Battery pole piece and lithium ion battery

Abstract

The utility model discloses a battery pole piece and a lithium ion battery. The pole piece comprises a current collector and an active material layer arranged on at least one surface of the current collector, the middle part of the pole piece is provided with a pole lug groove, the pole lug groove is a through groove along the Y direction, the pole lug groove is provided with a pole lug, and the pole lug comprises a connecting section positioned in the pole piece and an exposed section positioned outside the pole piece; wherein the width w1 of the tab and the width w2 of the tab groove meet the following relation: 0.6 < = w1 / w2 < = 1. The through tab groove is formed in the middle of the pole piece, and the tab is arranged in the tab groove, so that an electron transmission path can be obviously optimized, and the internal resistance of the pole piece is reduced; meanwhile, by reasonably controlling the proportional relation between the width of the tab and the width of the tab groove, the occupation of the tab groove on the area of an active substance can be reduced to the greatest extent while the welding reliability and the conductivity of the tab are ensured, and the space utilization rate of the pole piece is improved, so that the energy density of the battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to lithium ion battery technical field especially relates to a battery pole piece and lithium ion battery. BACKGROUND

[0002] Lithium ion batteries, as a kind of high efficient energy storage equipment, are widely used in portable electronic devices, electric vehicles and renewable energy storage fields. With the continuous improvement of the performance requirements of these applications on batteries, the design and manufacturing technology of batteries are also constantly changing. Among them, the design of battery pole piece plays a crucial role in the overall performance of the battery.

[0003] In the traditional design of lithium ion batteries, the tab is usually welded on the empty foil area at both ends of the aluminum foil (positive electrode) or copper foil (negative electrode). Although this design is relatively simple in manufacturing process, it has several obvious shortcomings: first, electrons need to cross a large distance on the pole piece to reach the tab, which increases the transmission distance of the electrons, resulting in increased internal resistance of the battery. Higher internal resistance not only reduces the charge and discharge efficiency of the battery, but also increases the heat generated by the battery during operation. Excessive heat not only affects the performance and life of the battery, but also may pose a potential threat to the safety of the battery.

[0004] To solve this problem, some battery manufacturers have begun to try to weld the tab at the middle position of the pole piece. This design does indeed shorten the average transmission distance of the electrons to some extent, helping to reduce the internal resistance and improve the performance of the battery. However, this improvement also brings new challenges. The current middle tab design often has the problem of unreasonable design of the tab welding position: the tab welding position occupies too much space, while the size of the tab itself is relatively small. This mismatch results in a large amount of space that could have been used for coating active material being wasted, thereby limiting the further improvement of the energy density of the battery.

[0005] Therefore, there is an urgent need for a new type of battery pole piece design that can optimize the electron transmission path, reduce the internal resistance, maximize the use of pole piece space, increase the coating area of active material, and improve the energy density of the battery. UTILITY MODEL CONTENTS

[0006] The utility model aims at: in view of the prior art's insufficient, provide a kind of battery pole piece, can in optimizing electron transmission path, reduce the internal resistance, while maximumly utilize pole piece space, improve the coating area of active material, improve the energy density of battery.

[0007] To achieve the above object, the utility model provides the following technical scheme:

[0008] A battery pole piece, comprising a current collector and an active material layer arranged on at least one surface of the current collector; a middle part of the pole piece is provided with a tab slot, the tab slot is a through slot along the Y direction, the tab slot is provided with a tab, the tab comprises a connecting section located in the pole piece and an exposed section located outside the pole piece; wherein the width w1 of the tab and the width w2 of the tab slot satisfy the relationship: 0.6≤w1 / w2≤1.

[0009] Preferably, the width w1 of the tab and the width w2 of the tab slot satisfy the relationship: 0.8≤w1 / w2≤1, more preferably 0.9≤w1 / w2≤1.

[0010] Preferably, the width w2 of the tab slot is 3-20mm, more preferably 6-15mm.

[0011] Preferably, the width w1 of the tab is 1.8-20mm, more preferably 3.6-15mm.

[0012] Preferably, the tab slot is coated with a temperature-resistant insulating adhesive tape, and the temperature-resistant insulating adhesive tape covers the connecting section of the tab; the heat-resistant temperature of the temperature-resistant insulating adhesive tape is ≥130℃.

[0013] Preferably, the area of the temperature-resistant insulating adhesive tape accounts for 30-200% of the area of the tab slot, more preferably 100-150%.

