Tailoring artificial solid electrolyte interphase via MoS2 sacrificial thin film for Li‑free all‑solid‑state batteries

Anode-free all-solid-state batteries (AFASSBs) hold great promise for next-generation electric mobility devices due to their potential to deliver superior energy density and stability by eliminating lithium from the anode. However, achieving uniform lithium plating and stable interfaces between sulfide solid electrolytes (SEs) and current collectors (CCs) remains a significant challenge. Now, researchers from the Korea Research Institute of Chemical Technology (KRICT) and Chungnam National University, led by Professor Ki-Seok An and Professor Sangbaek Park, have introduced a novel strategy to stabilize the interface of AFASSBs using controllable MoS₂ sacrificial thin films. Their findings, published in Nano-Micro Letters, demonstrate a remarkable improvement in cycling stability and capacity retention.

Why MoS₂ Sacrificial Thin Films Matter

• Enhanced Lithium Plating Uniformity: The addition of a MoS₂ sacrificial layer to AFASSBs significantly reduces the nucleation overpotential of lithium, enabling more uniform Li plating and stripping.
• Formation of High-Quality SEI Layer: The MoS₂ layer reacts with lithium to form an interlayer composed of Mo metal and Li₂S, which enhances the stability of the SE interface and improves the overall performance of AFASSBs.
• Superior Cycling Stability: AFASSBs assembled with MoS₂-coated CCs exhibit superior cycling stability and enhanced capacity compared to those with bare stainless steel (SUS) CCs.

Innovative Design and Mechanisms

• Controlled Growth of MoS₂: MoS₂ was controllably grown on CCs using metal–organic chemical vapor deposition (MOCVD), forming vertically aligned nanosheets that increase the contact area with the SEs.
• Conversion Reaction: The MoS₂ sacrificial layer undergoes a conversion reaction with the SEs, forming an interlayer of Mo metal and Li₂S. This interlayer facilitates uniform lithium deposition and improves the wettability of lithium.
• Optimal MoS₂ Thickness: The study found that an optimal MoS₂ thickness (MoS₂-15m) resulted in the best performance, with a 1.18-fold increase in initial discharge capacity and a sevenfold improvement in capacity retention compared to SUS CCs.

Future Outlook

• Scalability and Practical Applications: The scalable synthesis of MoS₂ sacrificial layers and their demonstrated performance improvements highlight their potential for practical AFASSB applications.
• Further Research: Future work may focus on optimizing the MoS₂ layer thickness and exploring other materials to further enhance the performance and stability of AFASSBs.
• Mechanistic Insights: This study provides valuable insights into the role of MoS₂ in stabilizing SE interfaces and improving lithium plating uniformity, offering a promising path for the development of high-performance AFASSBs.

Stay tuned for more groundbreaking advancements from Professor Ki-Seok An and Professor Sangbaek Park as they continue to push the boundaries of solid-state battery technology!