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EP-4738551-A2 - SECONDARY BATTERY, ELECTRONIC DEVICE, AND METHOD FOR MANUFACTURING SECONDARY BATTERY

EP4738551A2EP 4738551 A2EP4738551 A2EP 4738551A2EP-4738551-A2

Abstract

A secondary battery includes a housing and an electrode assembly. The housing includes a packaging film. The packaging film is wrapped around to enclose the electrode assembly. The housing further includes an adhesive layer. The packaging film is coated with the adhesive layer on a surface facing away from the electrode assembly. The adhesive layer includes a resin compound. A tensile elongation at break of the packaging film is φ 1 , and a tensile elongation at break of a part of the housing coated with the adhesive layer is φ 2 , wherein φ 2 < φ 1 .

Inventors

  • LI, RUI
  • LI, LIN
  • GUO, Peipei
  • HUANG, Zhiqi

Assignees

  • Ningde Amperex Technology Limited

Dates

Publication Date
20260506
Application Date
20260320

Claims (15)

  1. A secondary battery (100), comprising a housing (10) and an electrode assembly (20), wherein the housing (10) comprises a packaging film (11), and the packaging film (11) is wrapped around to enclose the electrode assembly (20), characterized in that the housing (10) further comprises an adhesive layer (12), the packaging film (11) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); and the adhesive layer (12) comprises a resin compound, a tensile elongation at break of the packaging film (11) is φ 1 , and a tensile elongation at break of a part of the housing (10) coated with the adhesive layer (12) is φ 2 , wherein φ 2 < φ 1 .
  2. The secondary battery (100) according to claim 1, characterized in that the resin compound comprises at least one of epoxy resin or phenolic resin.
  3. The secondary battery (100) according to claim 1 or 2, characterized in that the adhesive layer (12) further comprises a curing agent of the resin compound, a mass percentage of the curing agent in the adhesive layer (12) is 5% to 20%.
  4. The secondary battery (100) according to claim 3, characterized in that the curing agent is an amine compound or an acid anhydride compound.
  5. The secondary battery (100) according to claim 4, characterized in that the curing agent comprises at least one of aliphatic amine, aromatic amine, modified amine, or maleic anhydride.
  6. The secondary battery (100) according to any one of claims 1 to 5, characterized in that the adhesive layer (12) comprises acrylate ester.
  7. The secondary battery (100) according to any one of claims 1 to 6, characterized in that , along a length direction of the electrode assembly (X), the packaging film (11) comprises a first part (115), a second part (116), and a third part (117) connected in sequence; along a width direction of the electrode assembly (Y), the second part (116) comprises a first sub-part (1161), a second sub-part (1162), and a third sub-part (1163) connected in sequence; the second sub-part (1162) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); along the length direction of the electrode assembly (X), a length of the first part (115) is L 1 , and a length of the third part (117) is L 2 , satisfying: 1 mm ≤ L 1 ≤ 20 mm, and 1 mm ≤ L 2 ≤ 20 mm.
  8. The secondary battery (100) according to claim 7, characterized in that the first sub-part (1161) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); and/or, the third sub-part (1163) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); and/or, along the width direction of the electrode assembly (Y), the third part (117) comprises a third corner portion (1171), a second middle portion (1172), and a fourth corner portion (1173) connected in sequence; the second middle portion (1172) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); along the width direction of the electrode assembly (Y), a width of the third corner portion (1171) is W 3 , and a width of the fourth corner portion (1173) is W 4 , satisfying: 1 mm ≤ W 3 ≤ 20 mm, and 1 mm ≤ W 4 ≤ 20 mm..
  9. The secondary battery (100) according to claim 7 or 8, characterized in that , along the width direction of the electrode assembly (Y), the first part (115) comprises a first corner portion (1151), a first middle portion (1152), and a second corner portion (1153) connected in sequence; the first middle portion(1152) is coated with the adhesive layer (12) on a surface facing away from the electrode assembly (20); along the width direction of the electrode assembly (Y), a width of the first corner portion (1151) is W 1 , and a width of the second corner portion (1153) is W 2 , satisfying: 1 mm ≤ W 1 ≤ 20 mm, and 1 mm ≤ W 2 ≤ 20 mm.
  10. The secondary battery (100) according to claim 9, characterized in that , along a thickness direction of the electrode assembly (Z), a shape of a projection of the first corner portion (1151) is one of a square, a triangle, a sector, a polygon, or an irregular shape; and/or, along a thickness direction of the electrode assembly (Z), a shape of a projection of the second corner portion (1153) is one of a square, a triangle, a sector, a polygon, or an irregular shape.
  11. The secondary battery (100) according to any one of claims 1 to 10, further comprising a tab (20a) is provided and connected to the electrode assembly (20); and along a thickness direction of the electrode assembly (Z), a projection of the tab (20a) does not overlap a projection of the adhesive layer (12); and/or, a thickness of the adhesive layer (12) is 1 µm to 60 µm; and/or, 8.8 % ≤ φ 1 − φ 2 ≤ 59.8 % ; and/or, packaging film (11) comprises a first polymer layer (111), a first metal layer (112), a second polymer layer (113), and a third polymer layer (114) stacked in sequence; the third polymer layer (114) is coated with the adhesive layer (12) on a surface facing away from the second polymer layer (113); and the third polymer layer (114) comprises polyamide.
  12. The secondary battery (100) according to any one of claims 1 to 11, characterized in that the adhesive layer (12) further comprises an inorganic filler.
  13. The secondary battery (100) according to claim 12, characterized in that the inorganic filler comprises glass fiber, and a mass percentage of the glass fiber in the adhesive layer (12) is 10% to 50%; or, the inorganic filler comprises silicon dioxide, and a mass percentage of the silicon dioxide in the adhesive layer (12) is 5% to 30%.
  14. An electronic device, characterized in that the electronic device comprises the secondary battery (100) according to any one of claims 1 to 13.
  15. A method for manufacturing the secondary battery (100) according to any one of claims 1 to 13, the method comprising: providing the packaging film (11) and the electrode assembly (20), and wrapping the packaging film (11) around an outer surface of the electrode assembly (20); and providing the adhesive layer (12), and applying the adhesive layer (12) onto the surface of the packaging film (11) on the side facing away from the electrode assembly (20).

