Cylindrical battery
View Patent ↗The opening of a cylindrical battery case 1 with a bottom is sealed by a seal assembly 5 . The seal assembly 5 has an upper valve plate 13 , a lower valve plate 15 , and a bottom plate 16 . The bottom plate 16 has inner gas vent holes 21 . When the inner gas vent holes 21 are viewed from the axial direction of the battery case 1 , at least a part of each inner gas vent hole 21 overlaps a valve-hole forming portion 15 b of the lower valve plate 15 . With this configuration, for example, even when an electrode assembly 20 is pushed up by increased internal pressure of the battery to push up the bottom plate 16 , the valve hole is not closed.
1. A cylindrical battery comprising:
a power generating element comprising a positive electrode being capable of absorbing and desorbing lithium ions and serving as one of the first electrode and the second electrode, a negative electrode being capable of absorbing and desorbing lithium ions and serving as the other one of the first electrode and the second electrode, a separator interposed between the positive electrode and the negative electrode, and a lithium-ion conductive non-aqueous electrolyte;
a cylindrical battery case with a bottom for housing the power generating element; and
a seal assembly for sealing an opening of the battery case,
the seal assembly including a terminal plate with an outer gas vent hole, a bottom plate with an inner gas vent hole, and at least one valve plate disposed between the terminal plate and the bottom plate, the bottom plate being circular,
the terminal plate and the bottom plate being electrically connected via the valve plate,
the valve plate being circular and concentric with the bottom plate, and having an annular fragile portion which will rupture when the internal pressure of the battery increases so that a valve hole opens up in a portion of the valve plate at a center thereof,
wherein the bottom plate has a plurality of the inner gas vent holes, and when the inner gas vent holes are viewed from the axial direction of the battery case, only a part of each of the inner gas vent holes overlaps the portion of the valve plate in which the valve hole is to open up, and 50 to 80% of the total length of the annular fragile portion overlaps the inner gas vent holes such that the valve hole and the inner gas vent holes overlap with each other when viewed in the axial direction when the bottom plate is pushed upwardly by the power generating element into the valve plate, so as to allow gas inside said cylindrical battery case to be released to outside of said cylindrical battery case when the valve hole is opened.
2. A cylindrical battery comprising:
a power generating element;
a cylindrical battery case with a bottom for housing the power generating element; and
a seal assembly for sealing an opening of the battery case,
the seal assembly including a terminal plate with an outer gas vent hole, a bottom plate with an inner gas vent hole, and at least one valve plate disposed between the terminal plate and the bottom plate, the bottom plate being circular,
the power generating element including a first electrode and a second electrode,
the terminal plate and the bottom plate being electrically connected via the valve plate,
the valve plate being circular and concentric with the bottom plate, and having an annular fragile portion which will rupture when the internal pressure of the battery increases so that a valve hole opens up in a portion of the valve plate at a center thereof,
wherein when the inner gas vent holes are viewed from the axial direction of the battery case, only a part of at least one of the inner gas vent holes overlaps the portion of the valve plate in which the valve hole is to open up, and greater than 0 and less than 50% of the total length of the annular fragile portion overlaps the at least one of the inner gas vent holes, such that the valve hole and the at least one inner gas vent hole overlap with each other when viewed in the axial direction when the bottom plate is pushed upwardly by the power generating element into the valve plate, while the other inner gas vent hole or holes entirely overlap a portion of the bottom plate which is outside the fragile portion, so as to allow gas inside said cylindrical battery case to be released to outside of said cylindrical battery case when the valve hole is opened.
3. A cylindrical battery comprising:
a power generating element;
a cylindrical battery case with a bottom for housing the power generating element; and
a seal assembly for sealing an opening of the battery case,
the seal assembly including a terminal plate with an outer gas vent hole, a bottom plate with an inner gas vent hole, and at least one valve plate disposed between the terminal plate and the bottom plate, the bottom plate being circular,
the power generating element including a first electrode and a second electrode,
the terminal plate and the bottom plate being electrically connected via the valve plate,
the valve plate being circular and concentric with the bottom plate, and having an annular fragile portion which will rupture when the internal pressure of the battery increases so that a valve hole opens up in a portion of the valve plate at a center thereof,
wherein the bottom plate has an independent protrusion protruding from the bottom plate toward the valve plate, the protrusion being provided on a surface facing the valve plate of the bottom plate, and
when the protrusion is viewed from the axial direction of the battery case, the position of the protrusion overlaps a portion of the bottom plate which is outside the fragile portion, and at least part of a portion of the valve plate which is inside the fragile portion does not overlap the position of the protrusion such that the protrusion contacts the valve plate when the bottom plate is pushed upwardly by the power generating element into the valve plate and prevents the bottom plate from sealing the valve hole, so as to allow gas inside said cylindrical battery case to be released to outside of said cylindrical battery case when the valve hole is opened.
4. The cylindrical battery in accordance with claim 1 ,
wherein the positive electrode includes a positive electrode active material and a current collector comprising metal foil, and
the positive electrode active material comprises a lithium-containing transition metal oxide.
5. The cylindrical battery in accordance with claim 1 ,
wherein the negative electrode includes a negative electrode active material and a current collector comprising metal foil, and
the negative electrode active material comprises a carbonaceous material.
6. The cylindrical battery in accordance with claim 1 ,
wherein the valve plate includes an upper valve plate and a lower valve plate,
a peripheral portion of the lower valve plate and a peripheral portion of the bottom plate are in contact with each other,
a center portion of the lower valve plate and a center portion of the upper valve plate are in contact with each other, and
the lead-connection area of the bottom plate overlaps the portion of the valve plate in which the valve hole is to open up.