Electrochemical devices and electronic devices

Abstract

The present application relates to the technical field of electrochemical devices, and discloses an electrochemical device and an electronic device. The electrochemical device includes a first pole piece, a second pole piece and a diaphragm. Along the thickness direction of the first pole piece, diaphragms are arranged on both sides of the first pole piece, the edges of the two diaphragms exceed the first pole piece, and the local edges of the two diaphragms are connected to form a composite part and a receiving part, and the local edges of the two diaphragms are not connected to form a gap part. The first pole piece is arranged in the receiving part, and the first pole piece is provided with at least one first slot, at least one end of the first slot extends to the edge of the first pole piece to form an opening, and the opening of at least one first slot is arranged opposite to the gap part. The present application arranges the first slot on the first pole piece, and the opening of the first slot is arranged opposite to the gap part of the diaphragm, which is conducive to the flow of electrolyte from the gap part to the first pole piece, improves the wettability of the electrolyte and the active material of the first pole piece, and improves the charge and discharge performance of the electrochemical device.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of electrochemical devices, and in particular to an electrochemical device and an electronic device. Background Art

[0002] Electrochemical devices are used in electronic devices such as laptops, tablets, mobile phones, and wearable devices. Electrochemical devices provide electrical energy for electronic devices, allowing them to function normally. The charging and discharging process of electrochemical devices is a conversion process between chemical energy and electrical energy, which is accompanied by chemical reactions. In daily life, there is a great risk of explosion and fire due to improper use or damage of electrochemical devices. Therefore, how to balance the safety performance and charging and discharging performance of electrochemical devices is an important topic in the field of electrochemical devices. Summary of the invention

[0003] The main technical problem solved by the embodiments of the present application is to provide an electrochemical device and an electronic device that can effectively take into account both the safety performance and the charging and discharging performance of the electrochemical device.

[0004] In order to solve the above technical problems, a technical solution adopted in the embodiment of the present application is: to provide an electrochemical device including a first pole piece, a second pole piece and a diaphragm. The diaphragm is arranged between the first pole piece and the second pole piece. Along the thickness direction of the first pole piece, diaphragms are arranged on both sides of the first pole piece. The edges of the two diaphragms exceed the first pole piece, and the local edges of the two diaphragms are connected to form a composite part and a receiving part, and the local edges of the two diaphragms are not connected to form a gap part. The first pole piece is arranged in the receiving part, and the first pole piece is provided with at least one first slot, at least one end of the first slot extends to the edge of the first pole piece to form an opening, and the opening of at least one first slot is arranged opposite to the gap part. The electrochemical device of the embodiment of the present application is provided with a first slot on the first pole piece, and the opening of the first slot is arranged opposite to the gap part of the diaphragm, which is conducive to the flow of electrolyte from the gap part to the first pole piece, improves the wettability of the electrolyte and the active material of the first pole piece, and improves the charge and discharge performance of the electrochemical device.

[0005] In some embodiments, the first slot extends along the width direction of the first pole piece, and the gap is at least partially arranged in the width direction of the first pole piece. The first slot extends along the width direction of the first pole piece, so that the path of the first slot is shorter, and at least part of the gap is arranged in the width direction of the first pole piece, so that the electrolyte can more easily enter the first slot from the gap and infiltrate the active material layer located in the central area of ​​the first pole piece, thereby improving the infiltration effect.

[0006] In some embodiments, along the width direction of the first pole piece, the gap is formed on both sides of the diaphragm, both ends of the first slot extend to the edge of the first pole piece to form an opening, and both openings are arranged opposite to the gap. The electrolyte can enter the central area of ​​the first pole piece from both ends of the first slot, further accelerating the infiltration of the active material on the first pole piece.

[0007] In some embodiments, along the length direction of the first pole piece, the gap portion and the composite portion are alternately distributed; along the length direction of the first pole piece, the length L1 of the composite portion satisfies: 0.3mm≤L1≤15mm, and / or, the length L2 of the gap portion satisfies: 0.5mm≤L2≤5mm, and the length direction of the first pole piece is perpendicular to the width direction of the first pole piece. Setting the length of the composite portion of the diaphragm within the above range can effectively suppress the shrinkage of the diaphragm and improve the safety of the electrochemical device. Setting the length of the gap portion of the diaphragm within the above range can allow the edge of the diaphragm to have sufficient gap for the electrolyte to enter the receiving portion and infiltrate the first pole piece. In some embodiments, 1mm≤L1≤10mm, and / or, 1mm≤L2≤3mm.

