Lithium supplement anode pole piece and lithium ion battery
By setting a lithium replenishment layer on the anode of a lithium-ion battery and controlling its thickness using ultrasonic cleaning or vibration, the problem of internal short circuits and lithium plating caused by uneven lithium replenishment during the first cycle of lithium-ion batteries is solved, thus improving the battery's first-cycle efficiency and safety performance.
Patent Information
- Application Number
- CN202422893509.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-11-26
AI Technical Summary
Existing lithium-ion batteries suffer energy loss during the first cycle due to the anode consuming lithium ions to form an SEI film. Furthermore, excessive or insufficient lithium replenishment can lead to short circuits and lithium plating within the cell, especially in small steel-button cells and other wound cells where uneven thickness and lithium plating phenomena exist.
The lithium-replenishing anode electrode is adopted, which includes a current collector, an anode active material layer and a lithium-replenishing layer disposed on its outer surface. The thickness of the lithium-replenishing layer is controlled by ultrasonic cleaning or vibration to ensure that it has a linear relationship with the capacity ratio CB. The amount of lithium replenishing agent is precisely controlled to prevent short circuits and lithium plating in the cell.
It enables precise control of the amount of lithium replenishing agent, improves the safety performance of the cell during the first efficiency and charging and discharging process, prevents short circuits and lithium plating problems in the cell, and enhances the stability and safety of the battery.
Smart Images
Figure CN223527184U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to secondary battery technical field, concretely relates to a lithium supplementing anode pole piece and lithium ion battery. BACKGROUND
[0002] Lithium ion battery will consume lithium ion to form SEI film in anode in the first cycle process, causes a part of energy loss, and the anode pole piece lithium supplementing technology is the mature reliable in the existing lithium supplementing technology, can effectively supplement lithium ion consumed in the side reaction such as SEI film, and the lithium supplementing agent such as metal lithium, lithium powder, lithium alloy or lithium oxide is rolled on the anode surface, and the anode is prelithiated by the self-discharge of lithium supplementing agent. However, too much lithium supplementing agent causes internal short circuit of battery cell, lithium precipitation of anode, low first efficiency and other problems in the process of battery cell manufacturing, and insufficient lithium supplementing agent will lead to poor lithium supplementing effect, especially steel buckle small battery cell and other winding battery cell, the steel buckle battery cell because of the influence of the circumference ratio, the diameter of each winding is different, so the CB value exists difference, and the lithium supplementing layer of different thickness is needed, and the lithium precipitation phenomenon generally exists in the corner of other winding structure battery cell, and too much lithium supplementing agent is not suitable, so the thickness of lithium supplementing layer also needs to be controlled.
[0003] Therefore, it is necessary to provide a technical scheme to solve the above problems. UTILITY MODEL CONTENT
[0004] One of the purposes of the utility model is: in view of the shortage of prior art, a lithium supplementing anode pole piece is provided, so as to improve the problem of internal short circuit and lithium precipitation of battery cell caused by too much lithium supplementing agent on the anode surface.
[0005] In order to realize the above-mentioned purpose, the utility model adopts the following technical scheme:
[0006] A lithium supplementing anode pole piece, comprising:
[0007] A current collector;
[0008] An anode active material layer is arranged on at least one surface of the current collector;
[0009] A lithium supplementing layer is arranged on the outer surface of the anode active material layer;
[0010] Wherein, the thickness H of the lithium supplementing layer satisfies the relationship: H=(CB-1)*K1; wherein the unit of H is μm; K1 is the thickness coefficient, and 1≤K1≤3; CB is the ratio of the capacity of unit area anode pole piece to the capacity of unit area cathode pole piece.
[0011] Preferably, the thickness of the lithium supplementing layer is controlled by ultrasonic cleaning, and the thickness H of the lithium supplementing layer and the ultrasonic cleaning power P1 satisfy the relationship: H=h-K2*P1 / v1.
[0012] Wherein, the unit of P1 is W; h is the thickness of the lithium supplement layer after the anode pole piece is rolled, the unit is μm; v1 is the pole piece winding speed, the unit is m / s; K2 is the thickness coefficient, wherein 0.001≤K2≤0.002.