[0014] Preferably, the temperature-resistant insulating adhesive tape comprises a substrate and an adhesive layer arranged on the surface of the substrate; the substrate is PET, PP, PEEK, PI, PTFE, PA or PPS, and the adhesive layer is an acrylic adhesive, a silicone adhesive, a vinyl-acetate adhesive, a nitrile rubber adhesive or a chloroprene rubber adhesive. The temperature-resistant insulating adhesive tapes of the above-mentioned materials have good high-temperature resistance and insulation performance; in addition, it should be noted that other materials can also be used as long as they meet the corresponding temperature resistance and insulation requirements.

[0015] Preferably, the exposed section of the tab is provided with a tab adhesive; along the Y direction, the absolute value of the distance between the upper edge of the temperature-resistant insulating adhesive tape and the lower edge of the tab adhesive is 0.1-2mm.

[0016] Preferably, the connecting section of the tab is further coated with a layer of heat-conducting material. The heat-conducting material is at least one of heat-conducting silicone, graphene, carbon nanotube and phase change material, and the phase change material is preferably a solid-solid phase change material, such as polyethylene glycol. The heat-conducting and heat-dissipating performance of the tab can be improved by arranging the layer of heat-conducting material.

[0017] Preferably, both ends of the pole piece are provided with a blank foil area, and the blank foil area is coated with a temperature-resistant insulating adhesive tape.

[0018] Preferably, the current collector is a positive electrode current collector and / or a negative electrode current collector, the active material layer is a positive electrode active material layer and / or a negative electrode active material layer, the positive electrode active material layer is arranged on at least one surface of the positive electrode current collector, and the negative electrode active material layer is arranged on at least one surface of the negative electrode current collector.

[0019] The electrode piece is a positive electrode piece and / or a negative electrode piece, the middle part of the positive electrode piece is provided with a positive electrode tab slot, the positive electrode tab slot is a through slot along the Y direction, and the positive electrode tab slot is provided with a positive electrode tab; the middle part of the negative electrode piece is provided with a negative electrode tab slot, the negative electrode tab slot is a through slot along the Y direction, and the negative electrode tab slot is provided with a negative electrode tab.

[0020] The position opposite to the negative electrode tab of the positive electrode piece is attached with a temperature-resistant insulating adhesive tape; and / or, the position opposite to the negative electrode tab of the positive electrode piece is provided with an empty foil area, and the empty foil area is attached with a temperature-resistant insulating adhesive tape.

[0021] Preferably, the areal density of the positive electrode active material layer is 10-30 mg / cm 2 , more preferably 16-23 mg / cm 2 , and the areal density of the negative electrode active material layer is 5-15 mg / cm 2 , more preferably 5-12 mg / cm 2 .

[0022] In addition, the utility model also provides a kind of lithium ion battery, including the battery electrode piece described in any of the above.

[0023] Preferably, the outer surface of the lithium ion battery is attached with a layer of heat-conducting material; the heat-conducting and heat-dissipating performance of the battery can be improved.

[0024] Compared with the prior art, the battery electrode piece provided by the utility model has at least the following beneficial effects: by arranging a through tab slot in the middle part of the electrode piece and arranging a tab in the tab slot, the electronic transmission path can be significantly optimized, and the internal resistance of the electrode piece can be reduced. Compared with the conventional mode of arranging a tab at the edge, the utility model adopts the design of middle tab, which can shorten the transmission distance of electrons in the surface of the electrode piece, reduce the transmission resistance of current, thereby reducing polarization loss and improving the high-rate charge and discharge performance. At the same time, by reasonably controlling the proportional relationship between the width of the tab and the width of the tab slot, the tab slot can occupy the active material area to the maximum extent while ensuring the welding reliability and conductivity of the tab, the space utilization rate of the electrode piece can be improved, and the energy density of the battery can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1The utility model discloses an embodiment of the structure schematic diagram of battery pole piece.

[0026] Figure 2 The utility model discloses an embodiment of the structure schematic diagram of positive pole piece.

[0027] Figure 3 The utility model discloses an embodiment of the structure schematic diagram of negative pole piece.

[0028] In the drawing: 1, current collector;2, active material layer;3, tab slot;4, tab;5, tab glue;6, temperature resistant insulating adhesive paper;11, positive current collector;12, negative current collector;21, positive active material layer;22, negative active material layer;31, positive tab slot;32, negative tab slot;41, positive tab;42, negative tab. DETAILED DESCRIPTION

[0029] The technical scheme in the embodiments of the utility model will be apparently and completely described below with reference to the drawings in the embodiments of the utility model, and apparently, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative work belong to the range of protection of the utility model.

