Optimization of Electrolyte Conductivity for Li-ion Batteries Based on Mass Triangle Model

Mass triangle model was applied to lithium ion battery for electrolyte conductivity forecasting. Seven kinds of electrolytes with different proportions of 3 solvents were prepared. The solvent proportions of the seven electrolytes varied so as to make the seven coordinate points distribute in the ternary coordinate system to form a forcasting region by the connection of them. Their conductivities were tested and the conductivity value in the forecasting region was calculated based on the tested value by mass triangle model. Conductivity isolines formed in the region and blank area showing no forecasted value existed simultaneously. Optimized electrolyte with superior conductivity was selected according to conductivity variation trendency combined with the attention paid to the no-value-shown blank area. The conductivity of optimized electrolyte{m[ethyl carbonate(EC)]:m[propylene carbonate(PC)]:m[ethylmethyl carbonate(EMC)]=0.19:0.22:0.59} was 0.745 mS/cm at -40 ℃, increased by a factor of 51.4% compared to 0.492 mS/cm of common electrolyte[m(EC):m(PC):m(EMC)=1:1:1]. The accuracy of mass triangle model was demonstrated from the perspective that the maximum value existed in the blank area. Batteries with this optimized electrolyte exhibited a better performance.