阅读说明：本技术 一种锂离子电池负极材料补锂方法及电池的制备方法 (Lithium ion battery cathode material lithium supplementing method and battery preparation method ) 是由 唐胜利 郑正坤 刘右军 于 2019-09-30 设计创作，主要内容包括：本发明提供一种锂离子电池负极材料补锂方法及电池的制备方法,包括以下步骤：S1,将负极浆料涂覆于负极集流体上,通过碾压制成负极片；S2,将S1中制好的负极片与表面经过钝化的锂带进行压合,得到预存锂源的复合负极片,其中,所述复合负极片中的预存锂源的容量为所述复合负极片总容量的10～40％,所述压合的压力为0.5～10Mpa。相比于现有技术,本发明将性质活泼的金属锂进行钝化稳定,通过折算锂提供的容量预算预存锂的重量,并通过控制压合的压力以使得负极片与锂带紧密复合,以确保在后续循环过程中有足够的锂源补充由于副反应以及SEI膜不断增长修复等所消耗掉的锂离子,从而提升电池的循环性能,提高电池的容量。(The invention provides a lithium ion battery cathode material lithium supplementing method and a battery preparation method, and the method comprises the following steps: s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet; and S2, pressing the cathode plate prepared in the S1 and a lithium belt with a passivated surface to obtain a composite cathode plate with a pre-stored lithium source, wherein the capacity of the pre-stored lithium source in the composite cathode plate is 10-40% of the total capacity of the composite cathode plate, and the pressing pressure is 0.5-10 Mpa. Compared with the prior art, the method has the advantages that the metal lithium with active property is passivated and stabilized, the weight of the pre-stored lithium is calculated by converting the capacity provided by the lithium, the negative plate is tightly compounded with the lithium belt by controlling the pressing pressure, so that enough lithium source is ensured to supplement lithium ions consumed by side reaction, continuous increase and repair of an SEI film and the like in the subsequent circulation process, the circulation performance of the battery is improved, and the capacity of the battery is improved.)

1. A lithium supplementing method for a lithium ion battery negative electrode material is characterized by comprising the following steps:

s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet;

and S2, pressing the negative plate prepared in the step S1 with a passivated lithium belt to obtain a composite negative plate with a pre-stored lithium source, wherein the capacity of the pre-stored lithium source in the composite negative plate is 10-40% of the total capacity of the composite negative plate, and the pressing pressure is 0.5-10 MPa.

2. The method for supplementing lithium to the negative electrode material of the lithium ion battery as claimed in claim 1, wherein in the step S2, the surface of the lithium strip is coated with a lithium chloride material.

3. The lithium ion battery negative electrode material lithium supplementing method according to claim 2, wherein the thickness of the lithium chloride material is 0.1-1.5 mm.

4. The lithium ion battery negative electrode material lithium supplement method according to claim 2, characterized in that the dew point temperature in air is controlled to be less than or equal to 35 ℃.

5. The method for supplementing lithium to the anode material of the lithium ion battery according to claim 1, wherein in the step S2, the pressing method includes at least one of rolling, hot pressing and rolling.

6. The lithium ion battery negative electrode material lithium supplementing method according to claim 1, wherein in the step S2, the pressure of the pressing is 3-8 MPa.

7. The method for supplementing lithium to the anode material of the lithium ion battery according to claim 1, wherein in the step S1, the anode slurry comprises an anode active material, a conductive agent, a binder and a thickener.

8. A preparation method of a lithium ion battery is characterized by comprising the following steps:

s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet;

s2, pressing the negative plate prepared in the step S1 with a passivated lithium belt to obtain a composite negative plate with a pre-stored lithium source as a negative plate of the battery; the pre-stored lithium source capacity in the composite negative plate is 10-40% of the total capacity of the composite negative plate, and the pressing pressure is 0.5-10 Mpa;

s3, coating the positive electrode slurry on a positive electrode current collector, and rolling to prepare a positive plate, wherein the positive electrode slurry comprises lithium iron phosphate, a conductive agent and a binder;

and S4, winding or laminating the positive plate, the diaphragm and the composite negative plate to form a battery cell, putting the battery cell into the shell, and injecting, forming and grading to obtain the lithium ion battery.

