Negative electrode active slurry, negative electrode sheet of battery, and lithium-ion secondary battery

Abstract

A negative electrode active slurry, a negative electrode sheet of a battery, and a lithium-ion secondary battery. The negative electrode active slurry comprises the following constituent raw materials: a silicon-based negative electrode material and an inorganic lithium compound, wherein the inorganic lithium compound can react with active lithium to form a protective layer. In the constituent raw materials, the silicon-based negative electrode material is used as an active material component in a battery, can undergo an electrochemical reaction during the charging and discharging processes, and is a source of energy in the battery; and a very small amount of an inorganic lithium compound additive is added to the negative electrode slurry, which additive can undergo a reaction during the charging and discharging processes to form a firm protective layer so as to inhibit the growth of lithium dendrites, thereby inhibiting the occurrence of the phenomenon of lithium evolution on a surface of a negative electrode, and further prolonging the cycle life of the silicon-based negative electrode.

Description

Negative electrode active paste, battery negative electrode sheet and lithium-ion secondary battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311178296.1 filed on September 13, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of lithium-ion secondary batteries, and in particular to a negative electrode active slurry, a battery negative electrode sheet, and a lithium-ion secondary battery. Background Art

[0004] Silicon-based anodes have a theoretical specific capacity of up to 4200mAh / g and are widely used in high-energy-density lithium-ion batteries. However, silicon-based anodes are prone to lithium deposition during the charge and discharge process, especially when lithium-ion batteries are overcharged. Due to insufficient residual capacity in the anode, a layer of lithium metal will be deposited on the surface of the anode. On the one hand, lithium deposition will cause a large amount of lithium ion loss, resulting in increased internal resistance and capacity decay. On the other hand, if the deposited lithium continues to grow, lithium dendrites will be generated. The lithium dendrites will pierce the diaphragm, causing an internal short circuit and triggering thermal runaway, posing a great threat to battery safety. In other words, lithium deposition is divided into reversible lithium deposition and irreversible lithium deposition. As the battery ages, the amount of irreversible lithium deposition will accumulate, which will not only accelerate the capacity decay of the lithium-ion battery, but also cause internal short circuits due to the formation of lithium dendrites, resulting in safety issues.

[0005] Therefore, in order to improve the capacity and cycle performance of silicon-based negative electrodes, it is increasingly important to develop a technology to inhibit lithium plating.

[0006] Summary of the Invention

[0007] The present application provides a negative electrode active slurry, a battery negative electrode sheet and a lithium ion secondary battery to solve the technical problem that lithium deposition is easily generated on the negative electrode surface of existing silicon-based negative electrode lithium ion secondary batteries during the charge and discharge process.

[0008] In a first aspect, the present application provides a negative electrode active slurry, wherein the raw material components of the negative electrode active slurry include: a silicon-based negative electrode material and an inorganic lithium compound; wherein the inorganic lithium compound can react with active lithium to form a protective layer.

[0009] Optional optimization technical solution: The inorganic lithium compound includes at least one of the following: lithium nitrate, lithium nitrite, lithium sulfide, lithium nitride, lithium oxide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium carbonate, lithium hydroxide, lithium silicate, and lithium sulfate.

[0010] Optional optimization technical solution: The silicon-based negative electrode material includes at least one of the following: silicon-carbon negative electrode, silicon negative electrode, and silicon-oxygen negative electrode.

[0011] Optional optimization technical solution: relative to 1 part by weight of the silicon-based negative electrode material, the inorganic lithium compound is 0.05% to 20% by weight.

[0012] Optional optimization technical solution: relative to 1 part by weight of the silicon-based negative electrode material, the inorganic lithium compound is 2% to 10% by weight.

[0013] Optional optimization technical solution: The raw material components of the negative electrode active slurry also include: a solvent, a conductive agent and a binder.

[0014] Optional optimization technical solution: The solvent includes one of the following: water, N-methylpyrrolidone.

[0015] In a second aspect, the present application provides a battery negative electrode sheet, comprising a negative electrode sheet substrate and the negative electrode active slurry according to any one of the embodiments of the first aspect attached to at least a portion of the surface of the negative electrode sheet substrate.

