CN-122000515-A - Material recovery method for bipolar storage battery

Abstract

The present invention provides a method for easily separating collector foil of bipolar electrode by sufficiently removing adhesive layer contained in bipolar electrode. A material recovery method for a bipolar secondary battery comprising a lithium ion battery having a bipolar electrode provided with a positive electrode composite material on one surface of a collector foil and a negative electrode composite material on the other surface of the collector foil, wherein the collector foil is bonded to the positive electrode foil and the negative electrode foil via an adhesive layer containing an epoxy resin having a polyolefin as a basic skeleton, the material recovery method comprising a separation step of separating the positive electrode foil and the negative electrode foil by removing the adhesive layer of the collector foil, wherein the collector foil is heated to a temperature higher than the thermal decomposition temperature of the epoxy resin in an inert atmosphere in the separation step.

Inventors

• Hengshan Mountain friend is grand
• CHIKATO YUSUKE

Assignees

• 丰田自动车株式会社

Dates

Publication Date

20260508

Application Date

20251022

Priority Date

20241106

Claims (5)

1. 1. A material recovery method of a bipolar storage battery, the bipolar storage battery is composed of a lithium ion battery with bipolar electrodes, the bipolar electrodes are provided with positive electrode composite materials on one surface of a collector foil, the other surface of the collector foil is provided with negative electrode composite materials, the material recovery method of the bipolar storage battery is characterized in that, The current collecting foil is bonded to the positive electrode foil and the negative electrode foil via an adhesive layer containing an epoxy resin having polyolefin as a basic skeleton, The material recovery method of the bipolar secondary battery includes a separation step of separating the positive electrode foil and the negative electrode foil by removing the adhesive layer of the collector foil, In the separation step, the collector foil is heated to a temperature higher than the thermal decomposition temperature of the epoxy resin under an inert atmosphere.
2. 2. The method for recovering material of bipolar secondary battery as claimed in claim 1, wherein, In the separation step, the bipolar electrode including the positive electrode composite and the negative electrode composite is heated in the inert atmosphere at a heating temperature higher than the thermal decomposition temperature of the epoxy resin for a short heating time.
3. 3. The method for recovering material of bipolar secondary battery as claimed in claim 2, wherein, The heating time for a short time is a time before the binder contained in the positive electrode composite material is thermally decomposed, and a time before the binder contained in the negative electrode composite material is thermally decomposed.
4. 4. The method for recovering material of bipolar secondary battery as claimed in claim 2, wherein, The heating time for the short time is a time of 5 minutes or less.
5. 5. The method for recovering material of bipolar secondary battery as claimed in claim 1, wherein, In the separation step, the current collecting foil to be separated is in a state in which the positive electrode composite material and the negative electrode composite material are removed from each surface of the current collecting foil.

Description

Material recovery method for bipolar storage battery Technical Field The invention relates to a material recovery method of a bipolar storage battery. Background Patent document 1 discloses a bipolar electrode of a bipolar secondary battery, which includes a resin substrate, a resin adhesive, a positive electrode collector bonded to one surface of the substrate via the adhesive, and a negative electrode collector bonded to the other surface of the substrate via the adhesive. In the structure described in patent document 1, in the method of recovering a material from a bipolar secondary battery, when the binder contained in the bipolar electrode is removed, the bipolar electrode is heated to a temperature equal to or higher than the thermal decomposition temperature of the binder. Patent document 1 Japanese patent laid-open No. 2022-147471 Disclosure of Invention In the structure described in patent document 1, the epoxy resin constituting the adhesive is at least one of bisphenol a type epoxy resin and bisphenol F type epoxy resin. Both bisphenol a type epoxy resins and bisphenol F type epoxy resins contain benzene rings in the molecular structure. However, an epoxy resin containing benzene rings may remain residues even after thermal decomposition at high temperatures. Regarding thermal decomposition of epoxy resins, epoxy resins containing benzene rings drastically reduce weight around 500 ℃, but at 600 ℃ or more, a few% of the residues remain. The residue is mainly carbon, but may remain tar-like depending on temperature. In the structure described in patent document 1, since the binder is made of an epoxy resin containing a benzene ring, even if the bipolar electrode is heated to a temperature equal to or higher than the thermal decomposition temperature of the binder at the time of binder removal, a part of the binder remains as a residue, and it is difficult to separate the positive electrode collector and the negative electrode collector. The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method for recovering a material of a bipolar secondary battery, which can easily separate a collector foil of a bipolar electrode by sufficiently removing an adhesive layer included in the bipolar electrode. The method for recovering a material of a bipolar battery, which comprises a lithium ion battery having a bipolar electrode provided with a positive electrode composite material on one surface of a collector foil and a negative electrode composite material on the other surface of the collector foil, is characterized in that the collector foil is bonded to the positive electrode foil and the negative electrode foil via an adhesive layer containing an epoxy resin having a polyolefin as a basic skeleton, and the method for recovering a material of a bipolar battery comprises a separation step of separating the positive electrode foil and the negative electrode foil by removing the adhesive layer of the collector foil, and in the separation step, the collector foil is heated to a temperature higher than the thermal decomposition temperature of the epoxy resin in an inert atmosphere. Effects of the invention In the present invention, the collector foil of the bipolar electrode can be easily separated by sufficiently removing the adhesive layer included in the bipolar electrode. Drawings Fig. 1 is a cross-sectional view schematically showing a bipolar electrode in an embodiment. Fig. 2 is a flowchart showing a method of recovering a material of the bipolar secondary battery. Fig. 3 is a view showing separation of aluminum foil and copper foil by heat treatment of bipolar electrode. Fig. 4 is a diagram showing a case where the current collecting foil from which the electrode assembly has been removed is the object of separation in the separation step. Fig. 5 is a view showing separation of the aluminum foil and the copper foil by heat treatment of the current collecting foil. Detailed Description Hereinafter, a method for recovering a material of a bipolar secondary battery according to an embodiment of the present invention will be specifically described. The present invention is not limited to the embodiments described below. Fig. 1 is a cross-sectional view schematically showing a bipolar electrode in an embodiment. The bipolar electrode 1 includes a collector foil 2, a positive electrode composite 3, and a negative electrode composite 4. The bipolar electrode 1 is a member constituting a bipolar secondary battery. The bipolar secondary battery is a battery pack including a plurality of battery modules. The battery module is a battery pack having a plurality of battery cells. The battery module includes a plurality of bipolar electrodes 1. The bipolar secondary battery having the bipolar electrode 1 is mounted on an electric vehicle. Electric vehicles are either pure electric vehicles (BEV) or plug-in hybrid vehicles (PHEV). The current collecting