Batteries and electrical equipment

Abstract

The present application discloses a battery and an electrical device. The battery includes a pole piece and a tab. The pole piece includes a current collector and an active material layer disposed on the current collector. The tab is connected to the current collector and extends from the pole piece along the width of the pole piece. The tab includes a first region and a second region along the width of the pole piece. The first region is located between the second region and the active material layer. The first region has a thickness of t1, and the second region has a thickness of t2. 0.5% ≤ (t1-t2) / t1 ≤ 5%.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery and electrical equipment. Background Art

[0002] At present, the production process of battery pole pieces usually includes coating and cold pressing steps. Among them, cold pressing can make the pole piece compacted, which plays a very important role in improving the energy density and electrical performance of the battery. Since the active material layer area and the empty foil area that forms the pole ear have different degrees of extension during the cold pressing process, after the pole piece is cold pressed, in order to reduce the risk of deformation or warping of the pole ear, it is usually necessary to stretch and extend the empty foil area. However, this stretching and extending operation can easily cause the pole piece to break, affecting the cold pressing processing efficiency. In order to reduce the risk of pole piece breakage, the existing technology usually adopts a thicker current collector or reduces the compaction density of the pole piece. This measure is not only ineffective in improving the breakage phenomenon, but also causes a loss of energy density. Summary of the Invention

[0003] In view of the above situation, it is necessary to provide a battery that reduces the risk of electrode breakage and improves the battery energy density.

[0004] An embodiment of the present application provides a battery comprising a pole piece and a tab. The pole piece comprises a current collector and an active material layer disposed on the current collector. The tab is connected to the current collector and extends from the pole piece along the width of the pole piece. The tab comprises a first region and a second region along the width of the pole piece. The first region is located between the second region and the active material layer. The first region has a thickness of t1, the second region has a thickness of t2, and 0.5% ≤ (t1 - t2) / t1 ≤ 5%.

[0005] In the above-mentioned battery, the tab is arranged into a first region and a second region along the width direction of the pole piece. The first region is located between the second region and the active material layer. The second region is pre-extended by rolling before cold pressing, and the thickness t1 of the first region and the thickness t2 of the second region satisfy 0.5%≤(t1-t2) / t1≤5%. The thickness of the first region and the second region cannot differ too much. If the difference is too large, the band is likely to break due to stress concentration at the boundary. If the difference is too small, less than 0.5%, the second region cannot achieve the extension effect, and the tab is prone to warping and folding. Therefore, the thickness t1 of the first region and the thickness t2 of the second region satisfy 0.5%≤(t1-t2) / t1≤5%, which can reduce the phenomenon of band breakage of the pole piece after cold pressing, improve the processing efficiency, and thus enable the use of thinner current collectors and / or higher compaction density, thereby improving the energy density of the battery.

[0006] In some embodiments of the present application, 0.5%≤(t1-t2) / t1≤3%, which can further reduce the phenomenon of strip breakage of the electrode after cold pressing.

[0007] In some embodiments of the present application, 0.5%≤(t1-t2) / t1≤1.5%, which can further reduce the phenomenon of strip breakage of the electrode after cold pressing.

[0008] In some embodiments of the present application, since the electrode undergoes a cold pressing process during preparation, the current collector region covered by the active material layer has better ductility after cold pressing, and the second region has better ductility after pre-pressing. Since the first region is adjacent to the active material layer, it is not possible to process the first region as well, so the ductility is poor. During the electrode winding process, the first region is between the active material layer and the second region, and the electrode will arch in the second region, causing the electrode to warp or fold. Therefore, the area of ​​the first region is generally minimized to make the area of ​​the second region as large as possible. Therefore, along the thickness direction of the electrode, the projected area of ​​the electrode is S1, and the projected area of ​​the second region is S2, 60% ≤ S2 / S1 ≤ 95%, which is beneficial to reduce the warping or folding of the electrode, and improve the winding quality, battery cell flatness and energy density.

[0009] In some embodiments of the present application, 80%≤S2 / S1≤95%, which can further reduce the occurrence of adverse phenomena such as warping and bending of the tabs after cold pressing, and improve the winding quality and the flatness and energy density of the battery cell.

[0010] In some embodiments of the present application, the tab further includes a third region, which is disposed between the first region and the active material layer and connects the first region and the active material layer. A first insulating layer is disposed on the third region, located between the first region and the active material layer. The first insulating layer can provide insulation when the electrode sheets are wound or stacked to form an electrode assembly, thereby reducing the risk of a short circuit between the tab and another tab / pole sheet of opposite polarity due to burrs piercing the separator.