[0016] In a third aspect, the present application provides a lithium-ion secondary battery, comprising the battery negative electrode sheet described in any one embodiment of the second aspect.

[0017] Optional optimization technical solution: The lithium-ion secondary battery includes the following: lithium iron phosphate secondary battery, lithium-nickel cobalt manganese ternary secondary battery.

[0018] Compared with the prior art, the above technical solution of this application has the following advantages:

[0019] The negative electrode active slurry provided in the present application has a silicon-based negative electrode material as an active material component in the battery, which can undergo electrochemical reactions during the charging and discharging process and is the source of energy in the battery; and a very small amount of inorganic lithium compound is added to the negative electrode slurry, which can react with the active lithium during the charging and discharging process to form a solid protective layer, reduce the growth of lithium dendrites, thereby inhibiting the occurrence of lithium precipitation on the negative electrode surface, and thus extending the cycle life of the silicon-based negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] FIG1 is a scanning electron micrograph of the negative electrode active slurry provided in Example 1 of the present application. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0024] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible subranges and single numerical values ​​within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is intended to include any cited numeral (fractional or integer) within the indicated range.

[0025] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] First, the present application provides a negative electrode active slurry. As shown in FIG1 , the scanning electron micrograph of the negative electrode active slurry shows irregular spherical shapes. The raw materials for the negative electrode active slurry include a silicon-based negative electrode material and an inorganic lithium compound; the inorganic lithium compound reacts with the active lithium to form a protective layer.

[0028] The negative electrode active slurry provided in the embodiment of the present application has a silicon-based negative electrode material as an active material component in the battery, which can undergo electrochemical reactions during the charge and discharge process and is the source of energy in the battery; and a very small amount of inorganic lithium compound is added to the negative electrode slurry, which can react to form a solid protective layer during the charge and discharge process, reduce the growth of lithium dendrites, thereby inhibiting the occurrence of lithium precipitation on the negative electrode surface, and thus extending the cycle life of the silicon-based negative electrode.

[0029] In some embodiments, the inorganic lithium compound includes at least one of the following: lithium nitrate, lithium nitrite, lithium sulfide, lithium nitride, lithium oxide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium carbonate, lithium hydroxide, lithium silicate, and lithium sulfate.

[0030] In the embodiments of the present application, the inorganic lithium compound functions to form a strong protective layer during discharge, reduce the growth of lithium dendrites, thereby inhibiting the occurrence of lithium precipitation on the negative electrode surface, and thereby extending the cycle life of the silicon-based negative electrode. The inorganic lithium compound can be one or more of lithium nitrate, lithium nitrite, lithium sulfide, lithium nitride, lithium oxide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium carbonate, lithium hydroxide, lithium silicate, and lithium sulfate. Preferably, the inorganic lithium compound can be lithium nitrate.

[0031] In some embodiments, the silicon-based anode material includes at least one of the following: a silicon-carbon anode, a silicon anode, and a silicon-oxygen anode.

[0032] In the embodiments of the present application, the silicon-based negative electrode material, among the raw material components of the negative electrode active slurry, functions as the active material component in the battery, capable of undergoing electrochemical reactions during the charge and discharge processes and serving as the source of energy within the battery. The silicon-based negative electrode material can be one or more of a silicon-carbon negative electrode, a silicon negative electrode, or a silicon-oxygen negative electrode.

[0033] In some embodiments, the inorganic lithium compound is present in an amount of 0.05% to 20% by weight relative to 1 part by weight of the silicon-based negative electrode material.

[0034] In some embodiments, the inorganic lithium compound is present in an amount of 2% to 10% by weight relative to 1 part by weight of the silicon-based negative electrode material.

