Pole piece, battery and electric equipment

Abstract

The utility model relates to a pole piece, a battery and electric equipment, the pole piece comprises a current collector and an active material layer arranged on the current collector, the active material layer comprises a plurality of active material modules, the plurality of active material modules are arranged on the current collector at intervals, and a liquid retaining channel is formed in an empty foil area between two adjacent active material modules; the liquid retaining channel comprises a first liquid retaining channel extending along the length direction of the current collector and a second liquid retaining channel extending along the width direction of the current collector; the first liquid retaining channel and / or the second liquid retaining channel are / is curved. The pole piece disclosed by the utility model has a relatively high liquid retention effect, good rate capability, relatively low charge and discharge temperature rise and relatively long service life.

Description

Technical Field

[0001] The present disclosure relates to the field of batteries, and in particular, to a pole piece, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries are widely used in various fields such as power and energy storage. With the continuous increase in market demand, higher requirements are also put forward for the service life and safety performance of batteries. Lithium-ion batteries mainly include positive electrodes, negative electrodes, electrolytes and separators. The performance of the electrodes has a very important influence on the performance of the battery. Traditional large-surface electrodes are usually made into batteries in the form of a dressing area. During the battery charge and discharge cycle, especially in the second half of the life cycle, there is a high probability that the electrode material will expand, the electrolyte will flow back slowly, and the battery's charge and discharge rate capability will be limited. Even lithium precipitation may occur occasionally, and the battery's cycle life will be rapidly reduced.

[0003] In view of the above problems, technicians in this field have conducted numerous studies on the design of electrode sheets in order to meet market demand. There is an urgent need to develop an electrode sheet with excellent liquid retention performance to improve the service life and rate performance of the battery. Utility Model Content

[0004] The purpose of the present disclosure is to provide a pole piece, a battery, and an electrical device, wherein the pole piece has a higher liquid retention effect, better rate performance, lower charge and discharge temperature rise, and a longer service life.

[0005] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides a pole piece, the pole piece comprising a current collector and an active material layer disposed on the current collector, the active material layer comprising a plurality of active material modules, the plurality of active material modules being arranged on the current collector at intervals to form a liquid retaining channel in an empty foil area between two adjacent active material modules;

[0006] The liquid retaining channel comprises a first liquid retaining channel extending along the length direction of the current collector, and a second liquid retaining channel extending along the width direction of the current collector; the first liquid retaining channel and / or the second liquid retaining channel are curved.

[0007] Optionally, the curve is a broken line curve or a wavy line curve.

[0008] Optionally, the width of the liquid retaining channel is 0.5-2.5 mm.

[0009] Optionally, the widths of the plurality of active material modules are the same or different, and the lengths of the plurality of active material modules are the same or different. The width of the active material module is 25-125 mm, and the length is 50-250 mm.

[0010] Optionally, the thickness of the current collector is 6-15 μm, and the ratio of the width to the length of the current collector is 1:(0.1-1).

[0011] Optionally, the current collector has a width of 50-500 mm and a length of 50-5000 mm.

[0012] Optionally, the thickness of the active material layer is 30-120 μm, and the thickness of the plurality of active material modules is the same.

[0013] A second aspect of the present disclosure provides a battery, comprising a positive electrode, a separator, an electrolyte and a negative electrode, wherein the positive electrode and / or the negative electrode is the electrode sheet provided in the first aspect of the present disclosure.

[0014] Optionally, the positive electrode and the negative electrode of the battery are each independently the electrode sheet;

[0015] The maximum distance between two adjacent first liquid retaining channels of the positive electrode is greater than or equal to the maximum distance between two adjacent first liquid retaining channels of the negative electrode, and the maximum distance between two adjacent second liquid retaining channels of the positive electrode is greater than or equal to the maximum distance between two adjacent second liquid retaining channels of the negative electrode; the orthographic projection of the active material module of the positive electrode is included in the active material module of the negative electrode at the corresponding position.

[0016] Optionally, the battery comprises a plurality of positive electrodes, a plurality of negative electrodes, a plurality of separators and the electrolyte, and the positive electrodes and the negative electrodes are stacked and separated by the separators;

[0017] The number of the positive electrodes is recorded as n1, the number of the negative electrodes is recorded as n2, and the number of the separators is recorded as n3. The number of the positive electrodes, the negative electrodes and the separators satisfies n1=n2-1, n3=n1+n2+1.

[0018] Optionally, the assembly ratio of the battery is 91-97%.