[0011] In some embodiments of the present application, there is also a first dividing line at the junction of the first region and the second region, and the minimum distance between the first dividing line and the first insulating layer is d1, 0.1mm≤d1≤1mm, so that the first region has a certain width along the width direction of the pole piece. The first region can serve as a transition region between the pre-rolled and stretched second region and the active material layer, thereby improving the structural strength of the connection area between the first pole ear and the active material layer, reducing the risk of bending or breaking of the first pole ear at the connection with the active material layer, and improving the shock resistance of the battery.

[0012] In some embodiments of the present application, the first insulating layer satisfies at least one of the following a, b, and c: a. The thickness of the first insulating layer is less than the thickness of the active material layer; b. Along the width direction of the electrode piece, the length of the electrode ear is W1, and the length of the first insulating layer is W2, W2 / W1≤0.5, W2≥1mm; c. The first insulating layer includes an inorganic substance, and the material of the inorganic substance includes at least one of aluminum oxide, magnesium oxide, and titanium oxide.

[0013] In some embodiments of the present application, there are multiple tabs.

[0014] In some embodiments of the present application, the tab is a positive electrode tab.

[0015] An embodiment of the present application further provides an electrical device comprising the battery described in any of the aforementioned embodiments.

[0016] In the above-mentioned electrical equipment, the battery can reduce the phenomenon of pole piece breakage after cold pressing by arranging the pole ear into a first area and a second area, and pre-extending it by pressing in the second area, thereby enabling the use of a thinner current collector and / or a higher compaction density design, thereby improving the energy density of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of a battery in one embodiment of the present application.

[0018] Figure 2 This is a schematic diagram of the state of a battery before packaging in one embodiment of the present application.

[0019] Figure 3 yes Figure 2 View of the middle electrode assembly along section III-III.

[0020] Figure 4 This is a schematic structural diagram of a first electrode tab connected to a first electrode piece in an embodiment of the present application.

[0021] Figure 5 yes Figure 4 View of section VV.

[0022] Figure 6 yes Figure 4 A schematic structural diagram of an expanded embodiment of the structure shown.

[0023] Figure 7 yes Figure 6 View of section VII-VII.

[0024] Figure 8 yes Figure 4 A schematic structural diagram of an expanded embodiment of the structure shown.

[0025] Figure 9 yes Figure 8 View of section IX-IX.

[0026] Figure 10 yes Figure 4 A schematic structural diagram of an expanded embodiment of the structure shown.

[0027] Figure 11 yes Figure 10 View of section XI-XI.

[0028] Figure 12 yes Figure 4 A schematic structural diagram of an expanded embodiment of the structure shown.

[0029] Figure 13 This is a schematic structural diagram of a second electrode tab connected to a second electrode piece in an embodiment of the present application.

[0030] Figure 14 yes Figure 13 View of section XIV-XIV.

[0031] Figure 15 It is a structural diagram of an electrical device in an embodiment of the present application.

[0032] Description of main component symbols

[0033] Battery 100

[0034] Housing 10

[0035] Part 11

[0036] Part 212

[0037] Main body 13

[0038] Edge banding 14

[0039] Top edge 141

[0040] Side edge sealing 142

[0041] Electrode assembly 20

[0042] First pole piece 21

[0043] First current collector 211

[0044] First active material layer 212

[0045] Fourth Area 213

[0046] Second pole piece 22

[0047] Second current collector 221

[0048] Second active material layer 222

[0049] Diaphragm 23

[0050] First tab 30

[0051] First Area 31

[0052] Second area 32

[0053] Third Area 33

[0054] First dividing line 34

[0055] Second tab 40

[0056] First insulating layer 50

[0057] Second insulating layer 60

[0058] Electrical equipment 200

[0059] First direction Z

[0060] Second direction X

[0061] The third direction Y

[0062] The following specific implementation methods will further illustrate this application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0064] It should be noted that when an element is considered to be “connected” to another element, it may be directly connected to the other element or there may be a centrally disposed element. When an element is considered to be “disposed on” another element, it may be directly disposed on the other element or there may be a centrally disposed element.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0066] At present, the production process of battery pole pieces usually includes coating and cold pressing processes. Among them, cold pressing can compact the pole pieces, which plays a very important role in improving the energy density and electrical performance of the battery. Since the active material layer area and the empty foil area that forms the pole ear have different degrees of elongation during the cold pressing process, after the pole piece is cold pressed, in order to reduce the risk of deformation or warping of the pole ear, it is usually necessary to stretch and extend the empty foil area. However, this stretching and extension operation can easily cause the pole piece to break, affecting the cold pressing processing efficiency. In order to reduce the risk of pole piece breakage, the existing technology usually adopts a thicker current collector or reduces the compaction density of the pole piece. This measure is not only ineffective in improving the breakage phenomenon, but also causes a loss of energy density.