9. The method of claim 8, wherein in step S3, the lithium iron phosphate is a nanoscale or microscale material.

10. The preparation method of the lithium ion battery according to claim 8, wherein the excess coefficient of the composite negative electrode sheet to the positive electrode sheet is 1.2-1.5.

Technical Field

The invention relates to the field of lithium batteries, in particular to a lithium supplementing method for a lithium ion battery cathode material and a preparation method for a battery.

Background

The use of lithium ion batteries in the consumer sector is becoming increasingly saturated, while the growth in the field of power and energy storage batteries is accelerating. Under the pulling of new energy automobiles, the loading capacity of power lithium batteries can gradually exceed the consumer market, and the demand center of gravity of lithium ion batteries is in the development stage of transferring from the small battery market of the consumer battery market to the electric vehicle or the power battery market of energy storage. For lithium ion batteries applied in the fields of power and energy storage, the electrochemical performance requirements are significantly different compared with those of consumer electronic lithium ion batteries, particularly the requirements on cycle performance and service life. The requirement of the European and American energy storage market for the service life of the lithium ion battery is at least 10 years to about 20 years, so that the lithium ion battery applied in the field needs to have ultra-long cycle life and service life.

The main factors influencing the capacity attenuation of the lithium ion battery include the following aspects: temperature, charge and discharge multiplying power, cycle charge and discharge system and depth, stability of materials, preparation process and battery design. From the perspective of battery materials, the materials are further classified into a positive electrode, a negative electrode, an electrolyte, a diaphragm current collector and other auxiliary materials, and besides the property influence of the materials, the materials also have mutual cross influence, such as the matching of the type of the negative electrode material and an electrolyte system, and the use of the negative electrode material containing silicon element is significantly different from the graphite negative electrode in the aspects of an electrolyte solvent system, additives and lithium salt. In general, the capacity fade for lithium ion batteries can be summarized into three fundamental factors: 1) loss of cyclable lithium; 2) loss of active material or structural collapse results in a reduction in the available sites into or out of which lithium ions can be intercalated; 3) the loss of conductivity between the active materials or the deterioration of adhesion property to the current collector leads to an increase in polarization and thus deterioration. Therefore, one of the methods for increasing the capacity of a lithium ion battery is to increase the amount of lithium contained in the lithium ion battery and maintain the stability of a lithium source.

In view of the above, it is necessary to provide a technical solution to the above problems.

Disclosure of Invention

The invention aims to: the method for supplementing lithium to the negative electrode material of the lithium ion battery is characterized in that enough recyclable lithium sources are prestored in the negative electrode material, so that lithium ions consumed by side reactions, SEI (solid electrolyte interphase) film growing repair and the like are continuously supplemented by the prestored lithium sources in the subsequent circulation process, the circulation performance of the battery is improved, and the capacity of the battery is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

a lithium supplementing method for a lithium ion battery negative electrode material comprises the following steps:

s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet;

and S2, pressing the negative plate prepared in the S1 and the lithium belt with the passivated surface to obtain a composite negative plate with a pre-stored lithium source, wherein the capacity of the pre-stored lithium source in the composite negative plate is 10-40% of the total capacity of the composite negative plate, and the pressing pressure is 0.5-10 MPa. The method takes the passivated lithium belt as a lithium supplement material, and the lithium belt can be tightly combined with the negative plate by controlling the pressure of pressing, wherein the weight of the pre-stored lithium source can be controlled by converting the capacity provided by lithium, and is 10-40% of the total capacity of the negative plate. When the lithium source of the cathode is sufficient, lithium ions consumed by side reactions, SEI (solid electrolyte interphase) film continuous growth repair and the like can be continuously supplemented by the pre-stored lithium source in the subsequent cycle process, so that the cycle performance of the battery is improved, and the capacity of the battery is improved.

Preferably, in the step S2, the surface of the lithium ribbon is coated with a lithium chloride material. The surface of the lithium belt subjected to passivation can be a commercially available lithium belt, and a layer of lithium chloride material can be wrapped on the surface of the lithium belt, because lithium per se belongs to active metal, a passivation layer is wrapped on the surface of the lithium belt, so that the effect of protecting lithium can be achieved, and lithium chloride is adopted as a protective layer.

