Pre-lithiated material, its preparation method, pre-lithiation treatment method, battery and vehicle

Abstract

Embodiments of the present invention provide a prelithiation material, a preparation method thereof, a prelithiation treatment method, a battery and a vehicle. Among them, the material for electrode prelithiation includes a lithium substrate and a dense protective layer covering the surface of the lithium substrate. The dense protective layer contains Li element and Bi element or N element. The dense protective layer can have better stability in air relative to the lithium substrate, which can reduce the risk of the material for electrode prelithiation during use. The dense protective layer can have good compactness, which can effectively prevent the lithium substrate from directly contacting air or other reactive substances. At the same time, the dense protective layer does not affect the use effect of the lithium substrate during the electrode prelithiation process, and can provide a good lithium insertion effect during the prelithiation process, improving the first Coulomb efficiency of the lithium-ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a material for electrode prelithiation, a preparation method of a material for electrode prelithiation, a prelithiation treatment method for an electrode, a lithium-ion battery, and a vehicle. Background Art

[0002] Generally, during the first charge and discharge process of an electrode material, a certain amount of irreversible capacity is usually generated. The main sources of the irreversible capacity are the formation of the SEI (solid electrolyte interphase) film, side reactions on the electrode surface, and some irreversible forward reactions, etc. Generally, the SEI film generated during the first charge and discharge process usually consumes a certain amount of lithium, and this consumption is irreversible, thus usually resulting in a reduction in the first Coulombic efficiency of the lithium-ion battery.

[0003] In order to improve the first Coulombic efficiency of a lithium-ion battery, the electrode can be subjected to prelithiation treatment to make up for the lithium loss caused by the irreversible capacity, so as to achieve the effect of improving the first Coulombic efficiency. Prelithiation techniques generally include direct contact with lithium metal, electrochemical prelithiation, addition of lithium-containing active substances, and chemical prelithiation. However, since lithium metal or lithium compounds are usually substances with high reactivity. Therefore, during the prelithiation process, there are often potential safety hazards, resulting in the inability of prelithiation techniques to be well applied in actual production. Summary of the Invention

[0004] In view of the above problems, embodiments of the present invention are proposed to provide a material for electrode prelithiation, a preparation method of a material for electrode prelithiation, a prelithiation treatment method for an electrode, a lithium-ion battery, and a vehicle.

[0005] To solve the above problems, an embodiment of the present invention discloses a material for electrode prelithiation, including a lithium substrate, and a dense protective layer covering the surface of the lithium substrate, the dense protective layer containing Li element, and Bi element or N element.

[0006] Optionally, the dense protective layer includes LiNO 3 , Li 3 N, LiN x O y (0≤x≤3, 0≤y≤3) and Li 3 Bi at least one of them.

[0007] Optionally, it further includes a passivation layer covering the surface of the dense protective layer, the passivation layer including hexamine.

[0008] An embodiment of the present invention further provides a method for preparing a material for electrode prelithiation, the method comprising:

[0009] Dissolve bismuth nitrate in a solution of ethylene glycol monomethyl ether series compounds to obtain a reaction solution;

[0010] Bring a lithium substrate into contact with the reaction solution to form a dense protective layer on the surface of the lithium substrate; the dense protective layer contains Li element, and Bi element or N element.

[0011] Optionally, the step of bringing the lithium substrate into contact with the reaction solution to form a dense protective layer on the surface of the lithium substrate includes:

[0012] Immerse the lithium substrate in the reaction solution or shower the lithium substrate with the reaction solution to form a dense protective layer on the surface of the lithium substrate.

[0013] Optionally, the method further includes:

[0014] Spray hexamine on the surface of the dense protective layer to form a passivation layer.

[0015] Optionally, the concentration of the bismuth nitrate solution is 0.5-2%; the immersion time of the lithium substrate in the reaction solution or the shower time of the reaction solution on the lithium substrate is 5-20 minutes.

