CN203707250U - Lithium battery - Google Patents

Abstract

The utility model discloses a lithium battery. The lithium battery comprises a battery cell, wherein the battery cell comprises a positive pole piece, a negative pole piece, and an isolation film arranged between the positive pole piece and the negative pole piece; the positive pole piece comprises a positive pole current collector and a positive pole ear welded to the positive pole current collector; positive pole active materials are arranged on two sides of the positive pole current collector; the negative pole piece comprises a negative pole current collector and a negative pole ear welded to the negative pole ear of the negative pole current collector; a metal lithium layer is plated onto the surface of the negative pole current collector. According to the lithium battery provided by the utility model, the negative pole current collector is not required to be coated with a negative pole active material, so that the process is simplified, and the operation is simple and convenient; the metal lithium layer is plated onto the surface of the negative pole current collector, so that the characteristic of high energy of a primary lithium battery and the characteristic of high efficiency of a rechargeable lithium ion battery are effectively combined, and the energy density and the power density of the lithium battery are greatly increased; the lithium battery has the characteristics of high-efficiency, high energy, and low self-discharge rate, can satisfy the requirement of constant upgrading of electronic equipment, and can be widely applied to the electronic equipment.

Description

lithium battery

technical field

The utility model relates to the technical field of lithium batteries, in particular to a lithium battery with high power, high energy and low self-discharge rate.

Background technique

Lithium batteries have the advantages of wide operating temperature range, stable discharge voltage, low self-discharge rate, and long service life. They have been widely used in various fields, especially aerospace, military, long-life instrumentation, logistics tracking, automotive electronics, Mobile digital products and other fields. In recent years, with the continuous development of science and technology, the functions of electronic equipment have been continuously upgraded. Therefore, higher requirements have been placed on the energy and rate performance of lithium batteries. High-energy batteries have become a key research direction in the battery industry.

Lithium batteries are divided into lithium primary batteries (primary batteries) and lithium ion batteries (secondary batteries). Relatively speaking, lithium primary batteries have a higher energy density, mainly because the theoretical gram capacity of lithium metal negative electrodes is larger than that of lithium ion batteries using carbon-based negative electrodes. The theoretical gram capacity of lithium metal negative electrodes is 3860mAh/g, while carbon-based The theoretical gram capacity of the negative electrode is 372mAh/g, but because thin lithium metal negative electrodes are difficult to make, the output power of lithium primary batteries is low, and rechargeable lithium-ion batteries can usually meet the high power requirements of electronic devices, mainly Because its anode is a carbonaceous material with strong conductivity, and a layer of active material with adjustable thickness is adhered to the anode current collector by coating, and the contact area of the positive and negative electrodes is increased by winding or lamination. , thereby increasing the power density of the battery. However, the theoretical gram capacity of the negative electrode carbon material of rechargeable lithium-ion batteries is low, and in the structure of conventional lithium-ion batteries, although the power density of the battery is increased by winding or stacking, the energy density of the battery is reduced, so The structure of conventional rechargeable lithium-ion batteries is not conducive to increasing the energy density of the battery.

Utility model content

The purpose of the utility model is to provide a lithium battery, which has the advantages of high output power, high energy density and low self-discharge rate.

For reaching above-mentioned purpose, the utility model adopts following technical scheme:

A lithium battery, comprising a cell, the cell includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet includes a positive electrode current collector and is welded to the The positive electrode tab on the positive electrode current collector, the two sides of the positive electrode current collector are provided with positive active materials, the negative electrode sheet includes the negative electrode current collector and the negative electrode tab welded on the negative electrode current collector, the negative electrode current collector The surface is electroplated with a lithium metal layer.

By electroplating a metal lithium layer on the surface of the negative electrode current collector of the negative electrode sheet, it is no longer necessary to coat the negative electrode active material on the negative electrode current collector, which greatly saves the space of the lithium battery, simplifies the operation process, and improves the energy density of the lithium battery.

As a preferred solution of the lithium battery, the negative electrode current collector is made of metal foil or metal mesh; and/or, the positive electrode current collector is made of aluminum foil.

By making the negative current collector with metal foil or metal mesh, and then plating lithium on the metal foil or metal mesh by electroplating, the lithium layer of the negative electrode can be thinned, the tensile strength of the lithium layer can be increased, and a large current discharge of the battery can be realized. , improving the power density of the battery.

Preferably, the negative electrode current collector is any one of aluminum foil, tin foil, nickel foil, and copper foil.

