阅读说明：本技术 一种卷针、卷绕式电芯及卷绕式电芯的生产工艺 (Winding needle, winding type battery cell and production process of winding type battery cell ) 是由 张勇 张海生 蒋濛 胡庆波 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种卷针,为绝缘刚性材质的柱状针体。该卷针为由绝缘刚性材质制成的柱状针体,卷针卷绕于隔膜和极耳中并随电芯封装入电池壳体中,避免了现有技术中卷针拔出的操作,确保卷绕电芯的对齐度,从而克服现有述中银卷针拔出带来的电芯缺陷；电芯内部短路时,卷针和卷绕体同时上行顶压电池盖帽上的安全阀,实现快速泄压,改善现有中心针与电芯存在间隙脱离的缺陷；充放电过程中发热快,卷绕张力导致电芯的极片变形并向电芯内圈挤压,导致隔膜会出现松动甚至坍塌,与中心针相比,卷针与隔膜之间无间隙,卷针能为电芯提供良好的支撑作用,降低隔膜松动或坍塌几率。本发明还公开了一种包含卷针的卷绕式电芯以及该卷绕式电芯的生产工艺。(The invention discloses a winding needle which is a columnar needle body made of an insulating rigid material. The winding needle is a columnar needle body made of an insulating rigid material, is wound in the diaphragm and the tab and is packaged into the battery shell along with the battery cell, so that the operation of pulling out the winding needle in the prior art is avoided, the alignment degree of the wound battery cell is ensured, and the defect of the battery cell caused by pulling out the silver winding needle in the prior art is overcome; when the inside of the battery core is short-circuited, the winding needle and the winding body simultaneously move upwards to press a safety valve on the battery cap, so that the quick pressure relief is realized, and the defect that the existing center needle is separated from the battery core in a gap is overcome; the charge-discharge in-process is generated heat soon, and winding tension leads to the pole piece of electric core to warp and to electric core inner circle extrusion, leads to the diaphragm can appear becoming flexible even collapse, compares with central needle, and zero clearance between book needle and the diaphragm rolls up the needle and can provide good supporting role for electric core, reduces that the diaphragm is not hard up or the probability of collapsing. The invention also discloses a winding type battery cell comprising the winding needle and a production process of the winding type battery cell.)

1. A winding needle is characterized in that the winding needle is a columnar needle body made of insulating rigid materials.

2. The winding needle according to claim 1, wherein clamping holes are formed in two end faces of the columnar needle body, and the clamping holes are used for being matched with a winding needle clamp of a battery cell winding device.

3. The needle of claim 2 wherein said cylindrical body has a through hole disposed therein.

4. The needle of claim 3 wherein the through holes communicate with each other and/or the clamping holes.

5. The utility model provides a coiling formula electricity core, includes the winding body that forms by two-layer pole piece and two-layer diaphragm alternate range upon range of coiling, its characterized in that still includes the book needle, it is the column needle body of insulating rigid material to roll up the needle, roll up the needle with the inner circle diaphragm fixed connection of winding body.

6. The wound battery cell according to claim 5, wherein clamping holes are provided on two end faces of the cylindrical pin body, and the clamping holes are used for matching with a winding pin clamp of a battery cell winding device.

7. The wound electrical core of claim 5, wherein the end face of the winding pin is flush with the membrane of the wound body.

8. The production process of the winding type battery cell is characterized by comprising the following steps of:

s1, fixedly connecting the winding needle with the end part of the inner diaphragm;

s2, alternately laminating and winding the two layers of pole pieces and the two layers of diaphragms on the periphery of the winding needle; the two-layer separator includes the inner layer separator.

9. The production process of the wound battery cell of claim 8, wherein the fixed connection between the winding needle and the inner membrane is bonding.

10. The production process of the wound battery cell of claim 8, wherein clamping holes are formed in two end faces of the columnar pin body, and the clamping holes of the winding pin in the step S2 are detachably and fixedly connected with a winding pin clamp of the battery cell winding device.

Technical Field

The invention relates to the technical field of lithium battery production, in particular to a winding needle, a winding type battery cell and a production process of the winding type battery cell.

Background

The winding needle is one of the main tools for preparing the winding type battery core. As disclosed in CN206441823U and CN101212069A, the prior art winding needle is mostly formed by combining two winding needle units made of stainless steel, each winding needle unit includes a needle body and a fixing seat, and the fixing seat is used for fixedly connecting the needle body to the winding device. During winding, the diaphragm penetrates between the needle bodies of the two winding needle units to be clamped, the assembly planes of the two winding needles are both attached to the diaphragm and combined into a cylinder or an approximate cylinder, the fixing seat is connected with the winding machine, the winding machine drives the winding needles to rotate and guide the positive pole piece and the negative pole piece into the winding needles, and the winding needles are pulled out after the winding of the battery cell is completed.

