WO2017113999A1

WO2017113999A1 - Battery having winding structure

Info

Publication number: WO2017113999A1
Application number: PCT/CN2016/105421
Authority: WO
Inventors: 李炳江; 牛少军
Original assignee: 宁德新能源科技有限公司
Priority date: 2015-12-29
Filing date: 2016-11-11
Publication date: 2017-07-06
Also published as: CN205355186U

Abstract

A battery having a winding structure, relating to the technical field of batteries. The battery comprises a cell (4), formed by successively overlaying a first pole piece (1), an isolating film (3) and a second pole piece (2) with an electrical property opposite to that of the first pole piece (1) and then winding same in the same direction, and an electrolyte thereof. The first pole piece (1) comprises a first current collector (12) and a first active substance layer (11) attached to the surface of the first current collector (12). The second pole piece (2) comprises a second current collector (22) and a second active substance layer (21) attached to the surface of the second current collector (22). The first active substance layer (11) is provided with a first groove (111), and the second active substance layer (21) is provided with a second groove (211). The first groove (111) is located at the start end of the winding first pole piece (1), and the second groove (211) is located at the start end or the middle of the winding second pole piece (2). A first tab (5) is embedded in the first groove (111), and a second tab (6) is embedded in the second groove (211). The battery optimizes the positions where the tabs (5, 6) are located on the pole pieces (1, 2), so that the problems of the cell (4), such as low hardness, easy deformation and poor symmetry, are solved, and the passing rate of a battery abuse test is improved.

Description

Winding structure battery

Technical field

The utility model relates to the technical field of batteries, in particular to a battery with a winding structure.

Background technique

With the development of miniaturization and multi-functionality of electronic products, the requirements for the hardness and energy density of batteries are becoming higher and higher, which requires the symmetry of the cells to be good, and at the same time contributes to the same space. More capacity. As shown in Fig. 1, the battery core of the conventional winding structure has a blank current collector at the beginning of the positive and negative pole pieces, and the positive electrode tab 5' and the negative electrode tab 6' are generally directly soldered to the positive and negative pole pieces. On a blank current collector, such a battery has better symmetry and higher hardness, but its thickness is increased due to the thickness of the tab, so that the thickness of the solder tab region is the maximum thickness of the battery, and the thickness of the unwelded tab region is Relatively small, this part of the space cannot be fully utilized, which makes it difficult to further increase the energy density of the battery within a certain model size.

In view of this, an electric core of an embedded tab structure (ETS) has been proposed, that is, a groove is formed on the active material layer on the pole piece, so that the battery tab is embedded in the groove, which alleviates the thickness of the tab ear to some extent. The accumulation of battery thickness. Therefore, ETS cells have gradually become the direction of new development in the industry due to higher energy density and better dynamic structure. However, due to the design of the cell structure, ETS batteries have lower hardness and are more easily deformed, resulting in The pass rate of the battery abuse test is low. As shown in Fig. 2, the current ETS cell has a positive electrode tab 5' and a negative electrode tab 6' embedded in the middle of the cell sheet (M-M structure). The MM structure of the battery has the following defects: 1) the mechanical symmetry of the battery core is poor, resulting in the battery core is more easily deformed during the cycle, the cycle expansion rate is larger; 2) the bonding area of the separator and the pole piece The decrease leads to a decrease in the hardness of the battery core and a low pass rate of the impact test.

Therefore, under the premise of ensuring its high energy density and good dynamic structure, how to adjust the structural design of ETS cell to improve the deformation of the cell and improve the pass rate of battery abuse test is of great significance.

Utility model content

The purpose of the present invention is to provide a battery with a wound structure in view of the deficiencies of the prior art. While increasing the energy density of the cell, the structure and design of the cell are optimized by adjusting the position of the tab embedded in the wound pole piece, thereby improving the problem of low hardness, easy deformation, poor symmetry of the cell, and improving the battery abuse test. Passing rate.

