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Enhancing Anion-Selective Catalysis for Stable Lithium Metal Pouch Cells through Charge Separated COF Interlayer
Summary:
The authors from Xi’an Jiaotong University developed a tris(4-aminophenyl) amine-pyromeletic dianhydride covalent organic frameworks (TP-COF) material, achieving significant results in enhancing the stability and energy density of lithium metal batteries.
Background:
1. Lithium metal batteries (LMBs) are promising for high energy density applications, but the formation of a stable solid electrolyte interphase (SEI) on the lithium metal anode remains a challenge. Previous efforts to create a LiF-rich SEI through electrolyte engineering have been limited by issues such as reduced conductivity and increased costs. There is a need for an effective strategy to build a dense and LiF-rich SEI to enhance battery performance.
2. The authors proposed a selective catalysis anionic decomposition strategy using charge-separated TP-COF to regulate the composition and structure of the SEI, achieving a LiF-rich SEI that facilitates rapid Li⁺ transfer and suppresses dendritic Li growth.
Research Content:
1. Synthesis:
The authors synthesized TP-COF via a polycondensation reaction between tris(4-aminophenyl) amine (TAPA) and pyromellitic dianhydride (PMDA).
2. Characterizations:
1) BET analysis showed a specific surface area of 127.88 m²g⁻¹ and a pore size distribution with a peak at 1.3 nm.
2) SEM/TEM tests revealed a uniform distribution of C, N, and O elements, with a particle size of approximately 2.1 μm.
3) UV absorption spectra and Raman spectra confirmed the strong interaction between TP-COF and FSI⁻, resulting in a lower LUMO energy level and enhanced decomposition of FSI⁻.
3. Application:
The TP-COF interlayer was applied to a 6.5 Ah LiNi₀.₈Co₀.₁Mn₀.₁O₂ pouch cell, achieving an energy density of 473.4 Whkg⁻¹ and excellent cycling stability (97.4% retention over 95 cycles) under lean electrolyte conditions.
4. Mechanism:
The strong donor-acceptor unit structure of TP-COF induces local charge separation, enhancing the affinity to FSI⁻ and lowering its LUMO energy level, which accelerates FSI⁻ decomposition and forms a stable LiF-rich SEI. This SEI facilitates rapid Li⁺ transfer and suppresses dendritic Li growth.
Outlook:
This research demonstrates a novel strategy for constructing a stable SEI on lithium metal anodes, significantly enhancing the performance of high-energy-density lithium metal batteries. The findings provide a promising avenue for the practical application of LMBs.
Enhancing Anion-Selective Catalysis for Stable Lithium Metal Pouch Cells through Charge Separated COF Interlayer
Authors: Peiyu Zhao, Yanhua Zhang, Baoyu Sun, Rui Qiao, Chao Li, Pengqi Hai, Yingche Wang, Feng Liu, Jiangxuan Song
DOI: 10.1002/anie.202317016
Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202317016
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