Durante un período de tres meses, el automóvil promedio en los EE. UU. produce una tonelada métrica de dióxido de carbono. Multiplique eso por todos los autos que funcionan con gasolina en la Tierra, y ¿cómo se ve eso? Un problema insuperable.

Pero los nuevos esfuerzos de investigación dicen que hay esperanza si nos comprometemos con emisiones netas de carbono cero para 2050 y reemplazamos los vehículos que consumen mucha gasolina por vehículos eléctricos, entre muchas otras soluciones de energía limpia.

Para ayudar a nuestra nación a alcanzar este objetivo, científicos como William Chueh y David Shapiro están trabajando juntos para idear nuevas estrategias para diseñar baterías de larga distancia más seguras hechas de materiales sostenibles y abundantes en la Tierra.

Chueh es profesor asociado de ciencia e ingeniería de materiales en la Universidad de Stanford y tiene como objetivo rediseñar la batería moderna de abajo hacia arriba. Se basa en herramientas de última generación en las instalaciones de usuarios científicos del Departamento de Energía de EE. UU., como la fuente de luz avanzada (ALS) de Berkeley Lab y la fuente de luz de radiación de sincrotrón de Stanford de SLAC, instalaciones de sincrotrón que generan haces brillantes de luz de rayos X, para revelar la dinámica molecular de los materiales de las baterías en acción.

Durante casi una década, Chueh ha colaborado con Shapiro, un científico sénior del ALS y un destacado experto en sincrotrón, y juntos, su trabajo ha dado como resultado técnicas nuevas e impresionantes que revelan por primera vez cómo funcionan los materiales de las baterías en acción, en tiempo real. , a escalas sin precedentes invisibles a simple vista.

Discuten su trabajo pionero en esta sesión de preguntas y respuestas.

P:¿Qué despertó su interés en la investigación sobre baterías/almacenamiento de energía?

Chueh:Mi trabajo está impulsado casi por completo por la sostenibilidad. Me involucré en la investigación de materiales energéticos cuando era estudiante de posgrado a principios de la década de 2000; estaba trabajando en tecnología de celdas de combustible. Cuando me uní a Stanford en 2012, me resultó obvio que el almacenamiento de energía escalable y eficiente es crucial.

Hoy, estoy muy emocionado de ver que la transición energética lejos de los combustibles fósiles se está convirtiendo en una realidad y que se está implementando a una escala increíble.

Tengo tres objetivos:primero, estoy haciendo una investigación fundamental que sienta las bases para permitir la transición energética, especialmente en términos de desarrollo de materiales. Segundo, estoy capacitando a científicos e ingenieros de clase mundial que saldrán al mundo real para resolver estos problemas. Y luego tercero, estoy tomando la ciencia fundamental y traduciéndola al uso práctico a través del espíritu empresarial y la transferencia de tecnología.

Espero que eso le brinde una visión integral de lo que me motiva y lo que creo que se necesita para marcar la diferencia:es el conocimiento, la gente y la tecnología.

Shapiro:Mi experiencia es en óptica y dispersión coherente de rayos X, por lo que cuando comencé a trabajar en el ALS en 2012, las baterías no estaban realmente en mi radar. Me encargaron desarrollar nuevas tecnologías para la microscopía de rayos X de alta resolución espacial, pero esto llevó rápidamente a las aplicaciones y a tratar de descubrir qué están haciendo los investigadores en Berkeley Lab y más allá y cuáles son sus necesidades.

En ese momento, alrededor de 2013, había mucho trabajo en el ALS usando varias técnicas que explotaban la sensibilidad química de los rayos X blandos para estudiar las transformaciones de fase en los materiales de las baterías, en particular el fosfato de hierro y litio (LiFePO4), entre otros.

Quedé realmente impresionado con el trabajo de Will, así como con Wanli Yang, Jordi Cabana (antiguo científico de plantilla en el Área de Tecnologías Energéticas (ETA) de Berkeley Lab que ahora es profesor asociado en la Universidad de Illinois Chicago) y otros cuyo trabajo también construyó a partir del trabajo de los investigadores de ETA Robert Kostecki y Marca Doeff.

I knew nothing about batteries at the time, but the scientific and social impact of this area of research quickly became apparent to me. The synergy of research across Berkeley Lab also struck me as very profound, and I wanted to figure out how to contribute to that. So I started to reach out to people to see what we could do together.

As it turned out, there was a great need to improve the spatial resolution of our battery materials measurements and to look at them during cycling—and Will and I have been working on that for nearly a decade now.

Q:Will, as a battery scientist, what would you say is the biggest challenge to making better batteries?