[0035] In the embodiment of the present application, the negative electrode active slurry can control the thickness, composition and modulus of the protective layer by regulating the amount of inorganic lithium compound. Controlling the amount of inorganic lithium compound can suppress the growth of negative electrode lithium dendrites without reducing the reversible specific capacity of the negative electrode, thereby improving the performance of the battery. If the amount of the inorganic lithium compound is too much, to a certain extent, an excessively thick interface layer will be formed on the negative electrode surface during the charge and discharge process, resulting in uneven lithium deposition and dendrite growth; at the same time, it will also reduce the content of active materials in the electrode, causing the energy density of the silicon-based battery to decrease. If the amount of the inorganic lithium compound is too little, to a certain extent, a uniform interface layer cannot be formed on the negative electrode surface, resulting in uneven lithium deposition and dendrite growth. Specifically, the amount of the inorganic lithium compound can be 0.5% by weight, 1% by weight, 3% by weight, 5% by weight, 7% by weight, 9% by weight, 10% by weight, 15% by weight, 20% by weight, etc. Preferably, the inorganic lithium compound may be present in an amount of 2% to 10% by weight relative to 1 part by weight of the negative electrode material.

[0036] In some embodiments, the raw material components of the negative electrode active slurry further include: a solvent, a conductive agent, and a binder.

[0037] In some embodiments, the solvent comprises one of the following: water and N-methylpyrrolidone.

[0038] In the embodiments of the present application, the conductive agent serves to increase the electron transfer rate of the battery electrode. The conductive agent may be one or more of conductive graphite, Ketjen black, acetylene black, and conductive carbon black (SuperP). The binder serves to exhibit a strong adhesive effect after dissolving in a solvent during the preparation of the negative electrode electrode. The electrode is then coated to form the electrode. The binder may be one or more of carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), and polyacrylate. The solvent serves to dissolve the binder during the preparation of the negative electrode electrode. The binder is then mixed with the metal halide and the conductive agent to form a slurry, which is then coated to form the negative electrode electrode. The solvent may be one or more of water and N-methylpyrrolidone (NMP). Furthermore, the amounts of the conductive agent, binder, and solvent may be those commonly used in the art. This negative electrode active slurry is low-cost, can be produced industrially on a large scale, and has high commercial value.

[0039] In a second aspect, the present application provides a battery negative electrode sheet, comprising a negative electrode sheet substrate and the negative electrode active slurry according to any one of the embodiments of the first aspect attached to at least a portion of the surface of the negative electrode sheet substrate.

[0040] Conventional silicon-based lithium-ion batteries experience uneven lithium deposition during cycling, leading to the formation of lithium dendrites. This can also cause the active lithium to react with the electrolyte to produce dead lithium, making the battery susceptible to short circuits and irreversible lithium consumption, which can severely deteriorate battery performance. This negative electrode active slurry, which incorporates a very small amount of an inorganic lithium compound additive and is used in the preparation of battery negative electrode sheets and / or batteries, reacts during the charge and discharge process to form a strong protective layer, reducing the growth of lithium dendrites and thereby inhibiting the occurrence of lithium deposition on the negative electrode surface, thereby extending the cycle life of the silicon-based negative electrode.

[0041] In the embodiment of the present application, the negative electrode active slurry is applied to the negative electrode sheet of the battery, which can react during the charge and discharge process to generate a solid protective layer, reduce the growth of lithium dendrites, thereby inhibiting the occurrence of lithium plating on the negative electrode surface, and thereby extending the cycle life of the silicon-based negative electrode.

[0042] In a third aspect, the present application provides a lithium-ion secondary battery, comprising the battery negative electrode sheet described in any one embodiment of the second aspect.

[0043] In the embodiment of the present application, the negative electrode active slurry can regulate the thickness, composition and modulus of the protective layer by regulating the amount of inorganic lithium compound. The protective layer formed by the negative electrode active slurry can provide a good ion channel and is stable during the cycle, avoiding direct contact between the electrolyte and the lithium metal, preventing the occurrence of side reactions, and thus solving the continuous cracking and repair of the SEI film. Therefore, the negative electrode with composite layer protection can solve the safety problems caused by the growth of lithium dendrites at the negative electrode and the capacity drop caused by the continuous reconstruction of the SEI film. When the above-mentioned lithium ion battery negative electrode sheet is used as the negative electrode of a lithium ion secondary battery, its cycle performance can be greatly improved. In addition, the in-situ composite protective film preparation method is simple, the raw materials are easily available, and it is suitable for large-scale production.

