High-rate negative pole piece and preparation method thereof, sodium ion battery and electric equipment

Abstract

The invention relates to the technical field of sodium ion batteries, in particular to a high-rate negative electrode plate, a preparation method of the high-rate negative electrode plate, a sodium ion battery and electric equipment. The high-magnification negative electrode plate comprises a current collector and a negative electrode active layer, and the negative electrode active layer comprises a negative electrode active material, a conductive agent, a binder and a dispersing agent; the binder comprises polyacrylic acid, and the mass of the polyacrylic acid accounts for 0.01%-3% of the mass of the negative electrode active layer; and the sum of the mass of the binder and the mass of the dispersant accounts for 3-4.5% of the mass of the negative electrode active layer. A side chain of polyacrylic acid contains more functional groups and can form strong hydrogen bonds with the surface of a negative electrode active material, so that relatively strong adhesive force is provided, and meanwhile, the high-rate cycle performance of the battery is improved; moreover, by controlling the ratio of the binder to the dispersant, the stripping force of the negative pole piece can be improved, the flexibility of the negative pole piece can be improved, and the high-rate cycle of the battery can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a high-rate negative electrode plate and a preparation method thereof, a sodium ion battery and an electrical device. Background Art

[0002] Sodium-ion batteries have become an important alternative to lithium-ion batteries due to their abundant sodium resources, low cost, fast charging and discharging capabilities, and wide temperature range.

[0003] However, the negative electrode active materials (such as hard carbon) of sodium ion batteries face the following problems during high-rate charge and discharge: (1) Poor adhesion of the negative electrode slurry: The traditional binder system SBR+CMC has relatively poor adhesion, making it difficult to build an efficient and stable electron transport network, and the battery is prone to failure after high-rate cycling; (2) Poor interface stability, which accelerates capacity decay. Existing technologies have failed to solve the bottleneck of ion transport at high rates by adding carbon nanotubes to the negative electrode slurry to improve conductivity. Therefore, it is urgent to achieve coordinated optimization of electron / ion transport through innovation in the preparation of negative electrode sheets to improve the high-rate performance of sodium ion batteries.

[0004] In existing electrochemical systems, binders are key materials in battery anodes. Their primary function is to firmly bond the main anode materials together, preventing the active materials from falling off or separating during battery cell use. They also increase the contact area between materials, enhancing the conduction efficiency of electrons and ions, thereby improving the battery's power and energy density.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The first objective of the present invention is to provide a high-rate negative electrode sheet in which the polyacrylic acid side chains contain a large number of functional groups, which can form strong hydrogen bonds with the surface of the negative electrode active material, providing strong adhesion and improving the high-rate cycling performance of the battery. Furthermore, by controlling the ratio of the binder and dispersant, the peel force of the negative electrode sheet can be increased, improving the flexibility of the negative electrode sheet and further enhancing the high-rate cycling performance of the battery. This solves the problem of poor performance of sodium-ion batteries under high-rate and long-term cycling and capacity decay caused by poor interface stability under existing technologies.

[0007] The second object of the present invention is to provide a method for preparing a high-rate negative electrode sheet, which has a simple operation method, a short process, a low production cost, and is easy to achieve mass production.

[0008] A third object of the present invention is to provide a sodium ion battery having a long cycle life at high rates.

[0009] A fourth object of the present invention is to provide an electrical device.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0011] The present invention first provides a high-rate negative electrode plate, which includes a current collector and a negative electrode active layer. The negative electrode active layer includes a negative electrode active material, a conductive agent, a binder and a dispersant. The binder includes polyacrylic acid, wherein the mass of the polyacrylic acid accounts for 0.01% to 3% of the mass of the negative electrode active layer; the sum of the mass of the binder and the dispersant accounts for 3% to 4.5% of the mass of the negative electrode active layer.

[0012] Furthermore, the mass of the polyacrylic acid accounts for 1% to 3% of the mass of the negative electrode active layer.

[0013] Furthermore, the adhesive further comprises polyvinyl butyral and / or styrene butadiene rubber.

[0014] Furthermore, the mass of the polyvinyl butyral accounts for 0 to 0.5% of the mass of the negative electrode active layer.

[0015] Furthermore, the mass of the styrene-butadiene rubber accounts for 0-3% of the mass of the negative electrode active layer.

[0016] Furthermore, the dispersant includes carboxymethyl cellulose.

[0017] Furthermore, the mass of the dispersant accounts for 1% to 1.3% of the mass of the negative electrode active layer.

