Method for producing a folded electrical core of an electrode composite unit

Abstract

A method for manufacturing a folding electric core of an electrode composite unit includes: step a, providing a strip-shaped electrode composite unit, the electrode composite unit comprising multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, and step b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer. In such a method, the separator layer of the present invention is prevented from being cut into several separator pieces, thereby simplifying the production process. Meanwhile, the end of the electrode composite unit is folded up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form a electric core of battery, thus avoiding the traditional stacking of the separator layer, the negative electrode layer and the positive electrode layer in a certain order, thereby improving the production efficiency of the battery cell.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method of manufacturing an electric core of battery, in particular to a method for manufacturing a folding electric core of an electrode composite unit.BACKGROUND OF THE INVENTION

[0002] With the rapid development of society, lithium batteries are used in many products such as electric bicycles and notebook computers due to the advantages of light weight, high energy storage density, long service life, low self-discharge and environmental protection.

[0003] As we all know, an electric core of the existing lithium battery is mainly formed by stacking the negative electrode plate and the positive electrode plate at intervals, and a separator is arranged between the negative electrode plate and the positive electrode plate, and the topmost electrode layer and the bottommost electrode layer of the electric core are all negative electrode plates.

[0004] The existing method for manufacturing the electric core of the lithium battery is mainly to first lay a separator on the platform, then place a negative electrode plate on the separator, then place another separator on the negative electrode plate, and then place a positive electrode plate on the separator, ..., a complete electric core of battery is made by repeatedly placing the separator, the negative electrode plate and the positive electrode plate for multiple times. However, the existing manufacturing method of the lithium electric core of battery has the following defects: (1) the separator, the negative electrode plate and the positive electrode plate must be cut separately before stacking, which leads to complicated production steps; (2) during the production of lithium electric core of battery, it is necessary to stack the separator, the negative electrode plate, and the positive electrode plate in a certain order, which results in low production efficiency.

[0005] Therefore, there is an urgent need for providing a method for manufacturing a folding electric core of an electrode composite unit that simplifies the production process and improves the production efficiency to overcome the above-mentioned drawbacks.SUMMARY OF THE INVENTION

[0006] An objective of the present invention is to provide a method for manufacturing folding electric core of electrode composite unit, which simplifies production process and improves production efficiency.

[0007] To achieve the above objective, the present invention provides a method for manufacturing folding electric core of electrode composite unit, which includes: step a, providing a strip-shaped electrode composite unit, the electrode composite unit comprising multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer located on a top of the electrode composite unit comprising multiple top electrode units arranged in a row, a bottom electrode layer located on a bottom of the electrode composite unit comprising multiple bottom electrode units arranged in a row, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units, and a blank region greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and / or a tail end of the electrode composite unit; and step b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer.

[0008] Preferably, the number of the separator layer is odd, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have opposite polarities.

[0009] Preferably, the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer and the bottom electrode layer, from top to bottom.

[0010] Preferably, the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the first electrode units are aligned with the second electrode units in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the second electrode units.

[0011] Preferably, both of the first electrode layer and the second electrode layer are continuous strip-shaped electrodes.

[0012] Preferably, the top electrode units are staggered with the bottom electrode units in the vertical direction, and the number of the bottom electrode units is one more than the number of the top electrode units, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

[0013] Preferably, the top electrode units are staggered with the bottom electrode units in the vertical direction, and the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

[0014] Preferably, the number of the bottom electrode units is one more than the number of the top electrode units, each of the top electrode units is aligned with one of the bottom electrode units in the vertical direction, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

[0015] Preferably, the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units are aligned with the bottom electrode units in the vertical direction, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

[0016] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the first electrode layer, the second electrode layer and the bottom electrode layer at the tail head of the electrode composite unit, respectively.

[0017] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

[0018] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0019] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0020] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

[0021] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; an end section is reversed at the tail end of the electrode composite unit, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the other end of the end section.

[0022] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit.