[0044] In some embodiments, the lithium-ion secondary battery includes one of the following: a lithium iron phosphate secondary battery, and a lithium-nickel cobalt manganese ternary secondary battery.

[0045] In the embodiments of the present application, lithium iron phosphate secondary batteries and lithium-nickel cobalt manganese ternary secondary batteries are preferred lithium ion secondary batteries. When the lithium ion secondary batteries are working, the introduction of the negative electrode active slurry can reduce the volume strain of the negative electrode sheet and promote the rapid migration of lithium ions.

[0046] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0047] Example 1

[0048] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (4% wt lithium nitrate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0049] Example 2

[0050] The content of lithium nitrate additive is 0.5%wt, and the rest is the same as in Example 1. The details are as follows:

[0051] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (0.5% lithium nitrate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0052] Example 3

[0053] The content of lithium nitrate additive is 20%wt, and the rest is the same as in Example 1. The details are as follows:

[0054] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (20% wt lithium nitrate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0055] Example 4

[0056] The additive in the negative electrode slurry is 5%wt lithium nitrite, and the rest is the same as in Example 1. The details are as follows:

[0057] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (5% wt lithium nitrite), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0058] Example 5

[0059] The additive in the negative electrode slurry is 7%wt lithium sulfide, and the rest is the same as in Example 1. The details are as follows:

[0060] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (7% wt lithium sulfide), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0061] Example 6

[0062] The additive in the negative electrode slurry is 4%wt lithium nitride, and the rest is the same as in Example 1. The details are as follows:

[0063] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (4% wt lithium nitride), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0064] Example 7

[0065] The additive in the negative electrode slurry is 10% wt lithium oxide, and the rest is the same as in Example 1. The details are as follows:

[0066] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (10% wt lithium oxide), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0067] Example 8

[0068] The additive in the negative electrode slurry is 13%wt lithium fluoride, and the rest is the same as in Example 1. The details are as follows:

[0069] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (13% wt lithium fluoride), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0070] Example 9

[0071] The additive in the negative electrode slurry is 7%wt lithium chloride, and the rest is the same as in Example 1. The details are as follows:

[0072] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (7% wt lithium chloride), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0073] Example 10

[0074] The additive in the negative electrode slurry is 5%wt lithium bromide, and the rest is the same as in Example 1. The details are as follows:

[0075] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (5% wt lithium bromide), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0076] Example 11

[0077] The additive in the negative electrode slurry is 13%wt lithium iodide, and the rest is the same as in Example 1. The details are as follows:

[0078] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (13% wt lithium iodide), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0079] Example 12

[0080] The additive in the negative electrode slurry is 15%wt lithium carbonate, and the rest is the same as in Example 1. The details are as follows:

[0081] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (15% wt lithium carbonate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0082] Example 13

[0083] The additive in the negative electrode slurry is 8%wt lithium hydroxide, and the rest is the same as in Example 1. The details are as follows:

[0084] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (8% wt lithium hydroxide), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0085] Example 14

[0086] The additive in the negative electrode slurry is 13%wt lithium silicate, and the rest is the same as in Example 1. The details are as follows:

[0087] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (13% wt lithium silicate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0088] Example 15

[0089] The additive in the negative electrode slurry is 7%wt lithium sulfate, and the rest is the same as in Example 1. The details are as follows:

[0090] Preparation of negative electrode active slurry: A silicon-carbon negative electrode containing (7% wt lithium sulfate), Ketjen black and a binder (the weight ratio of sodium carboxymethyl cellulose and styrene-butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio of 8:1:1, water as solvent, solid content 4wt%).

[0091] Comparative Example 1

[0092] Preparation of negative electrode active slurry: Silicon carbon negative electrode, Ketjen black and binder (the weight ratio of sodium carboxymethyl cellulose and styrene butadiene rubber is 1:1) are slurried at room temperature and pressure (weight ratio is 8:1:1, water is used as solvent, solid content is 4wt%).

