Electrochemical Analysis of Li[sub 4]Ti[sub 5]O[sub 12] Electrode in All-Solid-State Lithium Secondary Batteries

All-solid-state Li – In ∕ Li 4 Ti 5 O 12 cells using the 80 Li 2 S ⋅ 20 P 2 S 5 solid electrolyte were assembled to investigate their rate performances and impedance behaviors. Furthermore, Li ∕ Li 4 Ti 5 O 12 cells using 1 mol dm − 3 Li P F 6 dissolved in ethylene carbonate and diethyl carbonate were fabricated for comparison to the all-solid-state cells. In the all-solid-state cells, resistance attributable to the lithium-ion transfer from the solid electrolyte to Li 4 Ti 5 O 12 spinel phase was observed during the lithium insertion into Li 4 Ti 5 O 12 spinel phase during the discharge process. Results clarified that the cells using the solid electrolyte showed higher resistance and larger activation energy for this lithium-ion transfer than the cells using the liquid electrolyte. Resistance was not observed in the charge process. The all-solid-state cell showed the average charge voltage of 1.9 V (vs Li) and reversible capacity of ∼ 80 mAh g − 1 at the charge current density of 1.3 mA cm − 2 and the discharge current density of 0.064 mA cm − 2 .