[0023] Preferably, the number of the separator layer is even, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have same polarities.

[0024] Preferably, the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer, a third electrode layer, a fourth separator layer, and the bottom electrode layer, from top to bottom.

[0025] Preferably, the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the third electrode layer comprises multiple third electrode units spaced apart from each other and arranged in rows, the first electrode units, the second electrode units and the third electrode units are aligned with one another in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the third electrode units.

[0026] Preferably, the first electrode layer, the second electrode layer and the third electrode layer are continuous strip-shaped electrodes.

[0027] Preferably, the top electrode units are staggered with the bottom electrode units in the vertical direction, and the top electrode units and the bottom electrode units have positive polarities.

[0028] Preferably, the number of the bottom electrode units is one more than the number of the top electrode units, each of the top electrode units is aligned with one of the bottom electrode units in the vertical direction, the top electrode units and the bottom electrode units have positive polarities.

[0029] Preferably, the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units are aligned with the bottom electrode units in the vertical direction, the top electrode units and the bottom electrode units have positive polarities.

[0030] Preferably, the number of the bottom electrode units is one more than the number of the top electrode units; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail head of the electrode composite unit, respectively.

[0031] Preferably, the number of the bottom electrode units is equal to the number of the top electrode units; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0032] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer, the third electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0033] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; an end section is reversed at the tail end of the electrode composite unit, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the third electrode layer and the bottom electrode layer at the other end of the end section.

[0034] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

[0035] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0036] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer, the third electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

[0037] Preferably, a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit; an end section is reversed at the tail end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the third electrode layer and the bottom electrode layer at the other end of the end section.

[0038] In comparison with the prior art, the method for manufacturing folding electric core of electrode composite unit according to the present invention includes step a, providing a strip-shaped electrode composite unit, the electrode composite unit including multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer including multiple top electrode units arranged in a row, a bottom electrode layer including multiple bottom electrode units arranged in a row, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units, and a blank region greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and / or a tail end of the electrode composite unit; and step b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer. In such a method, the separator layer of the present invention is prevented from being cut into several separator pieces, thereby simplifying the production process. At the same time, the end of the electrode composite unit is folded up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery, thus avoiding the traditional stacking of the separator layer, the negative electrode layer and the positive electrode layer in a certain order, thereby improving the production efficiency of the battery cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings: FIG. 1 is a flowchart of a manufacturing method of an electric core according to the present invention; FIG. 2 is a schematic diagram of an electrode composite unit according to a first embodiment of the present invention; FIG. 3 is a schematic diagram of an electric core according to a first embodiment of the present invention; FIG. 4 is a schematic diagram of an electrode composite unit according to a second embodiment of the present invention; FIG. 5 is a schematic diagram of an electric core according to a second embodiment of the present invention; FIG. 6 is a schematic diagram of an electrode composite unit according to a third embodiment of the present invention; FIG. 7 is a schematic diagram of an electric core according to a third embodiment of the present invention; FIG. 8 is a schematic diagram of an electrode composite unit according to a fourth embodiment of the present invention; FIG. 9 is a schematic diagram of an electric core according to a fourth embodiment of the present invention; FIG. 10 is a schematic diagram of an electrode composite unit according to a fifth embodiment of the present invention; FIG. 11 is a schematic diagram of an electric core according to a fifth embodiment of the present invention; FIG. 12 is a schematic diagram of an electrode composite unit according to a sixth embodiment of the present invention; FIG. 13 is a schematic diagram of an electric core according to a sixth embodiment of the present invention; FIG. 14 is a schematic diagram of an electrode composite unit according to a seventh embodiment of the present invention; FIG. 15 is a schematic diagram of an electric core according to a seventh embodiment of the present invention; FIG. 16 is a schematic diagram of an electrode composite unit according to an eighth embodiment of the present invention; FIG. 17 is a schematic diagram of an electric core according to an eighth embodiment of the present invention; FIG. 18 is a schematic diagram of an electrode composite unit according to a ninth embodiment of the present invention; FIG. 19 is a schematic diagram of an electric core according to a ninth embodiment of the present invention; FIG. 20 is a schematic diagram of an electrode composite unit according to a tenth embodiment of the present invention; FIG. 21 is a schematic diagram of an electric core according to a tenth embodiment of the present invention; FIG. 22 is a schematic diagram of an electrode composite unit according to an eleventh embodiment of the present invention; FIG. 23 is a schematic diagram of an electric core according to an eleventh embodiment of the present invention; FIG. 24 is a schematic diagram of an electrode composite unit according to a twelfth embodiment of the present invention; FIG. 25 is a schematic diagram of an electric core according to a twelfth embodiment of the present invention; FIG. 26 is a schematic diagram of an electrode composite unit according to a thirteenth embodiment of the present invention; FIG. 27 is a schematic diagram of an electric core according to a thirteenth embodiment of the present invention; FIG. 28 is a schematic diagram of an electrode composite unit according to a fourteenth embodiment of the present invention; FIG. 29 is a schematic diagram of an electric core according to a fourteenth embodiment of the present invention; FIG. 30 is a schematic diagram of an electrode composite unit according to a fifteenth embodiment of the present invention; and FIG. 31 is a schematic diagram of an electric core according to a fifteenth embodiment of the present invention; DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0040] In order to explain in detail the technical content, construction features, the purpose and effect achieved by the present invention, the following combined with the implementation and the attached drawings are described in detail.

