A lamination unit, a bidirectional electrode unit, a core pack, and a battery

Abstract

The application discloses a laminated unit, a bidirectional electrode unit, a core package and a battery. The laminated unit comprises a liquid retaining layer and a single-sided electrode sheet. The single-sided electrode sheet comprises a current collector and a material layer arranged on one side of the current collector. The current collector has a first side and a second side arranged oppositely, and has an ion channel communicating the first side and the second side. The material layer is attached to the first side of the current collector. The liquid retaining layer is attached to the second side of the current collector, and is used for absorbing electrolyte of the battery. Compared with the prior art, the liquid retaining layer capable of absorbing liquid is arranged on the second side of the current collector, so that the electrolyte not only penetrates from the outside of the material layer to the inside, but also penetrates from the current collector to the inside of the material layer, thereby forming a bidirectional liquid supply path in the thickness direction, significantly reducing the electrolyte concentration difference between the outside of the material layer and the inside close to the current collector, relieving the problem of insufficient ion supply on the inside, and effectively reducing the ion migration resistance and concentration polarization.

Description

Technical Field

[0001] This application relates to the field of new energy battery technology, and in particular to a stacked cell unit, a bidirectional electrode unit, a core pack, and a battery. Background Technology

[0002] With the widespread application of secondary batteries such as lithium-ion and sodium-ion batteries in new energy vehicles, energy storage systems, and portable electronic devices, the optimization of electrode structure has become a key direction for improving battery rate performance, energy density, and cycle life. In a typical stacked electrode, active material layers are usually coated or bonded to both sides of the current collector, and ion conduction and electron conduction are achieved through a separator and the counter electrode.

[0003] However, in the conventional structure described above, the electrolyte mainly penetrates from the outer surface of the active material layer and gradually diffuses inward. Since the current collector forms a relatively dense boundary on one side of the active material layer, it is difficult for the electrolyte to penetrate from the outside of the active material to the side closer to the current collector. This results in a lower electrolyte content and insufficient ionic conductivity in the active material region near the current collector. The resulting concentration difference between the inside and outside affects the uniformity of the electrode reaction. Utility Model Content

[0004] In view of the shortcomings of the prior art, this application provides a stacked unit, a bidirectional electrode unit, a core pack and a battery, which can improve the uniformity of electrolyte distribution and alleviate the concentration difference between the inner and outer sides.

[0005] To achieve the above objectives, this application adopts the following technical solution: A stacked cell includes a single-sided electrode and a liquid-retaining layer. The single-sided electrode includes a current collector and a material layer. The current collector has a first side and a second side disposed opposite to each other. The current collector has an ion channel connecting the first side and the second side. The material layer is attached to the first side of the current collector. The liquid-retaining layer is attached to the second side of the current collector and is used to absorb the electrolyte of the battery.

[0006] In one embodiment, the liquid-retaining layer is a porous material.

[0007] In one embodiment, the porous material is a porous carbon layer, aluminum foam, or copper foam.

[0008] In one embodiment, the pore size of the porous material is 10μm-200μm.

[0009] In one embodiment, the porosity of the porous material is 10% to 90%.

[0010] In one embodiment, the thickness of the liquid-retaining layer is 1μm to 10μm.

[0011] In one embodiment, the liquid-retaining layer has a plurality of perforations penetrating its two opposite surfaces, and the perforations are in communication with the current collector.

[0012] In one embodiment, the thickness of the current collector is 4μm to 50μm, the pore size of the current collector is 10μm to 200μm, and the porosity of the current collector is 10% to 80%.

[0013] This application also adopts the following technical solution: providing a bidirectional electrode unit, including the stacked unit of any of the above embodiments, wherein the stacked unit includes a plurality of single-sided electrodes symmetrically disposed on opposite sides of the liquid-retaining layer.

[0014] This application also adopts the following technical solution: providing a core package, including a positive electrode unit, a negative electrode unit and a separator, wherein a plurality of the positive electrode units and a plurality of the negative electrode units are stacked alternately in sequence, and the separator is provided between adjacent positive electrode units and negative electrode units; wherein the positive electrode unit is a bidirectional electrode unit of the above embodiment, and / or the negative electrode unit is a bidirectional electrode unit of the above embodiment.

[0015] This application also adopts the following technical solution: providing a battery, including a core pack and a housing as described in the above embodiments, wherein the core pack is disposed inside the housing, and the housing is provided with electrolyte.

