Browsing by Author "Zou, JS"

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    Enhanced high voltage stability of spinel‐type structured LiNi0.5Mn1.5O4 electrodes: targeted octahedral crystal site modification
    (Wiley, 2024-05-01) Zou, JS; Liang, G; Zhang, SH; Thomsen, L; Fan, Y; Pang, WK; Guo, ZP; Peterson, VK
    High‐voltage spinel‐type structured LiNi0.5Mn1.5O4 (LNMO) shows promise as a next‐generation high‐energy‐density lithium‐ion battery cathode material, however, capacity decay on extended cycling hinders its widespread adoption, underscoring an urgent need for further development. In this work, we introduce Zn at octahedral 16c crystal sites in LNMO with Fdm space group to improve rate capability and reduce the rapid capacity decay otherwise experienced during extended cycling. The current work resolves the detailed influence of isolated modification at octahedral 16c crystal sites, unveiling the mechanism for these performance improvements. We show that occupation of Zn at previously empty 16c sites prevents the migration of Ni/Mn to adjacent 16c sites, eliminating transformation to a rock‐salt type structured Ni0.25Mn0.75O2 phase above 4.8 V, preventing structure degradation and suppressing voltage polarization. This study provides insights into the fundamental structure‐function relationship of the LNMO battery cathode, pointing to pathways for the crystal structure engineering of materials with superior performance. © 2024 The Authors. Batteries & Supercaps published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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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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    Introducing 4s–2p orbital hybridization to stabilize spinel oxide cathodes for lithium-ion batteries
    (Wiley-VCH GmbH, 2022-04-25) Liang, GM; Olsson, E; Zou, JS; Wu, ZB; Li, JX; Lu, CZ; D'Angelo, AM; Johannessen, B; Thomsen, L; Cowie, BCC; Peterson, VK; Cai, Q; Pang, WK; Guo, ZP
    Oxides composed of an oxygen framework and interstitial cations are promising cathode materials for lithium-ion batteries. However, the instability of the oxygen framework under harsh operating conditions results in fast battery capacity decay, due to the weak orbital interactions between cations and oxygen (mainly 3d–2p interaction). Here, a robust and endurable oxygen framework is created by introducing strong 4s–2p orbital hybridization into the structure using LiNi0.5Mn1.5O4 oxide as an example. The modified oxide delivers extraordinarily stable battery performance, achieving 71.4 % capacity retention after 2000 cycles at 1 C. This work shows that an orbital-level understanding can be leveraged to engineer high structural stability of the anion oxygen framework of oxides. Moreover, the similarity of the oxygen lattice between oxide electrodes makes this approach extendable to other electrodes, with orbital-focused engineering a new avenue for the fundamental modification of battery materials. © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH - Open access.