Donggun Eum

All Publications

• Approaching the theoretical density limit of ultrahigh-nickel cathodes via cation-disorder-free 10-μm single-crystalline particles NATURE ENERGY Jeon, Y., Eum, D., Jang, H., Park, Y., Beak, M., Kim, K., Jung, D., Oh, M., Choi, I., Ko, K., Kim, Y., Kim, J., Han, S., Kang, K. 2026

  View details for DOI 10.1038/s41560-025-01909-3

  View details for Web of Science ID 001652589200001

• Recovery of High-Voltage Oxygen Redox Activity by Eliminating Residual Oxygen Dimers. Journal of the American Chemical Society Kim, Y., Kim, H. J., Jung, D. S., Seo, O., Tayal, A., Lim, H., Imada, S., Park, J., Cho, S. P., Jeon, Y., Kim, J., Eum, D., Kang, S., Kang, B., Kim, K., Ahn, H., Park, J., Jang, H. Y., Park, S. O., Noh, J., Lee, C., Lee, J. D., Ko, K. H., Jin, H., Kang, K. 2025

  Abstract

  Oxygen-redox layered oxides are promising electrode materials with the potential for superior energy density; however, their real-world employment is hindered by severe electrochemical irreversibility. The fundamental origin of this irreversibility has been difficult to pinpoint due to the complex evolution of both the structure and redox centers during cycling. Herein, we reveal that oxygen redox irreversibility is governed by the formation and persistence of oxygen dimer states and, for the first time, demonstrate the reversible recovery of the intrinsic high-voltage oxygen redox plateau (∼4.5 V vs Li/Li+), which is typically lost after initial charge. Our in-depth tracking of oxygen dimer behavior establishes a direct correlation between the recoverability of the high-voltage plateau and the residual concentration of oxygen dimers in the electrode material. Furthermore, we identify sluggish dimer dissociation kinetics as the root cause of the irreversible loss of high-voltage oxygen redox activity. More importantly, we demonstrate that these kinetically trapped oxygen dimers can be eliminated by facilitating electron transfer from transition metal to oxygen dimers via redox reshuffling at a moderately elevated temperature, thereby fully restoring the high-voltage oxygen redox activity. These findings clarify the role of oxygen dimer kinetics in redox irreversibility and provide valuable insights toward achieving voltage-hysteresis-free anionic redox in oxygen redox electrodes.

  View details for DOI 10.1021/jacs.5c11310

  View details for PubMedID 41088740

• Toward Practical Li-Ion Cells With Li/Mn-Rich Layered Oxide Cathodes: A Techno-Economic Perspective on Material and Cell Design. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Arifiadi, A., Oster, S., Eum, D., Voigt, D., Kulka, A., Hur, H., Winter, M., Kasnatscheew, J. 2025: e12467

  Abstract

  Li/Mn-rich layered oxide (LMR) cathode active materials offer a pathway towards high specific energy and low-cost Li ion batteries (LIBs) due to their high practical specific discharge capacity (>250 mAh g-1) at moderate discharge voltages (≈3.5 V). However, oxygen redox requires electrochemical activation at high cathode potentials (> 4.5 V vs Li|Li+), resulting in bulk degradation and surface reactivity. This perspective first summarizes the literature-known efforts to elucidate the oxygen redox mechanism and then proposes strategies for systematic R&D of LMR, supported with techno-economic analysis. Initially, bulk degradation should be addressed via compositional tuning and crystal modification. Subsequently, the microstructure, interphase, and electrolyte should be engineered, and finally, the charging protocol should be optimized. The various LMR chemistries with different Li to TM, Ni to Mn, and Co to Ni ratios are techno-economically analyzed, and perspectives on the ideal LMR composition are presented. Ultimately, the specific energy, energy density, and costs of LMR || graphite cells are compared to state-of-the-art cell chemistries.

