A thin layer lithium-ion type battery comprising, on a substrate (20, 30), a cathode current collector layer (22, 36) and an active portion constituted by a stack of a cathode layer (23, 35) made of material suitable for inserting lithium ions, an electrolyte layer (24, 34), and an anode layer (25, 33), wherein the cathode layer presents, across its thickness, porosity that varies between its interface with the cathode current collector layer and its interface with the electrolyte layer, the variation in the porosity being non-zero so as to improve cohesion at both interfaces.