[0067] An embodiment of the present application provides a battery comprising a pole piece and a tab. The pole piece comprises a current collector and an active material layer disposed on the current collector. The tab is connected to the current collector and extends from the pole piece along the width of the pole piece. The tab comprises a first region and a second region along the width of the pole piece. The first region is located between the second region and the active material layer. The first region has a thickness of t1, the second region has a thickness of t2, and 0.5% ≤ (t1 - t2) / t1 ≤ 5%.

[0068] In the above-mentioned battery, the tab is arranged into a first region and a second region along the width direction of the electrode sheet. The first region is located between the second region and the active material layer. The second region is pre-extended by pressing, and the thickness t1 of the first region and the thickness t2 of the second region satisfy 0.5%≤(t1-t2) / t1≤5%. The thickness of the first region and the second region cannot differ too much. If the difference is too large, the stress concentration at the boundary is likely to cause the tab to break. If the difference is too small, less than 0.5%, the second region cannot achieve the extension effect, and the tab is likely to warp or fold. Therefore, the thickness t1 of the first region and the thickness t2 of the second region satisfy 0.5%≤(t1-t2) / t1≤5%, which can reduce the phenomenon of tab breakage after cold pressing of the electrode sheet. The thickness of the first region and the second region cannot differ too much. If the difference is too large, the stress concentration at the boundary is likely to cause the tab to break. If the difference is too small, the second region cannot achieve the extension effect, and the tab is likely to warp or fold.

[0069] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0070] like Figure 1 、 Figure 2 and Figure 3 As shown, an embodiment of the present application provides a battery 100, including a shell 10, an electrode assembly 20, a first pole tab 30 and a second pole tab 40, the electrode assembly 20 is arranged inside the shell 10, and the first pole tab 30 and the second pole tab 40 are both connected to the electrode assembly 20 and extend out of the shell 10.

[0071] In one embodiment, the housing 10 includes a first portion 11 and a second portion 12 connected to each other. When the first portion 11 and the second portion 12 are connected facing each other, an internal space capable of accommodating the electrode assembly 20 is formed.

[0072] In one embodiment, the housing 10 includes a main body 13 and an edge seal 14. The edge seal 14 is connected to and extends from the main body 13. The electrode assembly 20 is disposed within the main body 13. The first electrode tab 30 and the second electrode tab 40 extend from the edge seal 14. In one embodiment, the edge seal 14 includes a top edge seal 141 and a side edge seal 142 connected to each other. The first electrode tab 30 and the second electrode tab 40 extend from the top edge seal 141.

[0073] In one embodiment, the first tab 30 and the second tab 40 are located on the same side of the main body 13. In other embodiments, the first tab 30 and the second tab 40 may also be located at opposite ends of the main body 13 (not shown).

[0074] The electrode assembly 20 includes a first electrode piece 21, a second electrode piece 22, and a separator 23. The separator 23 is disposed between the first electrode piece 21 and the second electrode piece 22. The first electrode piece 21, the separator 23, and the second electrode piece 22 are wound together to form the electrode assembly 20. The first electrode tab 30 is connected to the first electrode piece 21, and the second electrode tab 40 is connected to the second electrode piece 22. In other embodiments, the first electrode piece 21, the separator 23, and the second electrode piece 22 are stacked to form the electrode assembly 20 (not shown).

[0075] One of the first and second electrode tabs 30, 40 is a positive electrode tab, and the other of the first and second electrode tabs 30, 40 is a negative electrode tab. In one embodiment, the first electrode tab 30 is a positive electrode tab, the second electrode tab 40 is a negative electrode tab, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet. In one embodiment, the first electrode tab 30 is made of aluminum. In one embodiment, the second electrode tab 40 is made of copper, nickel, or a nickel alloy.

[0076] like Figure 4 and Figure 5 As shown, the first electrode sheet 21 includes a first current collector 211 and a first active material layer 212 provided on the surface of the first current collector 211, the first electrode tab 30 is connected to the first current collector 211, and the first electrode tab 30 extends from the first electrode sheet 21 along the first direction Z, wherein the first direction Z is the width direction of the first electrode sheet 21.

[0077] In the embodiment of the present application, the first electrode tab 30 and the first current collector 211 are integrally formed, and the first electrode tab 30 is cut from the first current collector 211. In one embodiment, the material of the first current collector 211 includes aluminum.

