Advancements in Current Collector for Next-Generation Anode-Free Solid-State Battery
Professor Yu Seung-ho’s group of the Department of Chemical and Biological Engineering in the College of Engineering and Dr. Choi Ji-won’s group at KIST applied a lithium-friendly metallic coating layer to the surface of an anode current collector to increase the interfacial stability of next-generation anode-free solid-state batteries, thereby ensuring long-term operation and presenting a direction for studies on anode-free solid-state battery systems.
Unlike lithium-ion batteries that use existing liquid electrolytes, solid-state batteries are next-generation batteries that use a solid electrolyte to improve stability by avoiding the ignition risk that occurs with an organic liquid electrolyte. In addition, of the four major elements of a battery, an anode-free battery, that is, one with no ‘anode’, is best able to increase energy density. Anode-free solid-state batteries with reduced ignition properties and increased energy densities are one of the types of next-generation batteries recently attracting much attention in academia. However, anode-free solid-state batteries have the disadvantage that long-term operation is difficult due to poor interfacial stability between the anode current collector and the solid electrolyte. Accordingly, studies have been conducted to improve interfacial stability and achieve long-term operation.
In an anode-free solid-state battery system, an anode current collector is stainless steel and has a low affinity for lithium, so lithium ions are not uniformly electrodeposited on the anode current collector during charging, causing lithium dendrites and short-circuiting of the battery. Therefore, to induce the uniform electrodeposition of lithium ions, a method coating the surface of an anode current collector with lithium-friendly material was studied. Particularly, silver (Ag), which has a high affinity for lithium, is known to cause an alloy reaction with lithium and lead to a significant performance improvement when used in an anode-free all-solid battery current collector.
The research group reported that a small amount of indium (In) when added to the silver, with its high lithium affinity, caused a synergic effect between indium and silver. The addition of the small amount of indium resulted in performance improvement of over three times compared to the previous case where the anode current collector was coated with silver only. The research group used the co-sputter coating technique to coat the anode current collector with both silver and indium, and revealed the effect of adding a small amount of indium by combining the results from an electrochemical analysis and computational chemistry.
Professor Yu of the Department of Chemical and Biological Engineering said, “Anode-free solid-state batteries are drawing attention in academia as a new type of battery system that can increase energy density.” He also added, “Our results showed that coating with a lithium-friendly metal is an effective strategy for improving the short lifespan of anode-free solid-state batteries. We hope that our results can contribute to improving the interfacial stability and performance of anode-free solid-state batteries.”
This study was supported by the National Research Foundation of Korea (NRF) under the Ministry of Science, ICT & Future Planning.