Chueh:Batteries have on the order of 10 metrics that you have to co-optimize at the same time. It's easy to make a battery that's good on maybe five out of the 10, but to make a battery that's good in every metric is very immensely challenging.

For example, let's say you want a battery that is energy dense so you can drive an electric car for 500 miles per charge. You may want a battery that charges in 10 minutes. And you may want a battery that lasts 20 years. You also want a battery that never explodes. But it's hard to meet all of these metrics at once.

What we're trying to do is understand how we can create a single battery technology that is safe, long-lasting, and can be charged in 10 minutes.

And those are the fundamental insights that our experiments at Berkeley Lab's Advanced Light Source are trying to do:To uncover those unexplained tradeoffs so that we can go beyond today's design rules, which would enable us to identify new materials and new mechanisms so that we can free ourselves from those restrictions.

Q:What unique capabilities does the ALS offer that have helped to push the boundaries of battery or energy storage research?

Chueh:In order to understand what's going on, we need to see it. We need to make observations. A key philosophy of my group is to embrace the dynamics and the heterogeneity of battery materials. A battery material is not like a rock. It's not static. You are charging and discharging it every day for your phones and every week for your electric cars. You're not going to understand how a car works by not driving it.

The second part is that heterogeneous battery materials are extremely length spanning. A battery cell is typically a few centimeters tall, but in order to understand what's going on inside the battery—and I have beautiful images for this—you want to see all the way down to the nanoscale and to the atomic scale. That's about 10 orders of magnitude of length.

What the Advanced Light Source empowers scientists like me to be able to do is to embrace the heterogeneity and dynamics of a battery in very unprecedented ways:We can measure very slow processes. We can measure very fast processes. We can measure things at the scale of many hundreds of microns (millionths of a meter). We can measure things at the nanoscale (billionth of a meter). All with one amazing tool at Berkeley Lab.

Shapiro:Scanning transmission X-ray microscopy (STXM) is a very popular synchrotron-based method. Most synchrotrons around the world have at least one STXM instrument while the ALS has three—and a fourth is on the way through the ALS Upgrade (ALS-U) project.

I think a few things make our program unique. First, we have a portfolio of instruments with specializations. One is optimized for light element spectroscopy so an element like oxygen, which is a critical ingredient in battery chemistry, can be precisely characterized.

Another instrument specializes in mapping chemical composition at very high spatial resolution. We have the highest spatial resolution X-ray microscopy in the world. This is very powerful for zooming in on the chemical reactions happening within a battery's individual nanoparticles and interfaces.

Our third instrument specializes in "operando" measurements of battery chemistry, which you need in order to really understand the physical and chemical evolution that occurs during battery cycling.

We have also worked hard to develop synergies with other facilities at Berkeley Lab. For instance, our high-resolution microscope uses the same sample environments as the electron microscopes at the Molecular Foundry, Berkeley Lab's nanoscience user facility—so it has become feasible to probe the same active battery environment with both X-rays and electrons. Will has used this correlative approach to study relationships between chemical states and structural strain in battery materials. This has never been done before at the length scales we have access to, and it provides new insight.

Q:How will the ALS Upgrade project advance next-gen energy storage technologies? What will the upgraded ALS offer battery/energy-storage researchers that will be unique to Berkeley Lab?

Shapiro:The upgraded ALS will be unique for a few reasons as far as microscopy is concerned. First, it will be the brightest soft X-ray source in the world, providing 100 times more X-rays on th sample than what we have today. Scanning microscopy techniques will benefit from such high brightness.

This is both a huge opportunity and a huge challenge. We can use this brightness to measure the data we get today—but doing this 100 times faster is the challenging part.

Such new capabilities will give us a much more statistically accurate look at battery structure and function by expanding to larger length scales and smaller time scales. Alternatively, we could also measure data at the same rate as today but with about three times finer spatial resolution, taking us from about 10 nanometers to just a few nanometers. This is a very important length scale for materials science, but today it's just not accessible by X-ray microscopy.

Another thing that will make the upgraded ALS unique is its proximity to expertise at the Molecular Foundry; other science areas such as the Energy Technologies Area; and current and future energy research hubs based at Berkeley Lab. This synergy will continue to drive energy storage research.

Chueh:In battery research, one of the challenges we have right now is that we have so many interesting problems to solve, but it takes hours and days to do just one measurement. The ALS-U project will increase the throughput of experiments and allow us to probe materials at higher resolution and smaller scales. Altogether, that adds up to enabling new science. Years ago, I contributed to making the case for ALS-U, so I couldn't be prouder to be part of that—I'm very excited to see the upgraded ALS come online so we can take advantage of its exciting new capabilities to do science that we cannot do today.