In order to achieve the above object, the present invention provides the following solutions:

A battery having a wound structure, comprising: a first pole piece, a separator, and a second core piece electrically opposite to the first pole piece, which are sequentially stacked and wound in the same direction, and an electrolyte thereof, a pole piece includes a first current collector and a first active material layer attached to a surface of the first current collector, the second pole piece includes a second current collector and a second active material layer attached to the surface of the second current collector, a first groove is disposed on the first active material layer of the first pole piece, and a second groove is disposed on the second active material layer of the second pole piece, the first groove is located at the first pole of the winding a starting end of the sheet, the second groove is located at a beginning or a middle of the wound second pole piece, the first pole is embedded in the first groove and is electrically connected to the first current collector, the second ear Inlaid in the second groove and electrically connected to the second current collector.

Wherein the first pole piece is a positive pole piece or a negative pole piece, the second pole piece is a negative pole piece or a positive pole piece; the first pole is a positive pole or a negative pole, the first The second tab is a negative pole or a positive pole; the positive tab is an aluminum tab, and the negative tab is a nickel tab. The positive electrode tab or the negative electrode tab may be mounted on the first groove on the first pole piece or the second groove on the second pole piece by laser welding, resistance welding, and ultrasonic welding. The utility model improves the symmetry of the battery core by adjusting the position of the positive and negative poles at the winding pole piece, reduces the loss of the energy density, and avoids the occurrence of the green glue in the same layer, thereby improving the stickiness of the battery core. The knot can significantly improve the hardness of the cell.

As a further improvement of the present invention, the battery of the wound structure further includes a glue layer disposed on the surface of the first tab and covering the entire first groove and/or disposed on the second pole The ear surface covers the entire second groove. The glue layer mainly serves as insulation protection and fixing for the ear.

As a further improvement of the present invention, the adhesive layer is a hot melt adhesive layer or a green rubber layer. Generally, a green rubber layer is attached to protect and fix the tabs, but at the same time, the bonding area between the pole pieces and the separator is reduced. Causes the hardness of the battery core to be low. Compared with green glue, hot melt adhesives are easy to melt under high temperature conditions, and have a good bonding effect between the separator and the pole piece, thereby improving the hardness of the battery core. Usually, the area covered by the hot melt after melting is larger than the area of the glue. These areas covered by the hot melt adhesive cannot be deintercalated normally, which may cause partial capacity loss.

As a further improvement of the present invention, the thickness a of the first tab is less than or equal to the depth b of the first recess, and the thickness c of the second tab is less than or equal to the depth d of the second recess. If the thickness of the tab is greater than the depth of the recess, the thickness of the battery is increased, resulting in a loss of energy density of the battery.

As a further improvement of the present invention, the length m of the first groove is smaller than the width n of the first pole piece, and the length p of the second groove is smaller than the width q of the second pole piece. When the first and second pole pieces of the battery are wider, the large-area blank groove area on the first and second pole pieces cannot correspond to the first and second tabs, and not only the recessed area corresponds to the first, The second pole piece is unevenly stressed, causing poor interface contact, affecting battery performance, and wasting space in the battery, and the energy density of the battery cannot be optimized.

As a further improvement of the present invention, in the unfolded state, the distance between the head and the tail of the second pole piece is defined as D1, and the middle of the wound second pole piece is defined as d1, d1 It is in the range of 1/10D1 to 7/10D1 calculated from the head of the second pole piece. The starting end of the wound first pole piece or the second pole piece is defined as w, and w is the area between the first pole piece or the second pole piece head and the midpoint of the first winding bend.

As a further improvement of the present invention, the first groove is formed by removing the first active material layer by laser cleaning, mechanical cleaning or styrofoam cleaning to expose the first current collector.

As a further improvement of the present invention, the second groove is formed by removing the second active material layer by laser cleaning, mechanical cleaning or styrofoam cleaning to expose the second current collector.