[0078] It should be noted that the area on the first electrode 21 where the first active material layer 212 is provided is also called the coating area, and the area on the first electrode 21 where the first current collector 211 is exposed and the area on the first electrode tab 30 where the first current collector 211 is exposed are also called the empty foil area.

[0079] In order to increase the compaction density of the first active material layer 212 and thereby increase the energy density of the battery 100, the first current collector 211 on the first pole piece 21 needs to be cold pressed before forming the first pole tab 30. During the cold pressing process, some particles of the first active material layer 212 are pressed and embedded into the first current collector 211, resulting in a decrease in the structural strength and ductility of the first current collector 211. When the empty foil area is stretched after the cold pressing, it is very easy to cause the first current collector 211 to break, affecting the processing quality rate. The first pole piece 21 provided in the present application is subjected to pressing of at least a portion of the empty foil area before cold pressing to pre-stretch it. Moreover, after the first current collector 211 is cut to form the first pole tab 30, the pre-pressed and stretched empty foil area constitutes at least a portion of the first pole tab 30.

[0080] The first electrode tab 30 includes a first region 31 and a second region 32 . The first region 31 is located between the second region 32 and the first active material layer 212 . The first region 31 connects the second region 32 and the first electrode sheet 21 .

[0081] The first electrode tab 30 has a first dividing line 34 . The first dividing line 34 is located at the junction of the first region 31 and the second region 32 . Along the first direction Z, the first region 31 and the second region 32 are respectively located on either side of the first dividing line 34 .

[0082] In the present application, the first dividing line 34 is formed by pre-pressing and stretching the first electrode piece 21, and the pre-pressed and stretched empty foil area constitutes the second area 32. In one embodiment, the first dividing line 34 is an indentation.

[0083] Along a second direction X perpendicular to the first direction Z, the thickness of the first region 31 is t1, the thickness of the second region 32 is t2, and 0.5%≤(t1−t2) / t1≤5%. The second direction X is the thickness direction of the first pole piece 21 .

[0084] In the battery 100 of the present application, before the first electrode sheet 21 is cold-pressed, part of the empty foil area is pressed to pre-stretch it, and the thickness t1 of the first area 31 that has not been pre-pressed and stretched and the thickness t2 of the second area 32 that has been pre-pressed and stretched meet 0.5%≤(t1-t2) / t1≤5%. The thickness difference between the first area 31 and the second area 32 cannot be too large. If the difference is too large, the stress concentration at the boundary will easily cause the strip to break. If the difference is too small, less than 0.5%, the second area 32 will not achieve the stretching effect, and the first electrode tab 30 will easily warp or fold. After the first electrode sheet 21 of the present application is cold-pressed, the thickness t1 of the first area 31 and the thickness t2 of the second area 32 meet 0.5%≤(t1-t2) / t1≤5%. Compared with other first electrode sheets 21 in which the empty foil area is stretched after cold pressing, the first electrode sheet 21 provided by the present application can reduce the phenomenon of strip breakage. Furthermore, the first pole piece 21 of the present application can also adopt a design of a thinner first current collector 211 and a first active material layer 212 with a higher compaction density while ensuring that the frequency of band breakage does not increase, thereby improving the energy density of the battery 100.

[0085] In one embodiment, 0.5%≤(t1-t2) / t1≤3%, which can further reduce the phenomenon of broken strips in the first electrode 21, and thus enable the use of thinner current collectors and / or higher compaction density designs, thereby improving the energy density of the battery.

[0086] In one embodiment, 0.5%≤(t1-t2) / t1≤1.5%, which can further reduce the occurrence of broken strips in the first pole piece 21. In one embodiment, the value of (t1-t2) / t1 is any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0087] In one embodiment, along the second direction X, the projected area of ​​the first electrode tab 30 is S1, and the projected area of ​​the second region 32 is S2, and 60% ≤ S2 / S1 ≤ 95%. Because the first region 31 has poor ductility, while the second region 32 has better ductility after pre-pressing and stretching, if the area of ​​the second region 32 is too small, it will easily warp or bend during the winding process of the first electrode sheet 21. Therefore, along the thickness direction of the first electrode tab 30, the projected area S1 of the first electrode tab 30 and the projected area S2 of the second region 32 meet the requirement of 60% ≤ S2 / S1 ≤ 95%, which helps to reduce warping and bending of the first electrode tab 30 and improve the flatness and energy density of the battery cell.

[0088] In one embodiment, 80%≤S2 / S1≤95%, which can further reduce the warping and bending of the first electrode tab 30 and improve the flatness and energy density of the battery cell.

[0089] In one embodiment, the value of S2 / S1 is any one of 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% and 100%.

