Lithium supplement agent, preparation method thereof and battery

Abstract

The invention discloses a lithium supplement agent, a preparation method thereof and a battery, and belongs to the technical field of battery materials. The lithium supplement agent comprises a porous spongy substrate and lithium salt filled in the surface and pores of the porous spongy substrate, wherein the porous spongy substrate contains a thickening agent, conductive carbon black and a modified catalyst. The modified catalyst is obtained by sintering at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide with graphene or carbon nanotubes; the lithium salt comprises at least two of lithium hydroxide, lithium carbonate and lithium oxalate. The lithium supplement agent is stable in structure, the first sufficient solution voltage can be as low as 4.0 V, and the preparation method is simple and suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a lithium supplement and a preparation method thereof, and a battery. Background Art

[0002] Lithium replenishers are functional additives that, through precise lithium replenishment, can maximize the potential of positive and negative electrode materials. Even minimal amounts can effectively improve battery performance, making them suitable for lithium battery materials in various systems. Lithium replenishers are primarily categorized as positive and negative electrode replenishers, depending on the method used. Positive electrode replenishment typically utilizes an electrochemical method, adding materials to the positive electrode that release active lithium through material decomposition during charging. Negative electrode replenishment, on the other hand, involves a variety of techniques, including self-discharge replenishment, physical replenishment, chemical replenishment, and electrochemical replenishment.

[0003] Lithium replenishment for the positive electrode is relatively simple and can be added during the homogenization of the positive electrode slurry, without the need for additional process improvements and at a low cost. There are two main categories of positive electrode lithium replenishers. One is lithium-rich inorganic substances, such as lithium nickelate and lithium ferrite. These lithium replenishers produce oxygen during replenishment, and the free nano-scale metal oxides remaining on the positive electrode side after replenishment can decompose the electrolyte, leading to battery degradation in the later stages of the cycle. The other is organic lithium salts, such as lithium oxalate, which have a high decomposition voltage and require the addition of a catalyst. Furthermore, the free nano-scale catalyst particles released after replenishment can decompose the electrolyte, leading to battery degradation in the later stages of the cycle.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The object of the present invention is to provide a lithium supplement and a preparation method thereof and a battery to solve or improve the above technical problems.

[0006] The present invention can be achieved like this:

[0007] In a first aspect, the present invention provides a lithium supplement agent, which includes a porous sponge-like substrate and a lithium salt filled in the surface and pores of the porous sponge-like substrate; wherein the porous sponge-like substrate contains a thickener, conductive carbon black and a modified catalyst, and the modified catalyst is derived from the sintering of at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide with graphene or carbon nanotubes; and the lithium salt includes at least two of lithium hydroxide, lithium carbonate and lithium oxalate.

[0008] In an optional embodiment, the lithium supplement has at least one of the following characteristics:

[0009] Feature 1: The mass ratio of conductive carbon black to lithium salt is (0.15-1):1;

[0010] Feature 2: The mass ratio of the modified catalyst to the lithium salt is (0.03-0.15):1;

[0011] Feature 3: The mass ratio of thickener to lithium salt is (0.001-0.025):1;

[0012] Feature 4: The thickener is a water-soluble thickener; preferably, the thickener comprises at least one of styrene-butadiene rubber, polyacrylic acid, and sodium carboxymethyl cellulose;

[0013] Feature 5: The conductive carbon black includes at least one of Super P, Cabot Black BP2000, Ketjen Black EJ-300J, and Ketjen Black ECP-600JD;

[0014] Feature 6: The single particle size of the modified catalyst is 5nm to 60nm;

[0015] Feature 7: The lithium salt is in the form of fragments; preferably, the particle size of the fragmented lithium salt is 0.8 μm to 10 μm.

[0016] In a second aspect, the present invention provides a method for preparing a lithium supplement as described in the aforementioned embodiment, comprising the following steps: adding conductive carbon black and a modified catalyst to an aqueous solution of a thickener, then adding dihydrated oxalic acid and anhydrous lithium hydroxide and mixing to obtain a mixed slurry; and baking and crushing the mixed slurry.

[0017] In an optional embodiment, the mass ratio of oxalic acid dihydrate to anhydrous lithium hydroxide is (2-2.5):1;

[0018] In an optional embodiment, the baking temperature is 80°C to 180°C.