  View details for DOI 10.1002/advs.202512467

  View details for PubMedID 41028968

• Electrochemomechanical failure in layered oxide cathodes caused by rotational stacking faults. Nature materials Eum, D., Park, S. O., Jang, H. Y., Jeon, Y., Song, J. H., Han, S., Kim, K., Kang, K. 2024

  Abstract

  Electrochemomechanical degradation is one of the most common causes of capacity deterioration in high-energy-density cathodes, particularly intercalation-based layered oxides. Here we reveal the presence of rotational stacking faults (RSFs) in layered lithium transition-metal oxides, arising from specific stacking sequences at different angles, and demonstrate their critical role in determining structural/electrochemical stability. Our combined experiments and calculations show that RSFs facilitate oxygen dimerization and transition-metal migration in layered oxides, fostering microcrack nucleation/propagation concurrently with cumulative electrochemomechanical degradation on cycling. We further show that thermal defect annihilation as a potential solution can suppress RSFs, reducing microcracks and enhancing cyclability in lithium-rich layered cathodes. The common but previously overlooked occurrence of RSFs suggests a new synthesis guideline of high-energy-density layered oxide cathodes.

  View details for DOI 10.1038/s41563-024-01899-9

  View details for PubMedID 38702413

  View details for PubMedCentralID 10861561

• Freedom of chemical space NATURE SUSTAINABILITY Edelman, D. A., Eum, D., Chueh, W. C. 2024; 7 (3): 234-235

  View details for DOI 10.1038/s41893-024-01297-8

  View details for Web of Science ID 001189384800020

• Structurally robust lithium-rich layered oxides for high-energy and long-lasting cathodes. Nature communications Jang, H. Y., Eum, D., Cho, J., Lim, J., Lee, Y., Song, J. H., Park, H., Kim, B., Kim, D. H., Cho, S. P., Jo, S., Heo, J. H., Lee, S., Lim, J., Kang, K. 2024; 15 (1): 1288

  Abstract

  O2-type lithium-rich layered oxides, known for mitigating irreversible transition metal migration and voltage decay, provide suitable framework for exploring the inherent properties of oxygen redox. Here, we present a series of O2-type lithium-rich layered oxides exhibiting minimal structural disordering and stable voltage retention even with high anionic redox participation based on the nominal composition. Notably, we observe a distinct asymmetric lattice breathing phenomenon within the layered framework driven by excessive oxygen redox, which includes substantial particle-level mechanical stress and the microcracks formation during cycling. This chemo-mechanical degradation can be effectively mitigated by balancing the anionic and cationic redox capabilities, securing both high discharge voltage (~ 3.43 V vs. Li/Li+) and capacity (~ 200 mAh g-1) over extended cycles. The observed correlation between the oxygen redox capability and the structural evolution of the layered framework suggests the distinct intrinsic capacity fading mechanism that differs from the previously proposed voltage fading mode.

  View details for DOI 10.1038/s41467-024-45490-x

  View details for PubMedID 38346943

  View details for PubMedCentralID 5241805

• Voltage decay and redox asymmetry mitigation by reversible cation migration in lithium-rich layered oxide electrodes. Nature materials Eum, D., Kim, B., Kim, S. J., Park, H., Wu, J., Cho, S., Yoon, G., Lee, M. H., Jung, S., Yang, W., Seong, W. M., Ku, K., Tamwattana, O., Park, S. K., Hwang, I., Kang, K. 2020

  Abstract

  Despite the high energy density of lithium-rich layered-oxide electrodes, their real-world implementation in batteries is hindered by the substantial voltage decay on cycling. This voltage decay is widely accepted to mainly originate from progressive structural rearrangements involving irreversible transition-metal migration. As prevention of this spontaneous cation migration has proven difficult, a paradigm shift toward management of its reversibility is needed. Herein, we demonstrate that the reversibility of the cation migration of lithium-rich nickel manganese oxides can be remarkably improved by altering the oxygen stacking sequences in the layered structure and thereby dramatically reducing the voltage decay. The preeminent intra-cycle reversibility of the cation migration is experimentally visualized, and first-principles calculations reveal that an O2-type structure restricts the movements of transition metals within the Li layer, which effectively streamlines the returning migration path of the transition metals. Furthermore, we propose that the enhanced reversibility mitigates the asymmetry of the anionic redox in conventional lithium-rich electrodes, promoting the high-potential anionic reduction, thereby reducing the subsequent voltage hysteresis. Our findings demonstrate that regulating the reversibility of the cation migration is a practical strategy to reduce voltage decay and hysteresis in lithium-rich layered materials.

  View details for DOI 10.1038/s41563-019-0572-4

  View details for PubMedID 31959949