Breakthrough Anode-Free EV Battery Promises Over 500-Mile Range on a Single Charge

‘Impossible’ Anode-Free EV Battery Promises 500+ Mile Range on a Single Charge

Research at the Andlinger Center for Energy and the Environment at Princeton University has unveiled a groundbreaking approach to manufacturing anode-free solid-state batteries that could surpass the limitations of traditional lithium-ion batteries. This innovation has the potential to not only enhance the longevity of batteries in laptops and smartphones but also enable electric vehicles (EVs) to travel over 500 miles on a single charge, according to a recent press release.

Lithium-ion batteries play a vital role in our transition from fossil fuels to renewable energy sources. They are integral to a wide range of applications, from portable electronics to large-scale energy storage. However, as energy demands continue to rise, the current energy storage densities of lithium-ion batteries may soon be insufficient, leading to a pressing need for improved battery technologies. Additionally, lithium-ion batteries are associated with risks of fire and thermal runaway.

To address these challenges, researchers are exploring solid-state electrolytes, which are capable of operating over a broader temperature range and offer safer, more efficient energy storage solutions. As part of a U.S. Department of Energy initiative called Mechano-Chemical Understanding of Solid Ion Conductors (MUSIC), Princeton researchers are focusing on enhancing manufacturing processes so that solid-state batteries (SSBs) can be produced at scale.

Building an Anode-Free SSB

Traditional battery designs consist of two electrodes: the positive electrode, known as the cathode, and the negative electrode, referred to as the anode. Each electrode is connected to the circuit via a thin metal foil called the current collector, while the electrolyte acts as a separator. Ions flow between the electrodes during charging and discharging, which is essential for battery operation. Previous studies have indicated that removing the anode allows ions to still flow from the cathode to the current collector, enabling the battery to function normally.

Creating a battery without an anode reduces costs and simplifies the manufacturing process, while also allowing for a more compact SSB design. However, achieving optimal contact between the solid electrolyte and the current collector is crucial for this to work effectively.

Factors Influencing Good Contact

Under the guidance of Kelsey Hatzell, an associate professor of mechanical and aerospace engineering, the Princeton research team investigated various factors that affect ion flow within the solid electrolyte and the uniformity of its deposition on the current collector. They examined the impact of applying external pressure on performance and discovered that low pressure resulted in uneven ion plating, creating hotspots and voids that could short-circuit the battery. Conversely, while higher pressures improved ion plating, they also intensified imperfections between the electrolyte and current collector, leading to fractures.

The team further explored whether applying a thin coating, or interlayer, between the current collector and the electrolyte could enhance ion plating. After testing various material combinations, they found that interlayers made from carbon and silver nanoparticles yielded the best results. Notably, the size of the silver nanoparticles played a critical role in achieving effective plating. When 200-nanometer silver nanoparticles were used, they produced spindle-like metal structures that compromised battery integrity over charging cycles. In contrast, 50-nanometer nanoparticles resulted in denser and more uniform plating, leading to higher power output and improved battery longevity.

Se Hwan Park, a researcher from Hatzell’s lab who contributed to this study, remarked, “Only a few groups have investigated the actual processes that occur in these interlayers. Among other findings, we demonstrated that the stability of these systems is linked to the morphology of the metal as it plates and strips from the current collector.”

Hatzell emphasized the importance of translating this research into real-world applications, stating, “The challenge will be getting from research to the real world in only a few years. 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.”