[0019] A third aspect of the present disclosure provides an electrical device, wherein the electrical device comprises the battery provided in the second aspect of the present disclosure.

[0020] Through the above technical scheme, the electrode disclosed in the present invention has multiple active material modules, which increase the directions and channels for the electrolyte to enter and exit the active material layer, which is conducive to the embedding and extraction of lithium ions and improves the ion conductivity rate; and curved liquid retention channels are arranged between the active material modules, which has greater resistance to electrolyte loss and can achieve stronger liquid retention capacity, which is beneficial to improving the service life of the battery.

[0021] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0023] Figure 1 It is a structural schematic diagram of a specific implementation of the pole piece disclosed in the present invention.

[0024] Figure 2 It is a structural schematic diagram of another specific implementation of the pole piece disclosed in the present invention.

[0025] Figure 3 It is a cross-sectional view of a specific embodiment of the pole piece disclosed in the present invention.

[0026] Description of Reference Numerals

[0027] 1. Current collector 2. Active material module 3. Liquid retention channel

[0028] 31. First liquid retaining channel 32. Second liquid retaining channel DETAILED DESCRIPTION

[0029] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0030] A first aspect of the present disclosure provides a pole piece, which includes a current collector 1 and an active material layer arranged on the current collector 1, wherein the active material layer includes a plurality of active material modules 2, and the plurality of active material modules are arranged at intervals on the current collector 1 to form a liquid retaining channel 3 in the empty foil area between two adjacent active material modules; the liquid retaining channel 3 includes a first liquid retaining channel 31 extending along the length direction of the current collector, and a second liquid retaining channel 32 extending along the width direction of the current collector; the first liquid retaining channel 31 and / or the second liquid retaining channel 32 are curved.

[0031] The disclosed electrode has multiple active material modules, which can increase the direction and channels for the electrolyte to enter and exit the active material layer, help the lithium ions to embed and exit, and rapidly increase the ion conductivity rate, thereby improving the rate capability of the battery and reducing the charge and discharge temperature rise. There are curved liquid retention channels between the active material modules, which can store more electrolyte. During the charge and discharge process, as the electrode material expands and contracts, the electrolyte can enter and exit more quickly, slowing down the degradation of the electrode material and helping to inhibit the occurrence of lithium precipitation, thereby effectively extending the service life of the battery.

[0032] like Figure 3As shown, in a specific embodiment of the present disclosure, the first main surface of the current collector 1 is provided with a first active material layer, and the first active material layer includes a plurality of first active material modules; the second main surface of the current collector is provided with a second active material layer, and the second active material layer includes a plurality of second active material modules; the position of the first active material module corresponds to the position of the second active material module, and the size of the first active material module is the same as the size of the second active material module. In the present disclosure, the first main surface and the second main surface are two surfaces extending and facing each other along the length direction of the current collector. This embodiment is beneficial for the empty foil area to absorb stress and ensure the flatness of the active material module.

[0033] According to the present disclosure, the length of the active material layer is less than or equal to the length of the current collector, and the length of the active material layer refers to the total length of the active material module and the empty foil area. In a preferred specific embodiment, the length of the active material layer is equal to the length of the current collector, that is, the liquid retaining channel is only provided in the empty foil area between two adjacent active material modules, and is not provided at the edge of the current collector, so as to avoid the electrode strength being reduced due to the softer empty foil area at the edge of the current collector, and the electrolyte is easily lost in the liquid retaining channel formed by the empty foil area at the edge, and it is not easy to play a role in retaining liquid. This preferred embodiment is more conducive to further improving the strength of the electrode and the liquid retaining effect of the electrode.

[0034] According to the present disclosure, a curved shape refers to a bent shape. Compared with a straight liquid retaining channel, a curved liquid retaining channel is longer, has greater resistance to electrolyte loss and stronger liquid retaining capacity, and can store more electrolyte. The present disclosure does not limit the specific form of the curved shape, as long as it has a curved shape. Figure 1 As shown, in a specific embodiment of the present disclosure, the curve is a wavy curve. Figure 2 As shown, in another specific embodiment of the present disclosure, the curve is in the form of a broken line.

[0035] According to the present disclosure, the width of the liquid retaining channel 3 can vary within a large range. In a specific embodiment, the width of the liquid retaining channel 3 is 0.5-2.5 mm, preferably 1.5-2.5 mm. The width of the liquid retaining channel 3 is appropriate within the above range, which avoids the problem that the width is too small, resulting in difficulty in coating the active material layer, or the width is too large, resulting in too fast electrolyte loss and failure to achieve capillary adsorption of electrolyte, resulting in a decrease in the liquid retaining capacity, thereby further improving the liquid retaining capacity of the liquid retaining channel.

