Daniel P. Abraham, Ph.D., Materials Scientist, Chemical Sciences and Engineering Division, Argonne National Laboratory is a featured presenter during the Next-Generation Battery Research conference at the 34th Annual International Battery Seminar & Exhibit in Fort Lauderdale.

Silicon as a Graphite Alternative, Performance Degradation Mechanisms and Maximizing Battery Longevity

1) Can you describe your current projects at Argonne National Lab and the resources that support them?

My lithium-ion battery projects at Argonne National Laboratory fall into three broad categories:

• Increasing cycle life and storage life of high-energy transportation batteries that are designed to operate at high voltages. This high-voltage operation is needed to increase energy and power densities – higher energy makes longer driving distances possible from a single charge and higher power allows rapid acceleration during driving and faster charging when the battery is depleted. But the performance of battery cells degrades faster at higher voltages – our task is to provide solutions that inhibit this degradation.
• Enabling the use of silicon as an alternative to graphite in battery negative electrodes. The shift from silicon to graphite can significantly increase the energy density of batteries. But the durability of silicon-containing electrodes is worse than that of graphite electrodes, because of the substantial volume changes during lithium-silicon alloying reactions. Our assignment is to design chemistries that improve electrode integrity and increase cell life.
• Examining relationships between the microstructure and electrochemical performance of battery electrodes. This performance is affected by the distribution of materials, porosity, thickness, and tortuosity in the electrodes. We are obtaining 3D images of electrode architectures, using microscopy and X-ray approaches, and relating these images to electrode electrochemical characteristics determined by employing multiple techniques.

The above projects are funded by the Office of Vehicle Technologies at the U.S. Department of Energy and we are grateful to our program managers, including Peter Faguy, Brian Cunningham, Tien Duong and David Howell.

2) What challenges must your field overcome to maximize the longevity of lithium-ion batteries?

Lithium-ion batteries include a broad spectrum of chemistries each with its own advantages and limitations – some chemistries provide high cell energy densities but at the expense of cell life; others provide high safety but at lower cell performance. Our work on cells with layered-oxide positive electrodes and graphite (or silicon) containing negative electrodes indicates that the following challenges need to be overcome to maximize battery longevity.

• Developing electrolytes that are stable both under the highly oxidizing conditions at the positive electrode and the highly reducing conditions at the negative electrode – such electrolytes will enable high-energy-dense, high-performance cells.
• Mitigating deterioration at electrode-electrolyte interfaces – stable interfaces protect both the electrode and electrolyte and help maintain cell performance under cycling and/or storage conditions.
• Minimizing transport of transition metals from the positive to the negative electrode – transport of elements (such as manganese) accelerates electrolyte reduction and lithium trapping reactions at the negative electrode leading to rapid capacity fade of battery cells.
• Optimizing chemistry and architecture of silicon-based electrodes to preserve electrode integrity during electrochemical cycling – modifications are also needed at the silicon-electrolyte interfaces to lessen lithium loss from undesired side reactions.

3) What are the most promising developments that have emerged from your research on performance degradation mechanisms in lithium-ion cells?

My research on lithium-ion battery projects has focused on highlighting performance degradation mechanisms, which include interactions and crosstalk between various parts of the cells. An understanding of these interactions is essential to developing components that enable better performance and longer cell life. Promising advances from our research include the following:

• Establishment of diagnostic protocols, which allow us to separately determine consequences of the highly oxidizing and highly reducing conditions within battery cells.
• Formulation of novel electrolyte additives, which form passivation films at the positive electrode and allow cells to operate at voltages that are higher than those used for commercial cells.
• Incorporation of positive and negative electrode coatings, which alleviate the adverse consequences of crosstalk between cell components.
• Electrode pre-lithiation techniques, which are critical to mitigating lithium loss and increasing the longevity of silicon-containing cells.

My colleagues and I at Argonne look forward to working with scientists and engineers in industry to solve problems that hinder commercialization of lithium battery cells. Furthermore, through ACCESS, we can help our public- and private-sector customers transform scientific advances in energy storage into products that have an impact on day-to-day life.

Speaker Information:

Daniel Abraham leads the effort at Argonne to identify performance degradation mechanisms in lithium-ion cells. He is responsible for the development of advanced diagnostic tools and techniques that include diffraction, microscopy, spectroscopy and electrochemistry methodologies. His work enables the development of battery materials and components that enhance cell performance, life, and safety. Dr. Abraham received his Ph.D. in 1993 from the University of Illinois at Urbana-Champaign.

Featured Presentation: Wednesday, March 22 during the Next-Generation Battery Research conference