Preferably, the negative electrode current collector adopts any one of aluminum mesh, tin mesh, nickel mesh and copper mesh.

As a preferred solution for lithium batteries, the negative electrode current collector is made of metal foil or metal mesh with a thickness of 6-25 μm; and/or, the surface of the negative electrode current collector is electroplated with metal lithium with a thickness of 8-80 μm layer.

More preferably, the surface of the negative electrode current collector is electroplated with a metal lithium layer with a thickness of 2-54 μm.

In the battery structure of the utility model, the negative electrode current collector is made of metal foil or metal mesh with a thickness of 6-25 μm, which saves space for the lithium battery, increases the loading capacity of the positive electrode, and improves the energy density of the lithium battery.

Optionally, the method of electroplating the lithium layer on the negative electrode current collector may adopt a conventional chemical electroplating method.

Preferably, the first formation process of the lithium battery is charged to 4.0V with a current of 0.05-0.2C, and then charged to 4.2V with a current of 0.2-1C. The extracted Li+ slowly deposits on the negative electrode current collector to form a uniform and dense lithium layer, which improves the safety of the battery, and through chemical formation, the reversible lithium in the positive electrode active material is extracted to form a delithiated positive electrode active material. Li+ electroplating It is deposited on the surface of the negative electrode current collector base to form the metal lithium negative electrode active material; during the discharge process of the battery, the Li+ released from the negative electrode dissociates to the positive electrode and intercalates into the positive electrode active material in the delithiated state.

Based on the metal foil or metal mesh as the current collector and the above-mentioned lithium deposition method, not only the tensile strength of the pole piece is improved, but also the rapid migration ability of lithium ions is improved, thereby increasing the power density.

As a preferred solution of the lithium battery, the positive electrode sheet also includes a positive electrode diaphragm arranged on both sides of the positive electrode current collector, the positive electrode active material is arranged on the positive electrode diaphragm, and the positive electrode lug is welded to the The first end of the positive electrode current collector, the positive electrode current collector also has a second end opposite to the first end, and the two sides of the positive electrode current collector near the second end are provided with exposed parts of different sizes, A positive insulating tape is provided at the first end, and the positive insulating tape wraps the first end of the positive current collector and the positive tab; and/or,

An end of the negative electrode current collector close to the negative electrode tab is provided with a negative electrode insulating tape, and the negative electrode insulating tape wraps the end of the negative electrode current collector close to the negative electrode tab and the negative electrode tab.

Preferably, the positive insulating tape is bonded to the positive current collector and the positive tab;

The negative electrode insulating tape is bonded to the negative electrode current collector and the negative electrode tab.

As a preferred solution of the lithium battery, the exposed lengths of the exposed parts disposed on both sides of the positive electrode collector near the second end along the length direction of the positive electrode collector are 5-15 mm and 15-45 mm, respectively, and The exposed length difference between the two exposed parts is between 10mm and 30mm.

As a preferred solution of a lithium battery, the negative electrode sheet, the separator, and the positive electrode sheet are sequentially wound into a cell, the length of the positive electrode current collector is greater than the length of the negative electrode current collector, and the positive electrode is The longer exposed side of the exposed part of the current collector near the second end is located on the outer ring of the battery core, and is used to wrap the negative electrode current collector.

Preferably, the length of the positive electrode current collector is 5-15 mm longer than that of the negative electrode current collector.

As a preferred solution of the lithium battery, the negative electrode current collector has a planar structure.

As a preferred solution of the lithium battery, the negative electrode current collector is provided with a concave-convex structure and/or a meandering structure.

By setting the concave-convex structure or tortuous structure on the negative electrode current collector, it can provide space for the current collector to expand and contract, increase the loading capacity of metal lithium per unit area, avoid the fracture of the positive electrode current collector and the negative electrode current collector due to the volume expansion of lithium plating, and improve the battery capacity. The amount of electrolyte in the medium; by setting the concave-convex structure or the tortuous structure on the negative electrode current collector, it can provide a buffering effect and improve the safety performance of the battery. It has the characteristics of simple structure, low cost and easy processing.

Preferably, the concave-convex structure or meandering structure is formed on the negative electrode current collector by rolling or embossing.

As a preferred solution of the lithium battery, the thickness of the positive electrode current collector is 12-25 μm; and/or, the thickness of the negative electrode current collector is 6-60 μm.

