Lithium Ion Batteries

Lithium-rich oxides and lithia-based cathodes can achieve exceptionally high energy density by utilizing oxygen-anion redox in addition to conventional transition-metal redox. 

However, their practical application is hindered by voltage decay, oxygen release, and poor cycling stability. Our research integrates in situ characterization to elucidate fundamental anion-redox mechanisms, binder–solvent compatibility studies to mitigate parasitic reactions, and defect/catalyst engineering to enhance reversibility. Through these combined approaches, we aim to establish design principles for high-energy, structurally stable, and long-life cathodes in advanced lithium-ion batteries. 

Ye Yeong Hwang‡, Ji Hyun Han‡, Sol Hui Park, Yun Jung Lee*, Chemical compatibility of polymer binders with a reversible anionic redox reaction in lithia-based cathodes, Journal of Materials Chemistry A, 11, 14086-14095, 2023
Ji Hyun Han‡, Ye Yeong Hwang‡, Soohyung Park, Jisu Shin, Kyung Joong Yoon*, Yun Jung Lee*, Synergistic effect of oxygen vacancy and dual electrocatalysts in activating anion redox in lithia-based cathodes, Journal of Materials Chemistry A, 10, 25055-25062, 2022

 Conventional cathodes undergo volumetric changes during cycling, generating internal strain and reducing battery life. In contrast, zero-strain cathodes exhibit negligible structural variation, enabling high operating voltage, large capacity, and long-term stability. Our research focuses on the mechanisms of zero-strain behavior, engineering strategies to exploit it, and advanced analytical methods to directly probe strain evolution. This approach provides key insights for designing durable, high-energy cathode materials for next-generation lithium-based batteries.

Sol Hui Park‡, Nam Kyeong Lee‡, Seong Gyu Lee, Ji Hyun Han, Yun Jung Lee*, Zero-Strain Cathodes for Lithium-Based Rechargeable Batteries: A Comprehensive Review, ACS Applied Energy Materials, 6, 1, 12-30, 2023 (invited review)