generation of electric-drive vehicles, by following a comprehensive research plan [1] which covers battery R&D, electric drive components, and vehicle & systems simulation & testing. Status updates on the Hybrid Electric Systems (HES) program R&D have been regularly provided at prior EVS meetings [e.g., 2-4]. VTO leverages significant resources to address the technical barriers which are preventing commercialization of electric drive vehicles (EDVs). VTO works with automakers and other industry stakeholders through partnerships such as the U.S. DRIVE (United States Driving Research and Innovation for Vehicle efficiency and Energy sustainability) to fund high-reward/high-risk research and enable improvements in critical components to enable more fuel efficient and cleaner vehicles. As shown in Table 1, there is significant U.S. commitment to HES and its FY 2015 budget of $142 million is nearly two and half times in size compared to its FY 2004 budget. EVS28 International Electric Vehicle Symposium and Exhibition 1

Table 1: Recent HES R&D budgets. Fiscal Year (FY) 2004 2005 2006 2007 2008 2009 HES Budget ($, Million) $57.3 $57.1 $55.6 $72.3 $92.1 $122.7 Fiscal Year (FY) 2010 2011 2012 2013 2014 2015 HES Budget ($, Million) $142.3 $145.8 $164.9 $156.4 $148.3 $142.0* *Presidential request 2 Goals, Barriers, and Strategies 2.1 Goals and Technical Barriers The commercialization of plug-in electric vehicles (PEVs) by making them costcompetitive with conventional internal combustion engine vehicles is an important VTO goal. This requires reducing the production cost of market-ready, high-energy, high-power batteries by 70% in near term and that of associated market-ready electric drive technology (EDT) systems at least 60% in the mid-term (compared with the 2009 costs). Technical targets for individual battery applications have been developed in collaboration with the United States Advanced Battery Consortium (USABC). Current targets for PEV batteries are included in the VTO program plan [1]. Additional performance targets (e.g., those for HEVs, EVs, and ultracapacitors) are available at the USABC website [5] and also in the VTO Energy Storage R&D annual progress report [6]. For the EDT and Vehicle Systems and Simulation Testing (VSST) the technical targets for peak power, costs, etc. can be found in the corresponding sections of the VTO multi-year program plan [1]. and technology development efforts by industry via cost-shared battery development efforts. These short- and long-term measures are described in greater detail in the next sections. 3 The EV Everywhere Grand Challenge DOE has in place a 10-Year Vision Plan entitled EV Everywhere Grand Challenge for facilitating the market feasibility of EDVs. EV Everywhere would enable American innovators to rapidly develop and commercialize the next generation of technologies achieve levels of cost, range, and charging infrastructure necessary for widespread EDV deployment. VTO collaborates with outside stakeholders and the DOE Office of Science, Office of Electricity, and the Advanced Research Projects Agency Energy (ARPA-E). The EV Everywhere Blueprint [7] describes the steps needed to meet its overall goal and additional technology-specific aggressive stretch goals developed in consultation with stakeholders across the industry. Figure 1 identifies the battery advancements necessary for commercial feasibility in EDV application. 4 Advanced Batteries R&D 2.2 Strategies Technology development in collaboration with industry partners can enable the rapid adoption of new technologies into production vehicles. VTO works with industry, universities, and national laboratories to support research on the nextgeneration energy storage and electric-drive technologies. To meet its EV/PEV goals and to speed up their commercialization, VTO utilizes a multi-pronged approach involving both near-term and long-term measures. An example of its nearterm measures includes its emphasis on clean energy initiatives like the EV Everywhere Grand Challenge [7] which focuses on the domestic production of cost-competitive PEVs. Over the longer term, the VTO R&D strategy involves funding topical research at national laboratories DOE supports energy storage R&D at multiple offices. These include the Office of Basic Energy Sciences (BES) (which does fundamental research to understand, predict, and control matter and energy at electronic, atomic, and molecular levels), ARPA-E (which conducts high-risk, translational research with potential for significant near-term commercial impact), the Office of Electricity Delivery and Energy Reliability (OE) (doing R&D on modernizing the electric grid, enhancing energy infrastructure, and mitigating impacts of supply disruptions), and the Office of Energy Efficiency and Renewable Energy (EERE) (supporting work on advanced clean, reliable, sustainable, and affordable technologies which would reduce energy consumption). EVS28 International Electric Vehicle Symposium and Exhibition 2

