In the lithium-sulfur (Li-S) context, LiNO₃ is known to improve the battery performance by forming efficient SEI layer on the lithium anode and consequently prevent or minimise chemical and electrochemical reduction of polysulfides on the anode and suppress the associated lithium polysulfides shuttle effect during cycling. Mikhaylik, from Sion Power Corp. [1], has patented, for the first time, a method that employs N-O bond containing additives, such as LiNO₃, in the electrolyte to suppress the PS shuttle effect. Herein, the modification of LiNO₃ additive concentration (0.05 to 0.4 mol kg^-1) in a C₄mpyr-TFSI electrolyte-based Li-S system, for the first time with the best of our knowledge, is investigated in which 0.1 mol kg^-1 was determined to be the optimum concentration in the blended IL-organic electrolyte as a result of higher conductivity and higher ion mobility.

Similar performance of cells with different nitrate additive concentrations at 50 ^oC confirms the correlation between ionic conductivity/viscosity and cell performance. Pulsed field gradient-NMR (PFG-NMR) is utilized to measure diffusion coefficients for cations and anion the electrolytes. The data shows higher diffusion coefficients (therefore higher mobility) for anion and cations in electrolyte containing 0.1 mol kg^-1 compared to electrolytes with higher or lower LiNO₃ additive at room temperature. Furthermore, the lower D values for TFSI^- and Li⁺ compared to pyrrolydinium cation confirms the transportation of Li⁺ in the form of [Li(TFSI)_n]^(n-1)- complex in the electrolyte.

1.            Mikhaylik, Y.V., Electrolytes for lithium sulfur cells. 2008, SION POWER CORPORATION: US.