As a further improvement of the present invention, the thickness of the hot melt adhesive layer or the green rubber layer is set to 5 to 50 μm. The thickness of the adhesive layer is too thin to provide insulation and protection; the thickness of the adhesive layer is too thick, which may cause loss of energy density of the battery.

The utility model has the beneficial effects that: while increasing the energy density of the battery core, the structure and design of the battery core are optimized by adjusting the position of the pole embedded in the wound pole piece, thereby improving the hardness of the battery core, the deformation is easy, and the symmetry is poor. And other issues, improve the pass rate of battery abuse testing.

DRAWINGS

1 is a schematic structural view of a battery of a conventional winding structure in the prior art.

2 is a schematic structural view of a prior art embedded tab structure battery.

3 is a schematic structural view of a battery of the winding structure of the present invention.

4 is a second structural schematic view of the battery of the winding structure of the present invention.

FIG. 5 is a schematic structural view of the first pole in the first pole piece of the present invention.

Figure 6 is a cross-sectional view of the first pole in the first pole piece of the present invention.

Figure 7 is a cross-sectional view of the first pole in the first pole piece of the present invention.

Figure 8 is a schematic view showing the structure of the second pole in the second pole piece of the present invention.

Figure 9 is a cross-sectional view of the second pole in the second pole piece of the present invention.

Figure 10 is a cross-sectional view of the second pole in the second pole piece of the present invention.

In the figure: 1-first pole piece, 11-first active material layer, 111-first groove, 12-first current collector, 2-second pole piece, 21-second active material layer, 211- Two grooves, 22-second current collector, 3-isolation film, 4-cell, 5-first tab, 6-second tab, 5'-positive tab, 6'-negative tab, 7 - a layer of glue.

detailed description

The present invention and its beneficial effects will be further described in detail below with reference to the specific embodiments and the accompanying drawings. However, the specific embodiments of the present invention are not limited thereto.

Embodiment 1

As shown in FIGS. 3-10, a battery having a wound structure, including a first pole piece 1, a separator 3, and a second pole piece 2 electrically opposite to the first pole piece 1 are sequentially stacked and wound in the same direction. The battery cell 4, and the electrolyte thereof, the first pole piece 1 includes a first current collector 12 and a first active material layer 11 attached to the surface of the first current collector 12, and the second pole piece 2 includes a second current collector 22 and a second active material layer 21 attached to the surface of the second current collector 22, the first active material layer 11 of the first pole piece 1 is provided with a first groove 111, and the second active material layer of the second pole piece 2 21 is provided with a second groove 211, the first groove 111 is located at the beginning end of the wound first pole piece 1, and the second groove 211 is located at the middle of the wound second pole piece 2, the first tab 5 Inlaid in the first groove 111, the second electrode 6 is embedded in the second groove 211. Wherein, the starting end w of the wound first pole piece 1 is the area between the head of the first pole piece 1 and the midpoint of the first winding bend; the middle of the wound second pole piece 2 is defined as D1, in the unfolded state, the distance from the head to the tail of the second pole piece 2 is defined as D1, and d1 is in the range of 1/10D1 to 7/10D1 calculated from the head of the second pole piece 2.

The first groove 111 is formed by removing the first active material layer 11 by laser cleaning, mechanical cleaning, or styrofoam cleaning to expose the first current collector 12, and the second groove 211 is formed in the same manner. The depth of the first groove 111 and the second groove 211 are both 0.1 mm, the first pole piece 1 is a positive pole piece, the second pole piece 2 is a negative pole piece, and the first pole 5 is a positive pole. The second tab 6 is a negative electrode tab, and the thickness of the positive electrode tab and the negative electrode tab are both 0.1 mm, and the thickness of the positive electrode tab and the negative electrode tab are both 0.5 mm. Wherein, the positive electrode tab is an aluminum tab, and the negative electrode tab is a nickel tab. The tab is also attached with a green glue layer, and the green glue layer 7 is disposed on the surface of the first tab 5 and covers the entire first groove 111 and the surface of the second tab 6 and covers the entire second groove 211. The thickness of the green rubber layer is set to 10 μm, and the purpose of the green rubber layer is mainly to insulate and protect the tabs. Since the positive electrode tab is located at the center of the battery core 4, this improves the symmetry of the battery core 4 to a certain extent, and at the same time avoids the occurrence of the green rubber in the same layer, thus improving the adhesion of the battery core 4, and The hardness of the battery cell 4 can be significantly improved.