[0041] Referring to FIGS. 1-31, a method for manufacturing folding electric core of electrode composite unit includes: steps a, providing a strip-shaped electrode composite unit 100, the electrode composite unit having multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer 10 located on a top of the electrode composite unit 100 including multiple top electrode units 11 arranged in a row, a bottom electrode layer 90 located on a bottom of the electrode composite unit 100 including multiple bottom electrode units 91 arranged in a row, a blank region greater than or equal to a length of one electrode unit being reserved between two adjacent top electrode units, a blank region 110 greater than or equal to a length of one electrode unit being reserved between two adjacent bottom electrode units, and a blank region 110 greater than or equal to a length of one electrode unit being reserved on at least the top electrode unit or the bottom electrode unit of a head end and / or a tail end of the electrode composite unit 100; and step b, alternatively folding the head end of the electrode composite unit 100 up and down, with the length of one electrode unit 120 as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the an electric core of battery including a top electrode unit and a bottom electrode unit that are both negative electrodes and covered by the separator layer.

[0042] More specifically, FIGS. 1-15 respectively show a first to eighth embodiment of the present invention is shown. Specifically, the separator layer includes odd layers, the top electrode layer 10 located on the top of the electrode composite unit 100 and the bottom electrode layer 90 located on the bottom of the electrode composite unit 100 have opposite polarities. The electrode composite unit includes the top electrode layer 10, a first separator layer 20, a first electrode layer 30, a second separator layer 40, a second electrode layer 50, a third separator layer 60 and the bottom electrode layer 90, from top to bottom. Specifically, the first electrode layer 30 includes multiple first electrode units 31 spaced apart from each other and arranged in rows, the second electrode layer 50 includes multiple second electrode units 51 spaced apart from each other and arranged in rows, the first electrode units 31 are aligned with the second electrode units 51 in a vertical direction, the top electrode units 11 are aligned with the first electrode units 31, and the bottom electrode units 91 are aligned with the second electrode units 51. It's worth noting that, both of the first electrode layer 30 and the second electrode layer 50 may be continuous strip-shaped electrodes, as configured by people ordinarily skilled in the art.