[0013] Preferably, the ultrasonic cleaning power P1 and the CB value satisfy the relationship: P1=[h-(CB-1)*K1]*v1 / K2.
[0014] Preferably, the thickness h of the lithium supplement layer after the anode pole piece is rolled is 5-10 μm.
[0015] Preferably, the thickness of the lithium supplement layer is controlled by ultrasonic oscillation, and the thickness H of the lithium supplement layer and the ultrasonic oscillation power P2 satisfy the relationship: H=K3*P2 / v2.
[0016] Wherein, the unit of P2 is W; v2 is the pole piece winding speed, the unit is m / s; K3 is the thickness coefficient, wherein 0.001≤K3≤0.002.
[0017] Preferably, the ultrasonic oscillation power P2 and the CB value satisfy the relationship: P2=(CB-1)*K1*v2 / K3.
[0018] Preferably, the CB value is 1.01-1.1; and / or, the thickness H of the lithium supplement layer is 0.01-0.2 μm.
[0019] Preferably, the anode active material layer comprises anode active substance, and the anode active substance comprises any one of graphite, silicon-carbon mixture, phosphorus-carbon mixture, nitride and lithium titanate.
[0020] Preferably, the lithium supplement layer contains lithium supplement agent, and the lithium supplement agent comprises any one of metallic lithium, lithium alloy, lithium powder and lithium oxide.
[0021] The second purpose of the utility model lies in providing a lithium ion battery, which comprises the lithium supplement anode pole piece of any one of the above.
[0022] Compared with the prior art, the lithium supplement anode pole piece provided by the utility model has the advantages that: the lithium supplement anode pole piece comprises a current collector, an anode active material layer arranged on at least one surface of the current collector, and a lithium supplement layer arranged on the outer surface of the anode active material layer; the thickness of the lithium supplement layer is linearly related to the CB value; the amount of lithium supplement agent is accurately controlled; the thickness coefficient is related to the effective substance composition of the anode main material; the amount of lithium supplement agent is accurately controlled; the problems of internal short circuit and lithium precipitation in the battery cell are prevented; and the safety performance of the battery cell during the initial efficiency and the charging and discharging process is improved. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 It is a structure schematic view of the lithium supplement pole piece of the utility model embodiment 1.
[0024] 1 - current collector; 2 - anode active material layer; 3 - lithium supplement layer. DETAILED DESCRIPTION
[0025] In order to make the technical scheme and advantages of the present application clearer, the following will further describe the present application and its beneficial effects in detail with specific embodiments, but the embodiments of the present application are not limited thereto.
[0026] The terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Thus, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.
[0027] The first aspect of the present application aims to provide a lithium supplement anode tab, which comprises a current collector 1, an anode active material layer 2 arranged on at least one surface of the current collector 1, and a lithium supplement layer 3 arranged on the outer surface of the anode active material layer 2.
[0028] The thickness H of the lithium supplement layer 3 satisfies the relationship: H = (CB-1)*K1; wherein the unit of H is μm; K1 is a thickness coefficient, wherein 1≤K1≤3; the thickness coefficient K1 is obtained from production experience, which is an empirical value; when K1<1, the change of the thickness of the lithium supplement layer is less affected by the change of the thickness of the tab, and the change of the thickness of the lithium supplement layer is not obvious, and at this time, K1≡1 is preferred. When K1>3, the change of the thickness of the lithium supplement layer is greatly affected by the change of the thickness of the tab, and there is a risk of excessive lithium supplement, and at this time, K1≡3 is preferred; CB is the ratio of the capacity per unit area of the anode tab to the capacity per unit area of the cathode tab.
[0029] The value of K1 is related to the specific composition of the anode active material, for example, the K1 of graphite material is 2, and the K1 of silicon-carbon material is 2.5.
[0030] CB = (anode active material gram capacity * anode surface density * anode active material content ratio) ÷ (cathode active material gram capacity * cathode surface density * cathode active material content ratio).
