New priming method improves battery life by up to 44%

Exclusive new battery technology

Researchers at Rice University have developed a scalable method for improving the life of lithium-ion batteries using prelithium, a process that coats silicon anodes with stabilized lithium metal particles, improving battery life by up to 44%.

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Rice University engineers advance prelithium and unveil lithium trapping mechanism.

The potential of silicon-anode batteries to transform energy storage solutions is critical to achieving climate goals and fully realizing the capabilities of electric vehicles.

However, the persistent leakage of Li-ion into silicon anodes is a significant obstacle to the development of next-generation Li-ion batteries.

Scientists at Rice University’s George R. Brown School of Engineering have developed an easily scalable method for optimizing prelithium, a process that helps mitigate lithium loss and improves battery life cycles by coating silicon anodes with lithium particles. stabilized lithium metal (SLMP).

Quan Nguyen and Sibani Lisa Biswal

Quan Nguyen (left), Sibani Lisa Biswal and collaborators have developed a prelithium technique that helps improve the performance of lithium-ion batteries with silicon anodes. Credit: Jeff Fitlow/Rice University

Sibani chemical and biomolecular engineer Lisa Biswal’s Rice lab found that spray-coating anodes with a mixture of particles and a surfactant improved battery life by 22% to 44%. Battery cells with a higher amount of coating initially achieved higher stability and cycle life. However, there was a drawback: When cycled to full capacity, more particle coating led to more lithium trapping, causing the battery to fade faster in subsequent cycles.

The study is published in ACS Applied Energy Materials.

Replacing graphite with silicon in lithium-ion batteries would significantly improve their energy density (the amount of energy stored relative to weight and size) because graphite, which is made of carbon, may contain fewer lithium ions than lithium. silicon. It takes six carbon atoms for each single lithium ion, while only one for silicon[{» attribute=»»>atom can bond with as many as four lithium ions.

Quan Nguyen

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. Thats why theres 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 batterys lithium reserve even further.

Sibani Lisa Biswal and Quan Nguyen

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 batterys 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 youre 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

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 its 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 wont 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 Rices 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.

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