Secondary cell

• US 20050058908A1
• Filed: 09/16/2004
• Published: 03/17/2005
• Est. Priority Date: 09/17/2003
• Status: Abandoned Application

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Yoshimura, Seiji, Imachi, Naoki
• Application Number:
  US10/941,852
• Publication Number:
  US 20050058908A1
• Time in Patent Office: Days
• US Class Current: 429/233
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 50/55 on the same side of the cell
• CPC Class Codes: H01M 50/553 Terminals adapted for prismatic, pouch or rectangular cells
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

The present invention provides a secondary cell having a rolled-up electrode unit accommodated into an outer body. While an uncoated portion of a positive electrode projects at one of axially opposite ends of the rolled-up electrode unit to form a projection, an uncoated portion of a negative electrode projects at the other end to form a projection. Each of the two projections is formed with a current collecting auxiliary portion obtained by bringing each pair of the uncoated portions into ultrasonic pressing contact with each other. An electrode tab is attached to each of the positive electrode and the negative electrode. Outer ends of the two electrode tabs project outward beyond the outer body. The two outer ends provide a pair of positive and negative electrode terminal portions.

Claims

1. A secondary cell having a rolled-up electrode unit 4 comprising a positive electrode 41 and negative electrode 43 which are each in the form of a strip and which are rolled up into a spiral form with a separator 42 interposed between the electrodes, the rolled-up electrode unit 4 being accommodated into an outer body 11, the positive electrode 41 and the negative electrode 43 each comprising a current collector in the form of a strip and an active substance applied to a surface of the current collector, the rolled-up electrode unit 4 generating power to be delivered to the outside via a pair of positive and negative electrode terminal portions 20, 30,

wherein each of the positive electrode and the negative electrode has an uncoated portion which is not coated with the active substance and which is formed at one of axially opposite ends of the electrode unit and which is formed along an edge of the current collector, the rolled-up electrode unit 4 having a projection 48 at one end of the axially opposite ends of the electrode unit and which is formed by the uncoated portion of the positive electrode projecting therefrom, the rolled-up electrode unit 4 having a projection 48 at the other end and which is formed by the uncoated portion of the negative electrode projecting therefrom, each of the projections 48 being provided with a current collecting auxiliary portion 5 formed by joining to each other each of the adjacent uncoated portions, the rolled-up electrode unit 4 comprising a pair of electrode tabs 2, 3 each in the form of a strip, a base end of the electrode tab 2 being connected to the positive electrode 41 while a base end of the electrode tab 3 being connected to the negative electrode 43, a pair of outer end portions of the electrode tabs 2, 3 extending to the outside through the outer body 11, and the pair of outer end portions forming a pair of positive and negative electrode terminal portions 20, 30, respectively.

2. A secondary cell according to claim 1, wherein the rolled-up electrode unit 4 has a flat shape formed perpendicularly to its winding axis, the outer body 11 being formed by a laminate sheet comprising two resin layers and a metal layer interposed between the resin layers, each of the positive electrode 41 and the negative electrode 43 being formed with an uncoated rolled-up portion 410 not coated with the active substance at an end portion longitudinally of the current collector, the electrode tab having its base end connected to the uncoated rolled-up portion 410 and projecting perpendicularly to the winding axis of the rolled-up electrode unit 4.

3. A secondary cell according to claim 1, wherein the rolled-up electrode unit 4 has a flat shape formed perpendicularly to its winding axis, the outer body 11 being formed by a laminate sheet comprising two resin layers and a metal layer interposed between the resin layers, each of the positive electrode 41 and the negative electrode 43 being formed with an uncoated rolled-up portion 410 not coated with the active substance at an end portion longitudinally of the current collector, the electrode tab having its base end connected to the uncoated rolled-up portion 410 and projecting parallel to the winding axis of the rolled-up electrode unit 4.

4. A secondary cell according to claim 1, wherein the current collecting auxiliary portion 5 is formed by bringing each pair of the adjacent uncoated portions into ultrasonic pressing contact with each other.

5. A secondary cell according to claim 1, wherein the current collecting auxiliary portion 5 comprises a current collection auxiliary pin 51 extending through the projection 48 of the rolled-up electrode unit 4, the current collection auxiliary pin 51 comprising a barrel portion 52 extending through the projection 48 and a pair of pressing portions 53, 53 projecting from opposite ends of the barrel portion 52, the pair of pressing portions 53, 53 holding the projection 48 by pressure between its opposite sides, the holding pressure allowing each pair of the adjacent uncoated portions to be in pressing contact with each other.

6. A secondary cell according to claim 1, wherein the current collecting auxiliary portion 5 comprises a current collecting auxiliary member 54 for holding the projection 48 of the rolled-up electrode unit 4 between its opposite sides, the current collecting auxiliary member 54 comprising a male lug 55 and a female lug 56 which are fittable to each other with the projection 48 interposed therebetween, the pressing force applied by the male lug 55 and the female lug 56 causing each pair of the adjacent uncoated portions to be in pressing contact with each other.