[0016] The present invention also provides a method for prelithiation treatment of an electrode, the method comprising:

[0017] Bond a material for electrode prelithiation to a battery electrode sheet, and hot roll the material for electrode prelithiation and the battery electrode sheet at 50-100 °C; wherein, the material for electrode prelithiation includes a lithium substrate and a dense protective layer covering the surface of the lithium substrate, and the dense protective layer contains Li element, and Bi element or N element;

[0018] During the pressing process, embed the Li element in the material for electrode prelithiation into the battery electrode sheet, and at the same time, the dense protective layer in the material for electrode prelithiation migrates to the surface of the battery electrode sheet to form an electrode protective layer.

[0019] The present invention also provides a lithium ion battery, which includes an electrode prepared by using the material for electrode prelithiation as described in the embodiment of the present invention, or includes a material for electrode prelithiation prepared by using the preparation method of the material for electrode prelithiation as described in the embodiment of the present invention, and then further includes an electrode prepared based on the material for electrode prelithiation, or includes an electrode obtained by treating with the prelithiation treatment method of the electrode as described in the embodiment of the present invention.

[0020] The present invention also provides a vehicle, which includes the lithium-ion battery as described in the embodiments of the present invention.

[0021] The embodiments of the present invention have the following advantages:

[0022] The material for electrode prelithiation in the embodiments of the present invention includes a lithium substrate and a dense protective layer covering the surface of the lithium substrate. The dense protective layer contains Li element, and Bi element or N element. The dense protective layer can have better stability in air relative to the lithium substrate, which can reduce the risk during the use of the material for electrode prelithiation. The dense protective layer can have good denseness, which can effectively prevent the lithium substrate from directly contacting with air or other reactive substances. At the same time, the dense protective layer does not affect the use effect of the lithium substrate during the electrode prelithiation process, and can provide a good lithium insertion effect during the prelithiation process, improving the first Coulombic efficiency of the lithium-ion battery. Detailed embodiments

[0023] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0024] The embodiments of the present invention provide a material for electrode prelithiation, which includes a lithium substrate and a dense protective layer covering the surface of the lithium substrate. The dense protective layer contains Li element, and Bi element or N element.

[0025] Specifically, the lithium substrate may include lithium metal, such as lithium tape, lithium sheet, etc. Lithium metal usually has relatively high reactivity. To improve the stability of the lithium substrate containing lithium metal, a dense protective layer can be covered on the surface of the lithium substrate. The dense protective layer can include Li element, and Bi element or N element. The dense protective layer can have better stability in air relative to the lithium substrate, which can reduce the risk during the use of the material for electrode prelithiation. The dense protective layer can have good denseness, which can effectively prevent the lithium substrate from directly contacting with air or other reactive substances. At the same time, the dense protective layer does not affect the use effect of the lithium substrate during the electrode prelithiation process, and can provide a good lithium insertion effect during the prelithiation process, improving the first Coulombic efficiency of the lithium-ion battery.

[0026] In addition, when the dense protective layer contains Bi element, the Bi element can promote the uniform deposition of Li ions on the electrode surface and inhibit the formation of lithium dendrites during the subsequent prelithiation treatment process, thereby better improving the charge-discharge rate performance and further enhancing the effect of electrode prelithiation.

[0027] In an embodiment of the present invention, the dense protective layer includes LiNO 3 、Li3 N, LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3) and Li 3 at least one of Bi.

[0028] Specifically, the dense protective layer may include LiNO 3 , Li 3 N, LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3) and Li 3 at least one of Bi. LiNO 3 , Li 3 N, LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3) and Li 3 Bi can all provide good protection and have good denseness.

[0029] In one embodiment of the present invention, it further includes a passivation layer covering the surface of the dense protective layer, and the passivation layer includes hexamine.

[0030] Specifically, a passivation layer can be further covered on the surface of the dense protective layer to further improve the protection of the lithium substrate. Specifically, the passivation layer can be hexamine, and hexamine can have good corrosion inhibition ability and can be used to slow down the corrosion of metal materials. By coating hexamine, the contact between the lithium substrate and air to generate lithium oxide can be further inhibited, so that the lithium substrate can be more stably used in the prelithiation process.

