Browsing by Author "Gu, L"

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    Controlled atomic solubility in Mn‐rich composite material to achieve superior electrochemical performance for Li‐ion batteries
    (Wiley, 2019-12-16) Lee, J; Zhang, Q; Kim, J; Dupre, N; Avdeev, M; Jeong, M; Yoon, WS; Gu, L; Kang, B
    The quest for high energy density and high power density electrode materials for lithium-ion batteries has been intensified to meet strongly growing demand for powering electric vehicles. Conventional layered oxides such as Co-rich LiCoO2 and Ni-rich Li(NixMnyCoz)O2 that rely on only transition metal redox reaction have been faced with growing constraints due to soaring price on cobalt. Therefore, Mn-rich electrode materials excluding cobalt would be desirable with respect to available resources and low cost. Here, the strategy of achieving both high energy density and high power density in Mn-rich electrode materials by controlling the solubility of atoms between phases in a composite is reported. The resulting Mn-rich material that is composed of defective spinel phase and partially cation-disordered layered phase can achieve the highest energy density, ≈1100 W h kg−1 with superior power capability up to 10C rate (3 A g−1) among other reported Mn-rich materials. This approach provides new opportunities to design Mn-rich electrode materials that can achieve high energy density and high power density for Li-ion batteries. © 1999-2021 John Wiley & Sons, Inc.
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    Fully exploited oxygen redox reaction by the inter‐diffused cations in Co‐free Li‐rich materials for high performance Li‐ion batteries
    (Wiley, 2020-09-09) Lee, J; Dupre, N; Jeong, M; Kang, SY; Avdeev, M; Gong, Y; Gu, L; Yoon, WS; Kang, B
    To meet the growing demand for global electrical energy storage, high-energy-density electrode materials are required for Li-ion batteries. To overcome the limit of the theoretical energy density in conventional electrode materials based solely on the transition metal redox reaction, the oxygen redox reaction in electrode materials has become an essential component because it can further increase the energy density by providing additional available electrons. However, the increase in the contribution of the oxygen redox reaction in a material is still limited due to the lack of understanding its controlled parameters. Here, it is first proposed that Li-transition metals (TMs) inter-diffusion between the phases in Li-rich materials can be a key parameter for controlling the oxygen redox reaction in Li-rich materials. The resulting Li-rich materials can achieve fully exploited oxygen redox reaction and thereby can deliver the highest reversible capacity leading to the highest energy density, ≈1100 Wh kg−1 among Co-free Li-rich materials. The strategy of controlling Li/transition metals (TMs) inter-diffusion between the phases in Li-rich materials will provide feasible way for further achieving high-energy-density electrode materials via enhancing the oxygen redox reaction for high-performance Li-ion batteries. © 2020 The Authors.
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    A general approach to 3D-printed single-atom catalysts
    (Springer Nature Limited, 2023-01-02) Xie, FX; Cui, XL; Zhi, X; Yao, D; Johannessen, B; Lin, T; Tang, JN; Woodfield, TBF; Gu, L; Qiao, SZ
    A mass production route to single-atom catalysts (SACs) is crucial for their end use application. To date, the direct fabrication of SACs via a simple and economic manufacturing route remains a challenge, with current approaches relying on convoluted processes using expensive components. Here, a straightforward and cost-effective three-dimensional (3D) printing approach is developed to fabricate a library of SACs. Despite changing synthetic parameters, including centre transition metal atom, metal loading, coordination environment and spatial geometry, the products show similar atomic dispersion nature of single metal sites, demonstrating the generality of the approach. The 3D-printed SACs exhibited excellent activity and stability in the nitrate reduction reaction. It is expected that this 3D-printing technique can be used as a method for large-scale commercial production of SACs, thus enabling the use of these materials in a broad spectrum of industrial applications. © 2023 The Author(s), under exclusive licence to Springer Nature Limited.
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    Uncovering the potential of M1‐site‐activated NASICON cathodes for Zn‐Ion batteries
    (Wiley, 2020-02-20) Hu, P; Zou, Z; Sun, XW; Wang, D; Ma, J; Kong, QY; Xiao, DD; Gu, L; Zhou, XH; Zhao, JW; Dong, SM; He, B; Avdeev, M; Shi, S; Cui, GL; Chen, LQ
    There is a long‐standing consciousness that the rhombohedral NASICON‐type compounds as promising cathodes for Li+/Na+ batteries should have inactive M1(6b) sites with ion (de)intercalation occurring only in the M2 (18e) sites. Of particular significance is that M1 sites active for charge/discharge are commonly considered undesirable because the ion diffusion tends to be disrupted by the irregular occupation of channels, which accelerates the deterioration of battery. However, it is found that the structural stability can be substantially improved by the mixed occupation of Na+/Zn2+ at both M1 and M2 when using NaV2(PO4)3 (NVP) as a cathode for Zn‐ion batteries. The results of atomic‐scale scanning transmission electron microscopy, analysis of ab initio molecular dynamics simulations, and an accurate bond‐valence‐based structural model reveal that the improvement is due to the facile migration of Zn2+ in NVP, which is enabled by a concerted Na+/Zn2+ transfer mechanism. In addition, significant improvement of the electronic conductivity and mechanical properties is achieved in Zn2+‐intercalated ZnNaV2(PO4)3 in comparison with those of Na3V2(PO4)3. This work not only provides in‐depth insight into Zn2+ intercalation and dynamics in NVP unlocked by activating the M1 sites, but also opens a new route toward design of improved NASICON cathodes. © 1999-2021 John Wiley & Sons, Inc.