The following problems exist in the current cell winding process: due to the friction between the winding needle and the diaphragm, the winding needle can generate the following defects of the battery cell in the process of pulling out: the diaphragm causes certain damage, the diaphragm is taken out of the inner layer of the winding core, the inner ring of the diaphragm is folded and deformed after the needle is pulled out, and the alignment degree of the winding core is damaged. Especially, the battery with longer cylindrical pole piece is wound on the automatic winding all-in-one machine, the diaphragm with the aluminum oxide coating is easy to be drawn out badly, the yield of the wound product is greatly influenced, and the manufacturing cost is increased.

The improved technical scheme mainly comprises the following two steps: firstly, communicated air holes are formed in a winding needle, and the winding needle is pulled out to inflate the winding needle so that the winding needle and an inner-layer diaphragm are inflated, and the contact area and the friction force of the winding needle and the inner-layer diaphragm are reduced; secondly, a high polymer material layer with low friction coefficient such as polytetrafluoroethylene or polyurethane is arranged on the surface of the winding needle. However, the winding needle with the two structures also needs to be pulled out, and the battery core defect caused by the pulling out of the needle cannot be fundamentally solved.

Disclosure of Invention

One of the objectives of the present invention is to overcome the drawbacks of the prior art, and to provide a winding needle, which can be retained in an electrical core, and overcomes the drawback that the winding needle is pulled out to damage a separator.

In order to achieve the technical effects, the technical scheme of the invention is as follows: a winding needle is characterized in that the winding needle is a columnar needle body made of insulating rigid materials.

The preferable technical scheme is that clamping holes are formed in two end faces of the columnar needle body and are used for being matched with a needle winding clamp of the battery cell winding device.

The preferable technical scheme is that a through hole is arranged in the columnar needle body.

The preferable technical scheme is that the through holes are communicated with each other and/or the through holes are communicated with the clamping holes.

The invention also provides a winding type battery cell, which comprises a winding body formed by alternately laminating and winding two layers of pole pieces and two layers of diaphragms, and is characterized by further comprising a winding needle, wherein the winding needle is a columnar needle body made of an insulating rigid material, and the winding needle is fixedly connected with an inner ring diaphragm of the winding body.

The preferable technical scheme is that clamping holes are formed in two end faces of the columnar needle body and are used for being matched with a needle winding clamp of the battery cell winding device.

Preferably, the end face of the winding needle is flush with the diaphragm of the winding body.

The invention also aims to provide a production process of the winding type battery cell, which is characterized by comprising the following steps of:

s1, fixedly connecting the winding needle with the end part of the inner diaphragm;

s2, alternately laminating and winding the two layers of pole pieces and the two layers of diaphragms on the periphery of the winding needle; the two-layer separator includes the inner layer separator.

The preferable technical scheme is that the fixed connection of the winding needle and the inner-layer diaphragm is bonding.

The preferable technical scheme is that clamping holes are formed in two end faces of the columnar needle body, and the clamping holes of the winding needle in the S2 are detachably and fixedly connected with a winding needle clamp of the battery cell winding device.

The invention has the advantages and beneficial effects that:

the winding needle is a columnar needle body made of an insulating rigid material, the needle body is wound in a diaphragm and a tab and is packaged into a battery shell along with a battery cell, the operation of pulling out the winding needle in the prior art is avoided, the alignment degree of the wound battery cell is ensured, and the defect of the battery cell caused by the pulling out of the silver winding needle in the prior art is overcome;

when the inside of the battery core is short-circuited, the winding needle and the winding body simultaneously move upwards to press a safety valve on the battery cap, so that the quick pressure relief is realized, and the defect that the existing center needle is separated from the battery core in a gap is overcome;

the charge-discharge in-process is generated heat soon, and winding tension leads to the pole piece of electric core to warp and to electric core inner circle extrusion, leads to the diaphragm can appear becoming flexible even collapse, compares with central needle, and zero clearance between book needle and the diaphragm rolls up the needle and can provide good supporting role for electric core, reduces that the diaphragm is not hard up or the probability of collapsing.

Drawings

FIG. 1 is a cross-sectional view of the needle of example 1 taken along a central axis;

FIG. 2 is a cross-sectional view of the needle of example 2 taken along a central axis;

FIG. 3 is a cross-sectional view of the needle of example 3 taken along a central axis;

fig. 4 is a schematic end-face structure diagram of a wound cell in example 4;

fig. 5 is a cross-sectional view of the wound cell of example 4 along the central axis of the winding needle;

in the figure: 1. a needle body; 2. clamping holes; 3. a first through hole; 4. a second through hole; 5. and (4) winding the body.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

Insulating rigid material

The selection of the insulating rigid material includes, but is not limited to, an inorganic insulating material, an organic insulating material, a mixed insulating material formed by mixing an inorganic insulating material and an organic insulating material, or a composite material formed by laminating and coating the above materials. In view of the self weight of the battery, the preferred insulating rigid material is a polymer organic insulating material or an insulating plastic containing an inorganic insulating filler, the insulating rigid material includes, but is not limited to, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, epoxy resin, silicone resin, ABS engineering plastic, polyamide, polyimide, polyester, etc., the more preferred insulating rigid material is selected from polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and the more preferred insulating rigid material is polyethylene or polypropylene having the same material as the separator.

