Electrochemical Characteristics of All-Solid Lithium Ion Battery with Lithium Titanate/Lithium Lanthanum Zirconium Oxide Composite Electrode

Composite anodes for all solid-state lithium secondary batteries based on lithium titanate (Li₄Ti₅O₁₂) were fabricated by a wet process. The effect of the content of polyethylene oxide in the lithium titanate composite anode on the interfacial control for enhancing the ionic conductivity and binding between the constituent materials in the electrode was examined. The content of Super-P and garnet-type lithium lanthanum zirconium oxide in the composite lithium titanate electrode was fixed and the electrochemical characteristics of a half-cell were evaluated as a function of the lithium titanate and polyethylene oxide content in the electrode, where the polyethylene oxide content was varied from 35–70 wt%. A maximum discharge capacity of about 160 mAh g⁻¹ was obtained with the electrode comprising lithium titanate, lithium lanthanum zirconium oxide, Super-P, and polyethylene oxide in a weight ratio of 40:10:10:40. This value is about 94% of the theoretical capacity (170 mAh g⁻¹) of the lithium titanate electrode, and was almost equal to the half-cell capacity of the liquid-type congener. Furthermore, when this composite lithium titanate electrode was fabricated and evaluated in the full cell of an all-solid lithium secondary battery, a discharge capacity of about 140 mAh g⁻¹ was obtained.