The above-mentioned battery cells were placed in a battery package, and 1 mol/L of LiPF ₆ /(EC+PC+DEC) electrolyte was injected therein, wherein ethylene carbonate (EC), propylene carbonate (PC), and ethylene carbonate were injected. The volume ratio of the ester (DEC) was 1:1:1; and the 616790 model (the thickness of the finished battery was 6.1 mm, the width was 67 mm, and the length was 90 mm) was obtained by the process of aging and aging.

Embodiment 2

Different from Embodiment 1, the first groove 111 is located at the beginning end of the wound first pole piece 1, and the second groove 211 is located at the beginning end of the wound second pole piece 2. The starting end w of the wound second pole piece 2 is the area between the head of the second pole piece 2 and the midpoint of the first winding bend. Since both the positive electrode tab and the negative electrode tab are located at the center of the battery cell 4, the symmetry of the battery cell 4 is increased, the hardness is increased, and the loss of energy density is reduced.

The rest is the same as Embodiment 1, and will not be described again.

Embodiment 3

Different from the first embodiment, the green rubber layer to which the first tab 5 and the second tab 6 are attached is replaced with a hot melt adhesive layer, and the thickness of the hot melt adhesive layer is set to 50 μm. The replacement of the green rubber layer with the hot melt adhesive layer is because the hot melt adhesive is easily melted under high temperature conditions, and a good bonding effect is exerted between the separator 3 and the pole piece, thereby improving the hardness of the battery core 4.

The rest is the same as Embodiment 1, and will not be described again.

Comparative embodiment 1

As shown in FIG. 1, a conventionally wound structure battery includes a positive electrode sheet, a separator, and a negative electrode sheet which are sequentially laminated and wound in the same direction, and an electrolyte thereof. Wherein, the initial ends of the positive and negative pole pieces are provided with a blank current collector, the positive electrode tab 5' is directly welded to the blank current collector of the positive electrode pole piece, and the negative electrode tab 6' is directly welded to the blank current collector of the negative electrode pole piece. The thickness of the positive electrode tab and the negative electrode tab are both 0.1 mm, and the thickness of the positive electrode tab and the negative electrode tab are both 0.5 mm. The positive electrode tab is an aluminum tab, the negative electrode tab is a nickel tab, and a green rubber layer having a thickness of 10 μm is attached to the solder joints of the positive and negative electrodes. The above-mentioned battery cells were placed in a battery package, and 1 mol/L of LiPF ₆ /(EC+PC+DEC) electrolyte was injected therein, wherein ethylene carbonate (EC), propylene carbonate (PC), and ethylene carbonate were injected. The volume ratio of the ester (DEC) was 1:1:1; and the 616790 model (the thickness of the finished battery was 6.1 mm, the width was 67 mm, and the length was 90 mm) was obtained by the process of aging and aging.

Comparative embodiment 2

As shown in FIG. 2, the battery of the prior art embedded tab structure differs from Embodiment 1 in the position of the tabs, and the positive electrode tab 5' and the negative electrode tab 6' are both embedded in the wound core tab. The middle part, the rest is the same as Embodiment 1, and will not be described again.

Battery performance test:

Cell impact test: For each of Embodiments 1 to 3 and Comparative Embodiments 1 and 2, 10 batteries were selected for impact test, and the impact test was carried out in accordance with GB 3241-2014.