[0030] Please refer to the drawings of the embodiments of the utility model Figure 1 According to the first aspect of the application, the application provides a kind of battery pole piece, including current collector 1 and the active material layer 2 of setting on the at least one surface of current collector 1;The middle part of pole piece is provided with tab slot 3, tab slot 3 is through slot along Y direction, tab slot 3 is provided with tab 4, and tab 4 includes the connecting section in pole piece and the exposed section outside pole piece;Wherein, the width w1 of tab 4 and the width w2 of tab slot 3 satisfy the relationship: 0.6≤w1 / w2≤1.

[0031] Wherein, the application is through the middle part of pole piece and sets tab slot 3 and tab 4, optimizes electronic transmission path, significantly shortens the average transmission distance of electron on pole piece, to effectively reduce battery internal resistance;Low internal resistance not only improves the charge-discharge efficiency of battery, but also reduces the heat generation in working process, improves the safety and life of battery.In addition, the application ensures that tab slot 3 space is maximized by reasonably designing the width ratio of tab 4 and tab slot 3, while retaining enough operating space for the welding of tab 4, maximally reducing the non-active material area, improving the coating area of active material, thereby improving the energy density of battery.

[0032] In an embodiment according to the application, the width w1 of the tab 4 and the width w2 of the tab slot 3 satisfy the relationship: 0.8≤w1 / w2≤1; further preferably 0.9≤w1 / w2≤1. Optimizing the ratio of the width of the tab 4 to the width of the tab slot 3 can minimize the occupation of the active material area by the tab slot 3 while ensuring the welding reliability of the tab 4, thereby further improving the energy density of the battery.

[0033] In an embodiment according to the application, the width w2 of the tab slot 3 is 3-20 mm, further preferably 6-15 mm. For example, it can be 6 mm, 8 mm, 10 mm, 12 mm or 15 mm, etc. While ensuring the strength and current carrying capacity of the tab 4, the non-active area is minimized, and the space utilization is optimized.

[0034] In an embodiment according to the application, the width w1 of the tab 4 is 1.8-20 mm, further preferably 3.6-15 mm. For example, it can be 3 mm, 4.5 mm, 5.5 mm, 6.5 mm, 7.5 mm, 8.5 mm, 9.5 mm, 10.5 mm, 11.5 mm, 12 mm or 15 mm, etc. While ensuring the strength and current carrying capacity of the tab 4, the non-active area is minimized, and the space utilization is optimized.

[0035] In an embodiment according to the application, the tab slot 3 is coated with a temperature-resistant insulating adhesive tape 6, and the temperature-resistant insulating adhesive tape 6 covers the connecting section of the tab 4, increasing the safety of the battery cell and preventing short circuit; the area of the temperature-resistant insulating adhesive tape 6 accounts for 30-200% of the normal projection area of the tab slot 3, and the heat-resistant temperature of the temperature-resistant insulating adhesive tape 6 is ≥130℃. Preferably, the area of the temperature-resistant insulating adhesive tape 6 accounts for 100-150% of the normal projection area of the tab slot 3; this can effectively prevent the positive and negative electrodes from directly contacting due to the thermal shrinkage of the separator, and can also effectively cover the edge burrs of the current collector 1 and the tab 4, preventing the occurrence of short circuit of the battery cell and improving the safety of the battery cell. Preferably, the heat-resistant temperature of the temperature-resistant insulating adhesive tape 6 is 130℃-500℃; generally, the higher the heat-resistant temperature of the temperature-resistant insulating adhesive tape 6, the better, and in order to improve the safety of the battery cell, the heat-resistant temperature of the temperature-resistant insulating adhesive tape 6 is generally higher than the thermal shrinkage temperature of the separator.

[0036] In an embodiment according to the application, the temperature-resistant insulating adhesive tape 6 comprises a substrate and an adhesive layer provided on the surface of the substrate; the substrate is PET, PP, PEEK, PI, PTFE, PA or PPS, and the adhesive layer is an acrylic adhesive, a silicone adhesive, a vinyl-acrylic adhesive, a nitrile rubber adhesive or a chloroprene rubber adhesive. Among them, the temperature-resistant insulating adhesive tape 6 made of the above-mentioned materials has good high-temperature resistance and insulation performance; in addition, it should be noted that other materials of temperature-resistant insulating adhesive tape 6 can also be used as long as they meet the corresponding temperature resistance and insulation requirements.

[0037] In one embodiment of the present application, the exposed portion of the tab 4 is provided with tab glue 5. Along the Y direction, the absolute value of the distance between the upper edge of the heat-resistant insulating tape 6 and the lower edge of the tab glue 5 is 0.1-2 mm. This allows the heat-resistant insulating tape 6 to cover burrs on the edge of the tab 4, prevents the tape from being too large and affecting the top seal of the aluminum-plastic film, and reduces tape waste.