4X Cost Reduction 2X Size Reduction >2X Weight Reduction 2012 Battery Technology $600/kWh, 100 Wh/kg, 200 Wh/l, 400 W/kg 2022 Battery Technology $125/kWh, 250 Wh/kg, 400 Wh/l, 2,000 W/kg Lithium-ion batteries in today s electric drive vehicles use a combination of positive active materials based on nickel, manganese, or iron; matched with a carbon or graphite negative electrode. New concepts in lithium-ion technologies have the potential to more than double the performance and significantly reduce the cost. Beyond lithium-ion technologies (lithium metal, lithium sulfur, and lithium air) may also meet the challenge. Figure 1: Battery advancements needed to enable a large market penetration of PEVs. The R&D postures of various DOE offices are consistent with the applicable technology readiness levels (TRLs) of the supported technologies. Technologies at a lower TRL generally fall within the domain of BES and ARPA-E, whereas those at higher TRLs would generally be tackled by EERE. The EERE energy storage R&D projects (Table 2) cover a range of activities, from hardware development with industry to mid-term R&D and focused fundamental research all organized to complement each other. DOE maintains partnerships with the automotive industry through the USABC to support the development of such technologies. The goal is to help develop a U.S. domestic advanced battery industry making products which meet USABC goals. More information on individual energy storage R&D projects is available in the VTO Energy Storage R&D annual progress report [6]. 4.1 Advanced Battery Development A significant part of DOE energy storage R&D includes advanced battery development which includes systems and materials development projects. Private battery developers receive costshared funding for technology development. Several technologies developed partially under VTO-sponsored projects have moved into commercial applications over time. 4.2 Battery Testing, Analysis, and Design Another significant part of DOE energy storage R&D includes battery testing, analysis, and design. Battery technologies are evaluated according to the USABC Battery Test Procedures Manual (for EV batteries) [8], the Partnership for a New Generation of Vehicles (PNGV) Battery Test Procedures Manual (for HEV batteries) [9], or the PEV test procedure manual [10]. 4.3 Applied Battery Research The R&D program entitled Applied Battery Research (ABR) assists industrial developers of high-energy/high-power lithium-ion batteries meet the US-DRIVE long-term battery-level PEV energy density (~200 Wh/kg) goal, while satisfying cost, life, abuse tolerance, and lowtemperature performance goals. ABR projects cover materials development, calendar and cycle life studies, and abuse tolerance studies, utilizing the expertise of national laboratories, industry partners, and several universities toward this end. 4.4 Focused Fundamental Research The research activity called Focused Fundamental Research also called Batteries for Advanced Transportation Technologies (BATT) addresses fundamental issues of chemistries and materials associated with lithium batteries. EVS28 International Electric Vehicle Symposium and Exhibition 3

Table 2: An overview of EERE energy storage R&D projects in FY 2014 (from [6]). Project Area Project Topic Participants Advanced Battery Development USABC Battery Develoment Projects ENTEK, Envia Systems, JCI, Leyden Energy, LG Chem MI, Maxwell Technologies, Saft, SKI, Xerion Advanced Lithium Battery Cell Technology 3M, Amprius, Denso, OneD Material, PSU, Seeo, XALT Energy Low-cost Processing Research Applied Materials, JCI, Miltec UV International, Battery Testing, Analysis, and Design Applied Battery Research for Transportation Focused Fundamental Research Cost Assessments and Requirements Analysis Battery Testing Activities Battery Analysis and Design Activities Core Support Facilities Critical Barrier Focus: Voltage Fade in Lithium-, Manganese-Rich Layered- Layered Oxide Active Cathode Materials High Capacity Cell R&D: Improvments in Cell Chemistry, Composition, and Processing Process Development and Manufacturing R&D Cathode Development Anode Development Electrolyte Development Cell Analysis, Modeling, and Fabrication Diagnostics Beyond Lithium-Ion Battery Technologies Navitas, Optodot Corporation, SBIR ANL (2 proj), NREL (3 proj) ANL, INL, NREL, SNL CD-Adapco, EC Power (2 proj), GM, NREL (5 proj), ORNL, SNL