[0090] like Figure 6 and Figure 7 As shown, in one embodiment, the first electrode tab 30 further includes a third region 33 . The third region 33 is located between the first region 31 and the first active material layer 212 , and the third region 33 connects the first region 31 and the first active material layer 212 .

[0091] In one embodiment, the first tab 30 further has a second dividing line 35 . The second dividing line 35 is located at the junction of the first region 31 and the third region 33 . Along the first direction Z, the first region 31 and the third region 33 are located on both sides of the second dividing line 35 .

[0092] The battery 100 also includes a first insulating layer 50, which is disposed on the surface of the third region 33 and is connected to the first active material layer 212. When the first electrode sheet 21, the second electrode sheet 22, and the separator 23 are wound or stacked to form the electrode assembly 20, the first insulating layer 50 can provide insulation protection, reducing the risk of a short circuit between the first electrode tab 30 and the second electrode tab 40, thereby improving the safety performance of the battery 100. Compared to a battery 100 without the first insulating layer 50, burrs on the edge of the first electrode tab 30 can easily pierce the separator 23, thereby electrically connecting with the second electrode tab 40 and causing the battery 100 to short-circuit. In one embodiment of the present application, by providing the first insulating layer 50, the first insulating layer 50 can cover the burrs on the edge of the first electrode tab 30, thereby reducing the risk of a short circuit in the battery 100.

[0093] In one embodiment, the first active material layer 212 completely covers the first current collector 211 of the first electrode 21, and the first insulating layer 50 is connected to the first active material layer 212, which can reduce the exposed area of ​​the empty foil area, further reduce the risk of short circuit between the first electrode tab 30 and the second electrode tab 40, and improve the safety performance of the battery 100.

[0094] like Figure 8 and Figure 9 As shown, in one embodiment, a fourth region 213 is provided on the first electrode sheet 21. The fourth region 213 exposes the first current collector 211. The fourth region 213 is located between the first active material layer 212 and the first electrode tab 30, and connects the first active material layer 212 and the first electrode tab 30. In one embodiment, the fourth region 213 is located between the first active material layer 212 and the third region 33, and connects the first active material layer 212 and the third region 33.

[0095] The battery 100 also includes a second insulating layer 60, which is disposed on the surface of the fourth region 213 and connects the first insulating layer 50 and the first active material layer 212. When the first electrode 21, the second electrode 22, and the separator 23 are wound or stacked to form the electrode assembly 20, the second insulating layer 60 can act as an insulator, reducing the risk of a short circuit between the first electrode 21 and the second electrode 22, thereby improving the safety performance of the battery 100. Compared to a battery 100 without the second insulating layer 60, burrs on the edge of the first electrode 21 can easily pierce the separator 23 and thereby establish an electrical connection with the second electrode 22, causing the battery 100 to short-circuit. In one embodiment of the present application, by providing the second insulating layer 60, the second insulating layer 60 can cover the burrs on the edge of the first electrode 21, thereby reducing the risk of a short circuit in the battery 100.

[0096] like Figure 10 and Figure 11 As shown, in one embodiment, the first insulating layer 50 and the second insulating layer 60 are made of the same material and are formed in one step, which can simplify the preparation process of the battery 100, shorten the preparation cycle of the battery 100, and save costs.

[0097] For ease of understanding and description, as an example, the following further illustrates that the surfaces of the third region 33 and the fourth region 213 are both provided with the first insulating layer 50 .

[0098] In one embodiment, along the first direction Z, a first dividing line 34 is further provided at the junction of the first region 31 and the second region 32. The minimum distance between the first dividing line 34 and the first insulating layer 50 is d1, 0.1mm≤d1≤1mm, so that the first region 31 has a certain width along the first direction Z. The first region 31 can serve as a transition region between the pre-rolled and stretched second region 32 and the first pole tab 30, thereby improving the structural strength of the connection region between the first pole tab 30 and the first pole piece 21, reducing the risk of bending or breaking of the first pole tab 30 along the connection with the first pole piece 21, and improving the seismic performance of the battery 100.

[0099] In one embodiment, 0.4 mm ≤ d1 ≤ 1 mm, which can further ensure the structural strength of the connection area between the first electrode tab 30 and the first electrode sheet 21 , reduce the risk of the first electrode tab 30 bending or breaking along the connection with the first electrode sheet 21 , and improve the shock resistance of the battery 100 .

[0100] In one embodiment, the value of d1 is any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm and 1 mm.

[0101] In one embodiment, along the second direction X, the thickness of the first insulating layer 50 is t3, the thickness of the first active material layer 212 is t4, and t3<t4. In one embodiment, 50 μm≤t4≤150 μm.

