Battery composite current collector pole piece

Abstract

This invention belongs to the field of battery technology and discloses a composite current collector electrode, comprising a substrate layer, a thermally conductive layer, and an active coating layer stacked together. The thermally conductive layer has microfluidic channels on its surface in contact with the substrate layer, and also contains longitudinal and transverse thermally conductive structures. The active coating has phase change material capsules filled in the pores of its surface in contact with the thermally conductive layer. This invention achieves a dual-mode heat dissipation of "energy storage buffer + active heat dissipation" by embedding phase change material capsules inside the electrode. These capsules, along with the microfluidic channels and the transverse / longitudinal conductive structures, form a composite current collector electrode structure that synergistically dissipates heat, making it suitable for fast-charging power batteries and high-energy-density energy storage batteries.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and specifically relates to a composite current collector electrode for batteries. Background Technology

[0002] As a core component of new energy vehicles and energy storage systems, the thermal management performance of lithium-ion batteries directly determines the safety, cycle life, and upper limit of energy density of battery packs. However, with the popularization of high-energy-density materials such as high-nickel ternary cathodes and silicon-carbon anodes, and the promotion of fast charging technology (≥3C), the industry has specific requirements for the fast charging performance of power batteries. The fast charging performance of power batteries must meet the following core indicators:

[0003] Temperature rise control: During 5C charging and discharging, the surface temperature rise rate of the electrode is ≤3℃ / s, and the lateral temperature difference is ≤5℃;

[0004] Structural compatibility: The heat dissipation unit must be integrated inside the electrode to avoid occupying cell space (energy density loss ≤3%).

[0005] Process feasibility: Compatible with existing electrode coating and roll forming production lines, with a cost increase of ≤5%.

[0006] During fast charging, the instantaneous heat generated by the battery electrodes under high-rate conditions surges, and the existing electrode heat dissipation structure can hardly meet the requirements. The existing current collector heat dissipation path and heat dissipation technology solutions are all inadequate.

[0007] 1. The shortcomings of existing current collector heat dissipation paths are mainly manifested in unidirectional heat conduction dependence and uneven electrolyte wetting.

[0008] Among them, unidirectional thermal dependence refers to the fact that conventional electrodes use aluminum foil (positive electrode) / copper foil (negative electrode) as current collectors, and heat is conducted only through the plane of the metal foil (the thermal conductivity of aluminum foil is 238 W / m·K in the in-plane direction and only 5 W / m·K in the thickness direction). During 5C charge and discharge, the temperature in the central region of the electrode is 15-20°C higher than that at the edge, and local thermal stress causes cracking of the active material particles.

[0009] Uneven electrolyte wetting refers to the lack of directional flow structure on the surface of a homogeneous current collector, resulting in an electrolyte wetting time of up to 20-30 seconds (coating process requires ≤10 seconds), and the risk of localized boiling of the electrolyte at high magnification (vapor pressure increases by 300% when the temperature is ≥60℃).

[0010] 2. In order to improve heat dissipation performance, the industry has tried a variety of technical improvements, but the existing heat dissipation technology solutions still have significant shortcomings. The main problems are that the doping of thermal conductive additives increases the brittleness of the electrode, and the external heat dissipation module cannot suppress the instantaneous temperature rise inside the electrode.

[0011] Thermal conductive additive doping refers to adding thermally conductive fillers such as carbon nanotubes and graphene to the active coating. However, the filler is unevenly distributed, and the longitudinal thermal conductivity is only increased to 50-80 W / m·K, which also leads to increased electrode brittleness (cracking rate >15% when bending radius ≥10mm).

[0012] External heat dissipation modules (such as liquid cooling plates and heat pipes) rely on external heat dissipation of the battery module, with a response delay of >10 seconds, and cannot suppress the instantaneous temperature rise inside the electrode (the surface temperature rise rate of the electrode reaches 8-10℃ / s during 3C charging).

[0013] In conclusion, existing current collector heat dissipation paths and technologies for battery electrodes are unsuitable for fast-charging batteries with stringent thermal safety requirements. Utility Model Content

[0014] To address the above problems, this utility model provides a composite current collector electrode for batteries, employing the following technical solution:

[0015] A composite current collector for a battery includes a substrate layer, a thermally conductive layer, and an active coating layer stacked together.

[0016] The thermally conductive layer has microfluidic channels on its surface in contact with the substrate layer, and also has longitudinal and transverse thermally conductive structures. The active coating has phase change material capsules filled in the pores of its surface in contact with the thermally conductive layer.

[0017] Furthermore, the microfluidic channels are arranged along the length of the thermally conductive layer.

[0018] Furthermore, multiple microfluidic channels are spaced apart.

[0019] Furthermore, the microfluidic channel is filled with an electrolyte containing nano-Al2O3.

[0020] Furthermore, the lateral thermally conductive structure comprises a horizontal graphene array.