[0036] According to the present disclosure, the number of active material modules can be specifically set to more than 2 according to the size of the current collector, and the present disclosure does not impose specific restrictions on the number of active material modules. According to the present disclosure, the widths of the multiple active material modules are the same or different, preferably the same width, and the lengths of the multiple active material modules are the same or different, preferably the same length. In the present disclosure, the width and length of the active material module 2 can vary within a large range. In a specific embodiment, the width of the active material module is 25-125mm and the length is 50-250mm. Preferably, the width is 25-75mm and the length is 50-150mm. The size of the active material module within the above-mentioned size range is appropriate, which is conducive to further improving the liquid retention capacity and ion conductivity rate of the electrode, thereby extending the service life of the battery, improving the rate performance of the battery, and further reducing the charge and discharge temperature rise.

[0037] According to the present disclosure, the thickness of the current collector 1 can vary within a large range, for example, the thickness of the current collector 1 is 6-15 μm. In one specific embodiment, the current collector is a positive electrode current collector, and the thickness of the positive electrode current collector is 13-15 μm. In another specific embodiment of the present disclosure, the current collector is a negative electrode current collector, and the thickness of the negative electrode current collector is 6-8 μm. The ratio of the width to the length of the current collector 1 can also vary within a large range, for example, the ratio of the width to the length of the current collector is 1:(0.1-1), preferably 1:(0.2-1). When the size of the current collector meets the above conditions, the modular active material layer further shortens the lithium ion conduction path, effectively reduces the impedance, and the pole core can be integrated and enlarged to prepare an ultra-high capacity battery.

[0038] According to the present disclosure, the width and length of the current collector 1 can vary within a large range. In a specific embodiment, the width of the current collector is 50-500 mm and the length is 50-5000 mm; preferably, the width is 100-300 mm and the length is 100-1500 mm. The current collector within the above size range is of suitable size, which is beneficial to further improve the rate capability and cycle performance of the pole piece and reduce the charge and discharge temperature rise.

[0039] According to the present disclosure, the thickness of the active material layer on one side of the current collector can vary within a wide range. In a specific embodiment, the thickness of the active material layer is 30-120 μm, preferably 60-120 μm, and the thickness of multiple active material modules is the same.

[0040] According to the present disclosure, the active material contained in the active material layer is conventionally used by those skilled in the art, for example, it may include but is not limited to lithium iron phosphate, lithium cobaltate, lithium manganate, nickel cobalt manganate, etc. The present disclosure does not specifically limit the type of current collector, and the current collector is selected from metal foil or alloy foil. The metal foil includes copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold or silver foil, and the alloy foil includes stainless steel, or an alloy containing at least one element of copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold and silver. Optionally, the alloy foil is composed of the above elements as the main component. The metal foil may further contain doping elements, and the doping elements include but are not limited to one or more of platinum, ruthenium, iron, cobalt, gold, copper, zinc, aluminum, magnesium, palladium, rhodium, silver and tungsten. Generally, the current collector usually uses aluminum foil and copper foil. In a specific embodiment, the positive current collector is aluminum foil and the negative current collector is copper foil.

[0041] The pole piece disclosed in the present invention can be prepared by a grid coating method, wherein a slurry containing active materials is coated on a current collector by a curved anilox roller for continuous discharging to obtain a pole piece covered with an active material layer; the pole piece covered with the active material layer is baked, cut and pressed to obtain a pole piece.

[0042] A second aspect of the present disclosure provides a battery, comprising a positive electrode, a separator, an electrolyte and a negative electrode, wherein the positive electrode and / or the negative electrode is the electrode sheet provided in the first aspect of the present disclosure.

[0043] In a specific embodiment of the present disclosure, the positive electrode and the negative electrode of the battery are each independently the electrode sheet; the maximum distance between two adjacent first liquid retaining channels of the positive electrode is greater than or equal to the maximum distance between two adjacent first liquid retaining channels of the negative electrode, and the maximum distance between two adjacent second liquid retaining channels of the positive electrode is greater than or equal to the maximum distance between two adjacent second liquid retaining channels of the negative electrode; the orthographic projection of the active material module of the positive electrode is included in the active material module of the negative electrode at the corresponding position.