[0102] In other embodiments, t3 = t4 (not shown). In other embodiments, t3 > t4 (not shown).

[0103] In one embodiment, the length of the first insulating layer 50 along the first direction Z is W2, where W2 is ≥ 1 mm. The length of the first insulating layer 50 along the first direction Z is sufficient to ensure the protective effect of the first insulating layer 50 and reduce the risk of short circuiting of the battery 100. In one embodiment, W2 is ≥ 2 mm.

[0104] In one embodiment, along the first direction Z, the length of the first electrode tab 30 is W1, W2 / W1≤0.5. The dimensional relationship between the first electrode tab 30 and the first insulating layer 50 along the first direction Z is beneficial to improving the current conduction ability and heat dissipation ability of the first electrode tab 30, thereby improving the charge and discharge speed and heat dissipation efficiency of the battery 100.

[0105] In one embodiment, the first insulating layer 50 includes an inorganic material. In one embodiment, the material of the inorganic material includes but is not limited to at least one of aluminum oxide, magnesium oxide, and titanium oxide.

[0106] In one embodiment, the weight of the first active material layer 212 is G1, and 100 g / m^2≤G1≤300 g / m^2. The weight G1 of the first active material layer 212 refers to the weight of the first active material layer 212 coated per square meter on a single side surface of the first current collector 211.

[0107] In one embodiment, the compaction density of the first active material layer 212 is D1, 2.2 g / cm^3≤D1≤4.2 g / cm^3. The compaction density D1 of the first active material layer 212 refers to the weight of the first active material layer 212 per unit volume after the first electrode 21 is cold pressed.

[0108] like Figure 12 As shown, in one embodiment, there are multiple first tabs 30, and the multiple first tabs 30 are spaced apart along a third direction Y perpendicular to the first direction Z and the second direction X. Providing multiple first tabs 30 can not only increase the charge and discharge speed of the battery 100, but also improve the heat dissipation capability of the battery 100. Optionally, the number of first tabs 30 is two.

[0109] like Figure 13 and Figure 14As shown, the second electrode sheet 22 includes a second current collector 221 and a second active material layer 222 provided on the surface of the second current collector 221 . The second electrode tab 40 is connected to the second current collector 221 , and extends from the second electrode sheet 22 along the first direction Z.

[0110] In one embodiment, the second electrode tab 40 and the second current collector 221 are integrally formed, and the second electrode tab 40 is cut from the second current collector 221. In one embodiment, the material of the second current collector 221 includes any one of copper, nickel, or a nickel alloy.

[0111] Compared to the first electrode tab 30 and the first current collector 211, the second electrode tab 40 and the second current collector 221 have a higher structural strength and are more resistant to deformation. In one embodiment, the second electrode sheet 22 does not require stretching or extending the bare foil area after cold pressing. In one embodiment, the second electrode sheet 22 does not require pre-calendering of the bare foil area before cold pressing.

[0112] In one embodiment, before cold pressing, the second electrode sheet 22 is subjected to a pre-rolling operation on the blank foil area on the second electrode sheet 22. This can reduce the occurrence of tape breakage in the second electrode sheet 22 after cold pressing. In one embodiment, the pre-rolling operation on the blank foil area on the second electrode sheet 22 is the same as any of the aforementioned pre-rolling operations on the blank foil area on the first electrode sheet 21, and will not be further described in this application.

[0113] In one embodiment, the preparation process of the first electrode 21 is as follows:

[0114] 1) Mix 96% lithium cobalt oxide, 1.5% conductive carbon, 2.5% binder, and an appropriate amount of solvent (e.g., deionized water, N-methylpyrrolidone) to form a slurry with a solid content of approximately 75%;

[0115] 2) coating the slurry in step 1) on a portion of the surface of the first current collector 211, leaving a portion of the surface of the first current collector 211 exposed;

[0116] 3) Drying the slurry on the surface of the first current collector 211 in step 2) to obtain the first pole piece 21;

[0117] 4) Pre-rolling and stretching the blank foil area on the surface of the first pole piece 21 obtained in step 3), and then rolling the coated area of ​​the first pole piece 21 to obtain the first pole piece 21.

[0118] In one embodiment, the preparation process of the first electrode tab 30 is as follows: cutting the empty foil area of ​​the first electrode sheet 21 to obtain the first electrode tab 30 extending from the first electrode sheet 21 .

[0119] It should be noted that the aforementioned preparation process and technology of the first pole piece 21 are only examples, and this application does not make any specific restrictions on the composition and proportion of each material in the first pole piece 21.

