TECHNICAL FIELD

The present invention relates to a method for producing a secondary battery.

BACKGROUND ART

Prismatic secondary batteries, such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries, are used as driving power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs, PHEVs), and other vehicles.

In such a prismatic secondary battery, a battery case includes a bottomed, cylindrical prismatic outer body having an opening, and a sealing plate that seals the opening. The battery case houses, together with an electrolyte, an electrode body including a positive electrode plate, a negative electrode plate, and separator. A positive electrode terminal and a negative electrode terminal are attached to the sealing plate. The positive electrode terminal is electrical connected to the positive electrode plate with a positive electrode current collector interposed therebetween. The negative electrode terminal is electrically connected to the negative electrode plate with a negative electrode current collector interposed therebetween.

The positive electrode plate includes a positive electrode core made of metal and a positive electrode active material mixture layer formed on the surface of the positive electrode core. A positive electrode core-exposed portion without the positive electrode active material mixture layer is formed on part of the positive electrode core. A positive electrode current collector is connected to the positive electrode core-exposed portion. The negative electrode plate includes a negative electrode core made of metal and a negative electrode active material mixture layer formed on the surface of the negative electrode core. A negative electrode core-exposed portion without the negative electrode active material mixture layer is formed on part of the negative electrode core. A negative electrode current collector is connected to the negative electrode core-exposed portion.

For example, Patent Literature 1 proposes a prismatic secondary battery including a wound electrode body having a wound positive electrode core-exposed portion in one end part and having a wound negative electrode core-exposed portion in the other end part. Patent Literature 2 proposes a prismatic secondary battery including an electrode body having a positive electrode core-exposed portion and a negative electrode core-exposed portion in one end part.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Published Unexamined Patent Application No. 2009-032640

Patent Literature 2: Japanese Published Unexamined Patent Application No. 2008-226625

SUMMARY OF INVENTION

Technical Problem

For secondary batteries for use in vehicles, particularly, secondary batteries for use in EVs, PHEVs, and other vehicles, there is a need to develop secondary batteries having a high volumetric energy density and a large battery capacity. In the case of the prismatic secondary battery disclosed in Patent Literature 1, a battery case needs to contain left and right spaces used to dispose the wound positive electrode core-exposed portion and the wound negative electrode core-exposed portion, and an upper space between a sealing plate and the wound electrode body. These spaces impose a difficulty in increasing the volumetric energy density of secondary batteries.

Like the prismatic secondary battery disclosed in Patent Literature 2, the use of the electrode body including the positive electrode core-exposed portion and the negative electrode core-exposed portion in one end part makes it easy to provide a prismatic secondary battery having a high volumetric energy density.

The present invention is directed to a highly reliable secondary battery having a high volumetric energy density.

Solution to Problem

A method for producing a secondary battery according to an aspect of the present invention is a method for producing a secondary battery including:

an electrode body that includes a positive electrode plate and a negative electrode plate;

an outer body that has an opening and houses the electrode body;

a sealing plate that seals the opening;

an external terminal that is attached to the sealing plate;

a tab that is provided in the positive electrode plate or the negative electrode plate; and

a first current collector and a second current collector that electrically connect the tab to the external terminal.

The method includes:

a fixation step of electrically connecting the first current collector to the external terminal and fixing the first current collector to the sealing plate;

a first connection step of weld-connecting a stack of a plurality of the tabs to the second current collector; and

a second connection step of connecting the first current collector to the second current collector after the fixation step and the first connection step.

According to the above-described features, there is provided a highly reliable secondary battery having a high volumetric energy density since a stack of a plurality of the tabs can stably and strongly be weld-connected to the second current collector. Here, either one of the fixation step and the first connection step may be performed first.

Advantageous Effects of Invention

According to the present invention, there is provided a highly reliable secondary battery having a high volumetric energy density.