[0043] FIGS. 2-3 show a first embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, and the number of the bottom electrode units 91 is one more than the number of the top electrode units 11, the top electrode units 11 have positive polarities, and the bottom electrode units 91 have negative polarities. Further, at least one blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100; at least one blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the first electrode layer 30, the second electrode layer 50 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively, as shown in FIG. 2. In the case of a respective blank region being formed on the top electrode layer 10, the first electrode layer 30, the second electrode layer 50 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively, the tail end of the electrode composite unit 100 is formed with a composite separator layer. As shown in FIG. 2, in this embodiment, the folding method on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 2) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until a previous column before the tail end of the electrode composite unit 100 is folded, and finally folding downward the tail end of the electrode composite unit 100 to cover the bottom electrode unit 91 at the previous column.

[0044] FIGS. 4-5 show a second embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, and the number of the bottom electrode units 91 is one more than the number of the top electrode units 11. Further, at least one blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100, at least one blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 4, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 4) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding...until the tail end of the electrode composite unit 100 is folded.

[0045] FIGS. 6-7 show a third embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, and the number of the bottom electrode units 91 is equal to the number of the top electrode units 11; the top electrode units 11 have positive polarities, and the bottom electrode units 91 have negative polarities. Further, at least one blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100, at least one blank region greater than or equal to a length of one electrode unit is formed on the second electrode layer 50 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 6, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 6) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0046] FIGS. 8-9 show a fourth embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, and the number of the bottom electrode units 91 is equal to the number of the top electrode units 11. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the second electrode layer 50 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 8, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 8) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0047] FIGS. 10-11 show a fifth embodiment of the present invention. In this embodiment, the number of the bottom electrode units 91 is one more than the number of the top electrode units 11, each of the top electrode units 11 is aligned with each of the bottom electrode units 91 in the vertical direction; the top electrode units 11 have positive polarities, and the bottom electrode units 91 have negative polarities. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the tail end of the electrode composite unit 100. As shown in FIG. 10, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 10) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0048] FIGS. 12-13 show a sixth embodiment of the present invention. In this embodiment, the number of the bottom electrode units 91 is equal to the number of the top electrode units 11, each of the top electrode units 11 is aligned with each of the bottom electrode units 91 in the vertical direction; the top electrode units 11 have positive polarities, and the bottom electrode units 91 have negative polarities. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, respectively. An end section 130a is reversed at the tail end of the electrode composite unit 100, and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at one end of the end section 130a, and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the second electrode layer 50 and the bottom electrode layer 90 at the other end of the end section 130a. As shown in FIG. 12, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 12) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0049] FIGS. 14-15 show a seventh embodiment of the present invention. In this embodiment, the number of the bottom electrode units 91 is one more than the number of the top electrode units 11, each of the top electrode units 11 is aligned with each of the bottom electrode units 91 in the vertical direction. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the second electrode layer 50 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 14, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 14) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0050] FIGS. 16-31 respectively show an eighth to fifteenth embodiment of the present invention. Specifically, the separator layer includes an even number of layers, the top electrode layer 10 located on the top of the electrode composite unit 100 and the bottom electrode layer 90 located on the bottom of the electrode composite unit 100 have the same polarity. The electrode composite unit includes the top electrode layer 10, a first separator layer 20, a first electrode layer 30, a second separator layer 40, a second electrode layer 50, a third separator layer 60 , a third electrode layer 70, a fourth separator layer 80 and the bottom electrode layer 90, from top to bottom. Specifically, the first electrode layer 30 includes multiple first electrode units 31 spaced apart from each other and arranged in rows, the second electrode layer 50 includes multiple second electrode units 51 spaced apart from each other and arranged in rows, the third electrode layer 70 includes multiple third electrode units 71 spaced apart from each other and arranged in rows, the first electrode units 31, the second electrode units 51 and the third electrode units 71 are aligned with one another in the vertical direction, the top electrode units 11 are aligned with the first electrode units 31, and the bottom electrode units 91 are aligned with the third electrode units 71. In other embodiments, the first electrode layer 30, the second electrode layer 50 and the third electrode layer 70 may be continuous strip-shaped electrodes, which are not limited however.