[0038] In one embodiment of the present application, the connecting section of the tab 4 is further coated with a layer of thermally conductive material. The thermally conductive material is at least one of thermally conductive silicone, graphene, carbon nanotubes, and phase change material, wherein the phase change material is preferably a solid-solid phase change material, such as polyethylene glycol. Providing a thermally conductive material layer can accelerate heat conduction at the tab 4, reduce local temperature rise, and improve the heat dissipation performance and safety of the pole piece. Thermally conductive silicone, graphene, carbon nanotubes, and other materials have high thermal conductivity, while phase change materials can absorb excess heat at the tab 4, both of which can significantly improve the thermal conductivity and heat dissipation performance of the tab 4.

[0039] In one embodiment of the present application, hollow foil areas are provided at both ends of the electrode sheets, and these areas are covered with heat-resistant insulating tape 6. When the battery cell is exposed to high temperatures, due to the excellent heat-resistant properties of the heat-resistant insulating tape 6, even if the separator undergoes thermal contraction, direct contact between the hollow foil areas of the positive and negative electrode sheets will not occur, thus preventing a short circuit in the battery. This effectively improves the safety of the battery. Furthermore, the provision of the heat-resistant insulating tape 6 also helps prevent dust contamination and corrosion, effectively protecting the stability and lifespan of the battery cell.

[0040] In one embodiment according to the present application, Figures 2-3 As shown, the current collector 1 is a positive electrode current collector 11 and / or a negative electrode current collector 12, the active material layer 2 is a positive electrode active material layer 21 and / or a negative electrode active material layer 22, the positive electrode active material layer 21 is provided on at least one surface of the positive electrode current collector 11, and the negative electrode active material layer 22 is provided on at least one surface of the negative electrode current collector 12;

[0041] The electrode sheet is a positive electrode sheet and / or a negative electrode sheet. A positive electrode tab slot 31 is provided in the middle of the positive electrode sheet. The positive electrode tab slot 31 is a through slot along the Y direction. The positive electrode tab slot 31 is provided with a positive electrode tab 41. A negative electrode tab slot 32 is provided in the middle of the negative electrode sheet. The negative electrode tab slot 32 is a through slot along the Y direction. The negative electrode tab slot 32 is provided with a negative electrode tab 42.

[0042] The position opposite to the negative electrode tab 42 of the positive electrode tab is attached with a temperature-resistant insulating adhesive paper 6; and / or, the position opposite to the negative electrode tab 42 of the positive electrode tab is provided with an empty foil area, and the empty foil area is attached with the temperature-resistant insulating adhesive paper 6. By attaching the temperature-resistant insulating adhesive paper 6 at the position opposite to the negative electrode tab 42 of the positive electrode tab, the edge burr of the negative electrode tab 42 can be effectively prevented from damaging the positive electrode tab or causing lithium precipitation of the negative electrode due to uneven thickness; in addition, when the battery cell is in a high-temperature condition, since the temperature-resistant insulating adhesive paper 6 has good high-temperature resistance, even if the isolation film shrinks due to heat, the direct contact between the positive electrode tab and the negative electrode tab will not cause the battery to short circuit, effectively improving the safety performance of the battery.

[0043] In an embodiment according to the present application, the positive current collector 11 is an aluminum foil or an alloy material thereof, and the negative current collector 12 is a copper foil or an alloy material thereof; the positive active material layer 21 comprises a positive active material, a conductive agent and a binder; and the negative active material layer 22 comprises a negative active material, a conductive agent and a binder. The positive active material can include but is not limited to lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, etc.; the negative active material can include but is not limited to natural graphite, artificial graphite, mesophase microcarbon spheres, hard carbon, soft carbon, silicon, silicon-carbon material, etc.; the conductive agent can include but is not limited to conductive carbon black, acetylene black, ketjen black, carbon nanofiber, carbon nanotube, graphene, etc.; and the binder can include but is not limited to polyvinylidene fluoride, butadiene rubber, polyvinyl alcohol, polyurethane, etc. The ratio of the active material layer slurry and the preparation thereof are conventional techniques in the art, which will not be described in detail here.

[0044] In an embodiment according to the present application, the surface density of the positive active material layer 21 is 10-30 mg / cm 2 , and is further preferably 16-23 mg / cm 2 ; and the surface density of the negative active material layer 22 is 5-15 mg / cm 2 , and is further preferably 5-12 mg / cm 2 . By reasonably matching the surface densities of the positive and negative active material layers 22, the energy density can be improved while the matching of the positive and negative capacities is taken into account, the problems such as lithium dendrite in the charging and discharging process of the battery are avoided, and the cycle life is prolonged.

