Conductivity and applications of Li-biphenyl-1,2-dimethoxyethane solution for lithium ion batteries

The total conductivity of Li-biphenyl-1,2-dimethoxyethane solution (Li x Bp(DME)9.65, Bp = biphenyl, DME = 1,2-dimethoxyethane, x = 0.25, 0.50, 1.00, 1.50, 2.00) is measured by impedance spectroscopy at a temperature range from 0 °C to 40 °C. The Li1.50Bp(DME)9.65 has the highest total conductivity 10.7 mS/cm. The conductivity obeys Arrhenius law with the activation energy , ). The ionic conductivity and electronic conductivity of Li x Bp(DME)9.65 solutions are investigated at 20 °C using the isothermal transient ionic current (ITIC) technique with an ion-blocking stainless steal electrode. The ionic conductivity and electronic conductivity of Li1.00Bp(DME)9.65 are measured as 4.5 mS/cm and 6.6 mS/cm, respectively. The Li1.00Bp(DME)9.65 solution is tested as an anode material of half liquid lithium ion battery due to the coexistence of electronic conductivity and ionic conductivity. The lithium iron phosphate (LFP) and Li1.5Al0.5Ti1.5(PO4)3 (LATP) are chosen to be the counter electrode and electrolyte, respectively. The assembled cell is cycled in the voltage range of 2.2 V–3.75 V at a current density of 50 mA/g. The potential of Li1.00Bp(DME)9.65 solution is about 0.3 V vs. Li+/Li, which indicates the solution has a strong reducibility. The Li1.00Bp(DME)9.65 solution is also used to prelithiate the anode material with low first efficiency, such as hard carbon, soft carbon and silicon.