Sanyo Electric Co., Ltd.

Takuya Yamawaki

Eiji Okutani

Masakazu Yamada

Yohei Muroya

Tomokazu Yamanaka

Shinichirou Yoshida

Ryuhei Kai

A secondary battery production method is provided, with which deformation of a current collector is reduced. The method produces a secondary battery including: an electrode assembly having positive and negative electrode plates; and a positive electrode current collector. The positive electrode plate includes a positive electrode core and a positive electrode active material layer, and the electrode assembly includes a positive electrode core-stacked portion. The method includes: an electrode assembly production step of producing the electrode assembly; and an ultrasonic bonding step of ultrasonically bonding the positive electrode current collector to the positive electrode core-stacked portion. The positive electrode current collector has a thin-walled portion. In the ultrasonic bonding step, the thin-walled portion and the positive electrode core-stacked portion are sandwiched between a horn and an anvil, and the thin-walled portion and the positive electrode core-stacked portion are ultrasonically bonded together.

Method for producing secondary battery

A rolled electrode assembly having a positive electrode plate and a negative electrode plate is housed in a prismatic outer body having as mouth together with non-aqueous electrolyte, and the mouth of the prismatic outer body is sealed by a sealing plate made of metal. The rolled electrode assembly is housed in the prismatic outer body, with the outer surface of the rolled electrode assembly covered by an insulating sheet except for the outer surface facing the sealing plate. The arithmetic mean roughness (Sa) of at least one surface of the insulating sheet disposed between the rolled electrode assembly and the prismatic outer body is 0.3 &#x3bc;m or more.

Secondary battery

A conductive member including an opening portion is connected to a positive terminal and is integrally secured to a sealing plate together with an outer insulating member and a second insulating member. The conductive member opening portion is sealed by a deformable plate. A base portion of a positive electrode current collector is connected to the deformable plate. A first insulating member that is disposed between the deformable plate and the base portion of the positive electrode current collector includes a pair of first catch portions that are disposed so as to be aligned in a longitudinal direction of the sealing plate and a pair of second catch portions that are disposed so as to be aligned in a transverse direction of the sealing plate. The first catch portions and the second catch portions are connected to the second insulating member disposed between the sealing plate and the conductive member.

A positive electrode sheet is electrically connected to a positive terminal with a positive electrode current collector, a deformable plate, and a conductive member interposed therebetween. When the pressure inside a battery is higher than or equal to a predetermined value, the deformable plate is deformed toward a sealing plate and an annular groove formed on a base portion of the positive electrode current collector is broken due to deformation of the deformable plate so that a conductive path between the positive electrode sheet and the positive terminal is disconnected. A first insulating member disposed between the deformable plate and the base portion of the positive electrode current collector includes a first rotation preventing protrusion on a surface thereof on a wound electrode body side and outside an outer circumferential edge of the base portion of the positive electrode current collector.

Secondary Battery

A battery includes a battery case, an electrode assembly, positive and negative electrode collectors, a sealing body, an external terminal, a conducting member, a deforming plate, and a first insulating member. The positive or negative electrode collector has a base portion facing the first insulating member, and a lead portion connected to the electrode assembly. A fixing portion fixing the base portion and the first insulating member to each other is provided in the first insulating member. The fixing portion is located nearer to the connection portion between the deforming plate and the positive or negative electrode collector than the sealing body side support position of the first insulating member. The outer peripheral edge of the electrode assembly side surface of the first insulating member is provided with a rib protruding to the electrode assembly side and extending along the outer peripheral edge of the base portion.

Growing community of inventors

Hyogo, Japan

Takuya Yamawaki