Provide analysis to support the EV Everywhere Grand Challenge and the DOE/United States Advanced Battery Consortium (USABC) identification of battery available energy, mass, volume, cost, discharge power, and charge power requirements that will enable broad commercial success of battery electric vehicles (EVs).
Technical Barriers
Current USABC EV battery targets were developed more than 20 years ago.
Documentation on their development is scarce, and the necessary vehicle performance for market success has changed since their creation.
Accomplishments
Developed a simulation-based approach to calculate EV battery technology requirements necessary to deliver the vehicle level
performance required for commercial success of EVs.
Implemented the process across a range of inputs and provided results to the USABC and to DOE for finalizing inputs and assumptions.
Introduction
EVs offer significant potential to reduce the nation’s consumption of gasoline and production of greenhouse gases as identified in the DOE EV Everywhere Grand Challenge. However, one large impediment to the commercial success and proliferation of these vehicles is limited battery technology. EVs on the market today come with a significant cost premium relative to their conventionally powered counterparts, even after significant federal and state purchase incentives. In addition, the range of the vehicle is typically restricted by limited battery energy to less than 100 miles. Furthermore, when an EV is based upon a platform designed for a conventional powertrain, the size of the battery necessary to achieve this limited range often subtracts from available passenger or cargo volume.
Improvements in battery technology have the capacity to resolve all of these issues. Accordingly, in support of Administration’s EV Everywhere Grand Challenge, DOE’s Vehicle Technology Office, working with USABC and others are directing significant resources towards the development of batteries for EVs. Historically, these developments have been focused towards a set of DOE/USABC EV battery targets developed more than 20 years ago. Documentation providing insight into the development of these targets is exceptionally scarce; thus, the justification for these values is unclear. For this reason, and on the basis that the necessary vehicle performance for market success has changed since the creation of the original targets, there is motivation to develop an updated set of EV battery technology targets.
In 2012, the USABC and DOE began the process of creating a new set of battery technology targets for EVs. It was desired that the requirements be designed to deliver an EV capable of broad market success in support of the EV Everywhere Grand Challenge. To this end, the resources provided by DOE VTO to the National Renewable Energy Laboratory (NREL) were leveraged to supply detailed technical analysis, guided by the insight of the USABC’s vehicle original equipment manufacturers (OEM) on consumer requirements and future technology trends.
IV.A.7 USABC Battery Technology Targets for BEVs Neubauer – NREL
Approach
The objective of this analysis is to support USABC and DOE identification of battery available energy, mass, volume, cost, discharge power, and charge power requirements that will enable broad commercial success of EVs. Working closely with USABC and DOE, NREL has developed a simulation-based approach to achieving this objective.
It begins by first specifying the relevant vehicle- level performance requirements necessary for commercial success; most relevant to this analysis are acceleration and range. Next, we select a vehicle platform with broad market appeal and define its mass and aerodynamic properties using forecasted values for our timeframe of interest. At this point, we calculate the required energy and power to meet our range and acceleration targets, then analyze the charge and discharge power requirements of varying durations
across multiple drive cycles using vehicle simulation software. Finally, we calculate available battery mass and volume, followed by allowable battery cost to provide cost-parity with a comparable conventionally powered vehicle. We leverage OEM input via the USABC throughout to ensure that all assumptions are relevant to the anticipated level of future vehicle technology and market expectations.
Results
At the request of the DOE and USABC, we applied this approach to multiple vehicle platforms (compact car, midsize sedan, and small SUV) and vehicle ranges (150 and 300 miles). For each vehicle platform we defined the total vehicle mass using a vehicle mass factor parameter (the ratio of total EV mass to total conventional vehicle mass) and varied this as well. Some high level results are shown in Figure IV - 29.
Figure IV - 29: Required end-of-life (EOL) pack specific energy and energy density as a function of vehicle range, platform, and mass factor
We have also simulated these configurations to
Neubauer – NREL IV.A.7 USABC Battery Technology Targets for BEVs
Figure IV - 30: Discharge (top) and charge (bottom) power requirements for a mid-size sedan with a vehicle mass factor of 1.2. In addition, cost requirements were calculated and
implications for beginning-of-life cell-level targets were extrapolated. All of this data was presented to USABC to support their target setting process.
Conclusions and Future Directions
This project successfully analyzed EV battery targets and the findings were provided to DOE and USABC. USABC subsequently selected new targets for its EV battery technology development programs using this input, which have been published10. To conclude
10 Please see the EV requirements listed in Chapter II of this report and those listed at the USCAR website (http://www.uscar.org/guest/article_view.php?articles_i d=87).
this work, NREL plans to publish on its target analysis process to guide future target-setting efforts.