[0016] The beneficial effects of this application are as follows: This application provides a stacked unit, a bidirectional electrode unit, a core pack, and a battery. The stacked unit includes a liquid-retaining layer and a single-sided electrode. The single-sided electrode includes a current collector and a material layer disposed on one side of the current collector. The current collector has a first side and a second side disposed opposite to each other and has an ion channel connecting the first side and the second side. The material layer is attached to the first side of the current collector. The liquid-retaining layer is attached to the second side of the current collector and is used to absorb the electrolyte of the battery. Compared with the prior art, this application, by providing a liquid-absorbing liquid-retaining layer on the second side of the current collector, allows the electrolyte to not only permeate from the outside of the material layer to the inside, but also from the current collector to the inside of the material layer, thereby forming a bidirectional liquid supply path in the thickness direction. This significantly reduces the electrolyte concentration difference between the outside of the material layer and the side near the inside of the current collector, alleviates the problem of insufficient ion supply on the inside, and effectively reduces ion migration resistance and concentration polarization. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of a core package according to this application is shown; Figure 2 Another structural schematic diagram of a core package according to this application is shown; Figure 3 A schematic diagram of the structure of a bidirectional electrode unit of this application is shown; Figure 4 A schematic diagram of the structure of a single-sided electrode sheet according to this application is shown; Reference numerals: 100, stacked unit; 1, single-sided electrode; 11, current collector; 12, material layer; 20, liquid retention layer; 200, bidirectional electrode unit; 300, core package; 30, diaphragm; 40, negative electrode unit; 50, positive electrode unit. Detailed Implementation

[0018] In this application, the terms "set up," "equipped with," and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0019] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] See Figure 1 This application provides a battery including a core pack 300 and a casing (not shown in the figure). An electrolyte is contained within the casing, and the core pack 300 is disposed within the casing and immersed in the electrolyte. The core pack 300 includes a positive electrode unit 50 and a negative electrode unit 40, and a separator 30 disposed between them. Multiple positive electrode units 50 and multiple negative electrode units 40 are alternately stacked to form a multilayer structure. A separator 30 is provided between adjacent positive electrode units 50 and negative electrode units 40 to achieve insulation isolation. The separator 30 not only prevents short circuits between the positive and negative electrodes but also has good ion conductivity, ensuring smooth migration of lithium ions during charging and discharging.

[0022] In this embodiment, the structure of the positive electrode unit 50 is used as an example for explanation. Specifically, the positive electrode unit 50 adopts a bidirectional electrode unit 200, and the structure of the negative electrode unit 40 can be set with reference to the positive electrode unit 50.

[0023] See Figure 3 The bidirectional electrode unit 200 includes a stacked unit 100, which includes a liquid-retaining layer 20 and a single-sided electrode 1. The single-sided electrode 1 includes a current collector 11 and a material layer 12 disposed on one side of the current collector 11. The current collector 11 has a first side and a second side disposed opposite to each other. The material layer 12 is attached to the first side of the current collector 11. The liquid-retaining layer 20 is attached to the second side of the current collector 11 and is used to absorb the electrolyte of the battery.

[0024] In practical applications, such as Figure 4 As shown, the single-sided electrode 1 is composed of a current collector 11 and a material layer 12. The current collector 11 has a first side and a second side arranged opposite to each other, and has an ion channel connecting the first side and the second side. The material layer 12 is attached to the first side of the current collector 11, and the liquid-retaining layer 20 is attached to the second side of the current collector 11. The liquid-retaining layer 20 can effectively adsorb and store electrolyte. During assembly, the core package 300 is placed in the housing, and electrolyte is injected into the housing. After the electrolyte is injected, the liquid-retaining layer 20 first adsorbs and stores a certain amount of electrolyte, and then continuously supplies electrolyte to the inside of the material layer 12 through the ion channel of the current collector 11, so that the side of the material layer 12 closest to the current collector 11 in the thickness direction receives additional electrolyte replenishment.

[0025] Compared to existing technologies, this application provides a liquid-absorbing liquid-retaining layer 20 on the second side of the current collector 11, allowing the electrolyte to not only permeate from the outside of the material layer 12 to the inside, but also from the current collector 11 to the inside of the material layer 12. This forms a bidirectional liquid supply path in the thickness direction, significantly reducing the electrolyte concentration difference between the outside of the material layer 12 and the inside near the current collector 11, alleviating the problem of insufficient ion supply on the inside, and effectively reducing ion migration resistance and concentration polarization.

[0026] It should be noted that the side of material layer 12 facing away from current collector 11 is the outer side, and the side facing current collector 11 is the inner side. Material layer 12 can be either a positive electrode active material layer 12 or a negative electrode active material layer 12, selected according to the matched electrochemical system. The positive electrode unit 50 uses a positive electrode active material, and the negative electrode unit 40 uses a negative electrode active material. Current collector 11 can be a metal foil with a through-pore or microporous structure, or it can be a conventional dense foil with its edges or parts roughened / opened to provide ion channels without affecting electron conduction.

