Current batteries have two significant limitations: their charging time and achievable range. The US Department of Energy (DOE) set a goal of fast-charging an electric vehicle (EV) battery in just 10 minutes. However, rapid charging of current Li-ion batteries can lead to issues like Li-metal plating on the carbon-anode and the potential formation of dangerous lithium dendrite shorts. To address these problems, researchers have been exploring Li-metal anodes, which offer higher energy density and improved EV range. However, the charging rate of Li-metal anodes has been hindered by the formation of lithium dendrite shorts.
A breakthrough has been made by Dr. Eric Wachsman and his research team at the University of Maryland's Maryland Energy Innovation Institute (MEI2). They developed a single-phase mixed ion- and electron-conducting (MIEC) garnet material and integrated it into their previously developed 3D architecture. This achievement not only met the DOE's fast-charge goal for Li cycling but exceeded it by a factor of 10.
The MIEC garnet's porous structure plays a crucial role in alleviating stresses on the solid electrolytes (SE) during cycling. By spreading the potential uniformly across the surface, it prevents local hot spots that could lead to the formation of dendrites.
This transformative material and architecture have immense potential for impact in the EV industry and other applications. The research paper titled “Extreme Lithium-Metal Cycling Enabled by a Mixed-Ion-Electron-Conducting (MIEC) Garnet 3D-Architecture” has been published in Nature Materials.
The Li cycling rates, quantity of Li per cycle, and cumulative Li cycling far exceeded the DOE's Fast Charge Goals for current density, per-cycle areal capacity, and cumulative capacity. Remarkably, this was achieved at room temperature with no applied pressure. With this Li cycling capability, EVs could perform 100% depth of discharge cycles every day for 10 years, surpassing any anticipated EV lifetime or warranty requirements.
Dr. Y. Shirley Meng, chief scientist at ACCESS Argonne National Lab and Professor in the Pritzker School of Molecular Engineering at the University of Chicago, praised the work of Dr. Wachsman's team. She acknowledged the superior rate capability of the lithium metal anode achieved through innovative 3D design and the unique architecture, which opens up new possibilities for next-generation high-energy rechargeable batteries.
Dr. Wachsman expressed his excitement over the achievement, noting that, in his 35 years of working on solid ion conducting materials, he had never seen ions being cycled at room temperature across a solid ceramic at such high current densities, especially from a solid metal. The successful demonstration of this high-rate dendrite-free Li metal in 3D MIEC structures is expected to drive the development of practical “Li-free” anode solid-state batteries.
Dr. Jürgen Janek, Director of the Center for Materials Research at Justus Liebig University Giessen, highlighted the significance of achieving current densities as high as reported by Dr. Wachsman's team, suggesting that it could be a game-changer on the route to competitive solid-state batteries.
Source: University of Maryland