SK Jung Research Group

In response to the requests, we are mainly trying to design and discover advanced new energy materials. Based on the discovery of novel materials, we systematically study on the material characterization and finally apply the material to the fabrication of electrochemical devices to bridge the fundamental knowledge to the energy storage and conversion technologies. We are focusing on the defining the key question with "What" and "How" and solving the core issues in energy research fields. This work presents a significant advancement in the understanding of the intricate chemo-mechanical degradation mechanisms in all-solid-state batteries (ASSBs) through a quantitative multi-length scale analysis, highlighting the novel functionality of the coating layer. We found that uncontrolled interfacial reactions and point-contact interfaces in uncoated cathode lead to heterogeneous particle reactions and uneven mechanical degradation. In contrast, the LiDFP coating not only mitigates the chemical decomposition of the solid electrolyte but also maintains enhances the reaction uniformity among particles and homogenizes mechanical degradation. In our study, we present a strategy to design structurally reversible conversion-type positive electrode materials by guiding favorable phase transitions. We demonstrate that forming a LiF-FeF2 nanocomposite enables the electrochemical synthesis of metastable tetragonal FeF3 (T-FeF3), which exhibits superior reversibility compared to conventional rhombohedral FeF3 (R-FeF3). Unlike R-FeF3, which undergoes irreversible structural rearrangements and induces compositional inhomogeneity during lithiation, T-FeF3 maintains structural similarity to FeF2, enabling smooth and reversible insertion–conversion reactions. This guided transition pathway sup