[0019] In an optional embodiment, the modified catalyst is obtained by mixing the catalytic raw material and the carrier and then sintering;

[0020] The catalytic raw materials include at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide, and the carrier includes graphene or carbon nanotubes.

[0021] In an optional embodiment, the mass ratio of the catalytic raw material to the carrier is (6-10):1;

[0022] and / or, the catalytic raw material contains at least cobalt nitrate or nickel nitrate;

[0023] And / or, the titanium dioxide is nano-sized; preferably, the particle size of the titanium dioxide is less than 30 nm;

[0024] And / or, the graphene is multilayer graphene; preferably, the number of layers of the multilayer graphene is 6 to 10;

[0025] And / or, the carbon nanotubes are single-walled carbon nanotubes; preferably, the single-walled carbon nanotubes have a diameter of 1 nm to 3 nm and a tube length of 6 μm to 20 μm.

[0026] In an optional embodiment, the sintering temperature is 400° C. to 1000° C.; the sintering atmosphere is a nitrogen atmosphere; and the sintering time is 1 hour to 8 hours.

[0027] In a third aspect, the present invention provides a battery comprising the lithium supplement according to the aforementioned embodiment.

[0028] The beneficial effects of the present invention include:

[0029] In the lithium supplement agent provided by the present invention, the lithium salt is tightly bonded to the interior and surface of the porous sponge-like substrate, resulting in a stable structure. After lithium supplementation, the lithium salt decomposes, but the modified catalyst in the porous sponge-like substrate is not released. This not only helps to increase the energy density of the battery, but also helps to improve the battery's cycle life. Furthermore, the lithium supplement agent has a low decomposition voltage, can quickly exert its lithium supplementation effect, has good lithium supplementation effect, and can effectively alleviate the problem of battery water drop in late cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a SEM image of the lithium supplement prepared in Example 1 of the present invention;

[0032] Figure 2 This is a SEM image of the positive electrode sheet obtained by further preparing the lithium supplement agent prepared in Example 1 of the experimental example after the positive electrode sheet was first charged to 4.6V. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0034] The lithium supplement agent, preparation method thereof, and battery provided by the present invention are described in detail below.

[0035] The present invention provides a lithium supplement agent, which comprises a porous sponge-like substrate and a lithium salt filled on the surface and in the pores of the porous sponge-like substrate.

[0036] The porous sponge-like substrate contains a thickener, conductive carbon black, and a modified catalyst, wherein the modified catalyst is obtained by sintering at least three of cobalt nitrate, nickel nitrate, calcium nitrate, and titanium dioxide with graphene or carbon nanotubes. The lithium salt includes at least two of lithium hydroxide, lithium carbonate, and lithium oxalate.

[0037] In the aforementioned lithium supplement, the thickener provides viscosity, bonding the conductive carbon black, modified catalyst, and lithium salt together. It also makes the lithium supplement brittle after drying, forming a loose, cracked, and agglomerated solid, which facilitates subsequent crushing and fine grinding. The conductive carbon black primarily enhances conductivity. The modified catalyst lowers the decomposition voltage of the lithium supplement, allowing for rapid onset of action. Furthermore, the graphene or carbon nanotubes contained in the modified catalyst not only support the catalytic material but, combined with the thickener's curing effect, effectively prevent the modified catalyst from releasing or falling off. Furthermore, the graphene or carbon nanotubes, along with the conductive carbon black, enhance the lithium supplement's conductivity.

[0038] In the above-mentioned lithium replenisher, the lithium salt is tightly compounded with the interior and surface of the porous sponge-like substrate and has a stable structure. After the lithium replenishment is completed, the lithium salt decomposes, but the modified catalyst in the porous sponge-like substrate is not released, which is beneficial to improving the energy density of the battery and the cycle life of the battery. The decomposition voltage of the lithium replenisher can be as low as 4.0V, which can quickly play a role in lithium replenishment.

[0039] In some optional embodiments, the mass ratio of conductive carbon black to lithium salt can be (0.15-1):1, such as 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1 or 1:1, etc., or it can be other values within the range of (0.15-1):1.

[0040] If the amount of conductive carbon black is too small, it will be detrimental to the decomposition of the lithium supplement agent and will increase the potential of lithium desorption; if the amount of conductive carbon black is too much, it will reduce the effect of the lithium supplement agent and the improvement of the battery's cycle performance will be limited.