[0008] In some embodiments, the number N1 of the openings at one end of the first slots arranged opposite to the gap portion satisfies: N1≥10, where N1 is a positive integer. By providing at least 10 first slots so that their openings are arranged opposite to the gap portion, it is helpful for the electrolyte to better infiltrate the active material layer of the first electrode sheet.

[0009] In some embodiments, the number N2 of the openings at both ends of the first slots that are arranged opposite to the gap portion satisfies: N2 ≥ 5, where N2 is a positive integer. By providing at least 5 first slots so that the openings at both ends thereof are arranged opposite to the gap portion, the electrolyte can infiltrate the middle area of ​​the first pole piece from both sides in the width direction of the first pole piece at the same time, thereby improving the infiltration effect on the first pole piece.

[0010] In some embodiments, along the length direction of the first pole piece, the groove width K of the first slot satisfies: 50um≤K≤100um; and / or, along the thickness direction of the first pole piece, the groove depth H of the first slot satisfies: 10um≤H≤25um. By limiting the groove width and groove depth of the first slot within the above range, on the one hand, it is beneficial for the electrolyte to flow in the first slot to infiltrate the active material layer on the first pole piece, and on the other hand, it will not reduce the active material layer on the first pole piece too much, thereby making the electrochemical device have a higher energy density. In some embodiments, 60um≤K≤80um; and / or, 15um≤H≤20um.

[0011] In some embodiments, along the length direction of the first pole piece, the spacing L3 between two adjacent first slots satisfies: 0.8mm≤L3≤2mm. By setting the spacing between two adjacent first slots within the above range, it is helpful for the electrolyte entering the first slot to infiltrate the active material layer near the first slot, so that the electrolyte fully infiltrates the active material layer in the length direction of the first pole piece. In some embodiments, 1mm≤L3≤1.5mm.

[0012] In some embodiments, the first pole piece is an anode pole piece, and the second pole piece is a cathode pole piece. When the diaphragm shrinks due to heat, the anode pole piece is exposed earlier than the cathode pole piece. Therefore, the diaphragm is wrapped on both sides of the anode pole piece and a composite area and a gap area are formed, which can reduce the probability of the diaphragm shrinking and exposing the anode pole piece, and improve the infiltration effect of the electrolyte on the active material layer on the anode pole piece.

[0013] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: to provide an electronic device including an electrochemical device.

[0014] The beneficial effects of the embodiment of the present application are as follows: the electrochemical device of the embodiment of the present application includes a first pole piece, a second pole piece and a diaphragm. The diaphragm is arranged between the first pole piece and the second pole piece, and along the thickness direction of the first pole piece, the diaphragms are arranged on both sides of the first pole piece, and the local edges of the two diaphragms are connected to form a composite part, and the local parts of the two diaphragms are not connected to form a receiving part and a gap part, and the gap part is located at the edge of the diaphragm. The first pole piece is arranged in the receiving part, and the first pole piece is provided with at least one first slot, at least one end of the first slot extends to the edge of the first pole piece to form an opening, and the opening of at least one first slot is arranged opposite to the gap part. The electrochemical device of the embodiment of the present application is provided with a first slot on the first pole piece, and the opening of the first slot is arranged opposite to the gap part of the diaphragm, which is conducive to the electrolyte flowing from the gap part to the first pole piece, improving the wettability of the electrolyte and the active material of the first pole piece, and improving the charge and discharge performance of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the following is a brief introduction to the drawings required for describing the specific embodiments. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0016] Figure 1 Schematic diagram of an electrochemical device according to an embodiment of the present application.

[0017] Figure 2 It is a schematic diagram of the first electrode and the diaphragm of the electrochemical device according to the embodiment of the present application.

[0018] Figure 3 is along Figure 2 Sectional view of AA.