[0093] The negative electrode active slurries prepared in Examples 1-15 and Comparative Example 1 were applied to the preparation of lithium ion battery negative electrode sheets and lithium ion secondary batteries, the steps of which are as follows:

[0094] The negative electrode active slurry prepared in Examples 1-15 and Comparative Example 1 was uniformly coated on the corresponding carbon-coated copper foil substrate, and then vacuum dried at 80°C for 12 hours. The obtained thin film material was compacted under a pressure of 10 MPa and cut into an electrode sheet with a diameter of 10 mm as the negative electrode of the simulated battery. The above-mentioned negative electrode sheet, separator, electrolyte of 1M lithium hexafluorophosphate ethylene carbonate and diethyl carbonate (volume ratio of 1:1) and LiNi0.8Co0.1Mn0.1O2 (NCM811) positive electrode sheet were assembled into a button battery in an argon-protected glove box.

[0095] The button cells assembled from Examples 1-15 and Comparative Example 1 were subjected to a battery cycle test at a current density of 1 mA / cm2. The test results are shown in Table 1.

[0096] Table 1 Cycling performance test results of lithium-ion secondary batteries

[0097] Table 1 shows that batteries containing lithium nitrate additives have a higher capacity retention rate after 300 cycles than batteries without additives, reaching over 97%. This is mainly because batteries containing lithium nitrate additives can form a strong protective layer during the charge and discharge process, reducing the growth of lithium dendrites, thereby inhibiting the occurrence of lithium plating and extending the cycle life of the silicon-carbon negative electrode.

[0098] The above technical solutions of the above embodiments of the present application have the following advantages compared with the prior art:

[0099] The negative electrode active slurry provided in the embodiment of the present application has a silicon-based negative electrode material as an active material component in the battery, which can undergo electrochemical reactions during the charging and discharging process and is the source of energy in the battery; and a very small amount of inorganic lithium compound is added to the negative electrode slurry, which can react with the active lithium during the charging and discharging process to form a solid protective layer, reduce the growth of lithium dendrites, thereby inhibiting the occurrence of lithium precipitation on the negative electrode surface, and thus extending the cycle life of the silicon-based negative electrode.

[0100] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A negative electrode active slurry, the raw material components of the negative electrode active slurry comprising: Silicon-based negative electrode material and inorganic lithium compound; wherein the inorganic lithium compound can react with active lithium to form a protective layer.

2. The negative electrode active slurry according to claim 1, wherein: The inorganic lithium compound includes at least one of the following: lithium nitrate, lithium nitrite, lithium sulfide, lithium nitride, lithium oxide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium carbonate, lithium hydroxide, lithium silicate, and lithium sulfate.

3. The negative electrode active slurry according to claim 1, wherein: The silicon-based negative electrode material includes at least one of the following: a silicon-carbon negative electrode, a silicon negative electrode, and a silicon-oxygen negative electrode.

4. The negative electrode active slurry according to any one of claims 1 to 3, wherein: Relative to 1 part by weight of the silicon-based negative electrode material, the inorganic lithium compound is 0.05% to 20% by weight.

5. The negative electrode active slurry according to claim 4, wherein: Relative to 1 part by weight of the silicon-based negative electrode material, the inorganic lithium compound is 2% to 10% by weight.

6. The negative electrode active slurry according to claim 1, wherein: The raw material components of the negative electrode active slurry also include: a solvent, a conductive agent and a binder.

7. The negative electrode active slurry according to claim 6, wherein: The solvent includes one of the following: water and N-methylpyrrolidone.

8. A battery negative electrode sheet, comprising a negative electrode sheet substrate and the negative electrode active slurry according to any one of claims 1 to 7 attached to at least a portion of the surface of the negative electrode sheet substrate. 9 . A lithium ion secondary battery, comprising the battery negative electrode sheet according to claim 8 .

10. The lithium ion secondary battery according to claim 9, wherein The lithium-ion secondary battery includes the following: a lithium iron phosphate secondary battery, a lithium-nickel cobalt manganese ternary secondary battery.

Images