Development of Na2FePO4F/Conducting-Polymer composite as an exceptionally high performance cathode material for Na-ion batteries

Na2FePO4F encircled by a nanolayer composed of a conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), is prepared using a simple low-temperature process, and X-ray diffraction analysis indicates that the Na2FePO4F-PEDOT composite is the pure phase without any impurities. The existence and uniform encapsulation of PEDOT on the surface of the Na2FePO4F particles are clearly confirmed through Fourier-transform infrared spectroscopy and transmission electron microscopy. The PEDOT coating results in remarkably enhanced electrochemical performance compared with that of pristine Na2FePO4F. At C/5 (1C = 124 mA g(-1)), the Na2FePO4F-PEDOT composite retains a specific capacity of similar to 123.1 mAh g(-1), which is close to its theoretical capacity. Even at 10C, the Na2FePO4F-PEDOT composite delivers a capacity of similar to 76.1 mAh g(-1), which is similar to 10 times higher than that of pristine Na2FePO4F under the same conditions. Furthermore, the Na2FePO4F-PEDOT composite maintains similar to 70% of its initial discharge capacity over 700 cycles at 1C.