Lithium secondary cell

A lithium secondary cell comprising:

• a positive electrode;
• a separator arranged on said positive electrode in a predetermined direction of superposition;
• a negative electrode arranged on said separator on a side opposite to said positive electrode in said direction of superposition;
• an electrolytic solution with which said positive electrode, said negative electrode, and said separator are impregnated;
• and
• a sheet-like cell case that covers said positive electrode and said negative electrode from both sides in said direction of superposition and houses therein said positive electrode, said separator, said negative electrode, and said electrolytic solution,
• wherein one electrode of said positive electrode and said negative electrode includes:
• a sheet-like current collector having conductivity;
• and
• an active material plate that is a plate-like ceramic sintered body containing a lithium composite oxide, said active material plate being bonded to said current collector via a conductive bonding layer,
• said conductive bonding layer penetrates into said active material plate through an entire surface of said active material plate facing said current collector,
• a penetration depth of said conductive bonding layer in said active material plate with respect to said direction of superposition is 3% or more and 80% or less of a thickness of said active material plate.