[0021] Furthermore, the horizontal graphene array is disposed between two adjacent microfluidic channels and close to the substrate layer.

[0022] Furthermore, the longitudinal thermally conductive structure comprises vertical carbon fiber bundles and vertical silver nanowires.

[0023] Furthermore, the vertical carbon fiber bundles and the vertical silver nanowires are both disposed between two adjacent microfluidic channels, and the horizontal graphene array, the vertical carbon fiber bundles, and the vertical silver nanowires intersect to form a three-dimensional framework.

[0024] Furthermore, the phase change material capsule includes a PCM capsule.

[0025] Furthermore, the wall material of the PCM capsule is a polyurethane / SiO2 composite shell, and the core material of the PCM capsule is a paraffin-based material.

[0026] The beneficial effects of this utility model are:

[0027] 1. This utility model embeds a phase change material capsule inside the electrode. The phase change material capsule, together with the microfluidic channel and the lateral / longitudinal conductive structure, forms a composite current collector electrode structure for synergistic heat dissipation, realizing a dual-mode heat dissipation of "energy storage buffer + active exhaust". It is suitable for fast-charging power batteries and high-energy-density energy storage batteries.

[0028] 2. This utility model achieves dynamic thermal buffering. The phase change material capsule absorbs instantaneous heat, and the surface temperature rise rate during 5C charging and discharging is ≤3℃ / s (conventional electrode ≥8℃ / s). The PCM capsule is implanted into the electrode by mixing with slurry, without the need for additional equipment.

[0029] 3. The electrode temperature of this utility model is uniform, and the transverse temperature difference of the electrode is ≤3℃.

[0030] 4. The electrode structure of this utility model is compact. The electrode capsule of this utility model is directly integrated inside the electrode, without the need for external heat dissipation components.

[0031] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of the structure of a battery composite current collector electrode according to an embodiment of the present invention is shown;

[0034] Figure 2 A schematic diagram of the heat dissipation path of the heat-conducting network and the PCM capsule according to an embodiment of the present invention is shown.

[0035] In the figure: 1. Substrate layer; 2. Microfluidic channel; 3. Thermal conductive layer; 4. Active coating; 5. Phase change material capsule; 31. Horizontal graphene array; 32. Vertical carbon fiber bundle; 33. Vertical silver nanowire. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," "longitudinal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings.

[0038] This invention provides a composite current collector electrode for batteries that integrates phase change energy storage and three-dimensional heat conduction. Through structural design, it reduces the instantaneous temperature rise rate and balances the temperature distribution of the electrode. It is suitable for fast-charging power batteries and high-energy-density energy storage batteries, such as lithium-ion batteries.

[0039] like Figure 1 As shown, a battery composite current collector includes a substrate layer 1, a thermally conductive layer 3, and an active coating layer 4 stacked together. For example, the substrate layer 1 can be made of aluminum foil (positive electrode) or copper foil (negative electrode) with a thickness of 5-20 μm.

[0040] like Figure 1 As shown, the thermally conductive layer 3 has microfluidic channels 2 on its surface in contact with the substrate layer 1. For example, the microfluidic channels 2 are arranged along the length of the thermally conductive layer 3, and multiple microfluidic channels 2 are spaced apart. For example, the spacing between two adjacent microfluidic channels 2 is 200-300 μm, and the multiple microfluidic channels 2 are parallel to each other. For example, the longitudinal cross-sectional shape of the microfluidic channel 2 is trapezoidal or semi-circular, and it can also be set to other shapes as needed. The depth of the microfluidic channel 2 can be 5-20 μm, and the width can be 40-80 μm.

[0041] For example, each microfluidic channel 2 is filled with an electrolyte containing nano-Al2O3, with a thermal conductivity ≥0.4W / m·K.

[0042] The thermally conductive layer 3 also includes longitudinal and transverse thermally conductive structures. For example, the transverse thermally conductive structure includes a horizontal graphene array 31, which has a height of 1-5 μm and a gradient density distribution (density decreases by 30% in the channel region). For example, the horizontal graphene array 31 is disposed between two adjacent microfluidic channels 2 and close to the substrate layer 1.

[0043] like Figure 1 As shown, for example, the longitudinal thermally conductive structure includes vertical carbon fiber bundles 32 and vertical silver nanowires 33. For example, the diameter of the vertical carbon fiber bundles 32 is 5-10 μm, and the diameter of the vertical silver nanowires 33 is 50-100 nm.

[0044] For example, vertical carbon fiber bundles 32 and vertical silver nanowires 33 are both disposed between two adjacent microfluidic channels 2, and horizontal graphene arrays 31, vertical carbon fiber bundles 32 and vertical silver nanowires 33 intersect to form a three-dimensional framework.

[0045] An active coating 4 is applied to the surface of the thermally conductive layer 3 facing away from the substrate layer 1. The active coating 4 has a thickness of 50-100 μm and its porosity gradually increases from 15% to 50% from the bottom layer to the top layer.