[0018] The present invention further provides a method for preparing a high-rate negative electrode sheet, comprising the following steps: coating a negative electrode slurry containing a negative electrode active material, a conductive agent, a binder and a dispersant on a current collector, and drying the mixture.

[0019] The present invention further provides a sodium ion battery, comprising a high-rate negative electrode plate.

[0020] The present invention also provides an electrical device comprising a sodium ion battery.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The high-rate negative electrode provided by the present invention uses polyacrylic acid, whose side chains contain a large number of functional groups. It can form strong hydrogen bonds with the surface of the negative electrode active material, providing strong adhesion and improving the high-rate cycle performance of the battery. In addition, by controlling the ratio of binder and dispersant, the peeling force of the negative electrode can be increased, the flexibility of the negative electrode can be improved, and the high-rate cycle performance of the battery can be further improved. This solves the problem of poor performance of sodium-ion batteries under high-rate long cycles and capacity decay caused by poor interface stability under existing technologies.

[0023] (2) The high-rate negative electrode provided by the present invention adopts polyacrylic acid and is combined with polyvinyl butyral and / or styrene-butadiene rubber, which not only improves the brittleness (flexibility) of the electrode, but also enhances the adhesion of the negative electrode slurry when it is coated on the electrode, firmly bonds the negative electrode main materials together, prevents the negative electrode active material from falling off or separating during the use of the battery cell, increases the contact area between the materials, and increases the conduction efficiency of electrons and ions, thereby improving the high-rate cycle performance of the battery.

[0024] (3) The use of the above-mentioned high-rate performance negative electrode can increase the capacity of the battery, thereby improving the ability of the sodium-ion battery to cycle for a long time at a high rate, and significantly improving the cycle life of the sodium-ion battery. 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 prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a schematic diagram of the flexibility test provided by the present invention. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0028] Unless otherwise specified, in the present invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," "third," and "fourth" serve only as non-exhaustive enumeration and description, and should not constitute closed-ended limitations on quantity.

[0029] Unless otherwise specified, the terms "include" and "comprising" used in the present invention may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0030] Unless otherwise specified, in the present invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0031] In a first aspect, the present invention provides a high-rate negative electrode plate, which includes a current collector and a negative electrode active layer arranged on the surface of the current collector, wherein the negative electrode active layer includes a negative electrode active material, a conductive agent, a binder and a dispersant.

[0032] Wherein, the binder includes polyacrylic acid (PAA), wherein the mass of the polyacrylic acid accounts for 0.01% to 3% of the mass of the negative electrode active layer; including but not limited to any one of 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3% or any range between two of them.

[0033] The sum of the masses of the binder and the dispersant accounts for 3% to 4.5% of the mass of the negative electrode active layer, including but not limited to any one of 3%, 3.2%, 3.3%, 3.5%, 3.8%, 4%, 4.2%, 4.3%, and 4.5%, or a range between any two of the values.

[0034] The polyacrylic acid side chain contains a large number of functional groups, which can form strong hydrogen bonds with the surface of the negative electrode active material, providing strong adhesion and improving the battery's high-rate cycling performance. Furthermore, by controlling the ratio of binder to dispersant, the peeling force of the electrode can be increased, improving the flexibility of the negative electrode, further enhancing the battery's high-rate cycling performance. This solves the problem of poor performance of sodium-ion batteries under high-rate and long-term cycling and capacity decay caused by poor interface stability under existing technologies.

[0035] In some specific embodiments, the mass of the polyacrylic acid accounts for 1% to 3% of the mass of the negative electrode active layer, which is beneficial for further improving the cycle life and retention rate of the battery at high rates.

[0036] In some specific embodiments, the binder further includes polyvinyl butyral (PVB) and / or styrene butadiene rubber (SBR).

[0037] Polyvinyl butyral has excellent softness and flexibility, which can alleviate problems such as the high glass transition temperature of PAA leading to high brittleness of the electrode.

[0038] In some specific embodiments, the mass of the polyvinyl butyral accounts for 0 to 0.5% of the mass of the negative electrode active layer, including but not limited to any one of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, or a range between any two of them.

[0039] In some specific embodiments, the mass of the styrene-butadiene rubber accounts for 0-3% of the mass of the negative electrode active layer, including but not limited to any one of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, and 3%, or a range between any two of them. Preferably, the mass of the styrene-butadiene rubber accounts for 0-2% of the mass of the negative electrode active layer.

