Square winding battery cell and battery

Abstract

The utility model provides a square winding battery cell which comprises a first pole piece, a diaphragm and a second pole piece, and the first pole piece, the diaphragm and the second pole piece are sequentially stacked and wound to form a winding core; a plurality of folded edges are alternately arranged on the first pole piece in the winding direction, a gasket assembly is arranged between every two adjacent folded edges, the side, facing the interior of the winding core, of the first pole piece is the inner side of the first pole piece, and the gasket assemblies protrude relative to the inner side of the first pole piece so that the folded edges can be straight edges. The square winding battery cell disclosed by the utility model is beneficial to increasing the energy density of the square winding battery cell.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery test technical field especially relates to a square winding electric core and battery. BACKGROUND

[0002] With the wide application of battery technology in various fields, especially in electric vehicles, energy storage systems and other high energy demand industries, the demand for ultra-thick square high volume energy density electric cores is increasing. These electric cores are favored for their high energy density and compact size. Currently, the production of ultra-thick square electric cores mainly relies on the direct winding process. However, this direct winding process has a significant defect: a large semicircular space is formed at both ends of the winding core, and the outer shape of these spaces is similar to a triangle, which makes these areas cannot be effectively utilized. This design flaw greatly reduces the volume energy density of the electric core, affecting the overall performance and efficiency of the battery. Therefore, the cuboid electric core can better utilize the space inside the battery case, making the overall energy density of the battery higher. However, during the winding process of the electric core, an arc-shaped edge will be formed at both ends, and if the arc-shaped edge is directly extruded into a straight edge, it will form a cavity at the corner position of the electric core, resulting in a lack of electrolyte at that position, which can cause lithium precipitation. Therefore, a new electric core is needed to optimize the design of the electric core, reduce the dead space, and improve the volume energy density. SUMMARY

[0003] The utility model aims at least solves one of the technical problems existing in the prior art. For this purpose, the utility model provides a square winding electric core, which is beneficial to increase the energy density of the square winding electric core.

[0004] The utility model further provides a battery.

[0005] According to the square winding electric core of the first aspect embodiment of the utility model, the first pole piece, the diaphragm and the second pole piece are sequentially stacked and wound to form a winding core; the first pole piece is alternately provided with a plurality of folded edges along the winding direction, a gasket assembly is arranged between adjacent folded edges, the side of the first pole piece facing the inside of the winding core is the inner side of the first pole piece, and the gasket assembly protrudes relative to the inner side of the first pole piece, so that the folded edges are all straight edges.

[0006] According to the square winding cell of the first aspect of the present application, at least the following beneficial effects are achieved: the gasket assembly is arranged to support the position of the bent edge, thereby avoiding the bent edge from becoming an arc-shaped bent edge during winding, so that the bent edge is a straight edge during winding, and the gasket assembly also avoids the position of the bent edge from forming a cavity during the hot-pressing formation process of the cell, so that the bent position has sufficient electrolyte, thereby avoiding lithium precipitation.

[0007] According to some embodiments of the present application, the first pole piece is a cathode piece.

[0008] According to some embodiments of the present application, the first pole piece includes a current collector and an active material, the active material is coated on the current collector, a groove is arranged on the active material, and the gasket assembly is arranged in the groove.

[0009] According to some embodiments of the present application, the cross section of the winding core is rectangular, and the normal direction of the cross section is the width direction of the first pole piece.

[0010] According to some embodiments of the present application, the material of the gasket assembly includes a gluey PMMA or a gluey PVDF or a gluey PE or a gluey solid electrolyte.

[0011] According to some embodiments of the present application, the two ends of the gasket assembly in the width direction of the first pole piece do not exceed the active material.

[0012] According to some embodiments of the present application, the gasket assembly is elastically deformable.

[0013] According to some embodiments of the present application, the height of the gasket assembly protruding relative to the first pole piece is not greater than 100 um.

[0014] According to some embodiments of the present application, the second pole piece is laminated on the side of the first pole piece facing the inside of the winding core.

