# 1 

# Memo

To: 

# Docket EPA-HQ-OAR-2010-0799

From: 

# Joseph McDonald, U.S. EPA-OTAQ-ASD

CC: 

# Ed Nam, U.S. EPA-OTAQ-ASD

Date: 

# Tuesday, November 29, 2011

Re: 

# Barnett 2009 Citation

The attached document contains a copy of material s presented by Brian Barnett of TIAX LLC at the

U.S. DOE/EERE 2009 Vehicle Te chnologies Program Annual Merit Review, May 19, 2009.PHEV BATTERYCOST ASSESSMENTes_02_barnettBrian BarnettDavid OferYong YangBookeun OhJane RempelTIAX LLCMay 19, 2009Chris McCoyTodd RhodesMildred HastbackaSuresh SririramuluThis presentation does not contain anyproprietary, confidential, or otherwiserestricted information2009 DOE Merit Review1ObjectiveTIAX’s objective was to assess cost implications “at a high level” of selectedbattery chemistries being considered for PHEV applications.PHEV BatteryCost AssessmentsSelectedBattery Chemistries•Insight into the relative benefits of alternative chemistries•Identification of factors with significant impact on cell pack costs•Identification of areas where more research could lead tosignificant reductions in battery costResults:2009 DOE Merit Review2ApproachWe employed a parametric approach in which TIAX’s cost model was appliedmany times with different sets of input parameters.TIAXCost MODELINPUTSConstraints/AssumptionsAPPLICATIONANALYSES•Battery Chemistries•SOC range•Electrode loadings•Power output•Power input•Fade•Cell format•Nominal battery pack voltage•Energy required (20 mile range)•PHEV annual production•Single variable sensitivity•Multi-variable sensitivity•“What if?”•PHEV battery costs and cost ranges•Factors with significant influence on battery costOUTPUTS2009 DOE Merit Review3The input variables defining the “base case” scenarios were agreed with DOEand included (1) cathode material, (2) electrode loading, and (3) percent fade.4x1x2x2=16•The requested cost modeling factors produced 16 different scenarios to beconsidered.–Each scenario based on a state-of-charge (SOC) range of 80% (agreed with DOE)–Other cost factors varied as part of asensitivity analysis of each scenario–Costs to be estimated at a production volume corresponding to 500,000 vehicles/yr•Note that it is not clear whether targetpower and fade levels can be met at theseloadings and over the modeledSOC range for all chemistries.For a 5.5 kWh-usable Li-ion battery pack for PHEV, assessed theimplications to the battery cost of using the following cost modelingfactors and conditions:Battery Configurations Modeled & CostedCathode MaterialAnode MaterialElectrode LoadingPercent FadeGraphiteLow (1.5 mAh/cm2)0%30%High (3 mAh/cm2)NCANCMLiFePO4LiMn2O42009 DOE Merit Review4Since Li-ion batteries of the design and size considered in this study have notbeen manufactured and tested, several key assumptions were made (andagreed with DOE) about the battery performance.•Power Output:Peak power (40 kW for 2 sec., or 20 kWfor 100 sec.) is available from thebattery even at low battery state of charge(SOC). Low temperature performance was notconsidered.•Power Input:The battery can be recharged at thepeak rate (30 kW) except when thebattery is at a high SOC.•Battery Life:The battery is assumed to be able toachieve the life defined in each of theselected scenarios.–5.5 kWh usable:Each design scenario to yield 5.5 kWh of usable energy (for 1Cdischarge) at end of life after accounting for assumed SOC limitation and fade–Nominal Li-ion cell energy:Energy for full discharge at 1C following charging–Fade:-0% scenarios provide 5.5kWh of usable energy at end of life with 0% fade.-30% scenarios provide 5.5 kWh of usable energyat end of life with 30% fade (i.e., thebattery size is 9.8 kWh nominal to deliver5.5 kWh of usable energy at end of life).–SOC range:-10-90 % (i.e., battery size is 6.9 kWhnominal to deliver 5.5 kWh usable).•Format:cylindrical cellKey Study Parameters / Assumptions for All Chemistries2009 DOE Merit Review5For cell production, the TIAX cost model yields estimates for the cost ofgoods sold (COGS), i.e.,manufacturing cost, including capital costs.TIAX Cost Model for Large Format CellsMaterials and manufacturingcost estimates were based onproduction of cylindrical formatcells in high volume.2009 DOE Merit Review6For PHEV battery production, the cost model assumes a verticallyintegrated manufacturing process fromcell fabrication through completedbattery system.CellProductionBattery PackAssemblyBatteryElectronicsAssemblyVertically Integrated ManufacturePHEV BatteryCost(ex-works)Materials•Cell•Electronics•Thermal Components•Pack ComponentsBattery ThermalManagementAssembly•All supplied materials, e.g., cell materials, packaging components, are treatedas outside-purchased andinclude supplier mark-ups.•No “supplier” mark-up is included on in-process goods(e.g. cells to be assembled into packs).TIAX Cost Model for Large Format Batteries2009 DOE Merit Review7Note:The PHEV battery manufacturing cost analysis assumed use of “current”materials and “current” processing technology in high volume production.“Current” Materials“Current” ProcessingTechnologies(500k vehicles/year)Improved MaterialsExistingManufacturingTechnology“Current” MaterialsImprovedManufacturingTechnologyImproved Materialsand ManufacturingTechnology“Current”Future