As a preferred solution for lithium batteries, the separator is a polypropylene-polyethylene-polypropylene composite layer separator, a polypropylene single-layer separator, a polyethylene single-layer separator, a polypropylene film coated with a metal oxide. Any one of acrylic separator and polyethylene separator coated with metal oxide.

The beneficial effects of the utility model are: the utility model does not need to coat the negative electrode active material on the negative electrode current collector of the lithium battery, the process procedure is simplified, and the operation is simple and convenient. By electroplating a metal lithium layer on the surface of the negative electrode current collector, the The high energy of the primary lithium battery and the high power of the rechargeable lithium ion battery have greatly improved the energy density and power density of the lithium battery. Demand, can be widely used in electronic equipment.

Description of drawings

Fig. 1 is the schematic cross-sectional view of the lithium battery described in the embodiment;

2 is a schematic plan view of the positive electrode sheet in the lithium battery described in the embodiment;

Fig. 3 is a schematic cross-sectional structure diagram of the positive electrode sheet in the lithium battery described in the embodiment;

4 is a schematic plan view of the negative electrode sheet in the lithium battery described in the embodiment;

Fig. 5 is a schematic cross-sectional structure diagram of a negative electrode sheet in the lithium battery described in the embodiment;

Fig. 6 is another schematic cross-sectional structure diagram of the negative electrode sheet in the lithium battery described in the embodiment;

Fig. 7 is another cross-sectional schematic diagram of the negative electrode sheet in the lithium battery described in the embodiment.

In the picture:

1. Housing; 2. Electrolyte; 3. Positive plate; 31. Positive current collector; 311. First end; 312. Second end; 32. Positive diaphragm; 33. Positive lug; 34. Positive insulating glue Paper; 4. Isolation film; 5. Negative plate; 51. Negative current collector; 511. Concave-convex structure; 52. Negative tab; 53. Negative insulating tape.

Detailed ways

The technical scheme of the utility model will be further described below in conjunction with the accompanying drawings and through specific embodiments.

As shown in Figure 1, the lithium battery of the present utility model comprises casing 1, electrolytic solution 2 and the electric core that is located in the casing, and electric core comprises positive electrode sheet 3, negative electrode sheet 5 and between positive electrode sheet 3 and negative electrode sheet 5. Between the isolation film 4.

Among them, the electrolyte 2 includes lithium salt and solvent, and the isolation film 4 adopts a polypropylene-polyethylene-polypropylene composite layer isolation film, a polypropylene single-layer isolation film, a polyethylene single-layer isolation film, and a metal oxide film coated on the surface. Any one of polypropylene isolation film and polyethylene isolation film coated with metal oxide. In this embodiment, the electrolyte 2 uses lithium hexafluorophosphate (LiPF6), and the separator 4 uses a polypropylene-polyethylene-polypropylene composite layer separator.

As shown in Figures 2 and 3, the positive electrode sheet 3 includes a positive electrode current collector 31 and a positive electrode tab 33 welded on one end of the positive electrode current collector 31, the two sides of the positive electrode current collector 31 are provided with positive active materials, and the positive electrode sheet 3 also includes a The positive electrode diaphragm 32 on both sides of the current collector 31, the positive electrode active material is arranged on the positive electrode diaphragm 32, the positive electrode current collector 31 has a first end 311 welded with a positive electrode tab 33, and a second end 312 opposite to the first end 311, The two sides of the positive electrode current collector 31 near the second end 312 are provided with exposed parts of different sizes, and the positive electrode insulating tape 34 is provided at the first end 311, and the positive electrode insulating tape 34 wraps the first end 311 and the first end 311 of the positive electrode current collector 31. Positive electrode tab 33.

The exposed lengths of the exposed parts disposed on both sides of the positive electrode current collector 31 near the second end 312 along the length direction of the positive electrode current collector 31 are 5-15 mm and 15-45 mm respectively, and the length difference between the two exposed parts is 10-30 mm Between, in this embodiment, the exposed length on the upper side of the positive electrode collector 31 is 10 mm, and the exposed length on the lower side of the positive electrode collector 31 is 32 mm.

The positive electrode current collector 31 is an aluminum foil with a thickness of 12-25 μm. In this embodiment, the positive current collector 31 is made of aluminum foil with a thickness of 16 μm and a length of 168 mm.