[0120] In order to verify the effect of pre-calendering the first electrode sheet 21 before cold pressing on reducing the breakage of the electrode sheet, and the effect of using a thinner current collector and / or a electrode sheet with a higher compaction density on the energy density of the battery 100, multiple sets of comparative tests were conducted. The specific information is as follows:

[0121] Multiple groups of first pole pieces 21 were selected for comparative example tests and example tests. In each comparative example test, the sample size of the first pole pieces 21 was 10, and in each example test, the sample size of the first pole pieces 21 was 10.

[0122] The average value of the tape breakage frequency of each first pole piece 21 after stretching and cold pressing the empty foil area and the average value of the energy density of the battery 100 including each first pole piece 21 in multiple groups of comparative examples are obtained.

[0123] Other specific information of the comparative example tests and example tests are as follows:

[0124] Comparative Example 1:

[0125] The first electrode sheet 21 is not pre-rolled. After the first electrode sheet 21 is cold-pressed, the empty foil area is stretched and extended. The coating weight of the first active material layer 212 is 150 g / m^2, and the compaction density of the first active material layer 212 is 3.85 g / cm^3.

[0126] Comparative Example 2:

[0127] The first electrode piece 21 is pre-rolled and then cold-pressed. After cold-pressing, the empty foil area is not further stretched. The coating weight of the first active material layer 212 is 150 g / m^2, the compaction density of the first active material layer 212 is 3.85 g / cm^3, and the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is: (t1-t2) / t1=10%. The minimum distance d1 between the first dividing line 34 and the first insulating layer 50 is 0.5 mm. The ratio of the area S2 of the second region 32 (pre-rolled region) to the area S1 of the first electrode tab 30 is 90%.

[0128] Comparative Example 3:

[0129] The only difference from Comparative Example 2 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=7%.

[0130] Example 1:

[0131] The first electrode piece 21 is pre-rolled and then cold-pressed. After cold-pressing, the empty foil area is not further stretched. The coating weight of the first active material layer 212 is 150 g / m^2, the compaction density of the first active material layer 212 is 3.85 g / cm^3, and the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is: (t1-t2) / t1=5%. The minimum distance d1 between the first dividing line 34 and the first insulating layer 50 is 0.5 mm. The ratio of the area S2 of the second region 32 (pre-rolled region) to the area S1 of the first electrode tab 30 is 90%.

[0132] The thickness of the first region 31 and the second region 32 is measured by selecting any three locations in the first region 31, measuring the thickness at each location with a vernier caliper, and then calculating the arithmetic average, which is the thickness of the first region 31. The thickness of the second region 32 is measured in the same manner.

[0133] Example 2:

[0134] The only difference from Example 1 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=3.5%.

[0135] Example 3:

[0136] The only difference from Example 1 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=3.0%.

[0137] Example 4:

[0138] The only difference from Example 1 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=2.5%.

[0139] Example 5:

[0140] The only difference from Example 1 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=1.5%.

[0141] Example 6:

[0142] The only difference from Example 1 is that the relationship between the thickness t1 of the first region 31 and the thickness t2 of the second region 32 is (t1-t2) / t1=0.5%.

[0143] Example 7:

[0144] The only difference from Example 6 is that the compaction density of the first active material layer 212 is 3.90 g / cm 3 .

[0145] Example 8:

[0146] The only difference from Example 6 is that the compaction density of the first active material layer 212 is 4.00 g / cm 3 .

[0147] Example 9:

[0148] The only difference from Example 6 is that the compaction density of the first active material layer 212 is 4.10 g / cm 3 .

[0149] Example 10:

[0150] The only difference from Example 6 is that the compaction density of the first active material layer 212 is 4.20 g / cm 3 .

[0151] Example 11:

[0152] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 0.1 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 95%.

[0153] Example 12:

[0154] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 0.3 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 93%.

[0155] Example 13:

[0156] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 0.7 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 85%.

[0157] Example 14:

[0158] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 1.0 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 80%.

[0159] Example 15:

[0160] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 1.2 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 75%.

[0161] Example 16:

[0162] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 1.5 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 60%.

[0163] Example 17:

[0164] The only difference from Example 6 is that the minimum distance d1 between the first boundary line 34 and the first insulating layer 50 is 1.6 mm, and the ratio of the area S2 of the second region 32 (pre-rolling region) to the area S1 of the first tab 30 is 55%.