[0019] The reference numerals in the specific implementation manner are as follows:

[0020] 100, electrochemical device; 10, packaging bag; 20, battery cell assembly; 21, first pole piece; 211, first slot; 2111, opening; 22, diaphragm; 221, composite part; 222, receiving part; 223, gap part; X, width direction; Y, length direction; Z, thickness direction. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element, or there can be one or more centered elements therebetween. The terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0022] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0023] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] The electrochemical device includes a packaging bag, a positive electrode sheet, a negative electrode sheet and a diaphragm. The diaphragm is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are contained in the packaging bag after being stacked or wound, and are filled with an electrolyte. The charging and discharging process of the electrochemical device is the conversion between chemical energy and electrical energy, and the charging and discharging process of the electrochemical device is accompanied by chemical reactions. During the use or transportation of electronic equipment, it is inevitable that it will fall or collide, which may cause damage or shrinkage of the diaphragm, and then cause the positive electrode sheet and the negative electrode sheet to directly contact and short-circuit, causing the electrochemical device to expand or even explode and catch fire.

[0025] In order to solve the problem of easy shrinkage of the above-mentioned diaphragm, the prior art performs a thermal composite treatment on the edges of the diaphragm on both sides of the pole piece, that is, fixes the edges of the diaphragm on both sides of the pole piece. However, the applicant of the present application found that after the thermal composite treatment of the diaphragm edge, the composite area will inhibit the contact between the electrolyte and the pole piece, and the electrolyte and the active material layer on the pole piece will not be well infiltrated, resulting in poor charge and discharge performance of the electrochemical device.

[0026] Based on the above problems, the present application provides an embodiment of an electrochemical device 100, by opening a groove on the active material layer of the electrode, and making the opening 2111 of the groove relative to the uncompounded area on the diaphragm 22, so that the electrolyte can enter the groove from the uncompounded area on the diaphragm 22, thereby effectively improving the wettability of the electrolyte and the active material layer of the electrode, thereby improving the charge and discharge performance of the electrochemical device 100.

[0027] In some embodiments, see Figures 1 to 3 The electrochemical device 100 includes a packaging bag 10 and a battery cell assembly 20. The battery cell assembly 20 is disposed inside the packaging bag 10. The packaging bag 10 is filled with an electrolyte, and the electrolyte is used to provide a place for electrochemical reaction for the battery cell assembly 20. The packaging bag 10 and the electrolyte are not limited in this application, and any packaging bag 10 and electrolyte in the prior art are applicable to this application.

[0028] The battery cell assembly 20 includes a first pole piece 21, a second pole piece and a diaphragm 22. The diaphragm 22 is disposed between the first pole piece 21 and the second pole piece, and is used to separate the first pole piece 21 and the second pole piece to prevent the two from directly contacting and short-circuiting. Along the thickness direction Z of the first pole piece 21, diaphragms 22 are disposed on both sides of the first pole piece 21, the edges of the two diaphragms 22 exceed the first pole piece 21, and the local edges of the two diaphragms 22 are connected to form a composite portion 221 and a receiving portion 222, and the two diaphragms 22 are partially unconnected to form a gap portion 223. Along the thickness direction Z of the first pole piece 21, there is a gap between the two diaphragms 22 at the gap portion 223, and the electrolyte can better enter the receiving portion 222 from the gap. The first pole piece 21 is disposed in the receiving portion 222 . The first pole piece 21 has at least one first slot 211 . At least one end of the first slot 211 extends to the edge of the first pole piece 21 to form an opening 2111 . The opening 2111 of at least one first slot 211 is disposed opposite to the gap portion 223 .

[0029] It is understandable that after the electrochemical device 100 is formed, the diaphragms 22 on both sides of the first pole piece 21 will definitely contact each other, and contacting each other is not necessarily a connection as defined in the present application. Only when the diaphragms 22 are bonded intentionally by thermal bonding, bonding, etc., can it be considered a connection. For example, the composite portion 221 is formed by thermal bonding of the diaphragms 22 on both sides, and the gap portion 223 is not subjected to such special treatment.

[0030] The electrochemical device 100 of the embodiment of the present application is provided with a first slot 211 on the first pole piece 21, and the opening 2111 of the first slot 211 is arranged opposite to the gap 223 of the diaphragm 22, which is conducive to the electrolyte flowing from the gap 223 to the first pole piece 21, improving the wettability of the electrolyte and the active material of the first pole piece 21, and improving the charge and discharge performance of the electrochemical device 100. The thermal composite part 221 is provided on the edge of the diaphragm 22, which is conducive to reducing the probability of the first pole piece 21 and the second pole piece being in direct contact and short-circuiting due to the contraction of the diaphragm 22, so that the safety performance and the charge and discharge performance of the electrochemical device 100 can be taken into account.