[0031] The embodiment of the present invention provides a preparation method of a material for electrode prelithiation, and the method includes:

[0032] Step 101, dissolving bismuth nitrate in a solution of ethylene glycol monomethyl ether series compounds to obtain a reaction solution;

[0033] Step 102, contacting the lithium substrate with the reaction solution to form a dense protective layer on the surface of the lithium substrate; the dense protective layer contains Li element, and Bi element or N element.

[0034] Specifically, in order to form a protective layer on the surface of the lithium strip, bismuth nitrate can be first dissolved in a solution of ethylene glycol monomethyl ether series compounds, so that bismuth nitrate can be uniformly dispersed in the solution of ethylene glycol monomethyl ether series compounds to obtain a reaction solution. Subsequently, the lithium substrate can be contacted with the reaction solution, so that bismuth nitrate in the solution can react with the lithium substrate to uniformly form a dense protective layer containing Li element and Bi element or N element on the surface of the lithium substrate, thereby isolating the lithium substrate from the air, reducing the risk of the material used for electrode prelithiation during use, and at the same time, the dense protective layer will not affect the effect of electrode prelithiation.

[0035] Among them, the ethylene glycol monomethyl ether series compounds can be ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, etc.

[0036] In a specific implementation, when the lithium substrate contacts the reaction solution containing bismuth nitrate, lithium and bismuth nitrate undergo a redox reaction to in-situ form a dense surface protective layer. The redox reaction mainly includes the following:

[0037] (1) Bi(NO3) 3 + 3Li = 3LiNO 3 + Bi

[0038] (2) LiNO 3 + Li = Li 3 N + LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3)

[0039] (3) 3Li + Bi = Li 3 Bi

[0040] The dense protective layer containing LiNO 3 , Li 3 N, LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3), Li 3 Bi has relatively good stability in the air with respect to the lithium substrate, and can reduce the risk of the material used for electrode prelithiation during use.

[0041] In an embodiment of the present invention, the step of contacting the lithium substrate with the reaction solution to form a dense protective layer on the surface of the lithium substrate includes:

[0042] Sub-step S11, immersing the lithium substrate in the reaction solution or showering the lithium substrate with the reaction solution to form a dense protective layer on the surface of the lithium substrate.

[0043] Specifically, the contact method between the lithium substrate and the reaction solution can be to immerse the lithium substrate in the reaction solution or to shower the lithium substrate with the reaction solution. In both cases, the lithium substrate can fully react with bismuth nitrate in the reaction solution to form a dense protective layer.

[0044] In a specific implementation, the concentration of bismuth nitrate in the reaction solution and the reaction duration between the lithium substrate and the reaction solution, that is, the duration for which the lithium substrate is immersed in the reaction solution or the duration for which the reaction solution showers the lithium substrate, can be determined according to actual needs. Generally speaking, if the concentration of bismuth nitrate in the reaction solution is higher, or the reaction duration between the lithium substrate and the reaction solution is longer, the formed dense protective layer will be thicker, which can better inhibit the growth of lithium dendrites and improve the rate performance of the lithium-ion battery subsequently. However, if the concentration of bismuth nitrate in the reaction solution is too high, or the reaction duration between the lithium substrate and the reaction solution is too long, it may result in too little lithium metal contained in the lithium substrate, which may lead to the inability to provide an obvious lithium supplement effect for the lithium-ion battery. Therefore, the concentration of bismuth nitrate in the reaction solution and the reaction duration between the lithium substrate and the reaction solution can be selected appropriately according to actual needs. Optionally, the concentration of bismuth nitrate can be 0.5% - 2%, and the reaction duration between the lithium substrate and the reaction solution can be 5 - 20 minutes.

[0045] In an embodiment of the present invention, the method further includes:

[0046] Sub-step S21, spraying hexamine on the surface of the dense protective layer to form a passivation layer.

[0047] Specifically, after forming a dense protective layer on the surface of the lithium substrate, hexamine can be further sprayed on the surface of the dense protective layer to further improve the protection of the lithium substrate. Hexamine can have good corrosion inhibition ability and can be used to slow down the corrosion of metal materials. By coating hexamine, the contact between the lithium substrate and air to generate lithium oxide can be further inhibited, enabling the lithium substrate to be used more stably in the prelithiation process.