Battery energy density test: The batteries of Embodiments 1 to 3 and Comparative Embodiments 1 to 2 were charged at a constant current of 0.5 C at a temperature of 25 ° C to 4.35 V, and then charged to 0.05 C at a constant voltage; then, 0.5 C was discharged to 3.0 V, and measured. The volumetric energy density of the battery at this time.

The test results are shown in Table 1:

Table 1:

It can be seen from the above test results that compared with the conventionally wound structure battery (Comparative Embodiment 1), the utility model adopts the embedded core structure of the battery core, and can significantly improve the energy density of the battery under the same size; Compared with the technical battery core (Comparative Embodiment 2), the utility model optimizes the structure and design of the battery core by adjusting the position of the pole embedded in the wound pole piece, thereby improving the symmetry of the battery core, low hardness, easy deformation and the like. The pass rate of its battery abuse test has increased significantly.

Variations and modifications of the above-described embodiments can also be made by those skilled in the art in light of the above disclosure. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious modifications, substitutions or variations made by those skilled in the art based on the present invention are within the scope of the present invention. In addition, although the specific terms are used in the specification, these terms are merely for convenience of description and do not constitute any limitation to the present invention.

Claims

A wound structure battery comprising a first pole piece (1), a separator (3) and a second pole piece (2) electrically opposite to the first pole piece (1) are sequentially stacked and wound in the same direction a battery core (4), and an electrolyte thereof, the first pole piece (1) includes a first current collector (12) and a first active material layer (11) attached to a surface of the first current collector (12), The second pole piece (2) comprises a second current collector (22) and a second active material layer (21) attached to the surface of the second current collector (22), characterized in that: the first pole piece (1) a first recess (111) is disposed on the first active material layer (11), and a second recess (211) is disposed on the second active material layer (21) of the second pole piece (2), a first groove (111) is located at a beginning end of the wound first pole piece (1), and the second groove (211) is located at a beginning or a middle of the wound second pole piece (2), first a tab (5) is embedded in the first recess (111) and electrically connected to the first current collector (12), and a second lug (6) is embedded in the second recess (211) and second The current collector (22) is electrically connected.
The battery of the winding structure according to claim 1, wherein the first pole piece (1) is a positive electrode piece or a negative electrode piece.
The battery of the winding structure according to claim 1, wherein the battery of the wound structure further comprises a glue layer (7), and the glue layer (7) is disposed on the first pole (5) The surface covers the entire first groove (111) and/or is disposed on the surface of the second electrode (6) and covers the entire second groove (211).
The battery of the winding structure according to claim 3, characterized in that the glue layer (7) is a hot melt adhesive layer or a green rubber layer.
The battery of the winding structure according to claim 1, wherein a thickness a of the first tab (5) is less than or equal to a depth b of the first recess (111), the second tab The thickness c of (6) is less than or equal to the depth d of the second groove (211).
The battery of the winding structure according to claim 1, wherein a length m of the first groove (111) is smaller than a width n of the first pole piece (1), and the second groove ( The length p of 211) is smaller than the width q of the second pole piece (2).
The battery of the winding structure according to claim 1, wherein in the unfolded state, the distance from the head to the tail of the second pole piece (2) is defined as D1. The middle portion of the wound second pole piece (2) is defined as d1, and d1 is in the range of 1/10D1 to 7/10D1 calculated from the head of the second pole piece (2).
The battery of the winding structure according to claim 1, wherein the first recess (111) removes the first active material layer (11) by laser cleaning, mechanical cleaning or styrofoam cleaning to expose the first Formed by a current collector (12).
The battery of the winding structure according to claim 1, wherein the second recess (211) removes the second active material layer (21) by laser cleaning, mechanical cleaning or styrofoam cleaning to expose the first The second current collector (22) is formed.
The battery of the winding structure according to claim 4, wherein the thickness of the hot melt adhesive layer or the green rubber layer is set to 5 to 50 μm.