[0027] Furthermore, the stacked unit 100 in the bidirectional electrode unit 200 includes multiple single-sided electrodes 1 symmetrically arranged on opposite sides of the liquid-retaining layer 20. For example, when the number of single-sided electrodes 1 is two, two single-sided electrodes 1 are symmetrically arranged on opposite sides of the liquid-retaining layer 20 along its thickness direction, thereby forming the bidirectional electrode unit 200. The liquid-retaining layer 20 is sandwiched between the two single-sided electrodes 1, so that the two sides of the liquid-retaining layer 20 are respectively attached to the second side of the current collector 11 of the two single-sided electrodes 1. In this structure, the liquid-retaining layer 20 can simultaneously provide electrolyte replenishment to the material layers 12 on both sides, further improving the uniformity and efficiency of the electrolyte supply and enhancing the overall ion transport capability of the electrode. This bidirectional symmetrical design effectively expands the electrolyte distribution path.

[0028] Understandably, the number of single-sided electrodes 1 can be adjusted according to actual needs, and can be four, six or more.

[0029] It should be noted that the positive electrode unit 50 and the negative electrode unit 40 can adopt the same structure, for example, both can adopt the bidirectional electrode unit 200 of this application, such as... Figure 1 As shown; different structures can also be used, for example, one of the positive electrode unit 50 and the negative electrode unit 40 can use the bidirectional electrode unit 200 of this application, while the other can use a conventional electrode unit (e.g., material layers 12 are attached to both sides of the current collector 11), such as Figure 2 As shown.

[0030] In other embodiments, the bidirectional electrode unit 200 can also adopt different structures. For example, one side of the liquid-retaining layer 20 is attached to the second side of the current collector 11 of the single-sided electrode 1, and the other side is directly attached to the material layer 12, forming an asymmetrical structure. In this case, the liquid-retaining layer 20 can provide reverse replenishment to the material layer 12 on the current collector 11 side, and can also supply liquid to the active material layer 12 of the adjacent electrode through direct contact, thereby improving space utilization efficiency. This application does not limit this, and the combination of the liquid-retaining layer 20 and the electrode can be flexibly configured according to the cell design requirements.

[0031] In one embodiment, the electrolyte retention layer 20 is a porous material. The pore structure of the porous material can effectively improve the capillary adsorption capacity of the electrolyte. Preferably, it has a pore structure with a combination of through pores and closed pores to balance rapid electrolyte absorption and long-term retention.

[0032] Among them, the porous material can be selected as a porous carbon layer, aluminum foam, or copper foam, etc., which are conductive porous materials that can both play a liquid retention function and not significantly increase the internal resistance of the electrode.

[0033] In one embodiment, the pore size of the porous material is 10 μm to 200 μm. Within this range, a reasonable distribution of pore size helps to form a continuous capillary network, promoting rapid penetration and uniform distribution of the electrolyte in the thickness direction. A larger upper limit pore size (close to 200 μm) helps to reduce the viscous resistance of the liquid in the channels and increase the replenishment rate; a smaller lower limit pore size (close to 10 μm) ensures a certain capillary pressure and anti-gas resistance capability to promote spontaneous wetting of the electrolyte and inhibit gas gap retention. For example, the pore size can be 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, etc.

[0034] Furthermore, the porosity of porous materials can be set between 10% and 90% to balance electrolyte storage capacity and mechanical support strength. When the porosity is below 10%, the material's electrolyte storage capacity is limited, affecting the durability of electrolyte replenishment; above 90%, it may lead to a decrease in structural strength, making it difficult to maintain dimensional stability in the electrode stack. For example, the porosity of porous materials can be 50%, 40%, 30%, 20%, 10%, etc.

[0035] It should be noted that the porosity of porous materials can usually be measured using mercury intrusion porosimetry or gas adsorption methods, and the obtained value is usually a volume fraction.

[0036] The thickness of the electrolyte retention layer 20 can range from 1 μm to 10 μm. Within this thickness range, the electrolyte retention layer 20 ensures sufficient electrolyte storage space while effectively reducing the ion transport path length and interfacial impedance. An excessively thin electrolyte retention layer 20 may result in insufficient electrolyte storage, affecting the continuous replenishment capability during cycling; an excessively thick layer may increase the overall electrode thickness, which is detrimental to energy density improvement. For example, the thickness of the electrolyte retention layer 20 can be 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, etc.