[0040] The present invention adopts polyacrylic acid and is combined with a specific amount of polyvinyl butyral and / or styrene-butadiene rubber, which not only improves the brittleness (flexibility) of the electrode, but also enhances the adhesion of the negative electrode slurry when it is coated on the electrode, firmly bonds the negative electrode main materials together, prevents the negative electrode active material from falling off or separating during the use of the battery cell, increases the contact area between the materials, and increases the conduction efficiency of electrons and ions, thereby improving the high-rate cycle performance of the battery.

[0041] In some specific embodiments, the dispersant comprises carboxymethyl cellulose (CMC).

[0042] In some specific embodiments, the mass of the dispersant accounts for 1% to 1.3% of the mass of the negative electrode active layer, including but not limited to any one of 1%, 1.1%, 1.2%, and 1.3%, or a range between any two of them.

[0043] In some specific embodiments, the conductive agent includes conductive carbon black SP, but is not limited thereto.

[0044] In some specific embodiments, the negative electrode active material includes hard carbon, but is not limited thereto.

[0045] In a second aspect, the present invention provides a method for preparing the above-mentioned high-rate negative electrode sheet, comprising the following steps: coating a negative electrode slurry containing a negative electrode active material, a conductive agent, a binder and a dispersant on a current collector, and drying.

[0046] The operation method is simple, the process is short, the production cost is low, and batch production can be easily realized.

[0047] In some specific embodiments, the negative electrode slurry further includes a solvent.

[0048] In a third aspect, the present invention provides a sodium ion battery comprising a high-rate negative electrode plate.

[0049] The use of the above-mentioned high-rate performance negative electrode plate can increase the capacity of the battery, thereby improving the ability of the sodium-ion battery to cycle for a long time at high rates, and significantly improving the cycle life of the sodium-ion battery.

[0050] This high-rate negative electrode enables sodium-ion batteries to be used in a wider range of applications, making an important contribution to a more sustainable energy future.

[0051] In some specific embodiments, the sodium ion battery further includes a positive electrode plate, a separator and an electrolyte.

[0052] In a fourth aspect, the present invention provides an electrical device comprising a sodium ion battery.

[0053] The electrical equipment of the present invention is not particularly limited and may include, but is not limited to, the following types: laptop computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, etc.

[0054] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0055] Example 1

[0056] The method for preparing a high-rate negative electrode sheet and a sodium-ion battery provided in this embodiment includes the following steps:

[0057] (1) The sodium ion positive electrode material layered oxide Na 1.02 Cu 0.15 Fe 0.34 Mn 0.33 Mg 0.15 Ti 0.03 O2, conductive agent SP, conductive agent carbon nanotube CNT, binder PVDF, and additive oxalic acid are added to NMP solvent in a mass ratio of 95.8%:1.8%:0.5%:1.5%:0.4% respectively and stirred evenly to obtain a positive electrode slurry.

[0058] (2) The sodium ion negative electrode material hard carbon, conductive agent SP, binder SBR glue (dissolved in water, solid content 40%), auxiliary binder PAA, auxiliary binder PVB, dispersant CMC glue (dissolved in water, solid content 2%) were added to a mixed solvent of water and NMP at a mass ratio of 94.3%:1.4%:2.0%:1.0%:0%, 1.3% (based on dry weight, that is, the mass fraction of SBR in the binder SBR glue is 2.0%, and the mass fraction of CMC in the dispersant CMC glue is 1.3%), and stirred evenly to obtain a negative electrode slurry.

[0059] (3) The positive electrode slurry prepared in step (1) was coated on a 12 μm aluminum foil current collector, rolled, slit, and then rolled to obtain a positive electrode sheet; the surface density of the positive electrode sheet was 30 mg / cm 2 , compacted density is 3.25g / m 3 .

[0060] (4) The negative electrode slurry prepared in step (2) was coated on a 12 μm aluminum foil current collector, rolled, slit, and then rolled to obtain a negative electrode sheet with a surface density of 12.8 mg / cm 2 .

[0061] (5) A 16 μm thick polyethylene (PE) diaphragm is used to separate the positive electrode sheet and the negative electrode sheet and wind them together. After baking and ensuring the moisture content is qualified, the cylindrical 26700 battery cell is filled with liquid and sealed. The cylindrical cell is then converted into a sodium ion battery with electrochemical activity by chemical conversion.