[0051] FIGS. 16-17 show the eighth embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, both of the top electrode units 11 and the bottom electrode units 91 have positive polarities, and the number of the bottom electrode units 91 is one more than the number of the top electrode units 11. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100. As shown in FIG. 16, in this embodiment, the folding method on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 16) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding...until the last column of the electrode composite unit 100 is folded.

[0052] FIGS. 18-19 show a ninth embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction, and the number of the bottom electrode units 91 is equal to the number of the top electrode units 11. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 18, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 18) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0053] FIGS. 20-21 show a tenth embodiment of the present invention. In this embodiment, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction. At least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100, and at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the second electrode layer 50, the third electrode layer 70 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 20, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 20) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding...until the tail end of the electrode composite unit 100 is folded.

[0054] FIGS. 22-23 show an eleventh embodiment of the present invention. Specifically, the top electrode units 11 are staggered with the bottom electrode units 91 in the vertical direction. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the head end of the electrode composite unit 100. An end section 130a is reversed at the tail end of the electrode composite unit 100, and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at one end of the end section 130a, and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the third electrode layer 70 and the bottom electrode layer 90 at the other end of the end section 130a. As shown in FIG. 22, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 22) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the end section 130b of the electrode composite unit 100 is folded.

[0055] FIGS. 24-25 show a twelfth embodiment of the present invention. In this embodiment, the number of the bottom electrode units 91 is one more than the number of the top electrode units 11, and each of the top electrode units 11 is respectively aligned with one of the bottom electrode units 91 in the vertical direction. Both of the top electrode units 11 and the bottom electrode units 91 have positive polarities. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, respectively, and at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 at the tail end of the electrode composite unit 100. As shown in FIG. 24, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 24) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding...until the tail end of the electrode composite unit 100 is folded.

[0056] FIGS. 26-27 show a thirteenth embodiment of the present invention. In this embodiment, the number of the top electrode units 11 is equal to the number of the bottom electrode units 91, and each of the top electrode units 11 is respectively aligned with one of the bottom electrode units 91 in the vertical direction. Both of the top electrode units 11 and the bottom electrode units 91 have positive polarities. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, respectively, and at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 26, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 26) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0057] FIGS. 28-29 show a fourteenth embodiment of the present invention. In this embodiment, the number of the top electrode units 11 is equal to the number of the bottom electrode units 91, and each of the top electrode units 11 is respectively aligned with one of the bottom electrode units 91 in the vertical direction. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, respectively, and at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the second electrode layer 50, the third electrode layer 70 and the bottom electrode layer 90 at the tail end of the electrode composite unit 100, respectively. As shown in FIG. 28, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 28) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding... until the tail end of the electrode composite unit 100 is folded.

[0058] FIGS. 30-31 show a fifteenth embodiment of the present invention. Specifically, the number of the top electrode units 11 is equal to the number of the bottom electrode units 91, and each of the top electrode units 11 is respectively aligned with one of the bottom electrode units 91 in the vertical direction. Further, at least one blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at the head end of the electrode composite unit 100, respectively. An end section 130a is reversed at the tail end of the electrode composite unit 100, and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10 and the bottom electrode layer 90 at one end of the end section 130a, respectively; and a blank region 110 greater than or equal to a length of one electrode unit is formed on the top electrode layer 10, the third electrode layer 70 and the bottom electrode layer 90 at the other end of the end section 130a, respectively. As shown in FIG. 30, in this embodiment, the folding method performed on the electrode composite unit 100 includes: starting the folding at the head end (the left end of FIG. 30) of the electrode composite unit 100, firstly folding downward a folding unit 120 at the first column, then folding upward the leftmost folding unit 120 obtained at the previous folding, and then folding downward the leftmost folding unit 120 obtained at the previous folding...until the end section 130b of the electrode composite unit 100 is folded.

[0059] In the various embodiments provided above, it is worth noting that, the two separator layers are directly hot pressed together, if no electrode unit is formed therebetween.

