Preparation, Characterization And Modification Of The FeSe₂ Nanomaterials

Due to special photoelectric properties of chalcogenide, especially for selenide, they have gained increasing attention recently, become a hotspot for study. For FeSe2, there is few research focuing on electrochemical researches of FeSe2. FeSe2 semiconductor materials have import significance to research on lithium ion batteries, which have several advantages such as narrow bandgap, high electronic conductivity, high specific capacity and so on. However, the research results show that it need some research to overcome disadvantages such as quickly capacity fading, cycle stability and so on. FeSe2 nanomaterials was synthesized via hydrothermal reaction, moreover, FeSe2 nanomaterials were modified through two methods for improvement of electrochemical properties. The content of the article reads as follows:Under a appropriate concentration of polyvinyl alcohol solution, FeSe2 nanomaterials was synthesized via hydrothermal reaction with high crystallinity and pure phase. The structures of the FeSe2 nanomaterials were characterized via XRD, FESEM, and FeSe2 nanomaterials using as cathode materials were assembled fastener cell to measure electrochemical properties. First discharge capacity of FeSe2 nanomaterials is 362 mAh/g, fraction loss per cycle reaches 2.39% of by calculation after 50 cycles.Directly lithiated FeSe2 nanomaterials were synthesized by a hydrothermal reaction, the change of structures of the directly lithiated FeSe2 nanomaterials were characterized via XRD, FESEM, and measure electrochemical properties. The results of electrochemical properties tests of directly lithiated FeSe2 nanomaterials show that fraction loss per cycle after 50 cycles is 1.23%, cycle stability have been improved comparing with FeSe2 nanomaterials, then study the connection between properties and the change of the structure of before and after lithiation.Using glucose as carbon source, different mole ratio FeSe2/C composite nanomaterials were synthesized via hydrothermal reaction. And the as-prepared composite nanomaterials were heating under 500℃. The structures of the FeSe2/C composite nanomaterials were characterized via XRD, FESEM, Raman spectra. Before heat treatment, The results of electrochemical properties tests of FeSe2/C composite nanomaterials show that first discharge capacity decreasing as the amount of glucose increasing, fraction loss per cycle after 50 cycles minor reduce, comparing with FeSe2 nanomaterials, cycle stability have been improved a certain degree. After heat treatment, fraction loss per cycle after 50 cycles of FeSe2/C composite nanomaterials obviously reduce, cycle stability has been notable improved.