[0044] According to the present disclosure, the battery may have a plurality of stacked positive electrodes and negative electrodes. In a specific embodiment of the present disclosure, the battery includes a plurality of the positive electrodes, a plurality of the negative electrodes, a plurality of the separators and the electrolyte. The arrangement of the plurality of the positive electrodes, the plurality of the negative electrodes and the plurality of the separators is well known to those skilled in the art. In a specific embodiment, the positive electrodes and the negative electrodes are stacked and separated by the separators; the number of the positive electrodes is recorded as n1, the number of the negative electrodes is recorded as n2, and the number of the separators is recorded as n3. The number of the positive electrodes, the negative electrodes and the separators satisfies n1=n2-1, n3=n1+n2+1. In a specific embodiment, n1 is 1-60, n2 is 2-61, and n3 is 4-122.

[0045] According to the present disclosure, the assembly ratio refers to the thickness utilization rate of the battery shell, which is calculated according to the formula ρ=d2 / d1×100%, where d1 is the distance between the inner walls in the shell thickness direction; d2 is the thickness of the pole core. In a specific embodiment of the present disclosure, the assembly ratio of the battery is 91-97%.

[0046] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0047] Unless otherwise specified, the materials used in the examples were commercially available.

[0048] Example 1

[0049] The battery cell of the present embodiment contains the pole pieces disclosed herein, the material system of the pole pieces is that the positive electrode is lithium iron phosphate, the negative electrode is graphite, the electrolyte solute is lithium hexafluorophosphate, the battery cell size is 650*60*12mm, the assembly ratio is 93.5%, the number of stacking layers is 40 for the positive pole piece and 41 for the negative pole piece, and the electrolyte injection amount is 170g.

[0050] The current collector of the positive electrode sheet is provided with 15 active material modules of equal area, and the empty foil area with a spacing of 1.5mm between two adjacent active material modules forms a wavy liquid retention channel. The current collector of the negative electrode sheet is also provided with 15 active material modules of equal area, and the empty foil area with a spacing of 0.5mm between two adjacent active material modules forms a wavy liquid retention channel. The surface density of the positive and negative electrodes of the battery is 250g / m 2 and 118g / m 2 , the battery design capacity is 41Ah.

[0051] Example 2

[0052] A battery was prepared by the same method as in Example 1, with the only difference being that in this embodiment, the positive electrode sheet consisted of 9 active material modules of equal area, and the empty foil area with a spacing of 1.5 mm between two adjacent active material modules formed a wavy liquid retaining channel; the negative electrode sheet also consisted of 9 active material modules of equal area, and the empty foil area with a spacing of 0.5 mm between two adjacent active material modules formed a wavy liquid retaining channel. The designed capacity of the battery was 44.6 Ah.

[0053] Example 3

[0054] A battery was prepared by the same method as in Example 1, with the only difference being that the positive electrode sheet consisted of 9 active material modules of unequal width, and the empty foil area with a spacing of 2.5 mm between two adjacent active material modules formed a wavy liquid retaining channel, and the negative electrode sheet also consisted of 9 active material modules of unequal width, and the empty foil area with a spacing of 1.5 mm between two adjacent active material modules formed a wavy liquid retaining channel, and the battery design capacity was 41 Ah.

[0055] Example 4

[0056] The battery was prepared by the same method as in Example 1, except that the positive electrode sheet was provided with 15 active material modules of equal area, and the empty foil area with a spacing of 2.5 mm between two adjacent active material modules formed a wavy liquid retaining channel, and the negative electrode sheet was also provided with 15 active material modules of equal area, and the empty foil area with a spacing of 1.5 mm between two adjacent active material modules formed a zigzag liquid retaining channel. The battery design capacity was 35 Ah.

[0057] Comparative Example 1

[0058] This comparative example is a conventional battery pole piece, and the battery is prepared by the same method as in Example 1, except that the positive and negative electrodes of the battery are provided with the entire active material layer on the current collector, and are not divided into active material modules. The conventional battery design capacity is 50Ah.

[0059] Test Case

[0060] DCIR, charge temperature rise and 80% SOH cycle life at the same rate (1C).

[0061] 1. DCIR (DC internal resistance) test

[0062] (1) Capacity calibration, charging: at room temperature 25±5℃, charge at 0.5C constant current to 3.8V / cell, cut off at 0.02C for 1s and record a data; leave for 30min. Discharge: at room temperature 25±5℃, discharge at 0.5C constant current to 2.0V / cell, record a data for 1s and leave for 30min. Record the capacity C0 of the charge and discharge process.

