Lithium secondary battery

A lithium secondary battery comprising:

• a positive electrode layer composed of a cobalt-containing lithium complex oxide sintered body;
• a negative electrode layer composed of a titanium-containing sintered body;
• a ceramic separator interposed between the positive electrode layer and the negative electrode layer and containing MgO;
• an electrolytic solution with which the positive electrode layer, the negative electrode layer, and the ceramic separator are impregnated;
• and
• an exterior body comprising a closed space, the closed space accommodating the positive electrode layer, the negative electrode layer, the ceramic separator, and the electrolytic solution,
• wherein the positive electrode layer, the ceramic separator, and the negative electrode layer form one integrated sintered plate as a whole, whereby the positive electrode layer, the ceramic separator, and the negative electrode layer are bonded together, and
• wherein an interface between the negative electrode layer and the ceramic separator has a larger roughness than an interface between the positive electrode layer and the ceramic separator.