Galvanostatic characteristics of FeS2 in salt-solvate lithium bis(trifluoromethane)sulfonimide and linear ether electrolytes

The electrochemical characteristics of natural pyrite FeS2 in electrolytes based on salt-solvate mixtures (lithium bis(trifluoromethane)sulfonamide and linear ethers) have been investigated. The specific capacity (Q) of natural pyrite during cycling within the temperature range of 20–80°C 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, the specific capacity values are close and do not depend on the nature of the linear ether. In salt-solvate electrolytes, the specific capacity varies in the following range: monoglyme (MG) > tetraglyme (TG) > diglyme (DG), which is apparently due to the conductivity, which 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 the cycling as a whole. The specific capacity values of FeS2 at 60°C in DG (0.44 LiImid) and TG (0.5 LiImid) electrolytes appear to be almost equal and correspond to about 500 mA h/g. It is shown that the “open circuit voltage-introduced lithium amount” dependence does not differ significantly in diluted and salt-solvate electrolytes during the first cycle. However, the difference becomes more apparent during cycling of FeS2.