[0048] The embodiment of the present invention provides a method for prelithiation treatment of an electrode, and the method includes:

[0049] Step 201, attaching the material for electrode prelithiation to the battery electrode sheet and hot rolling the material for electrode prelithiation and the battery electrode sheet at 50 - 100°C; wherein, the material for electrode prelithiation includes a lithium substrate and a dense protective layer covering the surface of the lithium substrate, and the dense protective layer contains Li element and Bi element or N element;

[0050] Step 202, during the lamination process, embed the Li element in the material for electrode prelithiation into the battery electrode sheet, and at the same time, the dense protective layer in the material for electrode prelithiation migrates to the surface of the battery electrode sheet to form an electrode protective layer.

[0051] Among them, the battery electrode sheet can be a silicon-carbon negative electrode sheet, or a graphite negative electrode sheet, a silicon-oxygen negative electrode sheet, etc., and the present invention does not limit this.

[0052] Specifically, the material for electrode prelithiation prepared in the embodiments of the present invention can be prelithiated by being attached to the battery electrode sheet and using a hot roll lamination method. During the lamination process, the Li element in the material for electrode prelithiation can migrate under the action of an external force and enter the battery electrode sheet, thereby realizing lithium supplementation for the battery electrode sheet to improve the rate performance and first Coulomb efficiency of the lithium-ion battery.

[0053] At the same time, during the lamination process, the dense protective layer on the surface of the material for electrode prelithiation can also migrate to the surface of the battery electrode sheet under the action of an external force to form an electrode protective layer. The dense protective layer contains Li element and Bi element or N element, specifically including LiNO 3 、Li 3 N、LiN x O y (0 ≤x≤3, 0≤y≤3), Li 3 Bi. Among them, LiNO 3 、LiN x O y (0≤x≤3, 0≤y≤3) can effectively improve the ionic conductivity of the battery electrode sheet and reduce the interfacial impedance. Therefore, forming the electrode protective layer can protect the material for electrode prelithiation while forming an electrode protective layer on the surface of the battery electrode sheet, further improving the performance of the lithium-ion battery, so that the battery prelithiation treatment can obtain better results.

[0054] During the lamination process, since the peeling force of the material that may be used for electrode prelithiation may be greater than the adhesion force between the material for electrode prelithiation and the battery electrode sheet, resulting in the material for electrode prelithiation not being able to adhere well to the surface of the battery electrode sheet. For this reason, the material for electrode prelithiation can be hot roll laminated at 50 - 100 °C, so that the material for electrode prelithiation can be more easily and tightly attached to the battery electrode sheet, enabling the battery electrode sheet to obtain a better lithium supplementation effect.

[0055] In a specific implementation, in order to further improve the battery performance of a lithium-ion battery, tin can also be added during the lamination process of electrode prelithiation, so that the lithium substrate part in the material for electrode prelithiation can form a lithium-tin alloy with tin. The lithium-tin alloy has good electrochemical performance, which can promote the deintercalation and intercalation of lithium to be more easily carried out, thereby improving the rate performance of the lithium-ion battery.

[0056] An embodiment of the present invention provides a lithium-ion battery, which includes an electrode prepared from the material for electrode prelithiation as described in the embodiment of the present invention, or includes an electrode prepared from the material for electrode prelithiation obtained by the preparation method of the material for electrode prelithiation as described in the embodiment of the present invention, or includes an electrode obtained by treating with the prelithiation treatment method of the electrode as in the embodiment of the present invention. Among them, the specific structural form and working principle of the material for electrode prelithiation have been described in detail in the foregoing embodiments, and will not be elaborated here.

[0057] An embodiment of the present invention provides a vehicle, which includes the battery electrode lithium-ion battery as described in the embodiment of the present invention. Among them, the specific structural form and working principle of the material for electrode prelithiation used in the preparation of the electrode included in the lithium-ion battery have been described in detail in the foregoing embodiments, and will not be elaborated here.

[0058] To enable those skilled in the art to better understand the present invention, the following uses multiple specific embodiments to illustrate the preparation method of the material for electrode prelithiation of the present invention.

