Jung-Hyun Kim

Challenges and Approaches for High-Voltage Spinel Lithium-Ion Batteries

Lithium-ion (Li-ion) batteries have been developed for electric vehicle (EV) applications, owing to their high energy density. Recent research and development efforts have been devoted to finding the next generation of cathode materials for Li-ion batteries to extend the driving distance of EVs and lower their cost. LiNi(0.5)Mn(1.5)O(4) (LNMO) high-voltage spinel is a promising candidate for a next-generation cathode material based on its high operating voltage (4.75 V vs. Li), potentially low material cost, and excellent rate capability. Over the last decade, much research effort has focused on achieving a fundamental understanding of the structure-property relationship in LNMO materials. Recent studies, however, demonstrated that the most critical barrier for the commercialization of high-voltage spinel Li-ion batteries is electrolyte decomposition and concurrent degradative reactions at electrode/electrolyte interfaces, which results in poor cycle life for LNMO/graphite full cells. Despite scattered reports addressing these processes in high-voltage spinel full cells, they have not been consolidated into a systematic review article. With this perspective, emphasis is placed herein on describing the challenges and the various approaches to mitigate electrolyte decomposition and other degradative reactions in high-voltage spinel cathodes in full cells.

Layered LnBaCo2O5+δ perovskite cathodes for solid oxide fuel cells: an overview and perspective

Aligned with an ever growing interest to reduce the operating temperature of solid oxide fuel cells (SOFCs) that offer technical and economical benefits, materials research in the area of SOFC cathodes is being directed toward mixed ionic-electronic conducting (MIEC) oxides with perovskite or related structures due to their promising performances particularly at reduced temperatures (T < 800 °C). This article focuses on the recent progress in the A-site ordered, layered LnBaCo2O5+δ perovskite family of MIECs that have been most actively investigated in the last decade. While significant progress has been made in understanding the promising cathode activity of LnBaCo2O5+δ, much efforts are being put towards further fine-tuning their properties by exploring their derivative chemical compositions and optimizing microstructures via advanced cathode fabrication processes. Based on the literature data, an overview of the structure–composition–property–performance relationships of the LnBaCo2O5+δ-based layered perovskite family is presented here. The challenges and perspectives of the LnBaCo2O5+δ-based cathodes are also discussed in relation to the conventional perovskite oxide cathodes.