Browsing by Author "Yuwono, JA"

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    Enhancing the reaction kinetics and structural stability of high-voltage LiCoO 2 via polyanionic species anchoring
    (Royal Society of Chemistry (RSC), 2024-05-16) Zheng, W; Liang, GM; Guo, H; Li, JX; Zou, JS; Yuwono, JA; Shu, H; Zhang, S; Peterson, VK; Johannessen, B; Thomsen, L; Hu, WB; Guo, ZP
    Increasing the charging voltage to 4.6 V directly enhances battery capacity and energy density of LiCoO2 cathodes for lithium-ion batteries. However, issues of the activated harmful phase evolution and surface instability in high-voltage LiCoO2 lead to dramatic battery capacity decay. Herein, polyanionic PO43− species have been successfully anchored at the surface of LiCoO2 materials, achieving superior battery performance. The polyanionic species acting as micro funnels at the material surface, could expand LiCoO2 surface lattice spacing by 10%, contributing to enhanced Li diffusion kinetics and consequent excellent rate performance of 164 mA h g−1 at 20C (1C = 274 mA g−1). Crucially, polyanionic species with high electronegativity could stabilize surface oxygen at high voltage by reducing O 2p and Co 3d orbital hybridization, thus suppressing surface Co migration and harmful H1–3 phase formation and leading to superior cycling stability with 84% capacity retention at 1C after 300 cycles. Furthermore, pouch cells containing modified LiCoO2 and Li metal electrodes deliver an ultra-high energy density of 513 W h kg−1 under high loadings of 32 mg cm−2. This work provides insightful directions for modifying the material surface structure to obtain high-energy-density cathodes with high-rate performance and long service life. © Royal Society of Chemistry 2024.
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    Impurity tolerance of unsaturated Ni-N‑C active sites for practical electrochemical CO2 reduction
    (American Chemical Society (ACS), 2022-02-09) Leverett, J; Yuwono, JA; Kumar, P; Tran-Phu, T; Qu, JT; Cairney, JM; Wang, X; Simonov, AN; Hocking, RK; Johannessen, B; Dai, L; Daiyan, R; Amal, R
    Demonstrating the potential of the electrochemical carbon dioxide reduction reaction (CO2RR) in industrially relevant conditions is a promising route for achieving net-zero emissions through decarbonization. This requires a catalyst system that displays not only high activity and stability but also the capacity to deliver a consistent performance in the presence of waste stream impurities. To explore these opportunities, we investigate the role that the Ni coordination structure plays on the impurity tolerance of highly active single-atom catalysts (SACs) during CO2RR. The as-synthesized materials are highly active for CO2RR to CO, achieving a current density of 470 mA cm-2 and a CO selectivity of 99% in a CO2 electrolyzer. We demonstrate, through high-temperature pyrolysis, that a higher concentration of “unsaturated” Ni-N4-x-Cx sites significantly improves the tolerance to NOx, SOx, volatile organic compounds, and SCN- impurities in aqueous electrolyte, paving the way for SACs capable of CO2RR in industrial conditions. © 2022 American Chemical Society.
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    The promise of high-entropy materials for high-performance rechargeable Li-ion and Na-ion batteries
    (Elsevier, 2023-12-20) Zheng, W; Liang, G; Liu, Q; Li, JX; Yuwono, JA; Zhang, S; Peterson, VK; Guo, ZP
    Our growing dependence on rechargeable Li/Na-ion batteries calls for substantial improvements in the electrochemical performance of battery materials, including cathodes, anodes, and electrolytes. However, the performance enhancements based on traditional modification methods of elemental doping and surface coating are still far from the target of high-performance rechargeable batteries. Fortunately, the recent emergence of high-entropy materials preserving a stable solid-state phase for energy-related applications provides unprecedented flexibility and variability in materials composition and electronic structure, opening new avenues to accelerate battery materials development. This perspective first presents clear qualitative and quantitative definitions for high-entropy battery materials, as well as summarizes the enhancement mechanisms. Then, we comprehensively review state-of-the-art research progress and highlight key factors in the rational design of advanced high-entropy battery materials from both experimental and calculational aspects. Moreover, the challenges limiting the progress of this research are presented, alongside insights and approaches to address these issues at the research forefront. Finally, we outline potential directions for extending the future development of the high-entropy strategy to solve other critical issues in battery materials research. This perspective will guide researchers in their studies toward the development of high-performance rechargeable Li-ion and Na-ion batteries. © 2024 Elsevier Inc. - Open Archive