“Current” FutureProcessingTechnologyMaterials TechnologyTIAX Cost Model Assumptions“Current” materials implies currently available materials used in commercial rechargeable battery applications, noneof which have yet been used in commercial scale production of PHEV batteries.“Current” processing technologies implies those adapted from high volume cylindrical cell (18650) production, soldinto portable power applications.Since these batteries haveyet to be developed, theability of the current batterytechnologies to meet allperformance requirements isuntested.Various materials evaluatedwere assumed to meetperformance requirementswithin the modeled systems.2009 DOE Merit Review8Cell designs are built up from specific electrode properties.•Materials properties•Electrode loading & formulation•Anode/cathode ratioCalculate the total area ofelectrode/separator stack-upthat gives the nominal cellenergyCalculate the electrode lengthand the cell diameter•Jelly roll height•Mandrel diameter•Cell can thickness & heightCalculate weights of all cellcomponents and total cellweightData on 1stcycle efficiency andaverage voltage and capacity atdifferent C-ratesSpecifiedMeasured*CalculatedCalculate the thickness, massand energy of a singlecathode/anode/separator stack-upCalculate the nominal packenergy, number of cells, andnominal cell energy•Pack voltage•Available energy•SOC range* A combination of TIAXmeasurements andliterature dataCell Designs2009 DOE Merit Review9Optimized cell designs will inevitably be determined by complexinterrelationshipsbetween operational requirements/characteristics and designparameters, factors that cannot be integrated into this study at this time.Chemistry(cathode, anode,electrolyte)Fade(battery life)SOC limitsElectrode Design(loading,composition)OperatingRequirements &Characteristics(rate, duty cycle,temperature)Cell Designs2009 DOE Merit Review10Key model inputs were identified and a likely range of values establishedfor each.20.016.012.0Cathode – LiMn2O4($/kg)25.020.015.0Cathode – LiFePO4($/kg)29.025.021.0Wage Rate ($/hr)100.0100.098.0Process Parameters (units)2.92.51.0Separator ($/m2)23.020.017.0Anode ($/kg)52.645.040.0Cathode – NCM ($/kg)53.940.034.0Cathode – NCA ($/kg)Material Cost Inputs (units)2.92.52.1Cell components ($/cell)24.521.518.5Electrolyte ($/kg)High ValueBaselineLow ValueCost FactorInput Parameters Baseline Values and Low/High Ranges“Baseline” values were used forsingle pointprojections of cell costs;low and high values were used in multi-variable sensitivity analyses togeneratecost probabilitycurves.Process Yield (%)2009 DOE Merit Review11Analyses of the sensitivity of battery cost to input parameters were performedin order to determine factors with significant impact on battery cost.•Single variable sensitivity analyses were carried out using Crystal Ball® riskanalysis software/ tornado chart tool*.•Single variablesensitivity analysis manipulatesone input variableat a time,measuring the impact on the output and displays the results on a “tornadochart”•A tornado chart ranks input parameters interms of their impact on the output.–Input parameters can be assumptions and/or decision variables–Chart provides a convenient way to determine the relative sensitivity of the results toan entire set of input parameters.* Crystal Ball®is a trademark of Decisioneering, Inc.,www.decisioneering.comSingle Variable Sensitivity Analysis Impact of Inputs on Output2009 DOE Merit Review12•Multi-variable analysis: all input parameters varied statistically over the identified range foreach•Result of multi-variable analysis: aplot of battery cost vs. probability (distribution of batterycosts)Multi-variable analysis allowed us to answer the question “what is the effect onbattery cost of a combination of variations (from baseline) in key inputparameters?”StatisticForecastValues $/kWhMean359.56Median359.64Standard Deviation13.53Minimum313.43Maximum414.00TIAX Baseline*361.80Multi-variable Sensitivity AnalysisExample:LiFePO4/ 3.0 Loading / 0% Fade(short electrode, zero fade)* The forecast value using only TIAX “base case” inputparameters. This forecast value is a “single point”projection of battery cost.Battery CostMulti-Variable Sensitivity Analysis2009 DOE Merit Review13To help understand if and how battery costmight be driven closer to $250/kWh,we developed four additional “what if” scenarios to test the impact of extremevalues of related input parameters.Increase coater speed by a factorof 10 from 5 m/min to 50 m/minDouble all manufacturing process speedsAll cathode and anode active materials cost $5/kgAssumption VariablesBaselineCasesMade in ChinaCasesLabor Rate ($/hr)250.67*Equipment Discount Factor (%)100%67%**NCA Cost ($/kg)$40.00$28.04NCM Cost ($/kg)$45.00$37.96“Made in China”1234“WHAT IF” Scenarios(applied individually to Base Scenarios)* Bureau of Labor Statistics, Department of Labor, " International Comparisons of Hourly Compensation Costs in Manufacturing2006“;published in 2008** The Boston Consulting Group white paper, " Made in China: Why Industrial Goods Are Going Next"“What If?” Analysis2009 DOE Merit Review14Cost of cathode active material is a somewhat less important factor in batterysystem cost than might have been thought.•Upfront cell design is a critical factor in battery cost.–Electrode loading (i.e., electrode length) seems to be more significant thancathode active material cost, within the ranges evaluated–Active materials’ influence on cell design has greater impact on battery costthandoes the (cathode) active materials’ cost itself.•Manufacturing processing speed mattersResultsPHEV battery configurations modeled inthis study resulted in battery costs(COGS) ranging from $264/kWh to $710/kWh, or $1452 to $3905 for 5.5 kWhusable power.** These cost ranges were the output from the statistical,multivariable sensitivity analysis.2009 DOE Merit Review15There is significant overlap in battery costs among the four cathode classes,with wider variation within each chemistry than between chemistries.Plots of the resulting ranges of battery costs,grouped by cathode active material, showsignificant cost rangeoverlap between thecathode classes, with battery costs“bottoming” just below $300/kWh,and showwider variation within each chemistry thanbetween chemistries.Range of modeled costs asidentified in the (multivariable) sensitivity analyses;each bar represents onescenario.Modeled Li-ion PHEV Battery Cost($/kWh at 5.5 kWh, usable)NCANCMLiFePO4LiMn2O4Results$0$100$200$300$400$500$600$700$800