[0041] The mass ratio of the modified catalyst to the lithium salt can be (0.03-0.15):1, such as 0.03:1, 0.04:1, 0.05:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.10:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, or 0.15:1, or other values within the range of (0.03-0.15):1.

[0042] If the amount of modified catalyst is too small, it will be difficult to lower the decomposition voltage of the lithium supplement agent, and it will also easily lead to incomplete decomposition of the lithium salt; if the amount of modified catalyst is too much, it will easily lead to decomposition of the electrolyte and subsequent battery cycle failure.

[0043] The mass ratio of the thickener to the lithium salt may be (0.001-0.025):1, such as 0.001:1, 0.005:1, 0.010:1, 0.015:1, 0.020:1 or 0.025:1, or other values within the range of (0.001-0.025):1.

[0044] If the amount of thickener is too small, the conductive carbon black, modified catalyst and lithium salt cannot be solidified together. During oven drying, the components will precipitate one after another and agglomerate into lumps. If the amount of thickener is too much, the viscosity of the system will be too high, and it will not be possible to mix them evenly during stirring.

[0045] In some optional embodiments, the thickener is a water-soluble thickener, for example, may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA) and sodium carboxymethyl cellulose (CMC-Na).

[0046] The conductive carbon black may include, for example, at least one of Super P, Cabot Black BP2000, Ketjen Black EJ-300J, and Ketjen Black ECP-600JD.

[0047] In some optional embodiments, the single particle size of the modified catalyst can be 5nm to 60nm, such as 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm or 60nm, etc., or other values within the range of 5nm to 60nm.

[0048] If the single particle size of the modified catalyst is too small, it is easy to agglomerate and difficult to disperse, which is not conducive to uniform mixing; if the single particle size of the modified catalyst is too large, it is not conducive to contact with the lithium salt and its surface area is too small.

[0049] In some preferred embodiments, to ensure full coverage and tight binding of the lithium salt, the substances in the modified catalyst exist in both a composite form and an independent free form. In some embodiments, the modified catalyst is in the form of metallic cobalt, metallic nickel, etc., composited with graphene or carbon nanotubes, or in the form of cobalt tetroxide, cobalt monoxide, metallic cobalt, nickel monoxide, metallic nickel, titanium dioxide, cobalt titanate, calcium titanate, and nickel titanate, etc., existing independently and free.

[0050] In some optional embodiments, the lithium salt is in the form of fragments. Preferably, the particle size of the fragmented lithium salt can be 0.8 μm to 10 μm, such as 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or other values within the range of 0.8 μm to 10 μm.

[0051] The above-mentioned fragmented lithium salt is more conducive to decomposition. Because this process has a step of heating to remove the solvent, the small-particle lithium salt will grow, so it is difficult to obtain nano-scale lithium salt stably; if the particle size of the fragmented lithium salt is too large, it is not conducive to decomposition, and the pores after decomposition are too large, which is not conducive to the stability of the electrode structure.

[0052] As mentioned above, the lithium replenisher provided by the present invention has a low decomposition voltage, can quickly exert its lithium replenishment effect, has good lithium replenishment effect, can significantly improve the cycle performance of the battery, and can also maintain a stable structure and good conductive path after the battery reaction is complete, so as to stably exert electrical performance. This lithium replenisher is suitable not only for lithium-ion batteries but also for lithium solid-state battery systems.

[0053] Accordingly, the present invention also provides a method for preparing the lithium supplement, comprising the following steps: adding conductive carbon black and a modified catalyst to an aqueous solution of a thickener, then adding dihydrated oxalic acid and anhydrous lithium hydroxide and mixing to obtain a mixed slurry; and baking the mixed slurry. After baking, the mixed slurry may be further pulverized.

[0054] The mixed slurry is baked and dehydrated to obtain a porous sponge-like substrate and a lithium salt filled on the surface and in the pores of the porous sponge-like substrate. The conductive carbon black, the modified catalyst and the thickener together form a cross-linked porous sponge-like substrate.

[0055] The mass ratio of oxalic acid dihydrate to anhydrous lithium hydroxide can be (2-2.5):1, such as 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, or 2.5:1, or other values within the range of (2-2.5):1. By controlling the excess of anhydrous lithium hydroxide, a portion of the anhydrous lithium hydroxide reacts with oxalic acid dihydrate to form lithium oxalate, and the remaining anhydrous lithium hydroxide forms lithium carbonate during the baking process, thereby ensuring that the lithium salt has at least two components.

