(Invited) Nano-Engineered SEI Layers for Next Generation Lithium-Ion Batteries

The quest for high-performance lithium-ion batteries (LIBs) hinges on the continuous improvement of cathode materials. Dr. Marca Doeff's seminal contributions have propelled this approach, inspiring novel cathode materials. By studying the intricate interactions between cathode particles, coatings, and the solid electrolyte interphase (SEI) layer, we aim at engineering a high-energy-density and long-lasting next generation lithium-ion battery. We explore the latest advancements in cathode materials, with a focus on LiFePO4, LiMnFePO4, NCM811, and Li-S, introducing surface modifications by graphene and ALD coatings. Dr. Doeff's research has demonstrated the efficacy of carbon coatings in enhancing the rate capability and cycling stability of LFP-based batteries [1]. NCM811 is the most promising cathode material due to its high specific capacity and energy density, however, issues such as structural instability and capacity fading hinder its practical application. Through meticulous optimization of ALD coatings, our group has mitigated these challenges, leading to enhanced electrochemical performance and prolonged cycle life [2]. Li-S batteries offer a high theoretical specific capacity and low cost, making them attractive candidates for next-generation energy storage systems, however, polysulfide dissolution and shuttle effects pose significant challenges, limiting their practical viability. By leveraging ALD techniques, our group has engineered active coatings to enhance polysulfides conversion and stabilize the cathode cycling ability. The formation and stability of the SEI layer play a pivotal role in dictating the overall performance and safety of lithium-ion batteries. Graphene coatings and ALD treatments exert a profound influence on SEI layer formation, influencing ion transport kinetics, surface reactions, and interfacial stability. Graphene coatings not only enhance electronic conductivity but also modulate the SEI layer composition and morphology. Through synergistic interactions with electrolyte components, graphene coatings promote the formation of a robust and homogeneous SEI layer, thereby suppressing parasitic reactions and capacity degradation. ALD-enabled coatings offer precise control over film thickness and composition, enabling engineered interfaces with superior electrochemical performance. By depositing conformal ALD layers onto cathode surfaces, we can engineer SEI layers with enhanced chemical stability and ion permeability, leading