Researchers at Rice University have developed a scalable method to extend the life of lithium-ion batteries using prelithiation, a process that coats silicon anodes with stabilized lithium metal particles, resulting in longer battery life. Improved by up to 44%.
Engineers at Rice University have advanced prelithiation and elucidated the mechanism of lithium capture.
The potential of silicon anode batteries to transform energy storage solutions is critical to addressing climate change goals and fully enabling electric vehicle functionality.
Nevertheless, the continued loss of lithium ions in silicon anodes remains a major obstacle for the development of next-generation lithium-ion batteries.
Scientists at the George R. Brown School of Engineering at Rice University have developed prelithium, a process that reduces lithium loss and improves battery life cycles by coating silicon anodes with stabilized lithium metal particles (SLMPs). We have developed an easily extensible method to optimize optimization.
Quang Nguyen (left), Shivani Lisa Biswal and collaborators have developed a prelithiation technique that can help improve the performance of lithium-ion batteries with silicon anodes.Credit: Jeff Fitlow/Rice University
Chemical and biomolecular engineer Shivani Lisa Biswal’s Rice lab found that spray coating the anode with a mixture of particles and surfactants improved battery life by 22% to 44%. Battery cells with a higher amount of coating initially achieved higher stability and cycle life. However, it also had its drawbacks. When cycled at full capacity, the increased amount of particle coating increases lithium capture and accelerates battery degradation on subsequent cycles.
The research is published in ACS Applied Energy Materials.
Replacing graphite in lithium-ion batteries with silicon would greatly increase the energy density (amount of energy stored relative to weight and size) because graphite, which is made of carbon, can pack less lithium ions than silicon. improves to Six carbon atoms are required for each lithium ion, whereas silicon only has one.[{” attribute=””>atom can bond with as many as four lithium ions.
Quan Nguyen is a chemical and biomolecular engineering doctoral alum and lead author on the study. Credit: Jeff Fitlow/Rice University
“Silicon is one of those materials that has the capability to really improve the energy density for the anode side of lithium-ion batteries,” Biswal said. “That’s why there’s currently this push in battery science to replace graphite anodes with silicon ones.”
However, silicon has other properties that present challenges.
“One of the major problems with silicon is that it continually forms what we call a solid-electrolyte interphase or SEI layer that actually consumes lithium,” Biswal said.
The layer is formed when the electrolyte in a battery cell reacts with electrons and lithium ions, resulting in a nanometer-scale layer of salts deposited on the anode. Once formed, the layer insulates the electrolyte from the anode, preventing the reaction from continuing. However, the SEI can break throughout the subsequent charge and discharge cycles, and, as it reforms, it irreversibly depletes the battery’s lithium reserve even further.
Quan Nguyen (left) and Sibani Lisa Biswal. Credit: Jeff Fitlow/Rice University
“The volume of a silicon anode will vary as the battery is being cycled, which can break the SEI or otherwise make it unstable,” said Quan Nguyen, a chemical and biomolecular engineering doctoral alum and lead author on the study. “We want this layer to remain stable throughout the battery’s later charge and discharge cycles.”
The prelithiation method developed by Biswal and her team improves SEI layer stability, which means fewer lithium ions are depleted when it is formed.
“Prelithiation is a strategy designed to compensate for the lithium loss that typically occurs with silicon,” Biswal said. “You can think of it in terms of priming a surface, like when you’re painting a wall and you need to first apply an undercoat to make sure your paint sticks. Prelithiation allows us to ‘prime’ the anodes so batteries can have a much more stable, longer cycle life.”
While these particles and prelithiation are not new, the Biswal lab was able to improve the process in a way that is readily incorporated into existing battery manufacturing processes.
Quan Nguyen holds one of the batteries assembled using the prelithiation protocol described in the study. Credit: Jeff Fitlow/Rice University
“One aspect of the process that is definitely new and that Quan developed was the use of a surfactant to help disperse the particles,” Biswal said. “This has not been reported before, and it’s what allows you to have an even dispersion. So instead of them clumping up or building up into different pockets within the battery, they can be uniformly distributed.”
Nguyen explained that mixing the particles with a solvent without the surfactant will not result in a uniform coating. Moreover, spray-coating proved better at achieving an even distribution than other methods of application onto anodes.
“The spray-coating method is compatible with large-scale manufacturing,” Nguyen said.
Controlling the cycling capacity of the cell is crucial to the process.
“If you do not control the capacity at which you cycle the cell, a higher amount of particles will trigger this lithium-trapping mechanism we discovered and described in the paper,” Nguyen said. “But if you cycle the cell with an even distribution of the coating, then lithium trapping won’t happen.
“If we find ways to avoid lithium trapping by optimizing cycling strategies and the SLMP amount, that would allow us to better exploit the higher energy density of silicon-based anodes.”
Reference: “Prelithiation Effects in Enhancing Silicon-Based Anodes for Full-Cell Lithium-Ion Batteries Using Stabilized Lithium Metal Particles” by Quan Anh Nguyen, Anulekha K. Haridas, Tanguy Terlier and Sibani Lisa Biswal, 1 May 2023, ACS Applied Energy Materials.
DOI: 10.1021/acsaem.3c00713
Biswal is Rice’s William M. McCardell Professor in Chemical Engineering, a professor of materials science and nanoengineering, and associate dean for faculty development.
The study was funded by Ford Motor Co.’s University Research Program, the National Science Foundation, and the Shared Equipment Authority at Rice.