ANL (3 proj), SNL ANL (5 proj), ORNL 3M, ANL, Envia, Farasis, PSU, TIAX ANL (2 proj), ORNL (3 proj), NREL ANL, BNL, LBNL (2 proj), ORNL (2 proj), ORNL, PNNL, UC San Diego, U. Texas ANL, Binghamton U., Drexel U., GM, LBNL, NETL, NREL, Penn State U., PNNL, Stanford U., Texas A&M U., UC Berkeley, U. Pittsburgh, SLAC ANL, Daikin, URI, Wildcat BYU, HydroQuebec, LBNL (3 proj), MIT (2 proj) ANL, BNL, LBNL (2 proj), PNNL, U. Cambridge ANL (2 proj), ORNL, PNNL (3 proj), UC Berkeley, U. Texas, BNL/Univ Boston, BNL, SLAC It attempts to gain insight into system failures and models to predict them, optimizes systems, and researches new and promising materials. It emphasizes the identification and mitigation of failure modes, materials synthesis and evaluation, advanced diagnostics, and improved models. Battery chemistries are monitored continuously with periodic substitution of more promising components based on advice from within this activity, from outside experts and based on assessments of world-wide battery R&D. The work is carried out by a team which includes the Lawrence Berkeley National Laboratory (LBNL) and several other national labs, universities, and commercial entities. More information on BATT appears at its website [11]. BATT has recently been reorganized and is transitioning into a new activity named the advanced battery materials research (BMR), more information on which will appear in future reports. 4.5 Energy Storage Collaborative R&D In addition to the R&D described above, many VTO-funded small business innovation research (SBIR) projects focused on new battery materials and components provide valuable support to EV and HEV battery development efforts. DOE also conducts extensive ongoing coordination efforts with other government agencies, e.g., the Chemical Working Group of the Interagency Advanced Power Group (IAPG) and technical meetings sponsored by other government agencies. DOE is a member of the Executive Committee of the International Energy Agency (IEA) Implementing Agreement on Hybrid and Electric Vehicles and participates in various Annexes of the Implementing Agreement. It attends the IEA Executive Committee meetings held in various countries and provides status updates on other implementing agreements. EVS28 International Electric Vehicle Symposium and Exhibition 4

5 Recovery Act Projects 5.1 ARRA Manufacturing Projects The American Recovery and Reinvestment Act of 2009 (ARRA) (Public Law 111-5) was an economic stimulus package enacted by the 111th United States Congress in February 2009. As part of its implementation, the U.S. provided $2.4 Billion in one-time manufacturing grants [12] to accelerate the manufacture and deployment of the next generation of U.S.-made batteries and EDVs. The awards, distributed across the U.S., included $1.5 billion in grants to U.S.-based manufacturers to produce batteries and components and expand battery recycling capacity. The manufacturing areas for these ARRA projects included material supply, cell components, cell fabrication, pack assembly, and recycling. Table 3 lists some of the facilities where these manufacturing projects are located. 5.2 Current Status of ARRA Projects Most ARRA manufacturing facility projects for battery/materials have been completed and production has begun at the associated facilities. Figure 2 shows a geographical distribution of the various U.S. advanced battery manufacturingassociated domestic capabilities developed over the last six years. It is observed that the number of large-scale manufacturers for such batteries went up from zero to eight. Similarly impressive gains are observed in the number of battery materials producers, start-up battery companies as well as major battery R&D facilities. Table 3: Current Production Status for Some Battery Facilities Funded by ARRA Grants. Type Company Facility Location (Status) Cell & A123Systems Cathode, cell, pack assembly, Livonia & Romulus, MI (in production) Pack Dow Kokam Cell & pack assembly, Midland, MI (Production in pre-buy-off run) Production East Penn Advanced Lead Acid battery in PA (in production) EnerDel Cell production & pack assembly at Fishers & Mt Comfort, IN (Commercial pack assembly cells sourced from Korean affiliate) Exide Advanced lead acid battery, Columbus, GA (in production) General Motors Battery pack assembly at Brownstown, MI (Successful start of regular production for the Chevrolet Volt EREV battery pack) JCI Cell production & pack assembly, Holland, MI (in production) LG Chem, MI Cell & pack capability, Holland, MI (Phase I facility in production) SAFT Cell production, Jacksonville, FL (in production) Cathode TODA Battle Creek, Michigan (in production) BASF Elyria, OH (in production) Anode EnerG2 Albany, OR (in production) FutureFuel Batesville, AR (in production) Pyrotek Sanborn, NY (in production) Separator Celgard Charlotte, NC & Concord, NC (in production) Entek Lebanon, OR (engineering scoping completed) Electrolyte Honeywell Buffalo, NY & Metropolis, IL (Li-salt pilot plant operational) Novolyte Zachary, LA (equipment installation) (BASF) Lithium Rockwood Lithium Silver Peak, NV & Kings Mountain, NC (lithium hydroxide in production) Cell Hardware H&T Waterbury Waterbury, CT (in production) EVS28 International Electric Vehicle Symposium and Exhibition 5

