Abstract: A method of preparing a sintered solid electrolyte includes (a) coprecipitating a mixed solution including a lanthanum precursor, a zirconium precursor, a gallium precursor, a complexing agent, and a pH adjuster to provide a solid electrolyte precursor; (b) washing and drying the solid electrolyte precursor to provide a washed and dried solid electrolyte precursor; (c) mixing the washed and dried solid electrolyte precursor with a lithium source to provide a mixture; (d) calcining the mixture to provide a calcined solid electrolyte, which is a gallium (Ga)-doped lithium lanthanum zirconium oxide (LLZO), as represented by Chemical Formula 1 below, LixLayZrzGawO12,??Chemical Formula 1 where 5?x?9, 2?y?4, 1?z?3, and 0<w?4; and (e) sintering the calcined solid electrolyte at a temperature ranging from 1,000° C. to 1,300° C. to provide the sintered solid electrolyte, wherein a ratio (M1:M2) of moles (M1) of lithium element to moles (M2) of gallium element ranges from 6.7:0.1 to 5.8:0.4.

Abstract: Disclosed is a method of preparing a solid electrolyte, the method including (a) preparing a solid electrolyte precursor by subjecting a mixed solution composed of a lanthanum precursor, a zirconium precursor, a gallium precursor, a complexing agent, and a pH adjuster to coprecipitation, (b) washing and drying the solid electrolyte precursor, (c) preparing a mixture by mixing the washed and dried solid electrolyte precursor with a lithium source, and (d) calcining the mixture to give a calcined solid electrolyte, which is a gallium (Ga)-doped lithium lanthanum zirconium oxide (LLZO), as represented by Chemical Formula 1. A solid electrolyte having increased ionic conductivity and an improved potential window can be provided using the method of preparing the solid electrolyte.

Abstract: Disclosed is a bipolar all solid-state battery, which can efficiently control a manufacturing process thereof and can improve electric properties thereof. In an exemplary embodiment, the bipolar all solid-state battery includes a unit cell including a first current collector having a first surface and a second surface opposite to the first surface; a first active material coated on the first surface of the first current collector, a second current collector having a first surface and a second surface opposite to the first surface; a second active material coated on the first surface of the second current collector and facing the first active material; and an all solid-state electrolyte formed between the first active material and the second active material. When a plurality of the unit cells are stacked, the first current collector and the second current collector are connected to each other through surface contact.