[0062] In the high-rate negative electrode sheet prepared in this embodiment, the mass fraction of SBR is 2.0%, the mass fraction of PAA is 1.0%, the mass fraction of PVB is 0%, the mass fraction of CMC is 1.3%, and the total mass fraction of SBR, PAA, PVB and CMC is 4.3%.

[0063] Example 2

[0064] The preparation method of the high-rate negative electrode sheet and sodium-ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.0%, and the mass percentage of the auxiliary binder PAA is 2.0%.

[0065] Example 3

[0066] The preparation method of the high-rate negative electrode sheet and sodium-ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 0%, and the mass percentage of the auxiliary binder PAA is 3.0%.

[0067] Example 4

[0068] The preparation method of the high-rate negative electrode sheet and sodium-ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 0%, the mass percentage of the auxiliary binder PAA is 2.5%, and the mass percentage of the auxiliary binder PVB is 0.5%.

[0069] Example 5

[0070] The preparation method of the high-rate negative electrode plate and sodium ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.5%, the mass percentage of the auxiliary binder PAA is 1.5%, the mass percentage of the auxiliary binder PVB is 0%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0071] Example 6

[0072] The preparation method of the high-rate negative electrode plate and sodium ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.5%, the mass percentage of the auxiliary binder PAA is 1.5%, the mass percentage of the auxiliary binder PVB is 0.5%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0073] Example 7

[0074] The preparation method of the high-rate negative electrode plate and sodium ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.0%, the mass percentage of the auxiliary binder PAA is 1.5%, the mass percentage of the auxiliary binder PVB is 0%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0075] Example 8

[0076] The preparation method of the high-rate negative electrode plate and sodium ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.0%, the mass percentage of the auxiliary binder PAA is 1.5%, the mass percentage of the auxiliary binder PVB is 0.5%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0077] Example 9

[0078] The preparation method of the high-rate negative electrode plate and sodium ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.0%, the mass percentage of the auxiliary binder PAA is 1.0%, the mass percentage of the auxiliary binder PVB is 0%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0079] Example 10

[0080] The preparation method of the high-rate negative electrode plate and sodium-ion battery provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.0%, the mass percentage of the auxiliary binder PAA is 1.0%, the mass percentage of the auxiliary binder PVB is 0.5%, and the mass fraction of CMC in the dispersant CMC glue is 1.0%.

[0081] Comparative Example 1

[0082] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 2.5%, the mass percentage of the auxiliary binder PAA is 0%, and the mass percentage of the auxiliary binder PVB is 0.5%.

[0083] Comparative Example 2

[0084] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 2.0%, the mass percentage of the auxiliary binder PAA is 0%, and the mass percentage of the auxiliary binder PVB is 1.0%.

[0085] Comparative Example 3

[0086] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 1.5%, the mass percentage of the auxiliary binder PAA is 0%, and the mass percentage of the auxiliary binder PVB is 1.5%.

[0087] Comparative Example 4

[0088] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 3.0%, the mass percentage of the auxiliary binder PAA is 0%, and the mass percentage of the auxiliary binder PVB is 0%.

[0089] Comparative Example 5

[0090] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 0%, the mass percentage of the auxiliary binder PAA is 2.0%, and the mass percentage of the auxiliary binder PVB is 1.0%.

[0091] Comparative Example 6

[0092] The preparation method of the negative electrode plate and the sodium ion battery provided in this comparative example is basically the same as that in Example 1, except that: in step (2), the mass percentage of SBR in the binder SBR glue is 0%, the mass percentage of the auxiliary binder PAA is 1.5%, and the mass percentage of the auxiliary binder PVB is 1.5%.

[0093] In the negative electrode sheets prepared in each embodiment and each comparative example, the mass percentage of SBR is a (i.e., the mass fraction of SBR is a%), the mass percentage of PAA is b (i.e., the mass fraction of PAA is b%), the mass percentage of PVB is c (i.e., the mass fraction of PVB is c%), the mass percentage of CMC is d (i.e., the mass fraction of CMC is d%), and the sum of the mass percentages of SBR, PAA, PVB and CMC is s (i.e., s=a+b+c+d), where the values ​​of a, b, c, d and s are shown in Table 1, respectively.