Figure 2: Progress in U.S. domestic advanced battery manufacturing capabilities (from 2008 2013). 6 Recent Highlights The following is a brief summary of the key battery R&D-related technical accomplishments resulting from funding by HES which are described in greater detail in the corresponding section of the VTO Energy Storage R&D annual progress report [6]. 6.1 Electric Drive Vehicle Market 6.1.1 U.S. Electric Drive Vehicle Sales The U.S. represents the world s leading market for electric vehicles and is producing some of the most advanced PEVs available today. Consumer excitement and interest in PEVs is growing, with sales continuing to increase, despite the recent drop in gasoline prices. In 2012, PEV sales in the U.S. tripled, with more than 50,000 cars sold. In 2013, PEV sales increased by 85% with over 97,000 vehicles sold. In 2014, PEV sales increased by 23% with annual sales of 118,773 PEVs recorded. 6.1.2 PEV Recognition Awards PEVs also have won critical acclaim with awards such as 2011 World Car of the Year (Nissan Leaf), 2013 Motor Trend Car of the Year (Tesla Model S), the 2012 Green Car Vision Award Winner (Ford C-MAX Energi), and a plug-in electric vehicle (Chevrolet Volt) beat all other vehicle models in Consumer Reports owner satisfaction survey for two consecutive years. 6.1.3 Commercialization Linkages A 2013 analysis by RTI International in Research Triangle Park, NC determined that DOE s $971 million R&D investment in advanced battery technology for electric drive of vehicles (EDVs) from 1991-2012 directly led to the EVS28 International Electric Vehicle Symposium and Exhibition 6

commercialization of the 2.4 million EDVs sold between 1999-2012 that incorporate nickel metal hydride and Li- ion batteries, which are projected to reduce U.S. fuel consumption by $16.7 billion through 2020. The study also found that VTOfunded research contributed to knowledge base in energy storage that resulted in 112 patent families in energy storage over the timeframe 1976 to 2012 and is ranked first in patent citations among the top-ten companies. 6.2.3 Si Nanowaire Breakthrough Amprius Inc s Li-ion battery cells containing silicon nanowire anodes (and following the strategy shown in Figure 3) provided 260Wh/kg (~50% more specific energy than SOA cells) and demonstrated good cycle life (less than 5-7% fade after 290 cycles). 6.2 Advanced Batteries 6.2.1 Commercial Applications Several technologies, developed partially under VTO-sponsored projects, have moved into commercial applications. Hybrid electric vehicles on the market from BMW and Mercedes are using Li-ion technology developed under projects with Johnson Controls Inc. (JCI). JCI will also supply Li-ion batteries to Land Rover for hybrid drive sport utility vehicles. Li-ion battery technology developed partially with DOE funding of a USABC project at LG Chem is being used in GM s Chevrolet Volt extended-range electric vehicle (EREV), the Cadillac ELR EREV, and also in the Ford Focus EV battery. LG Chem will also supply Li-ion batteries to Eaton for hybrid drive heavy vehicles. 6.2.2 PEV Battery Cost Reduction The 2014 DOE PHEV Battery Cost Reduction Milestone of $300/kWh has been accomplished. DOE-funded research has helped reduce the current cost estimates from three DOE-funded battery developers for a PHEV 40 battery average $289 per kilowatt-hour of useable energy. This cost projection is derived using material costs and cell and pack designs, provided by the developers, input into ANL s Battery Production and Cost model (BatPaC); the cost is based on a production volume of at least 100,000 batteries per year. The battery cost is for batteries that meet the DOE/USABC system performance targets. The battery development projects focus on high voltage and high capacity cathodes, advanced alloy anodes, and processing improvements. Proprietary details of the material and cell inputs and cost models are available in spreadsheet form and in quarterly reports. DOE s goals are to continue to drive down battery cost to $125/kWh by 2022. Figure 3: Amprius nanowires address swelling issue by allowing Si to swell. 