[0031] In the present application, the relative arrangement of the opening 2111 and the gap portion 223 means that when the first slot 211 extends along the width direction X of the first pole piece 21, the projections of the opening 2111 and the gap portion 223 along the length direction Y of the first pole piece 21 at least partially overlap; when the first slot 211 extends along the length direction Y of the first pole piece 21, the projections of the opening 2111 and the gap portion 223 along the width direction X of the first pole piece 21 at least partially overlap.

[0032] In some embodiments, the battery cell assembly 20 of the present application may be a stacked battery cell assembly 20, for example, a plurality of first pole sheets 21 and a plurality of second pole sheets are alternately stacked in the thickness direction Z of the first pole sheet 21, and a plurality of diaphragms 22 are arranged between the first pole sheet 21 and the second pole sheet; or the battery cell assembly 20 may be a wound battery cell assembly 20, for example, after the first pole sheet 21 and the second pole sheet are stacked in the thickness direction Z of the first pole sheet 21, the first pole sheet 21 is wound along the length direction Y of the first pole sheet 21 with the width direction X of the first pole sheet 21 as the winding axis. It is sufficient that the opening 2111 of the first slot 211 on the first pole sheet 21 in the battery cell assembly 20 is arranged opposite to the gap portion 223 of the diaphragm 22.

[0033] In some embodiments, the first slot 211 is arranged on the active material layer of the first electrode sheet 21. This embodiment does not limit the extension direction and shape of the first slot 211. For example, the first slot 211 can extend along the length direction Y of the first electrode sheet 21, or extend along the width direction X of the first electrode sheet 21, or extend along a direction having an angle with the width direction X of the first electrode sheet 21; the shape of the first slot 211 can be a straight line, a curve, a wavy line, a broken line, or a combination of the former, as long as the opening 2111 formed by the first slot 211 at the edge of the first electrode sheet 21 is arranged relative to the gap portion 223 of the diaphragm 22.

[0034] As an example, the first slot 211 extends along the width direction X of the first pole piece 21, and the gap portion 223 is at least partially disposed in the width direction X of the first pole piece 21. Compared with extending in other directions, the first slot 211 extends along the width direction X of the first pole piece 21, so that the path of the first slot 211 is shorter, and at least a portion of the gap portion 223 is disposed in the width direction X of the first pole piece 21, so that the electrolyte can more easily enter the first slot 211 from the gap portion 223, and infiltrate the active material layer located in the central area of ​​the first pole piece 21, thereby improving the infiltration effect.

[0035] In some embodiments, along the width direction X of the first pole piece 21, gaps 223 are formed on both sides of the diaphragm 22, wherein the gaps 223 include at least one first gap 223a and at least one second gap 223b. The openings 2111 formed by both ends of the first slot 211 extending to the edge of the first pole piece 21 include a first opening 2111a and a second opening 2111b, wherein the first opening 2111a is arranged opposite to the first gap 223a on the corresponding side, and the second opening 2111b is arranged opposite to the second gap 223b on the corresponding side. The electrolyte can enter the central area of ​​the first pole piece 21 from both ends of the first slot 211, further accelerating the infiltration of the active material on the first pole piece 21. In other examples, at least one gap portion 223 is formed on at least one side of the diaphragm 22 along the length direction Y of the first pole piece 21. The gap portion 223 opened on the side of the diaphragm 22 along the length direction Y of the first pole piece 21 is conducive to the flow of electrolyte in the receiving portion 222, thereby further improving the wetting effect of the electrolyte on the active material of the first pole piece 21.

[0036] In some embodiments, along the length direction Y of the first pole piece 21, the gap portion 223 and the composite portion 221 are alternately distributed. Along the length direction Y of the first pole piece 21, the length L1 of the composite portion 221 satisfies: 0.3mm≤L1≤15mm, and / or, the length L2 of the gap portion 223 satisfies: 0.5mm≤L2≤5mm, and the length direction Y of the first pole piece 21 is perpendicular to the width direction X of the first pole piece 21. Setting the length of the composite portion 221 of the diaphragm 22 within the above range can effectively suppress the shrinkage of the diaphragm 22 and improve the safety of the electrochemical device 100. Setting the length of the gap portion 223 of the diaphragm 22 within the above range can ensure that there is sufficient gap at the edge of the diaphragm 22 for the electrolyte to enter the receiving portion 222 and infiltrate the first pole piece 21.

