Electrochemical Characteristics of FeS₂ in Salt-solvate Electrolytes Based on Mixtures of Lithium Bis(Trifluormethane)sulfonimide and Linear Ethers

CZU 541.135.3+541.135

Electrochemical characteristics of natural pyrite FeS₂ in electrolytes based on: salt-solvate mixtures – lithium bis(trifluoromethane)sulfonimide – linear ethers, have been investigated. The specific capacity (Q) of natural pyrite during cycling within the temperature range 20–80^оC has been estimated. It has been shown that at room temperature the Q value for FeS₂ depends on the concentration of lithium salt and on the linear ether nature. In diluted solutions specific capacity values are close and do not depend on the nature of linear ether. In salt-solvate electrolytes specific capacity varies in the range monoglyme (MG) > tetraglyme (TG) > diglyme (DG), which is apparently due to the conductivity that reduces in a similar sequence. The higher the temperature, the higher the discharge capacity of pyrite. It is typical for both the first cycle and cycling as a whole. Specific capacity values of FeS₂ at 60°C in electrolytes DG – 0.44 LiImid and TG – 0.5 LiImid appear to be almost equal and correspond to about 500 mAh/g. It has been shown that the “open circuit voltage – intercalled lithium amount” dependence does not differ significantly in diluted and salt-solvate electrolytes during the first cycle. But the difference becomes more apparent during cycling of FeS₂.

Keywords: natural pyrite, salt-solvate electrolytes, cycling, specific capacity, electrical conduction.