6.2.4 Battery design Software GM/Ansys/ESim/NREL developed and released a battery design software suite to reduce battery development time and cost. The software package permits thermal response, cycle life modeling, abuse response modeling of battery cells and packs (Figure 4). Customers are currently using this tool for battery design. (other tools) ANSYS BATTERY DESIGN TOOL (ABDT) Workbench Framework and UI has files Field Simulation (Fluent) templates Reduced-Order Models (ROM) Simplorer UI System Simulation (Simplorer) templates Figure 4: Conceptual view ANSYS battery design tool. 6.2.5 Cathode Slurry Processing Johnson Controls Inc. demonstrated certain novel cathode slurry processing techniques (Figure 5) that reduced N-Methylpyrrolidone (NMP) solvent EVS28 International Electric Vehicle Symposium and Exhibition 7

use by 32% and increased coated electrode density by 31%. Figure 5: JCI s cathode slurry processing technique: a) Inline mixer b) Calendared electrode (inline mixed). 6.2.6 Novel Binders Miltec International Inc. developed stable, firstof-its-kind, UV curable binders for Li-ion cathodes and demonstrated novel cathode slurry processing techniques. The process reduced NMP solvent use by 100%, achieved cathode containing 87% NMC, and achieved cathode thickness and porosity similar to those of conventional electrodes (~60 mm and ~25%). Prototype cells retained 50% of their capacity after 2,000 1C/1C cycles. 6.2.7 R&D Funding Awards In January 2014, DOE released a Funding Opportunity Announcement (FOA) that solicited proposals in the areas of energy storage, electric drive systems, lightweight materials, and auxiliary load reductions in support of the EV Everywhere Grand Challenge. In August 2014, DOE announced the selection of 19 new projects. The nineteen projects are aimed at reducing the cost and improving the performance of key PEV components. These include improving beyond Li-ion technologies that use higher energy storage materials, and developing wide bandgap (WBG) semiconductors that offer significant advances in performance while reducing the price of vehicle power electronics. Other projects focus on advancing lightweight materials research to help EVs increase their range and reduce battery needs, and developing advanced climate control technologies that reduce energy used for passenger comfort and increase the drive range of plug-in electric vehicles. Specifically, in the area of advanced batteries, 9 projects totaling $11.3 million, were awarded for beyond-lithium-ion battery technologies, including polycrystalline membranes, nanomaterials, high-capacity cathodes, Li-air batteries, Li-sulfur batteries, and electrolyte chemistries. All these projects were initiated in September 2014. In August 2014, DOE awarded 14 projects under its Incubator Program with small businesses and universities. Specifically, in the area of energy storage, DOE awarded 6 projects totaling $7.4 million related to battery design and manufacturing advancements. 7 Future R&D Directions Battery development projects on transformational technologies have the potential to significantly reduce the cost of HEV and micro-hybrid vehicle batteries and are therefore expected to continue. These include development of robust prototype cells containing new materials and electrodes offering a significant reduction in battery cost over existing technologies. R&D will also continue to expedite the development of more efficient electrode and cell designs and fabrication processes to reduce the cost of production of large format lithium-ion batteries. Pack-level innovations will continue to be sought to reduce the weight and cost of thermal management systems, structural and safety components, and system electronics (currently, non-active components of a battery can increase the volume and account for up to 70% of the battery weight), and to reduce the cost of the finished product. To further accelerate the market entry of advanced batteries, DOE will continue to support the scaleup, pilot production, and commercial validation of new battery materials and processes. (New materials for advanced cathodes, anodes, and electrolytes developed by universities, national laboratories, and industry are often limited in scope because of inability to commercially scaleup such materials.) Studies of recycling and reuse of lithium batteries will also continue. A larger portion of battery research will focus on beyond-lithium-ion battery technologies with the potential of having very high energy and low cost. Examples include solid-state (lithium metal with solid electrolytes), lithium sulfur and lithium air batteries. These promise two to five times higher theoretical energy densities than traditional Liion. Research is also needed to advance certain next generation non-lithium couples technologies (e.g., magnesium, zinc) from university/ laboratory arena to industrial development by developing/testing full cells. Table 4 contains a list of the many technologies being investigated or likely to be investigated as part of future R&D on advanced batteries. The two research areas listed in that table are described in greater detail below. EVS28 International Electric Vehicle Symposium and Exhibition 8

