Science for our
Nation's
Energy Future

Energy Frontier Research Center

Community Website
Frontiers in
Energy Research
Newsletter
November 2014

Multilayer Structures for Improved Battery Performance

Layering chromium and silicon gives birth to structurally robust electrodes that hold high amounts of charge

Liezel Labios

A newly designed, layered electrode allows a lithium-ion battery to retain a high charge capacity even after 1,000 charge/discharge cycles.

Developments toward higher capacity, longer lasting rechargeable batteries have been ongoing well before the march of the Energizer® Bunny. Indeed, the iconic notion of a battery that "keeps going and going and going" is increasingly being realized, especially with continual improvements in lithium-ion battery technologies.

At the Center for Electrical Energy Storage (CEES), researchers discovered a route to develop a new generation of lithium-ion battery materials. These batteries could essentially store more charge and retain it after extended charge/discharge cycles.

Traditionally, lithium-ion battery electrodes are built from intercalation materials, which are often layered crystal structures into which lithium ions can be reversibly inserted and extracted. These electrodes exhibit structural reversibility, because they maintain their layered structures throughout lithium-ion insertion (lithiation) and extraction (delithiation) processes. However, electrodes built from intercalation materials have low lithium-ion capacities, meaning the batteries have low charge capacities.

On the other hand, electrode frameworks built from compounds that alloy with lithium (such as silicon) provide batteries with much higher charge capacities. However, purely silicon-based electrodes lack the structural reversibility of intercalation-based electrodes. The silicon-based electrodes undergo dramatic volume and structural changes during lithiation and delithiation, which consequently deteriorate the electrode and reduce its charge capacity after repeated uses.

To achieve the best of both worlds, the team at CEES, led by Tim Fister, constructed a multilayer electrode composed of alternating silicon (Si) thin films and chromium silicide (Cr3Si) layers. The result was a Si/Cr3Si multilayer that combined the structural reversibility of an intercalation material with the high charge capacity provided by silicon.

"These multilayers allow us to control the direction of the expansion, which can help prevent issues—such as cracking and separation of the layers—that have previously plagued silicon electrodes," said Fister.

The team conducted real-time X-ray reflectivity studies to measure the volume and structure changes during lithiation and delithiation. Data from these studies revealed that the Si/Cr3Si multilayer expanded and contracted 3.3-fold vertically, but maintained its layered structure despite repeated volume changes. "We were surprised by how uniform and reversible the changes were," said Fister.

Additionally, electrochemical studies demonstrated the stability of the Si/Cr3Si multilayer throughout repeated charging and discharging cycles. Compared to a silicon film of identical thickness, the Si/Cr3Si multilayer retained a high charge capacity even after 1,000 cycles.

"This research could head in a variety of directions. For example, we're interested in using this structural reversibility to develop new design rules for the battery electrodes. The layered architecture could also be applied to other current collector morphologies, such as wires or spheres," explained Fister.

Acknowledgments

This work was supported by the Center for Electrical Energy Storage, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.

More Information

Fister TT, J Esbenshade, X Chen, BR Long, B Shi, CM Schlepütz, AA Gewirth, MJ Bedzyk, and P Fenter. 2014. "Lithium Intercalation Behavior in Multilayer Silicon Electrodes." Advanced Energy Materials 4:1301494. DOI: 10.1002/aenm.201301494

About the author(s):

  • Liezel Labios is a postdoctoral research associate in the Center for Molecular Electrocatalysis, an Energy Frontier Research Center led by Pacific Northwest National Laboratory. Her project focuses on synthesizing molybdenum compounds containing pendant amine groups as proton relays and exploring their reactivity in dinitrogen reduction and amine oxidation reactions.

Batteries that Keep Going, and Going, and Going

Alternately stacking silicon and chromium layers leads to rechargeable batteries that hold more charge

Scientists combine the best of silicon and intercalation materials to build long-lasting lithium batteries.

Drive farther. Replace batteries less often. These items are on nearly every electric car owner's wish list. Making these wishes a reality requires a long-lasting, rechargeable battery that stores a lot of charge. Particularly for lithium-ion batteries, the key is building an electrode—where the battery's reactions occur—that can withstand numerous charging and discharging cycles without losing its charge capacity or its structure. At the Center for Electrical Energy Storage, led by Argonne National Laboratory, researchers built a structurally reversible, high-capacity electrode by alternating silicon films with thin layers of chromium silicide. The electrode retained a high charge capacity and its structure after being charged and discharged 1,000 times. It expanded 3.3-fold vertically, but researchers demonstrated that the expansion was reversible and that the layering was maintained throughout the reaction. The study shows the benefits of layering silicon with chromium silicide for electrodes, wires, and other uses.

More Information

Fister TT, J Esbenshade, X Chen, BR Long, B Shi, CM Schlepütz, AA Gewirth, MJ Bedzyk, and P Fenter. 2014. "Lithium Intercalation Behavior in Multilayer Silicon Electrodes." Advanced Energy Materials 4:1301494. DOI: 10.1002/aenm.201301494

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.