Preferably, the thickness of the lithium chloride material is 0.1-1.5 mm. The conventional lithium chloride is a powdery substance, and needs to be pressed into a sheet shape to cover the lithium belt, the thickness of the sheet shape is controlled to be 01-1.5 mm, and the sheet shape cannot be too thick, so that the subsequent lithium supplement process is prevented from hindering the inlet and outlet of lithium ions and influencing the lithium supplement effect; but also not too thin to protect the lithium.

Preferably, the dew point temperature in the air is controlled to be less than or equal to 35 ℃. Because lithium chloride is easy to be wet, the moisture content of a workshop needs to be kept in the lithium supplementing process, the dew point temperature can be preferably kept to be lower than 35 ℃, and the whole working space is in a dry state.

Preferably, in the step S2, the pressing method includes at least one of rolling, hot pressing and rolling.

Preferably, in the step S2, the pressure of the pressing is 3 to 8 MPa. Under the pressure of the pressing, the control quantity of the pre-stored lithium source is easier, the problem of excessive lithium supplement frequently is avoided, and under the pressure, the lithium source can be better combined with the negative plate, so that a foundation is provided for subsequent lithium ion input.

Preferably, in the S1 step, the anode slurry includes an anode active material, a conductive agent, a binder, and a thickener. The negative active material can be at least one of graphite, silicon oxide and lithium titanate, wherein the graphite can also be doped with substances containing silicon or lithium powder and the like; the conductive agent can be carbon black, acetylene black, carbon nano tubes or graphene and other substances; the binder can be styrene butadiene rubber and/or polyvinylidene fluoride; the thickener may be sodium carboxymethylcellulose.

Another object of the present invention is to: the preparation method of the lithium ion battery comprises the following steps:

s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet;

s2, pressing the negative plate prepared in the S1 and the surface-passivated lithium belt to obtain a composite negative plate with a pre-stored lithium source, and using the composite negative plate as a negative plate of the battery; the capacity of a pre-stored lithium source in the composite negative plate is 10-40% of the total capacity of the composite negative plate, and the pressure of the pressing is 0.5-10 Mpa;

s3, coating the positive electrode slurry on a positive electrode current collector, and rolling to prepare a positive plate, wherein the positive electrode slurry comprises lithium iron phosphate, a conductive agent and a binder; the conductive agent can be carbon black, acetylene black, carbon nano tubes or graphene and other substances; the binder can be styrene butadiene rubber, polyvinylidene fluoride and the like;

and S4, winding or laminating the positive plate, the diaphragm and the composite negative plate to form a battery cell, putting the battery cell into the shell, and injecting, forming and grading to obtain the lithium ion battery.

Preferably, in the step S3, the lithium iron phosphate is a nano-scale or micro-scale material.

Preferably, the excess coefficient of the composite negative plate to the positive plate is 1.2-1.5. Within the excess coefficient, the lithium source prestored in the composite negative plate is enough to supplement lithium ions consumed by the SEI film formation, but the phenomenon of lithium dendrite caused by the excess lithium supplement is avoided.

The invention has the beneficial effects that:

1) the invention provides a lithium ion battery cathode material lithium supplementing method and a preparation method of a battery thereof, wherein the preparation method comprises the following steps: s1, coating the negative electrode slurry on a negative electrode current collector, and rolling to prepare a negative electrode sheet; and S2, pressing the cathode plate prepared in the S1 and a lithium belt with a passivated surface to obtain a composite cathode plate with a pre-stored lithium source, wherein the capacity of the pre-stored lithium source in the composite cathode plate is 10-40% of the total capacity of the composite cathode plate, and the pressing pressure is 0.5-10 Mpa. Compared with the prior art, the method has the advantages that the metal lithium with active property is passivated and stabilized, the weight of the pre-stored lithium is calculated by converting the capacity provided by the lithium, the negative plate is tightly compounded with the lithium belt by controlling the pressing pressure, so that enough lithium source is ensured to supplement lithium ions consumed by side reaction, continuous increase and repair of an SEI film and the like in the subsequent circulation process, the circulation performance of the battery is improved, and the capacity of the battery is improved.

2) The invention also provides a preparation method of the lithium ion battery, the cycle life of the obtained lithium iron phosphate battery can reach 8000-11000 times, and compared with the existing lithium iron phosphate battery, the cycle life of the lithium iron phosphate battery is greatly prolonged.

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the present invention and its advantageous effects will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.