[0060] In comparison with the prior art, the method for manufacturing folding electric core of electrode composite unit includes step a, providing a strip-shaped electrode composite unit 100, the electrode composite unit 100 including multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer 10 including multiple top electrode units 11 arranged in a row, a bottom electrode layer 90 including multiple bottom electrode units 91 arranged in a row, a blank region 110 greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units 11, a blank region 110 greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units 91, and a blank region 110 greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and / or a tail end of the electrode composite unit 100; and step b, folding the head end of the electrode composite unit 100 up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer. In such a method, the separator layer of the present invention is prevented from being cut into several separator pieces, thereby simplifying the production process. At the same time, the end of the electrode composite unit 100 is folded up and down alternatively, with the length of one electrode unit 120 as a unit of folding each time, to form an electric core of battery, thus avoiding the traditional stacking of the separator layer, the negative electrode layer and the positive electrode layer in a certain order, thereby improving the production efficiency of the battery cell.

[0061] While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangement included within the spirit and scope of the invention.

Claims

1. A method for manufacturing folding electric core of electrode composite unit, comprising steps of: a, providing a strip-shaped electrode composite unit, the electrode composite unit comprising multiple electrode layers, a separator layer being provided between two adjacent electrode layers having opposite polarities, a top electrode layer located on a top of the electrode composite unit comprising multiple top electrode units arranged in a row, a bottom electrode layer located on a bottom of the electrode composite unit comprising multiple bottom electrode units arranged in a row, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent top electrode units, a blank region greater than or equal to a length of one electrode unit being formed between two adjacent bottom electrode units, and a blank region greater than or equal to a length of one electrode unit being formed on at least the top electrode layer and the bottom electrode layer at a head end and / or a tail end of the electrode composite unit; and b, folding the head end of the electrode composite unit up and down alternatively, with the length of one electrode unit as a unit of folding each time, to form an electric core of battery; in the electric core of battery, two adjacent electrode units having opposite polarities, the electrode units at a top and a bottom of the electric core of battery being both negative electrodes and covered by the separator layer.

2. The method for manufacturing folding electric core of electrode composite unit according to claim 1, wherein the number of the separator layer is odd, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have opposite polarities.

3. The method for manufacturing folding electric core of electrode composite unit according to claim 2, wherein the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer and the bottom electrode layer, from top to bottom.

4. The method for manufacturing folding electric core of electrode composite unit according to claim 3, wherein the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the first electrode units are aligned with the second electrode units in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the second electrode units.

5. The method for manufacturing folding electric core of electrode composite unit according to claim 3, wherein both of the first electrode layer and the second electrode layer are continuous strip-shaped electrodes.

6. The method for manufacturing folding electric core of electrode composite unit according to claim 4 or 5, wherein the top electrode units are staggered with the bottom electrode units in the vertical direction, and the number of the bottom electrode units is one more than the number of the top electrode units, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

7. The method for manufacturing folding electric core of electrode composite unit according to claim 4 or 5, wherein the top electrode units are staggered with the bottom electrode units in the vertical direction, and the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

8. The method for manufacturing folding electric core of electrode composite unit according to claim 4 or 5, wherein the number of the bottom electrode units is one more than the number of the top electrode units, each of the top electrode units is aligned with one of the bottom electrode units in the vertical direction, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

9. The method for manufacturing folding electric core of electrode composite unit according to claim 4 or 5, wherein the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units are aligned with the bottom electrode units in the vertical direction, the top electrode units have positive polarities, and the bottom electrode units have negative polarities.

10. The method for manufacturing folding electric core of electrode composite unit according to claim 6, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the first electrode layer, the second electrode layer and the bottom electrode layer at the tail head of the electrode composite unit, respectively.

