Negative pole piece and battery

Abstract

The utility model relates to the technical field of lithium ion batteries, and discloses a negative pole piece and a battery. The lithium supplementing structure is arranged on the current collector; the lithium supplementing structure comprises a first active layer, a lithium supplementing layer and a second active layer; the first active layer is arranged on one side of the current collector and is provided with a circulation hole; the lithium supplementing layer is arranged on one side, far away from the current collector, of the first active layer; the second active layer is arranged on one side, far away from the first active layer, of the lithium supplementing layer, and the lithium supplementing structure is arranged, so that irreversible lithium loss caused by formation of a solid electrolyte phase interface film is counteracted, the coulombic efficiency of the first cycle of the battery is remarkably improved, the total capacity and the energy density of the battery are improved, and the service life of the battery is prolonged. Meanwhile, the method has the characteristics of simple process, simplicity and convenience in operation, low cost and high economic benefit.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium - ion batteries, in particular to a negative electrode plate and a battery. Background Art

[0002] During the first charging process of a lithium - ion battery, the organic electrolyte will be reductively decomposed on the surface of the negative electrode such as graphite to form a solid electrolyte interphase membrane (SEI membrane), permanently consuming a large amount of lithium from the positive electrode, resulting in a low Coulomb efficiency in the first cycle and reducing the capacity and energy density of the lithium - ion battery. To solve this problem, the electrode material is pre - lithiated to compensate for lithium loss, offsetting the irreversible lithium loss caused by the formation of the SEI membrane, so as to improve the total capacity and energy density of the battery.

[0003] Negative electrode pre - lithiation includes physical pre - lithiation, electrochemical pre - lithiation and chemical pre - lithiation. However, the pre - lithiated negative electrode has high chemical reactivity to oxygen and moisture in the air, and will become ineffective after being placed for too long. Moreover, the whole process has a large safety risk, high process requirements and is complex. Summary of the Utility Model

[0004] In view of this, the utility model provides a negative electrode plate and a battery to solve the problems that the pre - lithiated negative electrode has high chemical reactivity to oxygen and moisture in the air, will become ineffective after being placed for too long, and the whole process has a large safety risk, high process requirements and is complex.

[0005] In the first aspect, the utility model provides a negative electrode plate, which includes a current collector and a lithium - compensating structure; the lithium - compensating structure is arranged on the current collector; the lithium - compensating structure includes a first active layer, a lithium - compensating layer and a second active layer; the first active layer is arranged on one side of the current collector and is provided with a circulation hole; the lithium - compensating layer is arranged on the side of the first active layer away from the current collector; the second active layer is arranged on the side of the lithium - compensating layer away from the first active layer.

[0006] Beneficial effects: Through the arrangement of the first active layer and the second active layer, the lithium - compensating layer can be protected from the influence of oxygen and moisture in the air, the stability of the lithium - compensating layer is increased, and the lithium - compensating kinetics effect of the thick - coating electrode plate can be improved; by arranging a circulation hole on the first active layer, a lithium - compensating space can be formed in the first active layer, so that the lithium - compensating agent in the lithium - compensating layer penetrates into the circulation hole, reducing the lithium - ion transmission path and facilitating further improvement of the energy density of the battery. Through the arrangement of the lithium - compensating structure, the irreversible lithium loss caused by the formation of the SEI membrane is offset, the Coulomb efficiency of the first cycle of the battery is significantly improved, the total capacity and energy density of the battery are increased, and at the same time, it has the characteristics of simple process, easy operation, low cost and high economic benefits.

[0007] In an alternative embodiment, a plurality of the circulation holes are provided, and the plurality of circulation holes are sequentially arranged at intervals on the first active layer.

[0008] Advantageous effects: By providing a plurality of circulation holes, the lithium supplementation space formed in the first active layer can be increased, and the lithium ion transport efficiency is increased.

[0009] In an alternative embodiment, the plurality of circulation holes are uniformly arranged to form an array structure.

[0010] Advantageous effects: By uniformly arranging the plurality of circulation holes, the uniformity of lithium ion transport is improved, and the balance between safety and energy density is achieved.

[0011] In an alternative embodiment, the plurality of circulation holes include at least one blind hole, and the orifice of the blind hole is disposed on the side of the first active layer close to the lithium supplementation layer.

[0012] Advantageous effects: By providing the blind hole, it is convenient to control the depth of the circulation hole in the first active layer, so that the depth of the circulation hole is not affected by the thickness of the first active layer, thereby facilitating the control of the length of the lithium ion transport path and realizing the control of the lithium ion transport speed, and thus effectively controlling the lithium supplementation amount. And by disposing the orifice of the blind hole on the side of the first active layer close to the lithium supplementation layer, it helps to ensure the planar integrity of the side of the first active layer close to the current collector, improves the tightness of contact between the first active layer and the current collector, helps to improve the uniformity of lithium ions transported to the current collector, and ensures the uniform lithium ion transport effect.