As shown in Figures 4 and 6, the negative electrode sheet 5 includes a negative electrode current collector 51 and a negative electrode tab 52 welded to one end of the negative electrode current collector 51. The surface of the negative electrode current collector 51 is electroplated with a metal lithium layer, and the negative electrode current collector 51 is close to the negative electrode tab 52. One end of the negative electrode insulating tape 53 is provided, and the negative electrode insulating tape 53 wraps the end of the negative electrode current collector 51 close to the negative electrode tab 52 and the negative electrode tab 52 .

The negative current collector 51 is made of metal foil or metal mesh, and the thickness of the metal foil or metal mesh is 6-25 μm.

The metal foil material can be selected from any one of aluminum foil, tin foil, nickel foil, and copper foil, and the metal mesh can be selected from any one of aluminum mesh, tin mesh, nickel mesh, and copper mesh. In this embodiment, the negative electrode current collector 51 uses copper foil.

As shown in FIG. 6 , a concave-convex structure 511 is provided on the negative electrode current collector 51 of the negative electrode sheet 5 of this embodiment, and the concave-convex structure 511 can be formed by rolling or molding. In other embodiments, the negative electrode current collector 51 may also have other structural forms, for example, referring to FIG. 5 , the negative electrode current collector 51 of the negative electrode sheet 5 adopts a planar structure. Referring to FIG. 7 , the negative electrode current collector 51 of the negative electrode sheet 5 adopts an arc-shaped meandering structure.

In this embodiment, the positive insulating tape 34 is bonded to the positive current collector 31 and the positive tab 33 , and the negative insulating tape 53 is bonded to the negative current collector 51 and the negative tab 52 .

In this embodiment, the negative electrode sheet 5, the separator 4, and the positive electrode sheet 3 are sequentially wound into a cell, the length of the positive electrode current collector 31 is greater than the length of the negative electrode current collector 51, and the exposed part of the positive electrode current collector 31 near the second end 312 The side with a longer part of the exposed length (the lower side of the positive electrode collector 31 in FIG. 3 ) is located on the outer ring of the battery cell, and is used to wrap the negative electrode collector 51 .

The lithium battery described in this example is prepared by the following method:

(1) As shown in Figure 2, the production of the positive electrode sheet 3: lithium cobaltate (LiCoO2) with a gram capacity of 140mAh/g is used as the positive electrode active material, and the binder PVDF and the conductive agent Super-P are used at a ratio of 95:2 : The mass ratio of 3 is mixed and stirred evenly in NMP to make positive electrode slurry, and the positive electrode slurry is coated on both sides of the positive electrode current collector 31 at a density of 33.0 mg/cm2. The positive electrode current collector adopts a thickness of 16 μm and a length of 168mm aluminum foil, the lengths of the double-sided coating of the positive electrode slurry on the aluminum foil are 130 mm and 152 mm respectively to form the positive electrode diaphragm 32, wherein the exposed lengths of the exposed parts on both sides of the current collector at the second end 312 of the positive electrode current collector 31 are respectively 32mm and 10mm, cut into pole pieces with a thickness of 0.107mm and a width of 42mm by cold pressing, welding the positive pole lug 33 on the end and pasting the positive insulating tape 34 to obtain the positive pole piece 3;

(2) As shown in Figure 6, the production of the negative electrode sheet 5: take a 9 μm copper foil, cut it into a copper foil with a length of 153 mm and a width of 44 mm, and form a thickness of 20 μm and a concave-convex structure by rolling or molding 511 of the negative electrode current collector 51, weld the negative electrode tab 52 on the upper end of the current collector and paste the negative electrode insulating tape 53 to obtain the negative electrode sheet 5;

(3) Production of the isolation film 4: a polypropylene/polyethylene/polypropylene (PP/PE/PP) composite layer isolation film with a thickness of 16 μm, a length of 320 mm and a width of 46 mm;

(4) Preparation of electrolyte solution 2: adding lithium hexafluorophosphate (LiPF6) into the solvent, and mixing evenly to obtain the electrolyte solution;

(5) Production of lithium battery: wind the negative electrode sheet 5, separator 4 and positive electrode sheet 3 obtained above to obtain a lithium battery cell, then put the cell into the aluminum-plastic film packaging shell 1 and inject electrolytic Liquid 2 back seal;

(6) Formation and aging of lithium battery: Charge the lithium battery prepared in step (5) to 4.0V with a current of 13mA (0.05C), then charge it to 4.2V with a current of 52mA (0.2C), and then The lithium battery was aged in an oven at 45° C. for 48 hours and then molded to obtain a lithium battery with a model number of 68500 in this example.

