Polythiophene-Wrapped Olivine NaFePO4 as a Cathode for Na-Ion Batteries
| Autor: | Kyung Yoon Chung, Seong-Won Choi, Kyung-Wan Nam, Ji-Hoon Lee, Ghulam Ali, Byung Won Cho, Dieky Susanto |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Rietveld refinement Mineralogy 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology Electrochemistry 01 natural sciences Cathode 0104 chemical sciences law.invention chemistry.chemical_compound Coating Chemical engineering chemistry law Electrochemical reaction mechanism Electrode engineering Polythiophene General Materials Science 0210 nano-technology Current density |
| Zdroj: | ACS Applied Materials & Interfaces. 8:15422-15429 |
| ISSN: | 1944-8252 1944-8244 |
| DOI: | 10.1021/acsami.6b04014 |
| Popis: | The surface of olivine NaFePO4 was modified with polythiophene (PTh) to develop a high-performance cathode material for use in Na-ion batteries. The Rietveld refinement results of the prepared material reveal that PTh-coated NaFePO4 belongs to a space group of Pnma with lattice parameters of a = 10.40656 Å, b = 6.22821 Å, and c = 4.94971 Å. Uncoated NaFePO4 delivers a discharge capacity of 108 mAh g(-1) at a current density of 10 mA g(-1) within a voltage range of 2.2-4.0 V. Conversely, the PTh-coated NaFePO4 electrode exhibits significantly improved electrochemical performance, where it exhibits a discharge capacity of 142 mAh g(-1) and a stable cycle life over 100 cycles, with a capacity retention of 94%. The NaFePO4/PTh electrode also exhibits satisfactory performance at high current densities, and reversible capacities of 70 mAh g(-1) at 150 mA g(-1) and 42 mAh g(-1) at 300 mA g(-1) are obtained compared with negligible capacities without coating. The related electrochemical reaction mechanism has been investigated using in situ X-ray absorption spectroscopy (XAS), which revealed a systematic change of Fe valence and reversible contraction/expansion of Fe-O octahedra upon desodiation/sodiation. The ex situ X-ray diffraction (XRD) results suggest that the deintercalation in NaFePO4/PTh electrodes proceeds through a stable intermediate phase and the lattice parameters show a reversible contraction/expansion of unit cell during cycling. |
| Databáze: | OpenAIRE |
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