Argonne is a major player in the Department of Energy's (DOE's) PHEV energy storage research and development (R&D) program. DOE has implemented a relatively new program to develop plug-in hybrid electric vehicle (PHEV) technologies, with the goal of achieving the equivalent of a 40-mile all-electric driving range.
The key enabling technology needed to achieve this goal is a more optimal energy storage system. Argonne is a major player in DOE's PHEV energy storage R&D program. Argonne's activities in support of this DOE program include:
- Support for establishing energy storage requirements and baseline performance characteristics
- Transition DOE's applied R&D program to focus on Li-Ion battery materials and cell chemistries for PHEV applications
- Develop advanced electrode and electrolyte materials that will significantly increase the energy density and enhance the inherent abuse tolerance of Li-Ion batteries.
Energy Storage Requirements and Baseline Performance
Early in the PHEV program, DOE purchased several prototype Li-Ion PHEV batteries developed by Johnson Controls-Saft (JCS) for use in an Electric Power Research Institute (EPRI)-funded PHEV van demonstration program. Based on the specifications for these batteries, Argonne utilized its experience with a similar cell chemistry to develop a model of this prototype battery and then extended the model to design batteries with a range of power-to-energy ratios that could be produced using this same Li-Ion cell chemistry.
This battery model was then used in Argonne's PSAT vehicle simulation model to study PHEV vehicles with different all-electric range capabilities, to study alternative operational strategies, and to establish requirements for energy storage systems in different PHEV applications.
The results of this study were used to help establish the preliminary energy storage requirements for PHEVs made public by the United States Advanced Battery Consortium (USABC) and DOE. Model validation was performed once the JCS batteries were received and tested. Cells from one of the JCS batteries remain under test to establish baseline performance and life characteristics for this cell chemistry in a PHEV application.
The expertise and capabilities used in this study can help DOE, the USABC and battery developers study and better understand the many design and engineering trade-offs that would lead to an optimal battery system for a given cell chemistry.
Transition DOE's Applied R&D Program to Focus on PHEV Batteries
DOE established an applied R&D program in 1999 to help industrial developers of high-power Li-Ion batteries overcome key barriers for Li-Ion batteries in HEV applications. Argonne is the lead laboratory for this applied R&D program, the Advanced Technology Development (ATD) Program. Other contributing national laboratories include Brookhaven, Idaho, Lawrence Berkeley, and Sandia.
Now that the PHEV program is taking prominence, the program is transitioning to focus its R&D efforts on studying Li-Ion battery materials and cell chemistries that are considered appropriate for PHEV batteries. It is assessing the impact of the more stringent PHEV operational conditions on the aging characteristics of alternative cell materials and cell chemistries. In addition, the larger size cells and batteries needed for PHEV applications (versus HEV applications) places an increased emphasis on enhancing the inherent abuse tolerance of Li-Ion materials and cell chemistries. These factors, as well as low-temperature operation and cost barriers, are being studied for alternative cell materials and cell chemistries.
Development of Advanced Materials for PHEV Batteries
In 2007, DOE initiated several new research projects at Argonne to develop materials that would facilitate achievement of the 40-mile all-electric range equivalent, within the weight (120 kg) and volume (80 L) restrictions established for this type of PHEV battery system. These new material research projects incorporate work on a) stabilizing lithium metal for use as the anode to replace the currently used lithiated graphite or carbon, and b) development of cathode materials that possess much higher specific capacities than those currently used in Li-Ion cells. Success in one or both of these areas will result in a significant increase in the energy density of the resulting lithium battery system.
Additionally, a project dealing with the development of new electrolyte additives was established. The purpose of this project is to develop additives that will further stabilize the electrode/electrolyte interfaces to enhance the inherent abuse tolerance of the cell chemistry and to help achieve the calendar and cycle life goals under the stringent operational conditions experienced in PHEV applications.
Argonne is also involved in DOE's exploratory battery research program, the Batteries for Advanced Transportation Technologies (BATT) Program, administered through Lawrence Berkeley National Laboratory. Argonne's role in this program is to develop novel anode and cathode materials for use in transportation applications. Some of the materials being developed by Argonne in the BATT program could find application in PHEV batteries. The high capacity density of Argonne's inter-metallic anode materials could make them viable candidates for replacing lithiated graphite and carbon. Also, some of Argonne's patented structurally-integrated composite cathode materials are capable of delivering much higher specific capacities (greater than 250 mAh/g ) than conventional cathode materials (less than 160 mAh/g). Internally funded research is underway to render these materials acceptable for use in PHEV applications. This involves increasing the particle density and enhancing the rate capability of these materials.
Collaborative R&D with Industry
Argonne is internationally respected for its expertise in the area of lithium battery materials R&D. Argonne works with industrial firms on a variety of contracts, some of which are linked to PHEV applications. One of these projects is with EnerDel, a U.S. battery company being funded by the USABC/DOE.