A button battery, comprising a negative electrode cover, a positive electrode case, a sealing ring, a positive electrode, a separating diaphragm, a negative electrode and electrolyte, wherein the sealing ring is hermetically connected with the negative electrode cover and the positive electrode case and makes the negative electrode cover and the positive electrode case form a sealing cavity, and the positive electrode, the separating diaphragm, the negative electrode and the electrolyte are arranged in the sealing cavity; characterized in that the button battery further comprises a base arranged in the positive electrode case; the base comprises an outer ring wall, an inner ring wall, and a top wall for connecting the outer ring wall with the inner ring wall, and the outer ring wall, the inner ring wall and the top wall form an annular cavity, and the top wall abuts against the sealing ring; the annular cavity is provided with a first through hole for entering and exiting of electrolyte and/or gas; the positive electrode is located in an inner ring of the base, and an upper end face of the positive electrode has a boss structure and a lower end face of the positive electrode is provided with a chamfer; the top wall of the base extends toward the sealing ring to form an annular protrusion; an opening of the negative electrode cover is bent outward and extends upward to form a sealing edge, and the sealing ring is arranged on the sealing edge to seal the gap between an opening of the positive electrode case and an opening of the negative electrode cover; the annular protrusion is arranged just below the bending portion of the sealing edge; the top wall of the base is connected with the inner ring wall and the outer ring wall by arcs respectively; the inner ring wall and the outer ring wall of the base are annular walls arranged concentrically, and the annular cavity is an annular groove with an opening facing toward the bottom of the positive electrode case; characterized in that the bottom of the inner ring wall of the base has a flange extending inward in a direction perpendicular to the inner ring wall, and the flange is fit with the positive electrode case; the outer diameter of the base is adapted to the inner diameter of the positive electrode case, the outer ring wall of the base is provided with an elastic protrusion, and the base is buckle-connected with the positive electrode case through the elastic protrusion. an opening of the negative electrode cover is bent outward and extends upward to form a sealing edge, and the sealing ring is arranged on the sealing edge to seal the gap between an opening of the positive electrode case and an opening of the negative electrode cover; the annular protrusion is arranged just below the bending portion of the sealing edge; the top wall of the base is connected with the inner ring wall and the outer ring wall by arcs respectively; the inner ring wall and the outer ring wall of the base are annular walls arranged concentrically, and the annular cavity is an annular groove with an opening facing toward the bottom of the positive electrode case; characterized in that the bottom of the inner ring wall of the base has a flange extending inward in a direction perpendicular to the inner ring wall, and the flange is fit with the positive electrode case; the outer diameter of the base is adapted to the inner diameter of the positive electrode case, the outer ring wall of the base is provided with an elastic protrusion, and the base is buckle-connected with the positive electrode case through the elastic protrusion.