Research Area Next generation Liion batteries Beyond Li-ion batteries Table 4: List of future research topics for R&D related to advanced batteries. Research Topics New high voltage/high capacity cathodes High energy alloy anodes New and improved alloy anodes Advanced and novel electrolytes Separators Manufacturing innovations Enhanced abuse tolerance Improved thermal management Computer aided battery designs Fundamental issues associated with cycling Li metal anodes and potential solutions to those issues (coatings, novel oxide- and sulfide-based glassy electrolytes, and in situ diagnostics approaches) Additional issues for cathodes (stabilizing, polysulfides, smaller hysteresis, better rate, and better reversibility), anodes (Li metal interface, combatting formation of mossy lithium), and electrolytes (flammability, stability, solid electrolyte, etc.). Other beyond-lithium-ion research areas 7.1 Next Generation Li-ion Battery R&D This area s goal is to advance the performance of materials, designs, and processes that significantly improve the performance and reduce the cost of Li-ion batteries using a non-metallic anode. Specific areas of investigation include highenergy anodes (e.g., containing Si or Sn), high voltage cathodes, high voltage and non-flammable electrolytes, novel processing technologies, high energy and low cost electrode designs, and others. salt is known to react almost instantly with water, producing HF, which in turn attacks nearly all elements of the cell. This reaction contributes to the challenges in Li-ion cells high temperature capability. Work on new electrolytes and additives is focused on one or more of the following possible improvement areas: high voltage stability; high temperature stability, low temperature operation; abuse tolerance; lower cost; and possibly longer life through SEI stabilization. 7.1.1 High Voltage Cathodes The work on advanced cathodes primarily focuses on the Li-Mn rich oxide materials of general formula xli 2 MnO 3 (1-x)LiMO 2 (M = Ni, Mn, Co), the 5V spinel materials (LiMn 1.5 Ni 0.5 O 4 ), traditional NMC operated at higher voltages, and, to a lesser extent, on the higher voltage silicates and phosphates. Figure 6 shows the theoretical specific energies of some of the main cathode materials under investigation. 7.1.2 Advanced and Novel Electrolytes Current electrolytes typically include a blend of cyclic and linear carbonate solvents and LiPF 6 salt, and provide good performance and stability. However, the solvents are highly flammable with typically a high vapor pressure, causing them to out gas at elevated temperatures, building up pressure within cells over time. Also, the LiPF 6 Figure 6: Theoretical Cathode Energy Densities (LFP = Li iron phosphate, NMC = nickel, manganese, cobalt oxide, LNMO = 5V Ni Mn spinel, LCP = lithium cobalt phosphate, Li-Mn rich oxides). EVS28 International Electric Vehicle Symposium and Exhibition 9

The exploratory materials program is supporting seven electrolyte projects which are developing plastic-like glassy electrolytes; flame retardant liquid electrolytes; single ion conductor electrolytes (which would enable the use of much thicker electrodes); new salts providing better high temperature stability; and electrolytes that enable much lower temperature operation (see Figure 7) as well as theoretical investigation into high voltage stability and electrolyte blends that may lead to more stable SEIs on graphite. Work will continue on new flame retardant electrolyte additives, new inflammable solvents, and new salts that offer improved high temperature stability. Specific additives will be sought to help stabilize the SEI on alloy anodes, and to stabilize the surface of high voltage cathodes like LiMn 1.5 Ni 0.5 O 4. Figure 7: Discharge Capacity for a Baseline Electrolyte (left) and an Improved Methyl Proprionate Electrolyte (right) for Cells Cycled from C/10 to 5C. 7.1.3 Separators Current work is focusing on developing separators that provide enhanced abuse tolerance, better high voltage stability, and improved low temperature operation. Some of the technologies being developed include a ceramic impregnated separator that shows much improved low temperature performance and greatly increased high temperature melt integrityand a separator and process to permit direct deposition onto anode and/or cathode sheets. 