[0037] In a further embodiment, along the length direction Y of the first pole piece 21, the length L1 of the composite part 221 satisfies: 1mm≤L1≤10mm, and / or the length L2 of the gap part 223 satisfies: 1mm≤L2≤3mm. By further limiting the length of the composite part 221 and the length of the gap part 223, the number of composite parts 221 and the number of gap parts 223 of the diaphragm 22 can be increased under the condition of the same length, and the alternating distribution of the two can be more uniform, and the diaphragm 22 can have more gaps for the electrolyte to enter the receiving part 222 under the premise of effectively protecting and covering the first pole piece 21.

[0038] In some embodiments, the number N1 of the openings 2111 at one end of the first slot 211 and the gap portion 223 that are arranged relative to each other satisfies: N1 ≥ 10, and N1 is a positive integer. As described above, the shapes of the first slots 211 are various, and the positions of the openings 2111 formed by multiple first slots 211 on the edge of the first pole piece 21 are the same or different. The present application further defines that among the multiple first slots 211, the number of the openings 2111 at one end thereof and the gap portion 223 of the diaphragm 22 that are arranged relative to each other is N1, where N1 is at least 10. By setting at least 10 first slots 211 so that their openings 2111 and the gap portion 223 are arranged relative to each other, it is helpful for the electrolyte to better infiltrate the active material layer of the first pole piece 21.

[0039] In a further embodiment, the number N2 of the openings 2111 at both ends of the first slot 211 that are arranged opposite to the gap portion 223 satisfies: N2 ≥ 5, and N2 is a positive integer. The present application further defines that among the multiple first slots 211, the number of the openings 2111 at both ends that are arranged opposite to the gap portion 223 of the diaphragm 22 is N2, where N2 is at least 5. By setting at least 5 first slots 211 so that the openings 2111 at both ends are arranged opposite to the gap portion 223, the electrolyte can infiltrate the middle area of ​​the first pole piece 21 from both sides in the width direction X of the first pole piece 21 at the same time, thereby improving the infiltration effect on the first pole piece 21.

[0040] In some embodiments, along the length direction Y of the first pole piece 21, the groove width K of the first slot 211 satisfies: 50um≤K≤100um; and / or, along the thickness direction Z of the first pole piece 21, the groove depth H of the first slot 211 satisfies: 10um≤H≤25um. By limiting the groove width and groove depth of the first slot 211 within the above range, on the one hand, it is beneficial for the electrolyte to flow in the first slot 211 to infiltrate the active material layer on the first pole piece 21, and on the other hand, it will not reduce the active material layer on the first pole piece 21 too much, thereby making the electrochemical device 100 have a higher energy density. In a further embodiment, 60um≤K≤80um; and / or, 15um≤H≤20um.

[0041] In some embodiments, along the length direction Y of the first pole piece 21, the spacing L3 between two adjacent first slots 211 satisfies: 0.8mm≤L3≤2mm. By setting the spacing between two adjacent first slots 211 within the above range, it is helpful for the electrolyte entering the first slot 211 to infiltrate the active material layer near the first slot 211, so that the electrolyte fully infiltrates the active material layer in the length direction Y of the first pole piece 21. In some embodiments, along the length direction Y of the first pole piece 21, the spacing L3 between two adjacent first slots 211 satisfies: 1mm≤L3≤1.5mm.

[0042] In some embodiments, the first electrode 21 is an anode electrode, and the second electrode is a cathode electrode. During the charge and discharge process of the electrochemical device 100, in order to reduce the probability of lithium deposition in the battery cell assembly 20, the anode electrode is larger than the cathode electrode in both the length direction Y and the width direction X. When the diaphragm 22 shrinks due to heat, the anode electrode is exposed earlier than the cathode electrode. Therefore, the diaphragm 22 is coated on both sides of the anode electrode and a composite area and a gap area are formed, which can reduce the probability of the diaphragm 22 shrinking and exposing the anode electrode, and enhance the infiltration effect of the electrolyte on the active material layer on the anode electrode, so that the anode electrode and the cathode electrode can undergo an electrochemical reaction.

[0043] The present application also provides an electronic device, which includes an electrochemical device 100, and the electrochemical device 100 provides electrical energy for the electronic device. The structure and function of the electrochemical device 100 can be found in any of the above embodiments, and will not be described in detail here.