[0015] The battery according to the second aspect of the present application comprises the square winding cell according to any one of the above embodiments.

[0016] Additional aspects and advantages of the present application will be given in part in the following description, will become apparent from the following description, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A structure diagram of a winding core arranged in a shell in the prior art;

[0018] Figure 2 A structure schematic view of a square winding core of the utility model is set in the shell;

[0019] Figure 3 A structure schematic view of a square winding core of the utility model is set in the shell;

[0020] Figure 4 For Figure 3 The local enlarged schematic view is shown in the figure.

[0021] Figure 5 A structure schematic view of the first pole piece of the square winding core of the utility model is unfolded.

[0022] Reference numerals:

[0023] 1, shell; 2, winding core; 3, first pole piece; 31, current collector; 32, active material; 33, groove; 4, diaphragm; 5, second pole piece; 6, gasket assembly. DETAILED DESCRIPTION

[0024] The embodiments of the utility model are described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the utility model, and cannot be understood as a limitation of the utility model.

[0025] In the description of the utility model, it is understood that the orientation description, such as the orientation or position relationship indicated by up, down, etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and is not intended to indicate or imply that the device or element indicated must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the utility model.

[0026] In the description of the utility model, more than two means more than two. If there is a description of the first, the second is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0027] In the description of the utility model, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the utility model according to the specific content of the technical scheme.

[0028] The manufacturing process of the wound cell mainly includes the following steps: first, prepare the raw materials such as positive material, negative material, separator and electrolyte. The positive material is usually made of active material, conductive agent and binder mixed into slurry, and then coated on aluminum foil. The negative material is made of active material, conductive agent and binder mixed into slurry, and then coated on copper foil. Next, the coated positive and negative materials are dried to remove the solvent. The dried electrode material needs to be cut to form a certain size of electrode sheet. Then, the cut positive and negative sheets and the separator are stacked and wound in a certain order to form a wound cell. During winding, the electrode sheet and the separator need to be tightly attached to ensure the performance of the cell. The wound cell needs to be compacted to improve the volumetric energy density of the cell. After compaction, the cell will be cut to form a single cell. Finally, the single cell is subjected to formation treatment, i.e. charging and discharging under certain conditions to activate the active material inside the cell and form a stable electrochemical structure. After formation, the cell will be subjected to final detection and sorting, and the qualified cell can be used to assemble the battery pack.

[0029] Referring to Figure 1 In the process of winding, the electrode sheets need to be tightly attached to each other. In the early stage of winding, regardless of the shape, after the thickness of the winding reaches a certain degree, the winding core will have an arc-shaped edge, making the shape tend to be circular. In the cuboid shell, the arc-shaped edge of the winding core will occupy a large space and cause a large cavity in the shell, resulting in waste of space inside the shell and reduction of the energy density of the battery.

[0030] Secondly, after the electrode sheets are wound into a winding core, the shape of the winding core needs to be maintained and the winding core needs to be compacted. In the existing winding of electrode sheets, if the arc-shaped edge of the winding core is pressed into a straight edge during extrusion, a large cavity will appear at the bending position of the straight edge. At the same time, if the electrode sheets are forcibly wound into a straight edge, the straight edge of the winding core will be pressed into an arc shape during pressing.