[0013] In an alternative embodiment, the plurality of circulation holes include at least one through hole.

[0014] Advantageous effects: By setting the circulation hole as a through hole, direct contact between lithium ions and the current collector can be achieved, and the lithium ion transport efficiency is increased.

[0015] In an alternative embodiment, one or more layers are provided between the first active layer and the lithium supplementation layer, and the plurality of first active layers and the lithium supplementation layer are alternately stacked in sequence.

[0016] Advantageous effects: By providing a plurality of lithium supplementation layers, the lithium supplementation amount of the lithium supplementation structure can be ensured, and the lithium supplementation effect under a thick electrode can be achieved.

[0017] In an alternative embodiment, two sets of the lithium supplementation structures are provided, and the two sets of lithium supplementation structures are respectively disposed on both sides of the current collector.

[0018] Advantageous effects: By providing lithium supplementation structures on both sides of the current collector, the lithium supplementation amount can be further ensured, and the lithium supplementation efficiency can be improved, and the lithium supplementation effect under a thick electrode can be achieved.

[0019] In an alternative embodiment, the areal density ratio of the first active layer to the second active layer is (6-9):(1-4).

[0020] Beneficial effects: Since there are a plurality of flow holes provided on the first active layer, therefore, compared with the second active layer, the lithium ion transmission rate on the first active layer is faster. By controlling the areal density ratio of the first active layer to the second active layer to be (6-9):(1-4), the overall lithium ion transmission rate of the negative electrode sheet is ensured to be relatively fast, and the comprehensive performance of the prepared lithium battery is better.

[0021] In an alternative embodiment, the areal density of the negative electrode sheet is 150 g / m 2 ~250 g / m 2 .

[0022] Beneficial effects: When the areal density of the negative electrode sheet is less than 150 g / m 2 , the accuracy requirement for multi-layer coating in the process will increase, resulting in an increase in the difficulty of process implementation; when the areal density of the negative electrode sheet is greater than 250 g / m 2 , the negative electrode sheet is prone to cracking after coating in the process, and the flexibility of the negative electrode sheet is relatively low, which is not conducive to actual production. Therefore, when the areal density of the negative electrode sheet is 150 g / m 2 ~250 g / m 2 , the performance of the prepared lithium battery is better, and the process for preparing the negative electrode sheet is more simple and easy to implement in production.

[0023] In a second aspect, the present invention also provides a battery, including the above-mentioned negative electrode sheet.

[0024] Beneficial effects: Since the battery includes the negative electrode sheet, it has the same effects as the negative electrode sheet, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the related art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a side view of a negative electrode sheet according to an embodiment of the present invention;

[0027] Figure 2 It is a front view of the first active layer according to an embodiment of the present invention.

[0028] Description of the reference numerals:

[0029] 1. Current collector; 2. Lithium supplement structure; 21. First active layer; 211. Flow-through hole; 22. Lithium supplement layer; 23. Second active layer. Specific embodiments

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present utility model.

[0031] The following combines Figures 1 to 2 , and describes the embodiments of the present utility model.

[0032] According to an embodiment of the present utility model, on the one hand, a negative electrode tab is provided, including a current collector 1 and a lithium supplement structure 2; the lithium supplement structure 2 is disposed on the current collector 1; the lithium supplement structure 2 includes a first active layer 21, a lithium supplement layer 22, and a second active layer 23; the first active layer 21 is disposed on one side of the current collector 1 and is provided with flow-through holes 211; the lithium supplement layer 22 is disposed on a side of the first active layer 21 away from the current collector 1; the second active layer 23 is disposed on a side of the lithium supplement layer 22 away from the first active layer 21.

[0033] By providing the first active layer 21 and the second active layer 23, the lithium supplement layer 22 can be protected from the influence of oxygen and moisture in the air, the stability of the lithium supplement layer 22 can be increased, and the lithium supplement kinetics effect of the thick coating electrode can be improved; by providing the flow-through holes 211 on the first active layer 21, a lithium supplement space can be formed in the first active layer 21, so that the lithium supplement agent in the lithium supplement layer 22 penetrates into the flow-through holes 211, reducing the lithium ion transmission path and facilitating further improvement of the energy density of the battery. By providing the lithium supplement structure 2, the irreversible lithium loss caused by the formation of the SEI film is offset, the Coulomb efficiency of the first cycle of the battery is significantly improved, the total capacity and energy density of the battery are increased, and at the same time, it has the characteristics of simple process, easy operation, low cost, and high economic benefits.