7.1.4 Manufacturing Innovations Manufacturing costs can be a significant fraction of cell and system costs. DOE and U.S. DRIVE are investigating manufacturing techniques that have potential to increase cell performance while reducing cost, including: new UV and EV curable binders to permit faster and less expensive slurry drying; use of aqueous or dry binding technologies; and fast formation techniques. In the laboratory programs, researchers are investigating technologies to produce very thick (1 mm vs. 100 µm) electrodes with aligned pores; spray pyrolysis techniques for active material production; and new diagnostic technologies to investigate manufacturing techniques in situ. 7.1.5 Enhanced Abuse Tolerance The design of abuse tolerant energy storage systems begins with the specification of relevant abuse conditions and the desired responses to those conditions. The advanced material and cell programs fund projects to improve the intrinsic stability of Li-ion battery chemistries through development of new materials, and characterization of advanced commercial materials. Some of those research topics include coated cathodes and anodes, non-flammable electrolytes, solid polymer and glassy electrolytes, ceramic coated or impregnated separators, and overcharge shuttles and polymer overcharge protection materials. Researchers are also evaluating polymer materials that conduct electricity above a certain potential, thus providing an overcharge protection mechanism. An overcharge shuttle appropriate for Li iron phosphate batteries has been developed and licensed by Argonne. Coatings and concentration gradient cathode materials are also being developed with the goal of enabling higher voltage operation and enhancing abuse tolerance of Li-ion batteries. Also, phosphazene based electrolytes are being developed at INL and tested at SNL and are showing promise in reducing the EVS28 International Electric Vehicle Symposium and Exhibition 10

heat released during thermal runaway. Developers have developed a heat resistant layer to enhance the cells ability to avoid internal shorts; coated and ceramic impregnated separators to guard against internal short circuits; and novel thermal management technologies to closely control the temperatures that cells are exposed to. There are certain additional activities also, e.g.: preparing a Permanent SEI. The use of novel thermal management approaches could both manage the battery s temperature and potentially reduce overall cost. 7.1.6 Computer Aided Battery Design (CAEBAT) DOE has supported the development of Computer Aided Battery Design software with the goal of developing an integrated suite of battery design software tools. Electrochemical performance simulations and thermal design software are being improved and integrated to form a full battery design suite. 7.2 Beyond Li-Ion Battery R&D Beyond Li-ion technologies, such as Li/sulfur, and Li/air, offer a further increase in energy and potentially greater reductions in $/Wh compared to next-gen lithium ion batteries. However, these systems require many more breakthroughs, some on a fundamental material level, before they can be considered for real-world use. DOE is investigating the fundamental issues associated with cycling Li metal anodes as well as potential solutions to those issues. The main research topics for these investigation include: coatings, novel oxide and sulfide-based glassy electrolytes, and in-situ diagnostics approaches to characterize and understand Li metal behaviour during electrochemical cycling. Researchers are developing two separate electrolytes for Li/air systems; investigating the role of catalysts on Li/air cathode reversibility and hysteresis; novel carbons for Li/air cathode applications; novel sulfur cathode architectures based on mesoporous carbons; and polysulfide solvents to manage polysulfide concentrations in the electrolyte. Researchers in the advanced cell R&D program are also developing and testing a series of organosilicon electrolytes in Li air cells. Work by developers is focused on commercializing a block copolymer electrolyte that impedes Li dendrite formation (this technology has shown thousands of cycles with little capacity degradation, and has also shown good abuse tolerance through testing by independent third parties). Other work is progressing on a nanocomposite sulfur cathode (with accompanying electrolyte) (see Figure 8); and on a silane based electrolyte for use in Li/S cells. Figure 8: Performance