[0031] Referring to Figure 2 , Figure 3 and Figure 4The utility model discloses square winding electric core in first embodiment, comprising: first pole piece 3, diaphragm 4 and second pole piece 5, first pole piece 3, diaphragm 4 and second pole piece 5 are sequentially laminated and are wound and form the winding core 2, first pole piece 3 is alternately provided with multiple flanging along the winding direction, and spacer assembly 6 is arranged between adjacent flanging, and the side of first pole piece 3 towards the inside of winding core 2 is the inside of first pole piece 3, and spacer assembly 6 is protruded relative to the inside of first pole piece 3, to make the flanging all be straight edge. In the process of winding, the arc shape will appear in the position of pole piece bending, and with the increase of winding thickness, the arc shape at the bending position will be more and more big, until the arc edge is formed. Even multiple arc edges are connected together. Therefore, the spacer assembly 6 is arranged on the first pole piece 3, and the spacer assembly 6 supports the bending position of the pole piece when winding the pole piece, so that the arc edge is avoided to be formed in the position of pole piece bending. Meanwhile, the spacer assembly 6 can also absorb electrolyte, to avoid the lack of electrolyte at the bending position. At this time, when the winding core 2 is pressed after winding, the spacer assembly 6 supports the bending position of the winding core 2, so that the straight edge on the winding core 2 is avoided to be pressed into the arc edge. So that the winding core 2 can obtain stable straight edge structure. Meanwhile, the bending position also has sufficient electrolyte, and the lithium precipitation phenomenon is avoided.

[0032] Referring to Figure 5 When the spacer assembly 6 supports the bending position of the winding core 2 and forms the cuboid winding core 2, the length of each circle of the first pole piece 3 and the second pole piece 5 is longer when winding the winding core 2, that is, the length of the first pole piece 3 and the second pole piece 5 of the winding core 2 with the same number of turns is longer. This makes the energy of the winding core 2 more, and the energy density of the battery is higher in the cuboid battery shell 1, and the space inside the shell 1 is more fully utilized.

[0033] According to some embodiments of the utility model, the first pole piece 3 is a cathode piece. The active material 32 layer on the cathode piece of the battery is usually composed of conductive material, adhesive and active material 32. The active material 32 is the core of the battery chemical reaction, which participates in the electrochemical reaction and provides or stores electric energy. In different types of batteries, the composition of the active material 32 will be different. For example, in a lithium ion battery, the cathode active material 32 can be lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM) or lithium iron phosphorus (LFP) and the like. These materials release lithium ions when the battery is discharged, and absorb lithium ions again when charging. If the contact between the cathode piece and the electrolyte is not sufficient, the lithium precipitation phenomenon is prone to occur. Therefore, the spacer assembly 6 is arranged on the cathode piece, and after the spacer assembly 6 absorbs the electrolyte, the contact between the cathode piece and the electrolyte is more sufficient, so that the lithium precipitation of the cathode piece is effectively avoided.

[0034] According to some embodiments of the utility model, the first pole piece 3 includes a current collector 31 and an active material 32, the active material 32 is coated on the current collector 31, the active material 32 is provided with a groove 33, and the gasket assembly 6 is arranged in the groove 33. The groove 33 is opened on the active material 32, so that the arrangement of the gasket assembly 6 is stable, the dislocation of the gasket assembly 6 in the winding or pressing process is greatly avoided, and the setting position of the gasket assembly 6 is more accurate. Specifically, opening the groove 33 on the cathode sheet can reduce some active materials 32 on the negative electrode, and the lithium precipitation phenomenon of the battery can be more effectively avoided

[0035] According to some embodiments of the utility model, the section of the roll core 2 is rectangular, and the normal direction of the section is the width direction of the first pole piece 3. When winding the roll core 2, the roll core 2 with a polygonal section can be wound. However, since the shell 1 of the battery is more of a rectangular solid, preferably, the roll core 2 is also a rectangular solid, that is, the section of the roll core 2 is rectangular. At this time, the folded edge of the roll core 2 should include a plurality of upper side folded edges located on the upper side of the roll core 2, a plurality of lower side folded edges located on the lower side of the roll core 2, a plurality of left side folded edges located on the left side of the roll core 2, and a plurality of right side folded edges located on the right side of the roll core 2. On the first pole piece 3 before winding, the upper side folded edge, the right side folded edge, the lower side folded edge and the left side folded edge are arranged in turn in a cycle. And in the process of winding, since the thickness of the roll core 2 gradually increases, the length of the upper side folded edge, the right side folded edge, the lower side folded edge and the left side folded edge will gradually increase, so as to ensure that the gasket assembly 6 is located at the bending position of the roll core 2.