Battery System Cost ($/kWh)Cathode – LiMn2O4($/kg)Cathode – LiFePO4($/kg)Cathode – NCM ($/kg)Cathode – NCA ($/kg)20.016.012.025.020.015.052.645.040.053.940.034.0Material Cost Inputs (units)High ValueBaselineLow ValueCost FactorMaterial Cost Inputs to TIAX Battery Cost Model for Baseline CostOutputs and for Sensitivity Analyses (Single & Multivariable)24 scenarios modeled ** TIAX added a third,intermediate electrodeloading to reflect theloading most likely torepresent the PHEV batterymodeled here, resulting in atotal of 24 differentscenarios to be analyzedand costed.2009 DOE Merit Review16The projected costs for PHEV batteries in this study conform with what mightbe expected from consideration of 18650-based Li-ion battery costs.•18650 cells are a standardized Li-ion design currently produced in volumesapproaching 1 billion cells/year worldwide, using the most highly automatedprocesses currently available in the industry.–This production volume corresponds to about 10GWh/year, or enoughvolume in terms of materials and electrode area to yield about 1 millionPHEVs/year.•Current Li-ion OEM 18650cell costsare in the $200-$250/kWh range, of whichabout 60% are the materials costs as supplied to battery manufacturers, i.e.,powders, metal foils, separators, etc.•18650 cells are primarily used inbattery packsfor laptops, for which OEM costsrange from $400/kWh to more than $700/kWh.Results2009 DOE Merit Review17Within the PHEV battery scenarios modeled and evaluated, cathode activematerial cost by itself is not a majorfactor in driving system cost changes.•As expected qualitatively, higher fade leads tohigher battery cost; lower cathode capacityloading (i.e., longer electrode length) leads to higher battery cost.•Our cost model shows quantitatively the influence of fade and electrode length on batterysystem cost and, by implication, the cost reduction potential of new electrode designs thatpermit shorter, thicker electrodes.•The results of an extreme “what if” analysis to test the impact of reducing the cost of activematerials by as much as 90% reveals theimpact on battery cost to be comparativelymodest.Results2009 DOE Merit Review18The “made in China” and “doubling speed of all manufacturing processes”scenarios resulted in greater battery cost reductions than “10x coater speed”or “$5/kg active materials” in the NCA-based scenarios.NCAFor each of these “what if” scenarios,battery cost is (still) above $250/kWh.Base Scenario(from Table, p. 78)Representative Example:Results2009 DOE Merit Review19Generally, battery system cost is a function of fade level and of electrodelength, i.e., battery cost increases with increasing % fade and/or increasingelectrode length.0% fade3.0 mAh/cm20% fade2.25 mAh/cm20% fade1.5 mAh/cm230% fade3.0 mAh/cm230% fade2.25 mAh/cm230% fade1.5 mAh/cm2NCABattery CostCathode ActiveMaterial Cost0% fade,Increasing electrode length30% fade,Increasing electrode lengthBattery cost ranges from a low of about $2000 to a high of about $3200(about $364/kWh to about $581/kWh).$0$500$1,000$1,500$2,000$2,500$3,000$3,500