of a Li/S Cell with a New Electrolyte Developed by the Team of Penn State University, EC Power, Johnson Controls Inc., and Argonne National Laboratory. The challenges facing beyond lithium-ion battery systems are numerous, with issues remaining on the cathode, the anode, and the electrolyte. Some of the research that will be pursued in coming years includes: Efforts to stabilize the lithium metal interface during cycling. (Options to be evaluated include coatings, dopants, solid glassy electrolytes, electrolyte dopants, and others.) Expand and evaluate options for stabilizing the sulfur cathode. Recent attempts in the literature include core/shell like approaches and egg/yolk structures to isolate the polysulfides from direct contact with the electrolyte, the use of mesoporous carbon to slow the dissolution of polysulfides, and search for solvents to remove lithium sulfides from the anode interface. Fundamental investigation of reaction mechanisms and dynamics on the air cathode (likely in collaboration with the recently awarded Energy Storage Hub team). Impact of carbon structure and pore distribution on air cathode performance. Low cost catalysts for air cathodes. New electrolytes for air and sulfur batteries Use of highly volatile liquid electrolytes. In addition to the specific technical topics listed above, multi-valent materials, like Mg, EVS28 International Electric Vehicle Symposium and Exhibition 11

may be investigated along with other non-li systems like Na, Zn, or Al. 8 Conclusions DOE Vehicle Technologies R&D activities for hybrid electric systems include advanced batteries (which this paper focuses on), electric drive components, and simulation and testing for transportation applications and currently emphasize PEVs. The past successful commercialization of DOE-funded batteries is a testimony to the success already achieved by its cooperative programs. Future advances in HES technologies will be leveraged with progress in other enabling technologies (e.g., heat engines, lightweight materials, and fuels) to accomplish challenging VTO goals. The Program will continue to reassess longer-term candidate technologies for propulsion systems promising performance, life, and cost benefits. References [1] Office of Vehicle Technologies, Vehicle Technologies Multi-Year Program Plan, 2011-2015 http://www1.eere.energy.gov/vehiclesandfu els/pdfs/program/vt_mypp_2011-2015.pdf, accessed on 2015-01-20. [2] Howell, D., Current Fiscal Year (2012 2013) Status of the Hybrid and Electric Systems R&D at the U.S. DOE, the 27th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium (EVS27), Barcelona, Spain, November 17-20, 2013. [3] Howell, D., Hybrid and Electric Systems R&D at DOE: Fiscal Year 2011-2012 Status, the 26th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium (EVS26), Los Angeles, California, May 6-9, 2012. [4] Howell, D., FY 2009 Status Overview of D.O.E. Hybrid and Electric Systems R&D, the 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition, Shenzhen, China, Nov. 2010. [5] United States Advanced Battery Consortium (USABC)/ USCAR, http://www.uscar.org/guest/teams/12/u- S-Advanced-Battery-Consortium-LLC, accessed on 2015-01-20. [6] Vehicle Technologies Office, Energy Storage R&D, Fiscal Year 2013 Annual Progress Report, United States Department of Energy, Washington, DC, January 2014. [7] The EV Everywhere Grand Challenge Blueprint, http://energy.gov/eere/vehicles/downlo ads/ev-everywhere-grand-challenge-blueprint, accessed on 2015-01-20. [8] United States Advanced Batteries Consortium, USABC Electric Vehicle Battery Test Procedure Manual, Rev. 2, U.S. D.O.E., DOE/ID 10479, January 1996. [9] U.S. Department of Energy, PNGV Battery Test Procedures Manual, Rev. 2, August 1999, DOE/ID-10597. [10] U.S. Council for Automotive Research, RFP and Goals: Advanced Battery Development for PEVs, http://www.uscar. org/, accessed on 2015-01-20. [11] Berkeley Electrochemical Research Council, Batteries for Advanced Transportation Technologies, Lawrence Berkeley National Lab, http://batt.lbl.gov/home/, accessed on 2015-01-20. [12] The White House Press Release, Grants to Accelerate the Manufacturing and Deployment of the Next Generation of U.S. Batteries and Electric Vehicles, August 5, 2009. http://www.whitehouse.gov/the-pressoffice/24-billion-grants-acceleratemanufacturing-and-deployment-next-generationus-batter, accessed on 2015-01-20. Author David Howell Program Manager Hybrid Electric Systems Vehicle Technologies Office U.S. Department of Energy 1000 Independence Avenue, SW Washington, DC 20585 (USA) Tel: 202-586-3148 Fax: 202-586-2476 Email: David.Howell@ee.doe.gov EVS28 International Electric Vehicle Symposium and Exhibition 12