Research at the Andlinger Center for Energy and the Environment at Princeton University has produced exciting developments concerning the future of battery technology. A newly developed ‘anode-free’ solid-state battery promises to overcome long-standing limitations of traditional lithium-ion batteries, potentially powering not just electric vehicles but also aiding advancements in electric aviation. According to the research team, this breakthrough could allow electric vehicles to travel over 500 miles on a single charge and significantly increase battery life.
Lithium-ion batteries have been pivotal for transitioning away from fossil fuels and building the clean energy economy due to their ubiquity from powering small devices to providing grid-level energy storage. Yet, as energy consumption continues to surge, the limitations of lithium-ion batteries become increasingly apparent, particularly concerning energy storage density, safety risks, and susceptibility to thermal runaway. Consequently, researchers at various institutions, including Princeton, are seeking alternatives to lithium-based solutions through innovative projects like the one led by Kelsey Hatzell.
Hatzell, who is associated with mechanical and aerospace engineering at Princeton, heads the project, part of the U.S. Department of Energy's Mechano-Chemical Understanding of Solid Ion Conductors (MUSIC) initiative. Her team is focused on refining the manufacturing processes of solid-state batteries (SSBs), pushing the boundaries of how these batteries can be built efficiently, safely, and at scale.
The structure of conventional batteries involves two electrodes: the positive, known as the cathode, and the negative, referred to as the anode. Typically, each electrode is linked using thin metal foils called current collectors, with the electrolyte material separating them. Ions move between these two electrodes to enable charging and discharging. Hatzell’s research pioneers the concept of removing the anode entirely from the equation, which could lead to cost-effective manufacturing and create more compact battery designs.
One of the key findings from the research indicates how ions can still flow effectively from the cathode to the current collector, even without the traditional anode. This innovation, if executed properly, could transform the battery design and facilitate easier scaling of solid-state batteries for widespread use. A major focus of Hatzell’s team is ensuring optimal contact between the solid electrolyte and the current collector, which is fundamental for successful ion transfer.
The team carried out detailed studies to understand how external pressure influences the performance of ion plating on the current collector. They found low pressure resulted in uneven ion plating, leading to problematic hotspots and voids, which can compromise battery reliability by creating pathways for short circuits. Conversely, applying higher pressure improved ion distribution but created new challenges by forcing the layers too closely together, which amplified their imperfections and led to fracture risks.
Delving even more deeply, Hatzell’s team explored the concept of coatings or interlayers—that is, thin films applied between the current collector and the electrolyte—to optimize ion performance. Their experiments revealed promising results when using coatings made of carbon and silver nanoparticles. They discovered the size of these silver nanoparticles directly impacted the outcome of ion plating; smaller 50-nanometer particles tended to create dense, uniform deposits, whereas larger 200-nanometer particles resulted in less stable, filamentous structures leading to battery complications.
Se Hwan Park, one of the researchers involved, stated, "Only a few groups have investigated the actual processes... we demonstrated the stability of these systems is linked to the morphology of the metal as it plates and strips from the current collector." This quote highlights the importance of their research and the potential it has for advancing battery technology safely and sustainably.
Reflecting on the future challenges of this promising research, Hatzell notes, "The challenge will be getting from research to the real world... Hopefully, the work we’re doing now at MUSIC can underpin the development and deployment of these next-generation batteries at a meaningfully large scale." This encapsulates the hope and diligence behind modern battery research, as scientists remain focused on overcoming technical challenges to make these advancements available for the public.
The pursuit of efficient, safe, and reliable battery technology continues to gain momentum. By making significant strides with concepts like this new 'anode-free' solid-state battery, researchers at Princeton are at the forefront of developments destined to influence not only electric vehicles but various applications across the clean energy spectrum.