[0056] In some preferred embodiments, the amounts of the above substances can be adjusted so that the mass ratio of conductive carbon black to lithium salt in the lithium supplement is (0.15-1):1, the mass ratio of modified catalyst to lithium salt is (0.03-0.15):1, and the mass ratio of thickener to lithium salt is (0.001-0.025):1.

[0057] In some optional embodiments, after the addition of oxalic acid dihydrate and anhydrous lithium hydroxide, all materials can be mixed together for 1 hour to 8 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours, or other values within the range of 1 hour to 8 hours. Mixing can be achieved using any of a ball mill, a sand mill, a high-speed dispersing disk, and the like.

[0058] In some optional embodiments, the solid content of the mixed slurry is not less than 20 wt %.

[0059] In some optional embodiments, the baking temperature may be 80°C to 180°C, such as 80°C, 100°C, 120°C, 140°C, 160°C or 180°C, or other values within the range of 80°C to 180°C.

[0060] In some optional embodiments, the modified catalyst is obtained by mixing a catalytic raw material and a carrier and then sintering them, wherein the catalytic raw material includes at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide, and the carrier includes graphene or carbon nanotubes.

[0061] In some optional embodiments, the mass ratio of the catalytic raw material to the carrier can be (6-10):1, such as 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1 or 10:1, or other values within the range of (6-10):1.

[0062] In some preferred embodiments, the catalytic raw material contains at least cobalt nitrate or nickel nitrate.

[0063] In some optional embodiments, the titanium dioxide is nano-sized. Preferably, the particle size of the titanium dioxide is less than 30 nm.

[0064] In some preferred embodiments, the graphene is multilayer graphene; in some more preferred embodiments, the number of layers of the multilayer graphene is 6 to 10 layers.

[0065] In some preferred embodiments, the carbon nanotubes are single-walled carbon nanotubes; in some more preferred embodiments, the single-walled carbon nanotubes have a diameter of 1 nm to 3 nm and a tube length of 6 μm to 20 μm.

[0066] In some optional embodiments, the sintering temperature may be 400° C. to 1000° C., such as 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., or 1000° C., or other values within the range of 400° C. to 1000° C. Cobalt nitrate, nickel nitrate, calcium nitrate, and titanium dioxide may be sintered with graphene or carbon nanotubes to obtain various mixtures including cobalt tetroxide, cobalt monoxide, metallic cobalt, nickel monoxide, metallic nickel, titanium dioxide, cobalt titanate, calcium titanate, and nickel titanate.

[0067] The sintering atmosphere is a nitrogen atmosphere. The sintering time can be 1 hour to 8 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, or other values within the range of 1 hour to 8 hours.

[0068] As mentioned above, the preparation method of the lithium supplement provided by the present invention does not rely on freeze-drying or spray-drying of low-concentration solutions. The materials in the mixed slurry (solid content can be not less than 20wt%) are directly mechanically mixed, and then subjected to blast drying and crushing to obtain the lithium supplement. This method is simple and efficient, and can ensure stable and reliable production even for 10,000-ton-level lithium supplements.

[0069] In addition, the present invention also provides a battery containing the lithium supplement, and the battery can have a long cycle life.

[0070] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0071] Example 1

[0072] This embodiment provides a lithium supplement, the preparation method of which includes:

[0073] S1: Preparation of modified catalyst.

[0074] In 200 mL of pure water, 60 g of cobalt nitrate hexahydrate, 10 g of nickel nitrate hexahydrate, 0.3 g of titanium dioxide and 10 g of graphene were stirred and mixed for 0.5 h, and then sintered in a tube furnace at 450° C. under a nitrogen atmosphere for 1 h to obtain a modified catalyst.

[0075] The graphene is multilayer graphene with 6 to 10 layers. The titanium dioxide particle size is 30 nm. The single particle size of the modified catalyst is 5 nm to 60 nm, with an average particle size of 18 nm.

[0076] S2: preparing mixed slurry, baking and crushing.

