El nuevo método de cebado mejora la duración de la batería hasta en un 44 %

Investigadores de la Universidad de Rice han desarrollado un método escalable para mejorar la vida útil de la batería de iones de litio mediante prelitiación, un proceso que recubre los ánodos de silicio con partículas de litio metálico estabilizado, mejorando la vida útil de la batería hasta en un 44%.

Los ingenieros de la Universidad de Rice están logrando avances en la litiación previa y desentrañando el mecanismo de captura de litio.

El potencial de las baterías de ánodo de silicio para transformar las soluciones de almacenamiento de energía es clave para cumplir los objetivos climáticos y aprovechar al máximo las capacidades de los vehículos eléctricos.

Sin embargo, la pérdida persistente de iones de litio en los ánodos de silicio es un obstáculo importante para el desarrollo de baterías de iones de litio de próxima generación.

Los científicos de la Escuela de Ingeniería George R. Brown de la Universidad de Rice han desarrollado un método fácilmente escalable para optimizar la litiación previa, un proceso que ayuda a mitigar la pérdida de litio y mejora la vida útil de la batería al recubrir los ánodos de silicio con partículas de metal de litio estabilizado (SLMP).

Quan Nguyen (izquierda), Sibani Lisa Biswal y sus colaboradores han desarrollado una técnica de prelitiación que mejora el rendimiento de las baterías de iones de litio con ánodos de silicio. Crédito: Jeff Fitlow/Universidad Rice

El Rice Lab de la ingeniera química y biomolecular de Sibani, Lisa Biswal, descubrió que rociar los ánodos con una mezcla de partículas y un surfactante mejora la vida útil de la batería entre un 22 % y un 44 %. Las celdas de batería con una mayor cantidad de recubrimiento lograron inicialmente una mayor estabilidad y ciclo de vida. Sin embargo, había una desventaja: cuando se ciclaba a plena capacidad, una mayor capa de partículas provocaba una mayor captura de litio, lo que provocaba que la batería se desvaneciera más rápido en los ciclos posteriores.

El estudio se publica en ACS Applied Energy Materials.

Reemplazar el grafito con silicio en las baterías de iones de litio mejoraría drásticamente su densidad de energía, la cantidad de energía almacenada en relación con el peso y el tamaño, porque el grafito, que está hecho de carbono, puede contener menos iones de litio que el silicio. Se necesitan seis átomos de carbono para cada ion de litio, mientras que solo uno de silicio[{” 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.