Ali, Ghulam Lee, Ji-Hoon Susanto, Dieky Choi, Seong-Won Cho, Byung Won Nam, Kyung-Wan Chung, Kyung Yoon 2024-01-20T04:02:05Z 2024-01-20T04:02:05Z 2021-09-05 2016-06-22 1944-8244 https://pubs.kist.re.kr/handle/201004/123955 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 angstrom, b = 6.22821 angstrom, and c = 4.94971 angstrom. 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. English American Chemical Society SODIUM-ION ELECTROCHEMICAL PERFORMANCE ELECTRODE MATERIALS HIGH-CAPACITY LITHIUM LIFEPO4 PHOSPHATE POLYPYRROLE STABILITY COMPOSITE Polythiophene-Wrapped Olivine NaFePO4 as a Cathode for Na-Ion Batteries Article 10.1021/acsami.6b04014 1 ACS Applied Materials & Interfaces, v.8, no.24, pp.15422 - 15429 ACS Applied Materials & Interfaces 8 24 15422 15429 scie scopus 000378584800059 2-s2.0-84976286928 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Science & Technology - Other Topics Materials Science Article SODIUM-ION ELECTROCHEMICAL PERFORMANCE ELECTRODE MATERIALS HIGH-CAPACITY LITHIUM LIFEPO4 PHOSPHATE POLYPYRROLE STABILITY COMPOSITE olivine NaFePO4 polythiophene Na-ion batteries X-ray absorption spectroscopy Fe valence