[0094] Furthermore, the negative electrode sheets and sodium ion batteries prepared in the above-mentioned embodiments and comparative examples were subjected to the following tests: (1) At a temperature of 22-28°C and a humidity of ≤1.2%, the negative electrode sheets were subjected to a peeling force test, and the test results are shown in Table 1. (2) At a temperature of 22-28°C and a humidity of ≤1.2%, the negative electrode sheets were subjected to a flexibility test. The test method was to cut the rolled sheet into 5×20 cm strips, stack them end to end, and place them on a smooth surface, making sure that no creases appeared at the bends; Figure 1As shown, place the steel ruler vertically on the non-bending part of the electrode and slowly move it horizontally toward the bending part to observe the surface condition of the bending part; when a crease appears, stop moving the steel ruler and measure the distance h (crease distance) between the steel ruler and the crease. The smaller the h value, the better the flexibility. The test results are shown in Table 1. (3) At room temperature, the sodium ion battery was charged and discharged in the voltage range of 2 to 4.0 V and cycled at 2C / 2C. The discharge capacity retention rate of the sodium ion battery during the cycle was recorded. The test results are shown in Table 1. (4) At room temperature, the sodium ion battery was charged and discharged in the voltage range of 2 to 4.0 V and cycled at 3C / 3C. The discharge capacity retention rate of the sodium ion battery during the cycle was recorded. The test results are shown in Table 1.

[0095] Table 1 Values ​​of a, b, c, d, s, and test results of negative electrode and cell performance

[0096]

[0097]

[0098] As can be seen from Table 1, the negative electrode sheets prepared in each embodiment have a higher peel force, which indicates that the negative electrode sheets prepared in each embodiment have better adhesion. Furthermore, the sodium ion batteries prepared in each embodiment have a higher capacity retention rate at 2C / 2C and 3C / 3C, indicating that the sodium ion batteries prepared in each embodiment have better cycle performance at high rates. At the same time, compared with Examples 5, 7, and 9, the flexibility of the negative electrode sheets prepared after adding 0.5% PVB in Examples 6, 8, and 10 is significantly improved, which can achieve a good balance between cycle performance and flexibility.

[0099] However, since no PAA was added to the negative electrode sheets prepared in Comparative Examples 1 to 4, the peeling force of the negative electrode sheets decreased compared with Example 1, and the cycle performance of the sodium ion battery at high rate was significantly reduced.

[0100] At the same time, compared with Example 1, the negative electrode sheets prepared in Comparative Examples 5 to 6 have a PVB content higher than 0.5%, which results in a decrease in the peeling force of the negative electrode sheets and a decrease in the cycle performance of the sodium ion battery under 3C / 3C.

[0101] In summary, the high-rate negative electrode sheet provided by the present invention can significantly improve the cycle life of the battery at high rates, and improve the peeling force of the negative electrode sheet and the flexibility of the negative electrode sheet.

[0102] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A high-rate negative electrode plate, characterized in that: The high-rate negative electrode sheet includes a current collector and a negative electrode active layer, and the negative electrode active layer includes a negative electrode active material, a conductive agent, a binder and a dispersant; The binder comprises polyacrylic acid, wherein the mass of the polyacrylic acid accounts for 0.01% to 3% of the mass of the negative electrode active layer; The sum of the mass of the binder and the dispersant accounts for 3% to 4.5% of the mass of the negative electrode active layer.

2. The high-rate negative electrode sheet according to claim 1, characterized in that: The mass of the polyacrylic acid accounts for 1% to 3% of the mass of the negative electrode active layer.

3. The high-rate negative electrode sheet according to claim 1, characterized in that: The binder further comprises polyvinyl butyral and / or styrene butadiene rubber.

4. The high-rate negative electrode sheet according to claim 3, characterized in that: The mass of the polyvinyl butyral accounts for 0 to 0.5% of the mass of the negative electrode active layer.

5. The high-rate negative electrode sheet according to claim 3, characterized in that: The mass of the styrene-butadiene rubber accounts for 0-3% of the mass of the negative electrode active layer.

6. The high-rate negative electrode sheet according to any one of claims 1 to 5, characterized in that: The dispersant includes carboxymethyl cellulose.

7. The high-rate negative electrode sheet according to any one of claims 1 to 5, characterized in that: The mass of the dispersant accounts for 1% to 1.3% of the mass of the negative electrode active layer.

8. The method for preparing a high-rate negative electrode sheet according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: coating a negative electrode slurry containing a negative electrode active material, a conductive agent, a binder and a dispersant on a current collector, and drying the negative electrode slurry.

9. A sodium ion battery, characterized in that: It comprises the high-rate negative electrode sheet as claimed in any one of claims 1 to 7.

10. An electrical device, characterized in that: Comprising the sodium ion battery as claimed in claim 9.

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