[0046] like Figure 1 As shown, the active coating 4 has phase change material capsules 5 filling the pores on its surface in contact with the thermally conductive layer 3. For example, the phase change material capsules 5 can be PCM capsules, with a diameter of 10-30 μm, a polyurethane / SiO2 composite shell (1-2 μm thick) as the wall material, and a paraffin-based material with a phase change temperature of 40-60℃ as the core material. The PCM capsules are implanted into the electrode by mixing with a slurry, without the need for additional equipment (cost increase ≤5%).

[0047] like Figure 1 As shown, for example, the PCM capsule contacts the vertical carbon fiber bundle 32 and the vertical silver nanowire 33 to form a synergistic heat dissipation structure, such as... Figure 2 As shown, the heat dissipation path of the synergistic heat dissipation structure is as follows: part of the heat inside the battery enters the PCM capsule for energy storage through the vertical heat dissipation path, and part of the heat is conducted to the microfluidic channel 2 through the horizontal graphene array 31 / vertical carbon fiber bundle 32 of the thermally conductive layer 3. The heat stored in the PCM capsule is conducted to the microfluidic channel 2 through the horizontal graphene array 31 / vertical carbon fiber bundle 32 of the thermally conductive layer 3. The microfluidic channel 2 concentrates and dissipates the heat.

[0048] This invention integrates a phase change material capsule 5 and a three-dimensional thermally conductive network into a battery composite current collector electrode. By processing microfluidic channels 2 in the thermally conductive layer 3, a three-dimensional thermally conductive network consisting of a horizontal graphene array 31, a vertical carbon fiber bundle 32, and a vertical silver nanowire 33 is constructed. PCM capsules (wall material polyurethane / SiO2, core material paraffin-based phase change material) are dispersed in the pores of the active coating 4, achieving an electrode surface temperature rise rate ≤3℃ / s and a lateral temperature difference ≤3℃. This structure is compatible with existing battery processes and is suitable for fast-charging batteries with stringent thermal safety requirements.

[0049] The embedded integrated design of the PCM capsule, three-dimensional heat conduction network, and microfluidic channel 2 in this invention achieves dual-mode heat dissipation of "energy storage buffer + active heat dissipation".

[0050] The electrode of this invention achieves dynamic thermal buffering: the PCM capsule absorbs instantaneous heat, and the surface temperature rise rate during 5C charging and discharging is ≤3℃ / s (compared to ≥8℃ / s for traditional electrodes).

[0051] The electrode of this invention achieves temperature uniformity: the transverse temperature difference of the electrode is ≤3℃.

[0052] The electrode structure of this invention is compact: the PCM capsule is directly integrated inside the electrode, eliminating the need for external heat dissipation components.

[0053] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite current collector electrode for batteries, characterized in that, It includes a base layer (1), a thermally conductive layer (3), and an active coating layer (4) stacked together; The thermally conductive layer (3) has microfluidic channels (2) on the surface in contact with the base layer (1), and the thermally conductive layer (3) also has longitudinal thermally conductive structures and transverse thermally conductive structures. The active coating (4) has phase change material capsules (5) filled in the pores of the surface in contact with the thermally conductive layer (3).

2. The battery composite current collector electrode according to claim 1, characterized in that, The microfluidic channel (2) is arranged along the length of the heat-conducting layer (3).

3. The battery composite current collector electrode according to claim 2, characterized in that, The microfluidic channels (2) are arranged at intervals.

4. The battery composite current collector electrode according to claim 1, characterized in that, The microfluidic channel (2) is filled with an electrolyte containing nano-Al2O3.

5. The battery composite current collector electrode according to claim 1, characterized in that, The lateral thermally conductive structure includes a horizontal graphene array (31).

6. The battery composite current collector electrode according to claim 5, characterized in that, The horizontal graphene array (31) is disposed between two adjacent microfluidic channels (2) and close to the substrate layer (1).

7. The battery composite current collector electrode according to claim 6, characterized in that, The longitudinal thermally conductive structure includes vertical carbon fiber bundles (32) and vertical silver nanowires (33).

8. The battery composite current collector electrode according to claim 7, characterized in that, The vertical carbon fiber bundle (32) and the vertical silver nanowire (33) are both disposed between two adjacent microfluidic channels (2), and the horizontal graphene array (31), the vertical carbon fiber bundle (32) and the vertical silver nanowire (33) intersect to form a three-dimensional skeleton.

9. The battery composite current collector electrode according to any one of claims 1-8, characterized in that, The phase change material capsule (5) includes a PCM capsule.

10. The battery composite current collector electrode according to claim 9, characterized in that, The wall material of the PCM capsule is a polyurethane / SiO2 composite shell, and the core material of the PCM capsule is a paraffin-based material.

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