11. The method for manufacturing folding electric core of electrode composite unit according to claim 6, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

12. The method for manufacturing folding electric core of electrode composite unit according to claim 7, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

13. The method for manufacturing folding electric core of electrode composite unit according to claim 7, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

14. The method for manufacturing folding electric core of electrode composite unit according to claim 8, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

15. The method for manufacturing folding electric core of electrode composite unit according to claim 9, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; an end section is reversed at the tail end of the electrode composite unit, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the other end of the end section.

16. The method for manufacturing folding electric core of electrode composite unit according to claim 9, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer and the bottom electrode layer at the tail end of the electrode composite unit.

17. The method for manufacturing folding electric core of electrode composite unit according to claim 1, wherein the number of the separator layer is even, the top electrode layer located on the top of the electrode composite unit and the bottom electrode layer located on the bottom of the electrode composite unit have same polarities.

18. The method for manufacturing folding electric core of electrode composite unit according to claim 17, wherein the electrode composite unit comprises the top electrode layer, a first separator layer, a first electrode layer, a second separator layer, a second electrode layer, a third separator layer, a third electrode layer, a fourth separator layer, and the bottom electrode layer, from top to bottom.

19. The method for manufacturing folding electric core of electrode composite unit according to claim 18, wherein the first electrode layer comprises multiple first electrode units spaced apart from each other and arranged in rows, the second electrode layer comprises multiple second electrode units spaced apart from each other and arranged in rows, the third electrode layer comprises multiple third electrode units spaced apart from each other and arranged in rows, the first electrode units, the second electrode units and the third electrode units are aligned with one another in a vertical direction, the top electrode units are aligned with the first electrode units, and the bottom electrode units are aligned with the third electrode units.

20. The method for manufacturing folding electric core of electrode composite unit according to claim 18, wherein the first electrode layer, the second electrode layer and the third electrode layer are continuous strip-shaped electrodes.

21. The method for manufacturing folding electric core of electrode composite unit according to claim 19 or 20, wherein the top electrode units are staggered with the bottom electrode units in the vertical direction, and the top electrode units and the bottom electrode units have positive polarities.

22. The method for manufacturing folding electric core of electrode composite unit according to claim 19 or 20, wherein the number of the bottom electrode units is one more than the number of the top electrode units, each of the top electrode units is aligned with one of the bottom electrode units in the vertical direction, the top electrode units and the bottom electrode units have positive polarities.

23. The method for manufacturing folding electric core of electrode composite unit according to claim 19 or 20, wherein the number of the bottom electrode units is equal to the number of the top electrode units, the top electrode units are aligned with the bottom electrode units in the vertical direction, the top electrode units and the bottom electrode units have positive polarities.

24. The method for manufacturing folding electric core of electrode composite unit according to claim 21, wherein the number of the bottom electrode units is one more than the number of the top electrode units; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail head of the electrode composite unit, respectively.

25. The method for manufacturing folding electric core of electrode composite unit according to claim 21, wherein the number of the bottom electrode units is equal to the number of the top electrode units; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

26. The method for manufacturing folding electric core of electrode composite unit according to claim 21, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer, the third electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

27. The method for manufacturing folding electric core of electrode composite unit according to claim 21, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the head end of the electrode composite unit; an end section is reversed at the tail end of the electrode composite unit, and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the third electrode layer and the bottom electrode layer at the other end of the end section.

28. The method for manufacturing folding electric core of electrode composite unit according to claim 22, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer at the tail end of the electrode composite unit.

29. The method for manufacturing folding electric core of electrode composite unit according to claim 23, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

30. The method for manufacturing folding electric core of electrode composite unit according to claim 23, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the second electrode layer, the third electrode layer and the bottom electrode layer at the tail end of the electrode composite unit, respectively.

31. The method for manufacturing folding electric core of electrode composite unit according to claim 23, wherein a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at the head end of the electrode composite unit; an end section is reversed at the tail end of the electrode composite unit, respectively; a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer and the bottom electrode layer at one end of the end section, respectively; and a blank region greater than or equal to a length of one electrode unit is formed on the top electrode layer, the third electrode layer and the bottom electrode layer at the other end of the end section.