[0045] According to a second aspect of the present application, the present application further provides a lithium ion battery comprising the battery tab described in any of the above paragraphs.

[0046] In an embodiment according to the present application, the lithium ion battery comprises a roll core, an electrolyte and a soft package shell, the roll core comprises a positive electrode tab, a negative electrode tab and a separator arranged between the positive electrode tab and the negative electrode tab, the positive electrode tab, the separator and the negative electrode tab are sequentially stacked and wound to form the roll core, and the roll core and the electrolyte are jointly sealed inside the soft package shell. The positive electrode tab and the negative electrode tab are both the battery tab described above.

[0047] In an embodiment according to the application, the outer surface of the lithium ion battery is coated with a layer of heat-conductive material; the heat-conductive and heat-dissipating performance of the battery can be further improved, the temperature rise of the battery is inhibited, and the use reliability is improved.

[0048] It should be noted that the contents not described in detail in the specification belong to the prior art known to those skilled in the art, and will not be described here.

[0049] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the above specific embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present application all belong to the protection scope of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience of description and do not constitute any limitation on the present application.

Claims

1. A battery pole piece, characterized by: The battery pole piece comprises a current collector and an active material layer arranged on at least one surface of the current collector; a middle part of the pole piece is provided with a pole tab slot, the pole tab slot is a through slot in the Y direction, the pole tab slot is provided with a pole tab, the pole tab comprises a connecting section located in the pole piece and an exposed section located outside the pole piece; wherein the width w1 of the pole tab and the width w2 of the pole tab slot satisfy the relationship: 0.6≤w1 / w2≤1.

2. The battery pole piece of claim 1, wherein: The width w2 of the pole tab slot is 3-20 mm.

3. The battery pole piece of claim 1, wherein: The width w1 of the pole tab is 1.8-20 mm.

4. The battery pole piece of claim 1, wherein: The pole tab slot is covered with a temperature-resistant insulating adhesive tape, and the temperature-resistant insulating adhesive tape covers the connecting section of the pole tab; the heat-resistant temperature of the temperature-resistant insulating adhesive tape is ≥130℃.

5. The battery pole piece of claim 4, wherein: The area of the temperature-resistant insulating adhesive tape accounts for 30-200% of the area of the pole tab slot.

6. The battery pole piece of claim 4, wherein: The exposed section of the pole tab is provided with a pole tab adhesive; in the Y direction, the absolute value of the distance between the upper edge of the temperature-resistant insulating adhesive tape and the lower edge of the pole tab adhesive is 0.1-2 mm.

7. The battery pole piece of claim 1, wherein: The connecting section of the pole tab is also covered with a layer of heat-conducting material.

8. The battery pole piece of claim 1, wherein: Both ends of the pole piece are provided with an empty foil area, and the empty foil area is covered with a temperature-resistant insulating adhesive tape.

9. The battery pole piece of any one of claims 1-8, wherein: The current collector is a positive current collector and / or a negative current collector, the active material layer is a positive active material layer and / or a negative active material layer, the positive active material layer is arranged on at least one surface of the positive current collector, and the negative active material layer is arranged on at least one surface of the negative current collector; The pole piece is a positive pole piece and / or a negative pole piece, a middle part of the positive pole piece is provided with a positive pole tab slot, the positive pole tab slot is a through slot in the Y direction, the positive pole tab slot is provided with a positive pole tab, and a middle part of the negative pole piece is provided with a negative pole tab slot, the negative pole tab slot is a through slot in the Y direction, and the negative pole tab slot is provided with a negative pole tab; The positive pole piece and the negative pole tab are opposite to each other and are covered with a temperature-resistant insulating adhesive tape; and / or, the positive pole piece and the negative pole tab are opposite to each other and are provided with an empty foil area, and the empty foil area is covered with a temperature-resistant insulating adhesive tape.

10. A lithium-ion battery, characterized by: The battery pole piece comprises a current collector and an active material layer arranged on at least one surface of the current collector; a middle part of the pole piece is provided with a pole tab slot, the pole tab slot is a through slot in the Y direction, the pole tab slot is provided with a pole tab, the pole tab comprises a connecting section located in the pole piece and an exposed section located outside the pole piece; wherein the width w1 of the pole tab and the width w2 of the pole tab slot satisfy the relationship: 0.6≤w1 / w2≤1.

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