[0034] Specifically, the pore channels of the flow-through holes 211 are vertical pore channels and extend along the thickness direction of the first active layer 21. For thick coating electrodes, especially at high charge / discharge rates, the lithium ion concentration is limited in the part of the electrode close to the current collector 1, and a lithium concentration gradient is formed along the thickness of the active layer. By directly providing vertical pore channels on the first active layer 21, the pore tortuosity of the electrode can be reduced, the effective lithium ion diffusion coefficient can be increased, and thus the power performance of the battery can be improved.

[0035] Specifically, the circulation holes 211 can be formed by methods such as punching holes, pressing holes, or laser etching. Preferably, the circulation holes 211 are formed by laser etching. Laser etching has a certain degree of flexibility. The depth of etching the circulation holes 211 can be controlled by adjusting the laser energy, and there is no limitation on the shape of the etched circulation holes 211. In addition, the consistency of the etched holes is higher, the punching speed is fast, and the efficiency is higher.

[0036] Specifically, the circulation holes 211 can be of any shape such as circular, striped, rectangular, etc. Specifically, it can be selected according to the actual situation.

[0037] Specifically, the first active layer 21 is disposed on the current collector 1 by coating; a lithium supplement solution is applied on the first active layer 21 to form a lithium supplement layer 22; the second active layer 23 is disposed on the lithium supplement layer 22 by coating.

[0038] Specifically, the lithium supplement solution is made by mixing elemental lithium, graphene, and a non-aqueous solvent.

[0039] In one embodiment, a plurality of the circulation holes 211 are provided, and the plurality of circulation holes 211 are arranged at intervals in sequence on the first active layer 21.

[0040] By providing a plurality of circulation holes 211, the lithium supplement space formed in the first active layer 21 can be increased, and the lithium ion transmission efficiency is increased.

[0041] In one embodiment, the plurality of circulation holes 211 are uniformly arranged to form an array structure.

[0042] By arranging the plurality of circulation holes 211 uniformly, the uniformity of lithium ion transmission is improved, and the balance between safety and energy density is achieved.

[0043] In one embodiment, the plurality of circulation holes 211 include at least one blind hole.

[0044] By providing the blind hole, it is convenient to control the depth of the circulation hole 211 in the first active layer 21, so that the depth of the circulation hole 211 is not affected by the thickness of the first active layer 21. Thus, it is convenient to control the length of the lithium ion transmission path, realize the control of the lithium ion transmission speed, and thus effectively control the amount of lithium supplement.

[0045] In one embodiment, the orifice of the blind hole is disposed on the side of the first active layer 21 close to the lithium supplement layer 22.

[0046] By setting the opening of the blind hole on the side of the first active layer 21 close to the lithium replenishing layer 22, it helps to ensure the planar integrity of the side of the first active layer 21 close to the current collector 1, improves the closeness of the contact between the first active layer 21 and the current collector 1, helps to improve the uniformity of lithium ion transmission to the current collector 1, and ensures the uniform transmission effect of lithium ions.

[0047] In one embodiment, the plurality of flow holes 211 include at least one through hole.

[0048] By setting the flow hole 211 as a through hole, direct contact between lithium ions and the current collector 1 can be achieved, thereby increasing the transmission efficiency of lithium ions.

[0049] In a specific implementation, the flow hole 211 is made by laser etching, and the depth and shape area of ​​the laser etching path are determined according to the actual amount of lithium replenishment.

[0050] In a specific embodiment, the plurality of flow holes 211 are all through holes; or the plurality of flow holes 211 are all blind holes; or a portion of the flow holes 211 are through holes, and another portion of the flow holes 211 are blind holes.

[0051] In one embodiment, the first active layer 21 and the lithium replenishing layer 22 are provided in one or more layers, and the first active layer 21 and the lithium replenishing layer 22 are provided in a stacked and alternate manner.

[0052] Specifically, Figure 1 As shown, when the first active layer 21 and the lithium replenishing layer 22 are provided with one layer, along the direction away from the current collector 1, the structure of the negative electrode plate includes: the current collector 1, the first active layer 21, the lithium replenishing layer 22, and the second active layer 23; and the first active layer 21 is provided with a flow hole 211.

[0053] Specifically, when the first active layer 21 and the lithium replenishing layer 22 are provided with two layers (not shown in the figure), along the direction away from the current collector 1, the structure of the negative electrode plate includes: the current collector 1, the first active layer 21, the lithium replenishing layer 22, the first active layer 21, the lithium replenishing layer 22, the second active layer 23; and the two first active layers 21 are provided with flow holes 211.