[0036] According to some embodiments of the utility model, the material of gasket assembly 6 includes colloidal PMMA or colloidal PVDF or colloidal PE or colloidal solid electrolyte. Specifically, the chemical substance of gasket assembly 6 is colloidal PMMA / PVDF / PE / solid electrolyte glue mixture and other chemical substances. In this way, gasket assembly 6 can have good electrolyte absorption capacity, and gasket assembly 6 will not react with electrolyte, will not change the performance of electrolyte, and will not have an electrochemical reaction with cathode sheet and anode sheet, thereby avoiding short circuit and other phenomena that affect the performance of the battery cell. Secondly, gasket assembly 6 can also have certain elasticity or deformability, can absorb the tensile force of the outer sheet due to cyclic expansion without displacement, making the battery cell more stable during use and having a longer service life. In addition, gasket assembly 6 will not react with diaphragm 4, so gasket assembly 6 will not damage the structure of the battery cell, and the material used in gasket assembly 6 is relatively soft, so gasket assembly 6 will not pierce diaphragm 4, ensuring the safety of the battery cell. The material of battery diaphragm 4 mainly includes polyethylene (PE), polypropylene (PP), polyester (PET), and other polymer materials. These materials have good chemical stability, electrical insulation, and mechanical strength, can effectively isolate the positive and negative electrodes of the battery, prevent short circuit, and allow ions in the electrolyte to pass through, ensuring the charge and discharge performance of the battery. In recent years, with the development of technology, composite diaphragm 4 using ceramic coating and diaphragm 4 based on inorganic materials such as glass fibers and aramid fibers have also appeared to improve the safety and performance of the battery.

[0037] According to some embodiments of the utility model, the two ends of gasket assembly 6 in the width direction of first sheet 3 do not exceed active material 32. Specifically, gasket assembly 6 can be cylindrical, and the axis of the cylinder is arranged in the width direction of first sheet 3, so that first sheet 3 and second sheet 5 can be uniformly supported. This makes the shape of first sheet 3 and second sheet 5 more uniform after winding. On the other hand, gasket assembly 6 can also be arranged as a plurality of spaced protrusions, and the plurality of protrusions are arranged in the width direction of first sheet 3, so that the active material 32 on the negative sheet is more, and the content of electrolyte at the bending part can be further improved, so that the energy density of the battery cell is higher and the lithium precipitation phenomenon is avoided. When gasket assembly 6 supports the bending part of roll core 2 and forms rectangular roll core 2,

[0038] According to some embodiments of the present application, the gasket assembly 6 can be elastically deformed. When the gasket assembly 6 has a certain elastic deformation, under the extrusion of the first pole piece 3 and the second pole piece 5, the gasket assembly 6 will be more closely attached to the first pole piece 3 and the second pole piece 5. And at the bending position of the first pole piece 3 and the second pole piece 5, the shape of the required support structure is relatively complex, and the gasket assembly 6 can better support the first pole piece 3 and the second pole piece 5 and fill the cavity between the first pole piece 3 and the second pole piece 5, so that the shape of the core 2 is more neat.

[0039] According to some embodiments of the present application, the height of the gasket assembly 6 protruding relative to the first pole piece 3 is not greater than 100um. When the height of the gasket assembly 6 protruding relative to the first pole piece 3 is too high, the electrolyte will appear to be broken bridge lithium, which may cause lithium precipitation on the negative pole piece. Therefore, the height of the gasket assembly 6 protruding relative to the first pole piece 3 is limited according to the thickness of the positive and negative pole pieces. Taking the rectangular core 2 as an example, the number of turns of the core 2*(thickness of the positive pole piece+thickness of the negative pole piece+thickness of the diaphragm 4) is equal to the thickness of one side of the core 2 not containing the gasket assembly 6, which is also the actual thickness D of one side of the core 2. At this time, in order to maintain the rectangular shape of the core 2, the distance from the corner of the core 2 to the inside of the core 2 should be (√2)*D. In order to make the distance from the corner of the core 2 to the inside of the core 2 reach (√2)*D, the gasket assembly 6 is arranged at the corner of the core 2, so that the distance from the corner of the core to the inside of the core 2 increases from D to (√2)*D. That is, the thickness of the multiple gasket assemblies 6 stacked together is