[0077] Take 1g of sodium carboxymethyl cellulose (CMC2200) and put it into 200mL of deionized water. Stir for 10 minutes until it is completely dissolved. Then add 30g of Cabot carbon black BP2000, 10g of modified catalyst and 200mL of deionized water. After stirring for 0.5h, add 240g of oxalic acid dihydrate, 100g of anhydrous lithium hydroxide and 200g of deionized water. After stirring for 8h, a mixed slurry is obtained. The mixed slurry is baked in a forced air oven at 80°C overnight. Finally, the dried agglomerates are crushed to obtain a lithium supplement.

[0078] The SEM image of the lithium supplement prepared in this example is as follows: Figure 1 As shown by Figure 1 It can be seen that the lithium supplement comprises a porous sponge-like substrate and a lithium salt filled in the surface and pores of the porous sponge-like substrate, wherein the lithium salt is in the form of fragments with an average particle size of 1 μm to 2 μm.

[0079] In this lithium supplement, the mass ratio of conductive carbon black to lithium salt is 0.15:1; the mass ratio of modified catalyst to lithium salt is 0.05:1; and the mass ratio of thickener to lithium salt is 0.005:1. The modified catalyst contained in the porous sponge-like substrate includes cobalt tetroxide, cobalt monoxide, metallic cobalt, nickel monoxide, metallic nickel, titanium dioxide, and graphene (cobalt tetroxide, cobalt monoxide, metallic cobalt, nickel monoxide, metallic nickel, and titanium dioxide may all exist in free form). The lithium salt contained in the porous sponge-like substrate includes lithium hydroxide, lithium carbonate, and lithium oxalate.

[0080] Example 2

[0081] The difference between this embodiment and embodiment 1 is that in S2, the baking temperature of the blast oven is 120°C.

[0082] Example 3

[0083] The difference between this embodiment and embodiment 1 is that in S2, the baking temperature of the blast oven is 160°C.

[0084] Example 4

[0085] The difference between this embodiment and embodiment 1 is that in S2, a mixed slurry is obtained after stirring for 4 hours.

[0086] Example 5

[0087] The difference between this embodiment and embodiment 1 is that in S2, a mixed slurry is obtained after stirring for 2 hours.

[0088] Example 6

[0089] The difference between this embodiment and embodiment 1 is that: 250 g of oxalic acid dihydrate is added to S2.

[0090] Example 7

[0091] The difference between this embodiment and embodiment 1 is that: 220 g of oxalic acid dihydrate is added to S2.

[0092] Example 8

[0093] The difference between this embodiment and embodiment 1 is that 6 g of modified catalyst is added to S2, and the mass ratio of modified catalyst to lithium salt is 0.03:1.

[0094] Example 9

[0095] The difference between this embodiment and embodiment 1 is that 24 g of modified catalyst was added to S2, and the mass ratio of modified catalyst to lithium salt was 0.12:1.

[0096] Example 10

[0097] The difference between this embodiment and embodiment 1 is that 0.6 g of sodium carboxymethyl cellulose is added to S2, and the mass ratio of thickener to lithium salt is 0.003:1.

[0098] Example 11

[0099] The difference between this embodiment and embodiment 1 is that 1 g of sodium carboxymethyl cellulose and 1 g of polyacrylic acid are added to S2, and the mass ratio of thickener to lithium salt is 0.01:1.

[0100] Example 12

[0101] The difference between this embodiment and embodiment 1 is that: in S1, 40g of cobalt nitrate hexahydrate, 30g of nickel nitrate hexahydrate, 0.3g of titanium dioxide and 10g of graphene are added. The single particle size of the modified catalyst is 5nm to 60nm, and the average particle size is 14nm.

[0102] Example 13

[0103] The difference between this embodiment and embodiment 1 is that 10 g of cobalt nitrate hexahydrate, 60 g of nickel nitrate hexahydrate, 0.3 g of titanium dioxide, and 10 g of carbon nanotubes were added to S1. The single particle size of the modified catalyst was 5 nm to 60 nm, with an average particle size of 10 nm.

[0104] Example 14

[0105] The difference between this embodiment and embodiment 1 is that in S1, the sintering time is 2 hours. The single particle size of the modified catalyst is 5 nm to 60 nm, and the average particle size is 31 nm.

[0106] Example 15

[0107] This embodiment differs from Example 1 in that, in S1, the sintering temperature is 650°C. The modified catalyst contained in the porous sponge-like substrate includes cobalt tetroxide, cobalt monoxide, metallic cobalt, nickel monoxide, metallic nickel, titanium dioxide, cobalt titanate, nickel titanate, and graphene. The lithium salt contained in the porous sponge-like substrate includes lithium hydroxide, lithium carbonate, and lithium oxalate. The individual particles of the modified catalyst range from 5 nm to 60 nm, with an average particle size of 58 nm.