Compared with the prior art, the lithium battery of the present utility model has the following advantages:

①. High energy density: Since the battery cell structure of the lithium battery in this embodiment has a metal foil material with a thickness of 6-25 μm for the negative electrode current collector, this saves space for the lithium battery, can increase the loading capacity of the positive electrode, and improve the lithium battery. Energy Density;

②. High power density: The lithium battery of this utility model uses electroplating. During the charging process of the lithium battery, the positive electrode material comes out of Li+ and deposits on the negative electrode current collector to form a thin layer of lithium. Based on the metal foil material as the current collector And the way of lithium deposition not only improves the tensile strength of the pole piece, but also improves the rapid migration ability of lithium ions, thereby increasing the power density;

③. Low self-discharge rate: the utility model has a structure similar to that of a primary battery, and has an extremely low self-discharge rate.

In the description of the present utility model, it should be understood that the orientations or positional relationships such as "upper" and "lower" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operations, rather than indicating Or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, because it should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

It should be stated that the above-mentioned specific implementation methods are only preferred embodiments of the present utility model and the applied technical principles. Within the technical scope disclosed in the present utility model, any changes or changes that are easily conceivable by those skilled in the art Replacement should be covered within the protection scope of the present utility model.

Claims (10)

1. a lithium battery, it is characterized in that, comprise battery core, described battery core comprises positive plate, negative plate and the barrier film between described positive plate and described negative plate, described positive plate comprises plus plate current-collecting body and is welded in the positive pole ear on described plus plate current-collecting body, the two sides of described plus plate current-collecting body is provided with positive electrode active materials, and described negative plate comprises negative current collector and be welded in the negative lug on described negative current collector, and the surface electrical of described negative current collector is coated with lithium metal layer.

2. lithium battery according to claim 1, is characterized in that, described negative current collector adopts metal foil or wire netting to make; And/or,

Described plus plate current-collecting body adopts aluminium foil.

3. lithium battery according to claim 2, is characterized in that, metal foil or wire netting that described negative current collector employing thickness is 6～25 μ m are made; And/or,

It is 8～80 μ m lithium metal layers that the surface electrical of described negative current collector is coated with thickness.

4. lithium battery according to claim 2, it is characterized in that, described positive plate also comprises the anodal diaphragm that is arranged at described plus plate current-collecting body two sides, described positive electrode active materials is arranged on described anodal diaphragm, described positive pole ear is welded in the first end of described plus plate current-collecting body, described plus plate current-collecting body also has second end relative with described first end, the two sides of the described plus plate current-collecting body of close described the second end are provided with the exposed part of different size, be provided with anodal insulation gummed paper at described first end, described anodal insulating cement paper bag is wrapped up in first end and the described positive pole ear of described plus plate current-collecting body, and/or,

Described negative current collector is provided with negative pole insulation gummed paper near one end of described negative lug, and described negative pole insulating cement paper bag is wrapped up in end and the described negative lug of described negative current collector near described negative lug.

5. lithium battery according to claim 4, it is characterized in that, the exposed part that the two sides of the described plus plate current-collecting body of close described the second end arrange is respectively 5～15mm and 15～45mm along the exposed length of the length direction of described plus plate current-collecting body, and the exposed length difference of two described exposed parts is between 10～30mm.

6. lithium battery according to claim 5, it is characterized in that, described negative plate, described barrier film and described positive plate are sequentially wound as battery core, the length of described plus plate current-collecting body is greater than the length of described negative current collector, the side that the exposed length of the exposed part near the second end of described plus plate current-collecting body is long is positioned at the outer ring of described battery core, for wrapping up described negative current collector.

7. according to the lithium battery described in claim 1 to 6 any one, it is characterized in that, described negative current collector is planar structure.

8. according to the lithium battery described in claim 1 to 6 any one, it is characterized in that, on described negative current collector, be provided with concaveconvex structure and/or tortuous structure.

9. according to the lithium battery described in claim 1 to 6 any one, it is characterized in that, the thickness of described plus plate current-collecting body is 12～25 μ m; And/or,

The thickness of described negative current collector is 6～60 μ m.

10. according to the lithium battery described in claim 1 to 6 any one, it is characterized in that any one in the polyethylene barrier film that described barrier film is polypropylene-polyethylene-polypropylene composite bed barrier film, polypropylene individual layer barrier film, polyethylene individual layer barrier film, the surface-coated polypropylene barrier film that has metal oxide, surface-coated has metal oxide.