Hybrid carboxylate-Schiff-bases as electroactive anode materials for potassium-ion batteries
Three new crystalline potassium salts of hybrid carboxylate/Schiff-base oligomers are reported as electrochemically active anode materials for potassium ion batteries. One of them is constituted by the phenyl “dimer” KOOC-ϕ-C=N-ϕ-COOK (BSK-1) and the other two by the isomer “trimers” KOOC-ϕ-C=N-ϕ-N=...
| Autores: | , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/125100 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/125100 |
| Access Level: | acceso abierto |
| Palabra clave: | 546 K-ion batteries Batteries Anode Electrochemical energy storage Schiff-bases Structure Microstructure Coplanarity Química inorgánica (Química) 2303 Química Inorgánica |
| Sumario: | Three new crystalline potassium salts of hybrid carboxylate/Schiff-base oligomers are reported as electrochemically active anode materials for potassium ion batteries. One of them is constituted by the phenyl “dimer” KOOC-ϕ-C=N-ϕ-COOK (BSK-1) and the other two by the isomer “trimers” KOOC-ϕ-C=N-ϕ-N=C-ϕ-COOK (BSK-2 A) and KOOC-ϕ-N=C-ϕ-C=N-ϕ-COOK (BSK-2B). A structural model refined from powder X-ray diffraction data is discussed for the short (dimeric) salt. A pseudo-monoclinic unit cell, with space group P and lattice parameters a = 15.88(1) Å, b = 5.772(2) Å, c = 3.887(1) Å and β = 98.8(1)0, contains a single molecule. Crystal packing of the aromatic molecules can be described by a slipped π-stacking along the c-axis. All three oligomers are electrochemically active at voltages low enough to be used as anode in potassium ion batteries, at average voltages of 1.2 V vs K+/K for the dimer and 1.05 V vs K+/K for the trimers. Combined with 3.9 M KFSI in DME electrolyte, they show reversible capacities of 115 mAh/g (dimer), 233 mAh/g (BSK-2 A) and 104 mAh/g (BSK-2B) at C/10, with capacity retentions at 1C of 74% and 65% for the dimer and the trimers respectively. Based on the dQ/dV plots, the trimers react through two solid solution mechanisms, forming a stable radical intermediate, whereas the dimer changes from a single solid solution to a solid-solution+biphasic reaction. Future in-situ x-ray diffraction studies based on the solved crystal packing should enable to confirm these mechanisms. |
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