[0037] It should be noted that in this embodiment, the pore size of porous materials usually refers to the size of a single pore or channel, and the porosity usually refers to the proportion of pore volume to the total volume in the material.

[0038] In one embodiment, the electrolyte retention layer 20 may also employ other structures instead of porous materials. For example, the electrolyte retention layer 20 may have multiple perforations penetrating its two opposing surfaces, and these perforations are connected to the current collector 11. The perforations allow the electrolyte to flow directionally during charging and discharging through capillary action or an electric field, and also enable the electrolyte to flow from the second side to the first side of the current collector 11, thus alleviating the problem of insufficient ion supply inside the material layer 12.

[0039] It should be noted that the perforation can be cylindrical, conical, or polygonal, and the pore diameter can vary uniformly or gradually along the thickness direction of the liquid-retaining layer 20 to adjust the local wettability and fluid flux distribution.

[0040] In one embodiment, the thickness of the current collector 11 is 4μm to 50μm, the pore size of the current collector 11 is 10μm to 200μm, and the porosity of the current collector 11 is 10% to 80%. For example, the thickness of the current collector 11 can be 50μm, 40μm, 30μm, 20μm, 10μm, etc., the pore size of the current collector 11 can be 200μm, 150μm, 100μm, 50μm, etc., and the porosity of the current collector 11 can be 50%, 40%, 30%, 20%, 10%, etc.

[0041] Within this parameter range, the current collector 11 can provide a good electronic conductivity network and, together with the electrolyte retention layer 20, form an electrolyte transport channel. A proper match between pore size and porosity helps reduce concentration polarization during charging and discharging, improving the uniformity of current distribution. Simultaneously, optimizing the thickness of the current collector 11 balances mechanical strength and battery energy density requirements, avoiding a decrease in volume utilization due to excessive thickness.

[0042] For example, when the current collector 11 has a thickness of 20 μm, a pore size of 100 μm, and a porosity of 40%, effective electrolyte penetration and efficient electron conduction can be achieved while ensuring structural stability. This combination of parameters helps to improve the wettability of the electrode interface, reduce mass transfer resistance during the initial charge and discharge process, and thus improve the rate performance and cycle life of the battery.

[0043] It should be noted that the pore size of the current collector 11 is usually the characteristic size of the pores on the surface or inside the body, usually referring to the equivalent diameter of the opening or throat; the porosity of the current collector 11 is usually the proportion of the pore volume to the total volume.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0046] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A stacked cell unit for a battery, characterized in that, include: A single-sided electrode includes a current collector and a material layer. The current collector has a first side and a second side disposed opposite to each other. The current collector has an ion channel communicating between the first side and the second side. The material layer is attached to the first side of the current collector. A liquid-retaining layer is attached to the second side of the current collector, and the liquid-retaining layer is used to absorb the electrolyte of the battery.

2. The stacking unit according to claim 1, characterized in that, The liquid-retaining layer is a porous material.

3. The stacking unit according to claim 2, characterized in that, The porous material is a porous carbon layer, aluminum foam, or copper foam.

4. The stacking unit according to claim 2, characterized in that, The porous material has a pore size of 10μm-200μm.

5. The stacking unit according to claim 2, characterized in that, The porosity of the porous material is 10% to 90%.

6. The stacked unit according to any one of claims 1 to 5, characterized in that, The thickness of the liquid-retaining layer is 1μm to 10μm.

7. The stacked unit according to any one of claims 1 to 5, characterized in that, The liquid-retaining layer has multiple perforations penetrating its two opposite surfaces, and the perforations are in communication with the current collector.

8. The stacked unit according to any one of claims 1 to 5, characterized in that, The thickness of the current collector is 4μm to 50μm, the pore size of the current collector is 10μm to 200μm, and the porosity of the current collector is 10% to 80%.

9. A bidirectional electrode unit, characterized in that, The stacked unit includes the stacked unit according to any one of claims 1 to 7, wherein the stacked unit includes a plurality of single-sided electrodes symmetrically disposed on opposite sides of the liquid-retaining layer.

10. A core package, characterized in that, It includes a positive electrode unit, a negative electrode unit, and a separator. Multiple positive electrode units and multiple negative electrode units are stacked alternately in sequence, and the separator is provided between adjacent positive electrode units and negative electrode units. Wherein, the positive electrode unit is the bidirectional electrode unit as described in claim 9, and / or, the negative electrode unit is the bidirectional electrode unit as described in claim 9.

11. A battery, characterized in that, The invention includes the core package and the housing as described in claim 10, wherein the core package is disposed within the housing, and the housing contains an electrolyte.

Images