[0108] Comparative Example 1

[0109] This comparative example provides a lithium supplement, the preparation method of which comprises:

[0110] S1: preparing catalyst.

[0111] 10 g of commercial cobalt trioxide (particle size of 30 nm) was weighed and dried in an oven at 105° C. for 1 h to obtain a catalyst.

[0112] S2: Prepare mixed slurry and spray dry.

[0113] 40 g of commercial anhydrous lithium oxalate was weighed and dissolved in 600 mL of deionized water, and then 8 g of catalyst and 1 g of Ketjen black were added. After uniform dispersion, the mixture was spray-dried at a flow rate of 4 mL / min at 230 ° C to obtain a lithium oxalate lithium supplement.

[0114] Comparative Example 2

[0115] This comparative example provides a lithium supplement, the preparation method of which comprises:

[0116] S1: preparing catalyst.

[0117] 10 g of commercial nickel oxide (particle size of 30 nm) was weighed and dried in an oven at 105° C. for 1 h to obtain a catalyst.

[0118] S2: Prepare mixed slurry and spray dry.

[0119] 40 g of commercial anhydrous lithium oxalate was weighed and dissolved in 600 mL of deionized water, and then 8 g of catalyst and 1 g of Ketjen black were added. After uniform dispersion, the mixture was spray-dried at a flow rate of 4 mL / min at 230 ° C to obtain a lithium oxalate lithium supplement.

[0120] Comparative Example 3

[0121] This comparative example provides a lithium supplement, the preparation method of which comprises:

[0122] S1: preparing catalyst.

[0123] 5 g of commercial cobalt trioxide (particle size of 30 nm) and 5 g of commercial nickel oxide (particle size of 30 nm) were weighed and dried in an oven at 105° C. for 1 h to obtain a catalyst.

[0124] S2: Prepare mixed slurry and spray dry.

[0125] 40 g of commercial anhydrous lithium oxalate was weighed and dissolved in 600 mL of deionized water, and then 8 g of catalyst and 1 g of Ketjen black were added. After uniform dispersion, the mixture was spray-dried at a flow rate of 4 mL / min at 230 ° C to obtain a lithium oxalate lithium supplement.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 1 is that 0.6 g of modified catalyst was added to S2, and the mass ratio of the modified catalyst to the lithium salt was 0.003:1.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 1 is that in S1, no carrier (graphene or carbon tube) is used.

[0130] Comparative Example 6

[0131] The difference between this comparative example and Example 1 is that in S2, no thickener is used.

[0132] Test example

[0133] The lithium supplement prepared in Examples 1-16 and Comparative Examples 1-6 was applied to the positive electrode of a button cell battery, with the addition ratios being 90 wt% of the lithium supplement, 5 wt% of PVDF, and 5 wt% of Super P. The negative electrode consisted of a lithium sheet. After assembly, the battery was maintained at a constant temperature of 45°C and initially charged at a constant current of 0.2C to 4.6V. The button cells were tested using an electrochemical test channel for performance, including decomposition voltage and specific capacity. The water content of the lithium supplement in parts per million (ppm) was determined using Karl Fischer titration with a moisture analyzer.

[0134] Table 1 Test results

[0135]

[0136]

[0137] It can be seen from Table 1 that the lithium supplement provided by Examples 1 to 16 of the present invention can have a lower decomposition voltage than the lithium supplement provided by Comparative Examples 1 to 6. Examples 1 to 4, Examples 6 to 7, Example 13 and Example 16 can have a lower decomposition voltage than the lithium supplement provided by Comparative Examples 1 to 6 while also having a higher gram capacity, and can effectively improve the problem of high water content in the lithium supplement. After the first charge to 4.6V, the positive electrode plate is taken for an electron microscope photograph to show that the electrode structure can still maintain structural stability and maintain a conductive path after the lithium supplement reaction is complete. Figure 2 shown.

