No abstract

No abstract

No abstract

We study the influence of the ultrasonic treatment of pyrophyllite in different media on its structure and charge transfer and analyze the dependences of changes in the Gibbs free energy, resistance to charge transfer, and capacitance of the Helmholtz layer caused by the acoustic action on the amount of "guest" lithium x . It is shown that abnormally high diffusion coefficients of lithium cations for all investigated values of x represent a specific feature of the kinetics of intercalation in Li x Al 2 (OH) 2 [Si 2 O 5 ] 2 . At present, the major part of known systems for the electrochemical generation and accumulation of energy contain cathodic substances whose reserves are exhausted [1]. In view of severe requirements of the market to the cost of one watt-hour of energy and ecological safety, we encounter a problem of creation of a new resource base for the devices of autonomous power supply from the collection of low-cost, ecologically safe, and widespread natural substances. Since at present, there are no acceptable materials satisfying these requirements among the available synthetic structures, the most promising way is clearly connected with the formation of a base of natural minerals with sufficiently large resources. However, numerous natural minerals prove to be inefficient for the direct generation and accumulation of electric energy. Thus, the development of the procedures of their modification is a primary task.Among promising natural minerals, we can mention pyrophyllite ( Al 2 (OH) 2 [Si 2 O 5 ] 2 ) whose crystalline structure is shown in Fig. 1. It has "guest" positions required for intercalation and located between weakly connected aluminosilicate layers [2]. Polymorphism, isovalent isomorphism [3,4], and impurities (together with weak bonds between the layers) typical of pyrophyllite make it suitable for the efficient modification by ultrasonic irradiation [5][6][7][8], which belongs to possible and safe production-and-technological operations. In the literature, there is no information about the influence of ultrasound on the thermodynamic and kinetic properties of pyrophyllite important for the intercalation current formation. This fact motivated the appearance of the present work. Materials and Experimental ProcedureIn our experiments, we used ground pyrophyllite. We performed the ultrasonic irradiation of pyrophyllite with a mass of 0.2 g placed in heptane and in 1 mliter of 1М LiBF4 in γ -butyrolactone for 60 min at a frequency of 22 kHz.

No abstract