[0031] The thickness of the lithium supplement layer 3 is controlled by ultrasonic cleaning, and the thickness H of the lithium supplement layer 3 and the ultrasonic cleaning power P1 satisfy the relationship: H = h-K2*P1 / v1; wherein the unit of P1 is W; h is the thickness of the lithium supplement layer after the anode tab is rolled, and the unit is μm; v1 is the winding speed of the tab, and the unit is m / s; K2 is a thickness empirical coefficient, wherein 0.001≤K2≤0.002.
[0032] K2 is related to the roll compaction of the pole piece, when the roll compaction is greater than or equal to 1.5 g / cm 3 when the roll compaction is less than or equal to 1.5 g / cm 3 when K2 is less than 0.001, it indicates that the roll compaction is large, and the lithium supplement layer has a weak lithium intercalation effect, at this time, K2 is preferably equal to 0.001, in order to ensure that the power does not exceed the production capacity, the winding speed v1 of the pole piece needs to be reduced.
[0033] The ultrasonic cleaning power P1 and the CB value satisfy the relationship: P = [h-(CB-1)*K1]*v1 / K2.
[0034] The ultrasonic cleaning can clean the deep holes, fine seams and hidden places of the pole piece, has high cleaning precision, is simple to operate, easy to realize automatic control, improves the efficiency and consistency of the cleaning process, can efficiently remove the dust and impurities of the pole piece, effectively prevents the internal short circuit of the battery cell, has fast cleaning speed, improves the production efficiency, does not need to be contacted by hands, and is safe and reliable.
[0035] In the embodiment of the utility model, the thickness h of the lithium supplement layer 3 after the anode pole piece is rolled is 5-10 mu m. Specifically, it can be 5 mu m, 6 mu m, 7 mu m, 8 mu m, 9 mu m, 10 mu m, can include but not limited to the above listed values, and the utility model preferably is 5 mu m.
[0036] In an embodiment of the utility model, the thickness of the lithium supplement layer 3 is controlled by ultrasonic oscillation, and the thickness H of the lithium supplement layer 3 and the ultrasonic oscillation power P2 satisfy the relationship: H = K3*P2 / v2.
[0037] Wherein, the unit of P2 is W, v2 is the winding speed of the pole piece, and the unit is m / s, and K3 is the thickness empirical coefficient, and 0.001<=K3<=0.002.
[0038] In an embodiment of the utility model, the ultrasonic oscillation power P2 and the CB value satisfy the relationship: P2=(CB-1)*K1*v2 / K3. When K3 is less than 0.001, it indicates that the roll compaction is large, and the lithium supplement layer has a weak lithium intercalation effect, at this time, K3 is preferably equal to 0.001, in order to ensure that the power does not exceed the production capacity, the winding speed v1 of the pole piece needs to be reduced. When K3 is greater than 0.002, the roll compaction is small, at this time, K3 is preferably equal to 0.001, in order to ensure that the power does not exceed the production capacity, the winding speed v2 of the pole piece needs to be reduced.
[0039] The lithium supplement layer is coated by ultrasonic oscillation, lithium supplement agent is used as ultrasonic energy transmission medium, molecules of the medium are dispersed by using an ultrasonic generator, the density of the medium is reduced, the concentration of the lithium supplement agent is controlled, and the thickness of the lithium supplement layer is indirectly controlled.
[0040] In an embodiment of the present application, the CB value is 1.0-1.1; the reasonable CB value design is one of the key factors to ensure the performance and safety of the battery; the essence of the CB value is to ensure that the lithium vacancy provided by the anode can receive the active lithium ion provided by the cathode when the full battery is charged, to prevent the active lithium from being deposited and precipitated at the anode, and to ensure the safe operation of the battery.
[0041] In an embodiment of the present application, the thickness H of the lithium supplement layer is 0.01-0.2 μm, and can be 0.01 μm, 0.02 μm, 0.03 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.10 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.14 μm, 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.20 μm, and can include but is not limited to the above listed values.
[0042] In an embodiment of the present application, the anode active material layer comprises anode active substance, and the anode active substance comprises any one of graphite, silicon-carbon mixture, phosphorus-carbon mixture, nitride and lithium titanate.
[0043] In an embodiment of the present application, the lithium supplement layer contains lithium supplement agent, and the lithium supplement agent comprises any one of metallic lithium, lithium alloy, lithium powder and lithium oxide. The lithium foil is selected as the lithium supplement agent in the present application.