[0138] As can be seen from Example 1 and Comparative Examples 1 to 3, the catalytic raw material is first compounded with the carrier to prepare a modified catalyst, and then the modified catalyst is mixed with a thickener, conductive carbon black, dihydrated oxalic acid and anhydrous lithium hydroxide and baked. This can be done more directly than directly mixing the catalytic raw material with anhydrous lithium oxalate and conductive carbon black and then drying. This is more conducive to reducing the decomposition voltage of the lithium supplement agent, improving the low-voltage decomposition efficiency and improving the gram capacity of the lithium supplement agent. In addition, its production process saves water, has high output, requires low equipment investment, and is environmentally friendly.

[0139] In summary, the lithium replenisher provided by the present invention has a low decomposition voltage, can quickly play a lithium replenishing role, has a good lithium replenishing effect, can significantly improve the cycle performance of the battery, and after the battery reaction is complete, it can also maintain a stable structure and a good conductive path, and stably exert electrical performance.

[0140] In summary, the lithium replenisher provided by the present invention has a low decomposition voltage, can quickly play a lithium replenishing role, has a good lithium replenishing effect, can significantly improve the cycle performance of the battery, and after the battery reaction is complete, it can also maintain a stable structure and a good conductive path, and stably exert electrical performance.

[0141] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A lithium supplement, characterized in that: The lithium supplement comprises a porous sponge-like substrate and a lithium salt filled in the surface and pores of the porous sponge-like substrate; wherein the porous sponge-like substrate contains a thickener, conductive carbon black and a modified catalyst; the modified catalyst is derived from the sintering of at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide with graphene or carbon nanotubes; and the lithium salt comprises at least two of lithium hydroxide, lithium carbonate and lithium oxalate.

2. The lithium supplement according to claim 1, characterized in that The lithium supplement has at least one of the following characteristics: Feature 1: The mass ratio of the conductive carbon black to the lithium salt is (0.15-1):1; Feature 2: The mass ratio of the catalyst to the lithium salt is (0.03-0.15):1; Feature 3: The mass ratio of the thickener to the lithium salt is (0.001-0.025):1; Feature 4: The thickener is a water-soluble thickener; preferably, the thickener includes at least one of styrene-butadiene rubber, polyacrylic acid, and sodium carboxymethyl cellulose; Feature 5: The conductive carbon black includes at least one of Super P, Cabot Black BP2000, Ketjen Black EJ-300J, and Ketjen Black ECP-600JD; Feature 6: The single particle size of the modified catalyst is 5nm to 60nm; Feature 7: The lithium salt is in the form of fragments; preferably, the particle size of the fragmented lithium salt is 0.8 μm to 10 μm.

3. A method for preparing the lithium supplement according to claim 1 or 2, characterized in that: The method comprises the following steps: adding conductive carbon black and a modified catalyst into a thickener aqueous solution, then adding dihydrated oxalic acid and anhydrous lithium hydroxide and mixing them to obtain a mixed slurry; and baking and crushing the mixed slurry.

4. The preparation method according to claim 3, characterized in that The mass ratio of the oxalic acid dihydrate to the anhydrous lithium hydroxide is (2-2.5):

1.

5. The preparation method according to claim 3, characterized in that The baking temperature is 80℃~180℃.

6. The preparation method according to claim 3, characterized in that The modified catalyst is obtained by mixing a catalytic raw material and a carrier and then sintering; The catalytic raw materials include at least three of cobalt nitrate, nickel nitrate, calcium nitrate and titanium dioxide, and the carrier includes graphene or carbon nanotubes.

7. The preparation method according to claim 6, characterized in that The mass ratio of the catalytic raw material to the carrier is (6-10):

1.

8. The preparation method according to claim 6, characterized in that The catalytic raw material contains at least cobalt nitrate or nickel nitrate; And / or, the titanium dioxide is nano-sized; preferably, the particle size of the titanium dioxide is less than 30 nm; And / or, the graphene is multilayer graphene; preferably, the number of layers of the multilayer graphene is 6 to 10; And / or, the carbon nanotubes are single-walled carbon nanotubes; preferably, the single-walled carbon nanotubes have a diameter of 1 nm to 3 nm and a tube length of 6 μm to 20 μm.

9. The preparation method according to claim 7, characterized in that The sintering temperature is 400° C. to 1000° C.; the sintering atmosphere is a nitrogen atmosphere; and the sintering time is 1 hour to 8 hours.

10. A battery, characterized in that: The battery contains the lithium supplement according to claim 1 or 2.

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