(√2)-1

(√2)-1

(√2)-1

(√2)-1

[0040] According to some embodiments of the present application, the second pole piece 5 is stacked on the side of the first pole piece 3 facing the inside of the winding core 2. In battery design, the anode sheet is ingeniously placed on the inside of the cathode sheet winding, and this innovative layout brings many benefits. First of all, this design significantly reduces the internal resistance of the battery, thereby improving the power density of the battery. When the anode sheet is on the inside, the path of ions traveling between electrodes inside the battery becomes shorter, which not only speeds up the transmission of ions, but also reduces energy loss when diffusing in the electrolyte. This optimized ion flow path allows the battery to maintain stable power output even under high load working conditions. In addition, placing the anode sheet inside the cathode sheet winding helps to reduce the overall size of the battery. In the same volume of battery, this structural design allows the battery to store more energy, thereby improving the energy density. This means that in a limited space, a larger capacity battery can be installed, providing longer use time for the device. This is particularly important for portable electronic devices and electric vehicles and other applications. From the perspective of manufacturing, this design can also simplify the assembly process of the battery, as the winding of the anode sheet and the cathode sheet can be more compact and orderly. This not only improves production efficiency, but also helps to reduce production costs. At the same time, due to the optimization of the internal structure of the battery, the heat management of the battery also becomes easier, which helps to prolong the service life of the battery. In summary, the battery design with the anode sheet placed inside the cathode sheet winding not only improves the performance of the battery, but also optimizes the size and cost-effectiveness of the battery, providing new possibilities for energy solutions for modern electronic devices and electric vehicles.

[0041] According to the battery of the second aspect of the present application, the battery comprises the square winding core of any one of the above embodiments. The battery further comprises a shell 1, and the shell 1 is provided with a cavity for accommodating the square winding core. The square winding core is arranged in the cavity, and the shape of the square winding core is adapted to the shape of the cavity. Specifically, the shell 1 is arranged as a cuboid, the cavity is also arranged as a cuboid, and the square winding core is arranged as a cuboid adapted to the cavity.

[0042] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application.

Claims

1. A square wound battery cell, characterized by, Comprising: a first electrode sheet, a separator, and a second electrode sheet, which are sequentially stacked and wound to form a jelly-roll; a plurality of folds are alternately arranged on the first electrode sheet along the winding direction, a gasket assembly is arranged between adjacent folds, and the gasket assembly protrudes relative to the inner side of the first electrode sheet so that the folds are straight edges.

2. The square wound battery cell of claim 1, wherein, The first electrode sheet is a cathode sheet.

3. The square wound battery cell of claim 2, wherein, The first electrode sheet comprises a current collector and an active material coated on the current collector, a groove is arranged on the active material, and the gasket assembly is arranged in the groove.

4. The square-wound battery cell of claim 1, wherein, The cross section of the jelly-roll is rectangular, and the normal of the cross section is the width direction of the first electrode sheet.

5. The square-wound battery cell of claim 1, wherein, The material of the gasket assembly comprises gelatinous PMMA, gelatinous PVDF, gelatinous PE, or gelatinous solid electrolyte.

6. The square-wound battery cell of claim 3, wherein, The two ends of the gasket assembly in the width direction of the first electrode sheet do not exceed the active material.

7. The square-wound battery cell of claim 1, wherein, The gasket assembly is elastically deformable.

8. The square-wound battery cell of claim 1, wherein, The protrusion height of the gasket assembly relative to the first electrode sheet is not greater than 100 um.

9. The square-wound battery cell of claim 2, wherein, The second electrode sheet is stacked on the side of the first electrode sheet facing the inside of the jelly-roll.

10. A battery, characterized by A square jelly-roll comprising any one of claims 1-9.

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