Lithium nitrate and lithium trifluoromethanesulfonate ammoniates for electrolytes in lithium batteries

The liquid ammonia solutions of lithium nitrate and lithium trifluoromethanesulfonate (triflate) have been found to be highly conductive inorganic electrolytes with low vapor pressures. The important phases of the LiNO₃ · xNH₃ solutions (1.5 < x < 3.1) and those of the LiSO₃CF₃ · yNH₃ solutions (1.5 < y < 3.5) are documented. In addition, the temperature dependence of their conductivities, their electrical stability windows, and their NH₃ vapor pressures were determined. In summary, the lithium triflate ammoniate (LiCF₃SO₃ · 2NH₃) remains a liquid down to −10 °C. It has an electroactivity range of 3.8 V and a conductivity of 0.6 × 10⁻³ ω⁻¹ cm⁻¹ at −10 °C. The NH₃ vapor pressure is less than 1 bar at 60 °C. The lithium nitrate ammoniate (LiNO₃ · 2NH₃) has an electroactivity range of 3.5 V and a conductivity of 2.5 × 10⁻² ω⁻¹ cm⁻¹ at 20 °C. The freezing point of the nitrate ammoniate is between 3 °C and −10 °C depending on the stoichiometry. Its NH₃ vapor pressure remains below 1 bar up to 40 °C. In addition, Li/MnO₂ batteries were constructed and tested using the above mentioned electrolytes.