[0044] According to the second aspect of the present application, the present application further provides a lithium ion battery comprising a cathode sheet, an anode sheet, an electrolyte and a separator, wherein the anode sheet is the above-mentioned lithium supplement anode sheet. The preparation method of the lithium ion battery of the present application is known to those skilled in the art, and generally, the preparation method of the battery comprises placing the cell into the battery shell, adding the electrolyte, then sealing, and obtaining the battery.
[0045] In order to make the technical scheme and advantages of the present application clearer, the present application and its beneficial effects will be further described in detail below with reference to the specific embodiments and the accompanying drawings, but the embodiments of the present application are not limited thereto.
[0046] Unless otherwise specified, the raw materials used in the present application can be purchased from the market or commonly used in the art, and the methods in the following embodiments are conventional methods in the art unless otherwise specified.
[0047] Example 1
[0048] After the anode pole piece is coated with the anode active material graphite on the copper foil current collector 1, secondary rolling is performed, and lithium foil is uniformly coated on the anode active material layer 2 as a lithium supplement, and the lithium supplement layer 3 is rolled to a thickness of 5 μm; then the lithium supplement layer 3 is cleaned using an ultrasonic cleaning device, the cleaning agent is NMP solvent, the anode pole piece moves at a uniform speed under the ultrasonic cleaning device, and the winding speed of the pole piece during ultrasonic cleaning is consistent with the winding speed of the anode during secondary rolling, so that the thickness of the lithium supplement layer 3 satisfies the relationship formula H = (CB-1)*2 of the CB value of the design of the button cell per circle and the thickness of the lithium supplement layer of the anode pole piece, and the pole piece is dried after ultrasonic cleaning.
[0049] Among them, the CB value of the button cell designed per circle and the thickness of the lithium supplement layer of the anode pole piece are shown in Table 1.
[0050] Table 1
[0051]
[0052]
[0053] Preparation of lithium ion battery:
[0054] The anode pole piece, cathode pole piece, separator and electrolyte prepared above are made into a lithium ion battery according to a conventional process; wherein the cathode active material layer uses a cathode active substance of lithium nickel cobalt manganese oxide ternary material, the lithium salt of the electrolyte used is 1M LiPF6, and the solvent is EC:DEC:DMC 3:4:3; the separator is a PP film.
[0055] Example 2
[0056] The difference from Example 1 is that the lithium supplement is coated on the surface of the anode pole piece using an ultrasonic generator to form a lithium supplement layer, and no ultrasonic cleaning is performed.
[0057] The rest is the same as Example 1, which will not be repeated here.
[0058] Comparative Example 1
[0059] The difference from Example 1 is that after the lithium supplement is coated on the surface of the pole piece and rolled to a thickness of 5 μm, no ultrasonic cleaning is performed.
[0060] The rest is the same as Example 1, which will not be repeated here.
[0061] Comparative Example 2
[0062] The difference from Example 1 is that after the lithium supplement is coated on the surface of the pole piece and rolled to a thickness of 2 μm, no ultrasonic cleaning is performed.
[0063] The rest is the same as Example 1, which will not be repeated here.
[0064] Comparative Example 3
[0065] The difference from Example 1 is that the electrode assembly process is directly performed after the secondary rolling of the electrode sheet, and the electrode sheet is not pre-lithiated, that is, no lithium supplement is used on the surface of the anode electrode sheet.
[0066] The rest is the same as Example 1, which will not be repeated here.
[0067] The batteries prepared in the examples and comparative examples are respectively subjected to performance tests.
[0068] The first efficiency test: the sum of the charge capacity of the cell formation and the charge capacity of the cell sorting is compared with the full charge and discharge capacity of the sorting.
[0069] The lithium precipitation window test: the cell is directly charged to the design voltage of 4.4V at a rate of 3C, discharged to 3V at a rate of 0.5C, and cycled for 20 weeks. The cell is disassembled and observed whether there is lithium precipitation or purple stain on the anode interface under full charge.