[0063] (2) Main procedure: ① Adjust to 50% SOC: charge at 0.5C0 constant current for 1 hour; ② Standby: 2 hours; ③ Discharge: discharge at 1C0 constant current for 30 seconds; ④ Standby: 10 minutes; ⑤ Charge: charge at 1C0 constant current for 30 seconds.

[0064] (3) Calculate DCIR

[0065] Record the last voltage data of steps ② to ⑤, mark them as V1, V2, V3, and V4 in sequence, and calculate the DCIR value according to the following formula:

[0066] DCIR = (V1-V2) / C0×1000 (unit: mΩ),

[0067] DCIR charge = (V4-V3) / C0×1000 (unit: mΩ).

[0068] 2. Charging temperature rise test

[0069] ①Discharge: 0.5C constant current to 2.0V; leave for 2h. ②Charge: 1C0 constant current to 3.8V; leave for 2h. ③Discharge: 0.5C constant current to 2.0V; leave for 2h.

[0070] Record the capacity, voltage and temperature rise data of the charging process. Calculate the charging temperature rise according to the following formula: ΔT = T max -T min .

[0071] 3. Cycle test

[0072] ①Charge: 1C constant current charge to 3.8V. ②Discharge: 1C constant current discharge to 2.0V. Leave for 30 minutes between charge and discharge. ③Termination condition: Capacity retention rate drops to 80%.

[0073] Table 1

[0074]

[0075]

[0076] It can be seen from the above that the battery containing the electrode sheet disclosed in the present invention has good liquid retention ability, small battery impedance, long battery cycle life and low charging temperature rise under the same test conditions.

[0077] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0079] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A pole piece, characterized in that: The pole piece comprises a current collector (1) and an active material layer disposed on the current collector (1), the active material layer comprising a plurality of active material modules (2), the plurality of active material modules being arranged at intervals on the current collector (1) so as to form a liquid retaining channel (3) in an empty foil area between two adjacent active material modules (2); The liquid retaining channel comprises a first liquid retaining channel (31) extending along the length direction of the current collector, and a second liquid retaining channel (32) extending along the width direction of the current collector; the first liquid retaining channel (31) and / or the second liquid retaining channel (32) are curved.

2. The pole piece according to claim 1, characterized in that: The curve is a curved shape in the form of a broken line or a curved shape in the form of a wavy line.

3. The pole piece according to claim 1, characterized in that: The width of the liquid retaining channel (3) is 0.5-2.5 mm.

4. The pole piece according to claim 1, characterized in that: The widths of the plurality of active material modules (2) are the same or different, and the lengths of the plurality of active material modules (2) are the same or different. The width of the active material module (2) is 25-125 mm, and the length is 50-250 mm.

5. The pole piece according to claim 1, characterized in that: The thickness of the current collector (1) is 6-15 μm, and the ratio of the width to the length of the current collector is 1:(0.1-1).

6. The pole piece according to claim 1 or 5, characterized in that: The current collector (1) has a width of 50-500 mm and a length of 50-5000 mm.

7. The pole piece according to claim 1, characterized in that: The thickness of the active material layer on one side of the current collector is 30-120 μm, and the thicknesses of the plurality of active material modules are the same.

8. A battery, characterized in that: The battery comprises a positive electrode, a separator, an electrolyte and a negative electrode, and the positive electrode and / or the negative electrode is the electrode sheet according to any one of claims 1 to 7.

9. The battery according to claim 8, characterized in that The positive electrode and the negative electrode of the battery are each independently the electrode sheet; The maximum distance between two adjacent first liquid retaining channels (31) of the positive electrode is greater than or equal to the maximum distance between two adjacent first liquid retaining channels (31) of the negative electrode, and the maximum distance between two adjacent second liquid retaining channels (32) of the positive electrode is greater than or equal to the maximum distance between two adjacent second liquid retaining channels (32) of the negative electrode; the orthographic projection of the active material module of the positive electrode is included in the active material module of the negative electrode at the corresponding position.

10. The battery according to claim 8, characterized in that The battery comprises a plurality of positive electrodes, a plurality of negative electrodes, a plurality of separators and the electrolyte, wherein the positive electrodes and the negative electrodes are stacked and separated by the separators; The number of the positive electrodes is recorded as n1, the number of the negative electrodes is recorded as n2, and the number of the separators is recorded as n3. The number of the positive electrodes, the negative electrodes and the separators satisfies n1=n2-1, n3=n1+n2+1.

11. The battery according to claim 8, characterized in that The assembly ratio of the battery is 91-97%.

12. An electrical device, characterized in that: The electrical device comprises the battery according to any one of claims 8 to 11.

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