[0054] Specifically, when the first active layer 21 and the lithium replenishing layer 22 are provided with three layers (not shown in the figure), along the direction away from the current collector 1, the structure of the negative electrode plate includes: the current collector 1, the first active layer 21, the lithium replenishing layer 22, the first active layer 21, the lithium replenishing layer 22, the first active layer 21, the lithium replenishing layer 22, the second active layer 23; and the three layers of the first active layer 21 are provided with flow holes 211.

[0055] The first active layer 21 and the lithium replenishing layer 22 are provided with a negative electrode sheet structure of more than three layers, and so on, which will not be described in detail in this application.

[0056] It should be noted that the negative active materials in the first active layer 21 and the second active layer 23 may be the same or different.

[0057] By setting the multiple first active layers 21 and the lithium supplement layer 22, the lithium supplement amount of the lithium supplement structure 2 can be ensured, and the lithium supplement effect of the thick electrode can be realized.

[0058] In one embodiment, two sets of the lithium supplement structure 2 are provided, and the two sets of the lithium supplement structure 2 are respectively arranged on both sides of the current collector 1.

[0059] By arranging the lithium supplement structure 2 on both sides of the current collector 1, the lithium supplement amount can be further ensured, the lithium supplement efficiency can be improved, and the lithium supplement effect of the thick electrode can be realized.

[0060] In one embodiment, the areal density ratio of the first active layer 21 to the second active layer 23 is (6 - 9):(1 - 4).

[0061] Since a plurality of flow holes 211 are provided on the first active layer 21, the lithium ion transmission rate on the first active layer 21 is faster than that on the second active layer 23. By controlling the areal density ratio of the first active layer 21 to the second active layer 23 to be (6 - 9):(1 - 4), the overall lithium ion transmission rate of the negative electrode can be ensured to be relatively fast, and the comprehensive performance of the prepared lithium battery is better.

[0062] In one implementation manner of this embodiment, the areal density ratio of the first active layer 21 to the second active layer 23 is 6:1. In another implementation manner of this embodiment, the areal density ratio of the first active layer 21 to the second active layer 23 is 9:4.

[0063] In one embodiment, the areal density of the negative electrode is 150 g / m 2 ~250 g / m 2 .

[0064] When the areal density of the negative electrode is 150 g / m 2 ~250 g / m 2 , the performance of the prepared lithium battery is better, and the process for preparing the negative electrode is simpler and easier to realize in production. When the areal density of the negative electrode is less than 150 g / m 2 , the requirement for the accuracy of multi-layer coating in the process will increase, resulting in an increase in the difficulty of process implementation; when the areal density of the negative electrode is greater than 250 g / m 2 , the negative electrode is prone to cracking after coating in the process, and the flexibility of the negative electrode is low, which is not conducive to actual production.

[0065] In one implementation manner of this embodiment, the areal density of the negative electrode tab is 150 g / m 2 . In another implementation manner of this embodiment, the areal density of the negative electrode tab is 250 g / m 2 .

[0066] According to an embodiment of the present invention, on the other hand, a battery is further provided, including the above-mentioned negative electrode tab.

[0067] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A negative electrode plate, characterized in that: include: current collector(1); A lithium replenishing structure (2) is arranged on the current collector (1); the lithium replenishing structure (2) comprises a first active layer (21), a lithium replenishing layer (22) and a second active layer (23); the first active layer (21) is arranged on one side of the current collector (1) and is provided with a flow hole (211); the lithium replenishing layer (22) is arranged on a side of the first active layer (21) away from the current collector (1); and the second active layer (23) is arranged on a side of the lithium replenishing layer (22) away from the first active layer (21).

2. The negative electrode sheet according to claim 1, characterized in that: A plurality of the flow holes (211) are provided, and the plurality of flow holes (211) are sequentially arranged at intervals on the first active layer (21).

3. The negative electrode sheet according to claim 2, characterized in that: The plurality of flow holes (211) are evenly arranged to form an array structure.

4. The negative electrode sheet according to claim 2, characterized in that: The plurality of flow holes (211) include at least one blind hole, the opening of which is arranged on a side of the first active layer (21) close to the lithium replenishing layer (22).

5. The negative electrode sheet according to claim 2, characterized in that: The plurality of flow holes (211) include at least one through hole.

6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The first active layer (21) and the lithium replenishing layer (22) are provided with one or more layers, and the multiple layers of the first active layer (21) and the lithium replenishing layer (22) are sequentially stacked and alternately arranged.

7. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The lithium replenishing structure (2) is provided with two groups, and the two groups of the lithium replenishing structure (2) are respectively arranged on both sides of the current collector (1).

8. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The ratio of the surface density of the first active layer (21) to that of the second active layer (23) is (6-9):(1-4).

9. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The surface density of the negative electrode sheet is 150g / m 2 ~250g / m 2 .

10. A battery, characterized in that: A negative electrode sheet comprising the negative electrode sheet according to any one of claims 1 to 9.

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