[0044] The electrochemical device 100 of the embodiment of the present application includes a first pole piece 21, a second pole piece and a diaphragm 22. The diaphragm 22 is disposed between the first pole piece 21 and the second pole piece. Along the thickness direction Z of the first pole piece 21, the diaphragms 22 are disposed on both sides of the first pole piece 21, and the local edges of the two diaphragms 22 are connected to form a composite portion 221, and the two diaphragms 22 are partially unconnected to form a receiving portion 222 and a gap portion 223, and the gap portion 223 is located at the edge of the diaphragm 22. The first pole piece 21 is disposed in the receiving portion 222, and the first pole piece 21 is provided with at least one first slot 211, and at least one end of the first slot 211 extends to the edge of the first pole piece 21 to form an opening 2111, and the opening 2111 of at least one first slot 211 is disposed opposite to the gap portion 223. The electrochemical device 100 in the embodiment of the present application is provided with a first slot 211 on the first electrode sheet 21, and the opening 2111 of the first slot 211 is arranged relative to the gap portion 223 of the diaphragm 22, which is beneficial for the electrolyte to flow from the gap portion 223 to the first electrode sheet 21, thereby improving the wettability of the electrolyte and the active material of the first electrode sheet 21, and improving the charge and discharge performance of the electrochemical device 100.

[0045] To facilitate understanding of the technical concept and beneficial effects of the present application, the following experimental description is given using a lithium-ion battery as an example.

[0046] Embodiment 1:

[0047] [Preparation of cathode pole piece]: Aluminum foil is used as the cathode current collector, and a layer of functional coating slurry with a thickness of 1µm is evenly coated on the surface of the aluminum foil. The composition of the functional coating slurry is 89.5wt% high resistance material, 5wt% conductive carbon black, 5wt% lithium / sodium metal and lithium / sodium metal salt compounds and 0.5wt% lithium carbonate to prepare the cathode primer. The composition of lithium cobalt oxide slurry is 97.3wt% LiCoO2 (LCO), 1.6wt% polyvinylidene fluoride (PVDF) and 1.1wt% conductive carbon black, and then cold pressed to prepare the cathode pole piece.

[0048] [Production of anode pole piece]: 80% polyolefin and 20% carbon nanotubes are mixed to form a composite layer glue, and two copper foils with a thickness of 2µm are used to form a negative electrode current collector with a copper foil-composite layer-copper foil composite structure through a glue coating composite process, wherein the overall thickness H of the negative electrode current collector is 4.5µm. A layer of graphite slurry with a thickness of 1µm is evenly coated on the surface of the negative electrode current collector, and the composition of the graphite slurry is a combination of 97.7wt% artificial graphite, 1.3wt% carboxymethyl cellulose (CMC) and 1.0wt% styrene-butadiene rubber (SBR), and then cold pressed, and 20 first slots extending along the width direction of the anode pole piece are prepared on the anode pole piece to prepare the anode pole piece.

[0049] [Production of battery cell assembly]: Place diaphragms on both sides of the anode pole piece, and use a hot pressing packaging process to heat-seal both sides of the diaphragm in the width direction to form a composite part, and form at least one gap part with a length of 2 mm on the edges of both sides, so that the number N1 of the single-side opening of the first slot of the anode pole piece and the gap part relative to each other is controlled to be 1, and the number N2 of the two-side openings of the first slot and the gap part relative to each other is controlled to be 1. Alternately stack 10 anode pole pieces wrapped by diaphragms and 9 cathode pole pieces to form a battery cell assembly.

[0050] [Production of lithium-ion batteries]: Place the battery cell components in an outer packaging aluminum-plastic film, remove moisture at 80°C, inject electrolyte and package, and obtain a lithium-ion battery through a process of formation, degassing, and shaping.

[0051] Example 2-8: Except for the number N1 of the single-side opening and the gap portion of the first slot of the anode electrode and the number N2 of the two-side opening and the gap portion of the first slot, other parameters are the same as those in Example 1. Please refer to Table 1 below for details.

[0052] Comparative Example 1: The difference of the lithium-ion battery is that the diaphragms on both sides of the anode electrode are not provided with gaps, and other parameters are the same as those in Example 1. For details, please refer to Table 1 below.