Description

TECHNICAL FIELD This application relates to the technical field of batteries, and in particular, to a secondary battery, an electronic device, and a method for manufacturing the secondary battery. BACKGROUND As a power supply of an electronic device, a secondary battery is the key to ensuring the normal use of the electronic device. When damaged by an external force, the secondary battery is prone to internal short circuits, resulting in safety problems such as thermal runaway. SUMMARY Based on research, the applicant hereof finds that when a secondary battery is damaged by an external force, the packaging film is prone to stretch to an electrode plate under the action of the external force, thereby causing an aluminum layer of the packaging film to contact the electrode plate and consequently resulting in a short circuit. By coating the outer surface of the packaging film of a finished secondary battery with an adhesive layer that breaks at a tensile elongation at break lower than that of the packaging film, the housing includes both an adhesive layer and a packaging film, and the tensile elongation at break of the part, coated with the adhesive layer, of the housing is caused to be lower than the tensile elongation at break of the original packaging film. When the secondary battery is damaged by an external force, the housing can break earlier, and the stretch of the aluminum layer in the packaging film is reduced upon breakage, thereby reducing the probability of contact and short-circuiting between the aluminum layer and the electrode plate caused by excessive stretching. An objective of this application is to provide a secondary battery, an electronic device, and a method for manufacturing the secondary battery to alleviate the short-circuiting problem of the secondary battery. According to a first aspect of this application, a secondary battery is provided. The secondary battery includes a housing and an electrode assembly. The housing includes a packaging film. The packaging film is wrapped around to enclose the electrode assembly. The housing further includes an adhesive layer. The packaging film is coated with the adhesive layer on a surface facing away from the electrode assembly. The adhesive layer includes a resin compound. A tensile elongation at break of the packaging film is φ1, and a tensile elongation at break of a part of the housing coated with the adhesive layer is φ2, wherein φ2 < φ1. In the above technical solution, the packaging film is coated with the adhesive layer on the surface facing away from the electrode assembly. The adhesive layer includes a resin compound. The housing includes the adhesive layer and the packaging film. The tensile elongation at break φ2 of the part, coated with the adhesive layer, of the housing is less than the tensile elongation at break φ1 of the packaging film. In this way, the housing breaks earlier when damaged by an external force. The stretch of the housing is relatively small, thereby reducing the probability that the housing stretches to the electrode plate under the action of the external force, and consequently reducing the probability of contact and short-circuiting between the aluminum layer of the housing and the electrode plate. In some preferred embodiments, the adhesive layer includes a resin compound, thereby further reducing the tensile elongation at break of the part, coated with the adhesive layer, of the housing. In some preferred embodiments, the resin compound includes at least one of epoxy resin or phenolic resin, thereby further reducing the tensile elongation at break of the part, coated with the adhesive layer, of the housing. In some preferred embodiments, the adhesive layer further includes a curing agent of the resin compound. The curing agent can connect molecules or polymer chains of the resin compound to form a more stable reticular structure, thereby increasing the strength and hardness of the adhesive layer. In some preferred embodiments, the curing agent is an amine compound or an acid anhydride compound, thereby making it convenient for the curing agent and the resin compound to form a more stable reticular structure, and consequently increasing the strength and hardness of the adhesive layer. In some preferred embodiments, the curing agent includes at least one of aliphatic amine, aromatic amine, modified amine, or maleic anhydride, thereby making it convenient for the curing agent and the resin compound to form a more stable reticular structure, and consequently increasing the strength and hardness of the adhesive layer. In some preferred embodiments, a mass percentage of the curing agent in the adhesive layer is 5% to 20%. When the mass percentage of the curing agent in the adhesive layer is less than 5%, the curing reaction between the resin compound and the curing agent is insufficient. Setting the mass percentage of the curing agent in the adhesive layer to be greater than or equal to 5% is conducive to improving