Effect of Various Lithium Salts in TEGDME based Electrolyte for Li/Pyrite Battery

摘要

The effect of lithium salts such as LiPF_6, LiBF_4, LiCF_3SO_3 and LiN(CF_3SO_2)_2 (LiTFSI) in tetra(ethylene glycol) dimethyl ether (TEGDME) electrolyte on the ionic conductivity, interfacial resistance and discharge properties of Li/pyrite cell at room temperature was studied. The electrolytes had good ionic conductivity at room temperature in the range 0.61 to 1.86×10~(-3) S/cm. The discharge capacities of Li/pyrite cells with 1M LiPF_6 and LiBF_4 in TEGDME were lower compared to those of the other two non-HF containing salts. The best cycle performance was exhibited by LiTFSI in TEGDME electrolyte, with a discharge capacity of 438 mAhg~(-1) after 20 cycles, which is -49% of FeS_2 theoretical capacity (894 mAhg~(-1)). The good performance of LiTFSI-TEGDME electrolyte resulted mainly from its low interfacial resistance in Li/FeS_2 cells, which showed a decreasing trend with cycling.