[0070] The K value test: the voltage V1 of the cell at 50% SOC is measured, and the voltage V2 is measured after standing at room temperature for 3 days. K=(V1-V2) / 72, that is, the voltage drop per hour is mV / h.
[0071] The above test results are shown in Table 2.
[0072] Table 2
[0073]
[0074] Result analysis: from the above test results, it can be seen that the K value of the anode of Example 1 with the ultrasonic cleaning of the lithium supplement layer and the anode of Example 2 with the ultrasonic oscillation coating of the lithium supplement layer is smaller than that of the anode of Comparative Example 1 without ultrasonic cleaning of the lithium supplement layer and the anode of Comparative Example 2 without ultrasonic oscillation coating of the lithium supplement layer. The interface is disassembled without lithium precipitation and purple stain.
[0075] Compared with the anode without lithium supplement of Comparative Example 3, the first efficiency and K value have obvious advantages. It is proved that the cell with the ultrasonic cleaning of the lithium supplement layer process and the ultrasonic oscillation coating of the lithium supplement layer has improved stability and safety during the cell cycle.
[0076] Based on 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 based on the present application all belong to the protection scope of the present application. In addition, although some specific terms are used in the present application, these terms are only for convenience of explanation and do not constitute any limitation on the present application.
Claims
1. A lithium supplemented anode web, characterized in that, The lithium supplementing anode electrode sheet comprises: a current collector; an anode active material layer arranged on at least one surface of the current collector; a lithium supplementing layer arranged on an outer surface of the anode active material layer; wherein the thickness H of the lithium supplementing layer satisfies the relationship: H=(CB-1)*K1; wherein the unit of H is μm; K1 is a thickness coefficient, wherein 1≤K1≤3; and CB is the ratio of the capacity of the anode electrode sheet per unit area to the capacity of the cathode electrode sheet per unit area.
2. The lithium supplemented anode web of claim 1, wherein: The thickness of the lithium supplementing layer is controlled by ultrasonic cleaning, and the thickness H of the lithium supplementing layer and the ultrasonic cleaning power P1 satisfy the relationship: H=h-K2*P1 / v1; wherein the unit of P1 is W; h is the thickness of the lithium supplementing layer after the anode electrode sheet is rolled, and the unit is μm; v1 is the winding speed of the electrode sheet, and the unit is m / s; and K2 is a thickness empirical coefficient, wherein 0.001≤K2≤0.
002.
3. The lithium supplemented anode web of claim 2, wherein: The ultrasonic cleaning power P1 and the CB value satisfy the relationship: P1=[h-(CB-1)*K1]*v1 / K2.
4. The lithium supplemented anode web of claim 2, wherein: The thickness h of the lithium supplementing layer after the anode electrode sheet is rolled is 5-10 μm.
5. The lithium supplemented anode web of claim 1, wherein: The thickness of the lithium supplementing layer is controlled by ultrasonic oscillation, and the thickness H of the lithium supplementing layer and the ultrasonic oscillation power P2 satisfy the relationship: H=K3*P2 / v2; wherein the unit of P2 is W; v2 is the winding speed of the electrode sheet, and the unit is m / s; and K3 is a thickness empirical coefficient, wherein 0.001≤K3≤0.
002.
6. The lithium supplemented anode web of claim 5, wherein: The ultrasonic oscillation power P2 and the CB value satisfy the relationship: P2=(CB-1)*K1*v2 / K3.
7. The lithium supplemented anode web of any one of claims 1 to 6, characterized in that: The CB value is 1.01-1.1; and / or the thickness H of the lithium supplementing layer is 0.01-0.2 μm.
8. The lithium supplemented anode web of any one of claims 1-6, wherein: The anode active material layer comprises anode active substances, and the anode active substances comprise any one of graphite, silicon-carbon mixture, phosphorus-carbon mixture, nitride and lithium titanate.
9. The lithium supplemented anode web of any one of claims 1-6, wherein: The lithium supplementing layer contains a lithium supplementing agent, and the lithium supplementing agent comprises any one of metallic lithium, lithium alloy, lithium powder and lithium oxide.
10. A lithium-ion battery, characterized by: The lithium supplementing anode electrode sheet comprises the lithium supplementing anode electrode sheet according to any one of claims 1-9.