Synthesis And Electrochemical Properties Of The Alkali Metal Bismuth Sulfate Complexes

New energy materials are key to solving the shortage of energy. Among these materials, the sulfates play an important role in electrochemistry. In this work, the alkali metal bismuth sulfate complexes were synthesized by solid state reactions and the new compound Bi Cu2(Te O3)(SO4)(OH)3 was prepared by hydrothermal method. The single crystal diffraction data were collected on Bruker APEX-II CCD X-ray diffractometer, the crystal structure was solved by direct methods and refined by full-matrix least-square method using SHELX-2013 software. The electrochemical properties of the alkali metal bismuth sulfate complexes were characterized by cyclic voltammetry, impedance spectroscopy and charge-discharge method, The optical properties were investigated by Fourier transform infrared spectroscopy and UV-vis-Near Infrared spectroscopy. The main results are as follows:1. The compound Na Bi(SO4)2 crystallizes in the monoclinic space group P21/c with lattice parameters a = 9.4340(18)?, b = 7.0536(13)?, c = 9.4489(18) ?, β = 95.839(3)°, and Z = 4. Along [100] direction, the structure of Na Bi(SO4)2 is a two-dimensional [Bi(SO4)2]- layers linked by numerous SO4 tetrahedra and Bi O8 bicapped trigonal prisms, Na+ ions are located between the layers. In the structure, each SO4 tetrahedron is surrounded by four Bi O8 bicapped three prisms, the one O atom of SO42- connect two Bi atoms, the three remaining O atoms are each connected to one Bi atom.2. The compound KBi(SO4)2 crystallizes in the monoclinic space group C2/c with lattice parameters a = 13.052(2)?, b = 5.358(11)?, c = 9.413(18)?, β = 102.031(3)°, and Z = 4; The compound Rb Bi(SO4)2 crystallizes in the monoclinic space group C2/c with lattice parameters a =13.501(5)?, b =5.3688(19)?, c =9.467(3)?, β = 102.697(6)°, Z =4. The structure of both compounds can be described as that Bi O8 square antiprism is connected to adjacent Bi O8 square antiprism via two SO4 tetrahedra to form infinite [Bi(SO3)2]3+ chains viewing along the [100] drection. The parallel chains are linked via corner-sharing oxygen(O3) of SO42-, forming a two-dimensional [Bi(SO4)2]- layers in the ab plane, the layers are separated by K+ or Rb+. The Raman and infrared spectra confirmed the presence of S-O,O-Bi-O and lattice vibrations. The UV/vis spectrum of three compounds estimated the band gap to 4.46 e V 、4.18 e V and 4.15 e V.3. The new compound Bi Cu2(Te O3)(SO4)(OH)3 crystallizes in the monoclinic space group P21/n with lattice parameters a = 9.5513(15)?, b = 6.3022(10)?, c = 13.955(2) ?, β = 102.845(3)°, and Z = 4, The structure of this compound is a three-dimensional tunnel framework consisting of edge-sharing two-dimensional [Cu3O10]14- layers linked by Bi O8 bicapped trigonal prisms, Te O32-trigonal pyramids and SO42- tetrahedra. Raman and FTIR spectra were used to confirm the presence of various functional groups such as Te O32-, SO42-, OH- in the crystals. The UV/vis spectrum of the compound estimated the band gap to 3.85 e V.4. The alkali metal bismuth sulfate complexes were used as the electrode materials at first time. The high-frequency region of the AC impendance figure showed that the alkali metal bismuth sulfate complexes were suitable as electrode materials. In 6 M/L KOH solution, the specific capacitance of Na Bi(SO4)2, KBi(SO4)2 and Rb Bi(SO4)2 were 260, 338, 231 F / g at a scan rate of 5 m V / s.