Columnar needle body

The cross section of the columnar needle body is determined according to the shape of the winding core, and can be circular, oval, polygonal with the number of sides more than three, polygonal with smooth transition of end corners, flat and the like which are commonly used in the prior art because the winding needle does not need to be pulled out. The columnar needle body is an integrated needle body, or is formed by assembling and fixedly connecting more than two needle body parts. Preferably, the columnar needle body is an integrated needle body.

Clamping hole

The clamping hole is used for being matched with a winding needle clamp of the battery cell winding device, so that the winding needle is fixed between the winding needle clamps and rotates along with the winding needle clamps.

Specifically, the winding needle is in a shape of a regular circle, an ellipse, a polygon with the number of sides larger than three, and a polygon with smooth transition end corners, the clamping hole is a regular hexagonal hole, and the central axis of the regular hexagonal hole is coincided with the central axis of the winding needle; the winding needle is flat, the number of clamping holes in the winding needle is not limited to two, and the winding needle is required to be determined according to the clamping stability of the winding needle clamp.

Through hole

Common forms of vias include two: the first type is a first through hole which is consistent with the axial direction of the columnar needle body, the first through hole is communicated with the clamping hole, the number of the first through holes can be one or more, the number of the first through holes is one, the central axis of the first through hole is coincided with the central axis of the winding needle, and the orifice of the first through hole and the clamping hole are combined into a step hole shape; the second is a second through hole arranged between the side surfaces of the columnar pin body, namely, the opening of the second through hole is positioned on the side surface of the columnar pin body. Furthermore, the through holes are communicated with each other and/or the through holes are communicated with the clamping holes.

The through hole functions as: firstly, increasing the injection amount of electrolyte in the battery cell; secondly, accelerating the circulation of electrolyte in the center of the battery cell and the transmission of lithium ions; thirdly, the heat dissipation of the battery cell can be accelerated by the flowing of the electrolyte through the through hole.

Further, the first through hole is a frustum-shaped through hole, and an end orifice of a cover cap of the battery cell of the first through hole is smaller than an end orifice of a steel shell of the battery cell. When the battery cell with the structure is short-circuited, the gas in the first through hole acts on the side surface of the first through hole, and the winding type battery cell containing the winding needle is accelerated to push the cap safety valve.

Winding body formed by alternately laminating and winding two layers of pole pieces and two layers of diaphragms

The sequence of the alternate lamination of the two pole pieces and the two separators is generally: the laminated structure comprises an inner diaphragm, a pole piece, an outer diaphragm and a pole piece, and further comprises an inner diaphragm, a positive plate, an outer diaphragm and a negative plate in a common laminating sequence. The winding sequence is: the inner diaphragm is fed into a winding device for winding, and then sequentially fed into a positive plate or a negative plate, wherein the diaphragm is longer than the positive plate and the negative plate along the axial direction of the winding body, and the negative plate is longer than the positive plate so as to prevent the positive plate and the negative plate in the axial direction of the winding body from contacting.

Axial length of winding body and winding needle

Generally, in a wound battery core, the axial length of the positive electrode sheet roll > the axial length of the negative electrode sheet roll is greater than the axial length of the separator roll, and the axial length of the winding needle is greater than the axial length of the negative electrode sheet roll. In the production process of the winding type battery core, the membrane and/or the negative plate can be damaged by the fact that the winding needle clamp is pulled out inevitably, and in order to overcome the defects, the axial length of the winding needle is further equal to that of the membrane roll, namely the end face of the winding needle is flush with the membrane. The end face of the winding needle is flush with the diaphragm, so that the winding needle is in direct contact with the cap safety valve in a short circuit state.

The winding needle is fixedly connected with the end part of the inner diaphragm

The fixed connection of the winding needle and the end part of the inner-layer diaphragm comprises a detachable fixed connection and a non-detachable fixed connection, and the preferable fixed connection mode is bonding based on the integral cylindrical needle body winding needle. Based on the winding needle formed by assembling and fixedly connecting more than two needle body parts, the common fixing and connecting mode can be bonding, or clamping the end part of the inner-layer diaphragm between the needle body parts.

Battery cell winding device

The selection range of the battery cell winding device comprises a manual winding device and an automatic semi-automatic winding device, wherein winding needle fixtures are arranged in the manual winding device and the automatic semi-automatic winding device, and two ends of a winding needle are detachably and fixedly connected to the winding needle fixtures.