Cost ($)Cathode Active Material Cost ($)Total Battery Cost ($)Example:Results2009 DOE Merit Review20Doubling the speed of all manufacturing processes noticeably decreasedbattery cost in most cases.•Analysis of the modeled battery scenarios reveals thatseparator costandcoaterspeedare significant factors in battery system cost.–Example: Modeled costs for NCA-based PHEV batteries range from a low of about$2000 to a high of about $3200 (about $364/kWh to about $581/kWh);increasedseparator cost aloneaccounts for more than 25% of that difference.–Single variable sensitivity analyses of modeled costs show thatseparator costandcoater speedare of equal or greater impact on battery system cost than cathodematerial cost.The ability to employ a wide SOC range contributes significantly to reducingenergy storage costs.•Lower fade and wider SOC range both reduce cost by resulting in lower requirednominal battery energy and smaller battery size.–For example, increasing the SOC range from70% to 80% reduces battery costs by about12%.–Materials that support a wide SOC range, therefore, should help to reduce overall batterycosts.Results2009 DOE Merit Review21For each candidate battery chemistry, theinter-relationshipsbetweenoperational requirements/characteristics and design parameters are factorsthat should be established experimentally.Chemistry(cathode, anode,electrolyte)Fade(battery life)SOC limitsElectrode Design(loading,composition)OperatingRequirements &Characteristics(rate, duty cycle,temperature)Future Work2009 DOE Merit Review22These results point to specific areas of research with potential for reductionsin battery cost.Future WorkMaterialsCell/ElectrodeManufacturing•Materials thatsupport high power,and a wide SOCrange•Materials thatprovide minimalfade, impedancegrowth and calendaraging•New chemistry andelectrode designspermitting shorter,thicker electrodes•In general, chemistriesand designs that enablelower overall electrodearea per battery andminimize battery size willreduce cost.•Identification and adoptionof advanced processingtechnologies to increasecoater speedand/orotherunit operations significantly-perhaps materials-enabled•Fundamentally differentelectrode preparationprocesses...while meeting target requirements for power and energy.