[0053] Comparative Example 2: Except that the number N1 of the single-side opening and the gap portion of the first slot of the anode electrode is 0, and the number N2 of the two-side openings and the gap portion of the first slot is 0, other parameters are the same as those in Example 1. Please refer to Table 1 below for details.

[0054] [Capacity retention test item]: At 45°C, charge the lithium-ion battery to 4.45V at 0.5C constant current, charge at 4.45V constant voltage to a current of 0.025C, let it stand for 5 minutes, then discharge it to 3.0V at a constant current of 0.5C rate, and record the first cycle discharge value. Then, cycle the lithium-ion battery 300 times under the above conditions. With the first discharge capacity as 100%, repeat the charge and discharge cycle until the number of cycles reaches 300, and record and calculate the final discharge capacity retention rate.

[0055] Table 1

[0056]

[0057] According to the data in the above table, it can be seen that: providing a gap portion on the diaphragm and making the single-sided opening of at least one first slot position arranged opposite to the gap portion is beneficial to improving the wetting effect of the electrolyte on the anode electrode sheet, thereby improving the capacity retention rate of the lithium-ion battery; and the increase in the number of single-sided openings N1 of the first slot position and / or the number of double-sided openings N2 of the first slot position has a significant wetting effect of the electrolyte on the anode electrode sheet, which significantly and effectively improves the capacity retention rate of the lithium-ion battery.

[0058] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An electrochemical device, characterized in that: include: A first pole piece, a second pole piece and a diaphragm, wherein the diaphragm is arranged between the first pole piece and the second pole piece, and along the thickness direction of the first pole piece, the diaphragms are arranged on both sides of the first pole piece, the edges of the two diaphragms exceed the first pole piece, and the local edges are connected to form a composite part and a receiving part, and the local edges of the two diaphragms are not connected to form a gap part; along the length direction of the first pole piece and / or along the width direction of the first pole piece, the gap part and the composite part are alternately distributed; The first pole piece is arranged in the receiving portion, and the first pole piece is provided with at least one first slot, at least one end of the first slot extends to the edge of the first pole piece to form an opening, and at least one opening of the first slot is arranged opposite to the gap portion.

2. The electrochemical device according to claim 1, characterized in that The first slot extends along the width direction of the first pole piece, and the gap portion is at least partially arranged in the width direction of the first pole piece.

3. The electrochemical device according to claim 2, characterized in that The gap portions are formed on both sides of the diaphragm along the width direction of the first pole piece, and both ends of the first slot extend to the edge of the first pole piece to form openings, and the two openings are arranged opposite to the gap portions.

4. The electrochemical device according to claim 1, characterized in that Along the length direction of the first pole piece, the length L1 of the composite portion satisfies: 0.3mm≤L1≤15mm, and / or the length L2 of the gap portion satisfies: 0.5mm≤L2≤5mm, and the length direction of the first pole piece is perpendicular to the width direction of the first pole piece.

5. The electrochemical device according to claim 4, characterized in that 1mm≤L1≤10mm, and / or, 1mm≤L2≤3mm.

6. The electrochemical device according to claim 1, characterized in that The number N1 of the opening at one end of the first slot and the gap portion arranged opposite to each other satisfies: N1≥10, and N1 is a positive integer.

7. The electrochemical device according to claim 1, characterized in that The number N2 of the openings at both ends of the first slot that are arranged opposite to the gap portion satisfies: N2≥5, and N2 is a positive integer.

8. The electrochemical device according to claim 1, characterized in that Along the length direction of the first pole piece, the slot width K of the first slot satisfies: 50um≤K≤100um; and / or, Along the thickness direction of the first pole piece, the groove depth H of the first groove satisfies: 10um≤H≤25um.

9. The electrochemical device according to claim 8, characterized in that 60um≤K≤80um; and / or, 15um≤H≤20um.

10. The electrochemical device according to claim 1, characterized in that Along the length direction of the first pole piece, a distance L3 between two adjacent first slots satisfies: 0.8 mm≤L3≤2 mm.

11. The electrochemical device according to claim 10, characterized in that 1mm≤L3≤1.5mm.

12. The electrochemical device according to any one of claims 1 to 11, characterized in that: The first pole piece is an anode pole piece, and the second pole piece is a cathode pole piece.

13. An electronic device, characterized in that: Comprising the electrochemical device according to any one of claims 1 to 12.

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