BATTERY CURRENT COLLECTOR AND PREPARATION METHOD THEREOF, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK, AND ELECTRIC APPARATUS

1 . A battery current collector, comprising:

a foam metal layer ( 1 ); and

a strength enhancement layer ( 2 ), wherein the strength enhancement layer ( 2 ) is a sheet-shaped metal layer, and the strength enhancement layer ( 2 ) and the foam metal layer ( 1 ) are stacked and metallurgically bonded.

2 . The battery current collector according to claim 1 , wherein

the foam metal layer ( 1 ) and the strength enhancement layer ( 2 ) are welded together; or

the foam metal layer ( 1 ) and the strength enhancement layer ( 2 ) are sintered as a whole.

3 . The battery current collector according to claim 1 , wherein the foam metal layer ( 1 ) comprises a first foam metal layer ( 11 ) disposed on one side of the strength enhancement layer ( 2 ) and a second foam metal layer ( 12 ) disposed on the other side of the strength enhancement layer ( 2 ).

4 . The battery current collector according to claim 1 , wherein the strength enhancement layer ( 2 ) is provided with a through hole.

5 . The battery current collector according to claim 1 , wherein the battery current collector comprises a current collector body and an end portion located on an outer side of the current collector body along a width direction and used for forming a tab, wherein the current collector body comprises the foam metal layer ( 1 ) and the strength enhancement layer ( 2 ) that are stacked, and the end portion comprise the strength enhancement layer ( 2 ).

6 . The battery current collector according to claim 1 , wherein

both ends of the strength enhancement layer ( 2 ) in the width direction are flush with the foam metal layer ( 1 ); or

one end of the strength enhancement layer ( 2 ) in the width direction protrudes from the foam metal layer ( 1 ), and the other end is flush with the foam metal layer ( 1 ); or

both ends of the strength enhancement layer ( 2 ) in the width direction protrude from the foam metal layer ( 1 ).

7 . The battery current collector according to claim 1 , wherein

the foam metal layer ( 1 ) is made of at least one of copper, nickel, aluminum, iron, magnesium, titanium, steel, and alloy; and/or

the strength enhancement layer ( 2 ) is made of at least one of copper, nickel, aluminum, iron, magnesium, titanium, steel, and alloy.

8 . The battery current collector according to any one of claims 1 to 7 , wherein

thickness of the foam metal layer ( 1 ) is 10 μm-100 μm; and/or

thickness of the strength enhancement layer ( 2 ) is 4 μm-12 μm.

9 . The battery current collector according to claim 1 , wherein porosity of the foam metal layer ( 1 ) is 20%-90%, and optionally, the porosity of the foam metal layer ( 1 ) is 80%-85%.

10 . A preparation method of battery current collector, comprising:

a material compression step, comprising: laying a first layer of material for forming a foam metal layer ( 1 ) and compressing the first layer of material into a first layer of blank, wherein the first layer of material comprises metal powder and a pore-forming agent mixed in the metal powder; and laying a second layer of material for forming a strength enhancement layer ( 2 ) on the first layer of blank and compressing the second layer of material into a second layer of blank, wherein the second layer of material comprises metal powder; and

a sintering step, comprising: sintering the compressed materials formed in the material compression step.

11 . The preparation method according to claim 10 , wherein the material compression step further comprises: laying a third layer of material for forming the foam metal layer ( 1 ) on the second layer of blank and compressing the third layer of material into a third layer of blank, wherein the third layer of material comprises metal powder and a pore-forming agent mixed in the metal powder.

12 . The preparation method according to claim 11 , wherein compressing pressure for the first layer of material is less than or equal to compressing pressure for the third layer of material.

13 . The preparation method according to claim 11 , wherein

the compressing pressure for the first layer of material is 150 MPa-350 MPa; and

the compressing pressure for the third layer of material is 150 MPa-350 MPa.

14 . The preparation method according to claim 10 , wherein

the materials are in a protection atmosphere of inert gas when being sintered; and/or

sintering temperature of the materials is 700° C.-1000° C.; and/or

sintering duration of the materials is 5 hours-8 hours.

15 . A preparation method of battery current collector, comprising:

a welding step, comprising: stacking an alloy foil for forming a foam metal layer ( 1 ) and a metal foil for forming a strength enhancement layer ( 2 ), and heating the alloy foil and the metal foil so that the alloy foil and the metal foil are welded together to form an intermediate; and

a foaming step, comprising: placing the intermediate into a corrosive solution to remove one or more elements in the alloy foil, so that the alloy foil forms the foam metal layer ( 1 ).

16 . The preparation method according to claim 15 , wherein in the welding step, the alloy foil is stacked on both sides of the metal foil.

17 . The preparation method according to claim 15 , wherein

the corrosive solution comprises at least one of a diluted hydrochloric acid solution, an ammonium sulfate solution, an electrolyte obtained by mixing H 2 SO 4 and MnSO 4 , an acetic acid solution, a phosphoric acid solution, and a sulphuric acid solution; and/or

the alloy foil comprises a brass foil; and/or

the metal foil comprises a pure cooper foil.

18 . The preparation method according to claim 15 , wherein a plurality of through holes are formed on the metal foil before the alloy foil and the metal foil are stacked.

19 . A secondary battery, comprising the battery current collector according to claim 1 .

20 . An electric apparatus, characterized by comprising at least one of the secondary battery according to claim 19 .