[0165] For the aforementioned multiple comparative examples and embodiments, the number of times each first pole piece 21 breaks per unit length is obtained, and all first pole pieces 21 are tracked to obtain the energy density of the battery 100 containing each first pole piece 21. The frequency of folding of the first tab 30 in some embodiments is also obtained. The statistics are tabulated as follows:

[0166] Table 1

[0167]

[0168] Table 2

[0169]

[0170] Table 3

[0171]

[0172]

[0173] As can be seen from Table 1, compared with the first electrode piece 21 that is not pre-rolled before cold pressing, the first electrode piece 21 of the present application is pre-rolled for the empty foil area before cold pressing, which can improve the problem of the first electrode piece 21 being broken.

[0174] As can be seen from Table 2, the first electrode 21 according to the embodiment of the present application can withstand greater compaction strength, thereby increasing the compaction density of the first active material layer 212 and improving the energy density of the battery 100 .

[0175] As can be seen from Table 3, the use of the first electrode sheet 21 according to the embodiment of the present application can reduce the frequency of folding of the first electrode tab 30 and improve the yield of the battery 100 .

[0176] To sum up, in the battery 100 of the present application, the tab is arranged into a first region 31 and a second region 32 along the width direction of the pole piece, the first region 31 connects the second region 32 and the pole piece, and the second region 32 is pressed before cold pressing to pre-extend it, and the thickness t1 of the first region 31 and the thickness t2 of the second region 32 satisfy 0.5%≤(t1-t2) / t1≤5%, which can reduce the phenomenon of pole piece breakage after cold pressing, and thus can adopt a thinner current collector and / or a higher compaction density design to improve the energy density of the battery 100.

[0177] like Figure 15 As shown, an embodiment of the present application further provides an electric device 200 , comprising the battery 100 described in any of the aforementioned embodiments, and the battery 100 can provide electrical energy for the electric device 200 .

[0178] In one embodiment, the power-consuming device 200 includes electronic devices such as drones, mobile phones, watches, tablet computers, and laptop computers.

[0179] In the above-mentioned electrical equipment 200, the first electrode 21 of the battery 100 is pre-rolled and stretched on the empty foil area before cold pressing, which improves the problem of broken strips of the first electrode 21, and then adopts a thinner current collector and / or a higher compaction density design, thereby improving the energy density of the battery 100 and reducing the impact of the low energy density of the battery 100 on the electrical equipment 200.

[0180] In addition, those skilled in the art may also make other changes within the spirit of this application. Of course, these changes made according to the spirit of this application should be included in the scope disclosed in this application.

Claims

1. A battery, characterized in that: include: A pole piece, comprising a current collector and an active material layer disposed on the current collector; A tab connected to the current collector, extending from the pole piece along a width direction of the pole piece; Along the width direction of the electrode sheet, the electrode tab includes a first region that is not pre-rolled and extended before the electrode sheet is cold-pressed, and a second region that is pre-rolled and extended before the electrode sheet is cold-pressed, and the first region is located between the second region and the active material layer; Along the thickness direction of the pole piece, the thickness of the first region is t1, the thickness of the second region is t2, and 0.5%≤(t1-t2) / t1≤5%.

2. The battery according to claim 1, wherein 0.5%≤(t1-t2) / t1≤3%.

3. The battery according to claim 1, wherein 0.5%≤(t1-t2) / t1≤1.5%.

4. The battery according to claim 1, wherein Along the thickness direction of the tab, the projected area of ​​the tab is S1, the projected area of ​​the second region is S2, and 60%≤S2 / S1≤95%.

5. The battery according to claim 4, wherein 80%≤S2 / S1≤95%.

6. The battery according to claim 1, wherein Along the width direction of the electrode piece, the electrode tab also includes a third region, which is located between the first region and the active material layer and connects the first region and the active material layer. A first insulating layer is provided on the third region, and the first insulating layer is located between the first region and the active material layer.

7. The battery according to claim 6, wherein A first boundary line is further defined at the junction of the first region and the second region. The minimum distance between the first boundary line and the first insulating layer is d1, where 0.1 mm ≤ d1 ≤ 1 mm.

8. The battery according to claim 6, wherein The first insulating layer satisfies at least one of the following a, b, and c: a. The thickness of the first insulating layer is less than the thickness of the active material layer; b. Along the width direction of the electrode piece, the length of the electrode ear is W1, the length of the first insulating layer is W2, W2 / W1≤0.5, W2≥1mm; c. The first insulating layer includes an inorganic substance, and the material of the inorganic substance includes at least one of aluminum oxide, magnesium oxide, and titanium oxide.

9. The battery according to claim 1, wherein There are multiple tabs.

10. The battery according to claim 1, wherein The tab is a positive electrode tab.

11. An electrical device, characterized in that: The invention comprises a battery according to any one of claims 1 to 10.

Images