[0059] Example 1

[0060] (1) Dissolve bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0061] (2) Immerse the lithium strip in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium strip, obtaining the material for electrode prelithiation.

[0062] Subsequently, prelithiation treatment is performed on the silicon-carbon negative electrode sheet. The material for electrode prelithiation is laminated with the silicon-carbon negative electrode sheet, and the material for electrode prelithiation and the silicon-carbon negative electrode sheet are hot-rolled at 50 °C to obtain a prelithiated silicon-carbon negative electrode sheet. Subsequently, the prelithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the initial Coulomb efficiency is greater than 80%.

[0063] Example 2

[0064] (1) Dissolve bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 1%;

[0065] (2) The lithium ribbon is immersed in the reaction solution for 10 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0066] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0067] Example 3

[0068] (1) dissolving bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 0.5%;

[0069] (2) The lithium ribbon is immersed in the reaction solution for 20 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0070] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0071] Example 4

[0072] (1) dissolving bismuth nitrate in a diethylene glycol methyl ether solution to obtain a reaction solution having a bismuth nitrate concentration of 2%;

[0073] (2) The lithium ribbon is immersed in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0074] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0075] Example 5

[0076] (1) dissolving bismuth nitrate in triethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0077] (2) The lithium ribbon is immersed in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0078] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0079] Example 6

[0080] (1) dissolving bismuth nitrate in triethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0081] (2) The lithium ribbon is immersed in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0082] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0083] Example 7

[0084] (1) dissolving bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0085] (2) The reaction solution is sprayed on the lithium ribbon for 5 minutes to form a dense protective layer on the surface of the lithium ribbon, thereby obtaining a material for electrode pre-lithiation.

[0086] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 80%.

[0087] Example 8

[0088] (1) dissolving bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0089] (2) immersing the lithium ribbon in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium ribbon;

[0090] (3) Spraying 100 nm thick hexamethylenetetramine on the surface of the dense protective layer to form a passivation layer, thereby obtaining a material for electrode pre-lithiation.

[0091] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 50°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 90%.

[0092] Example 9

[0093] (1) dissolving bismuth nitrate in ethylene glycol methyl ether solution to obtain a reaction solution with a bismuth nitrate concentration of 2%;

[0094] (2) immersing the lithium ribbon in the reaction solution for 5 minutes to form a dense protective layer on the surface of the lithium ribbon;

[0095] (3) Spraying 50 nm thick hexamethylenetetramine on the surface of the dense protective layer to form a passivation layer, thereby obtaining a material for electrode pre-lithiation.

[0096] Afterwards, the silicon-carbon negative electrode sheet is pre-lithiated, the material for electrode pre-lithiation is bonded to the silicon-carbon negative electrode sheet, and a hot roller at 100°C is used to press the material for electrode pre-lithiation and the silicon-carbon negative electrode sheet to obtain a pre-lithiated silicon-carbon negative electrode sheet. Afterwards, the pre-lithiated silicon-carbon negative electrode sheet is applied to a lithium-ion battery of the NCM811 / silicon-carbon system, and the first coulombic efficiency is greater than 90%.

[0097] It can be seen that using the material for electrode pre-lithiation provided by the present invention to perform pre-lithiation treatment on the electrode pole piece can effectively improve the initial coulombic efficiency of the lithium-ion battery, so as to further improve the rate performance of the lithium-ion battery.

[0098] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0099] Finally, it should also be noted that in this text, relational terms such as first and second are only 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. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or terminal device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising said element.

[0100] The above has introduced in detail a material for electrode prelithiation, a preparation method of a material for electrode prelithiation, a prelithiation treatment method for an electrode, a lithium-ion battery, and a vehicle provided by the present invention. Specific examples are used in this text to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for prelithiation treatment of an electrode, characterized in that, the method comprises: dissolving bismuth nitrate in a solution of ethylene glycol monomethyl ether series compounds to obtain a reaction solution; bringing a lithium substrate into contact with the reaction solution to form a dense protective layer on the surface of the lithium substrate, thereby obtaining a material for electrode prelithiation; the dense protective layer contains Li element, Bi element and N element; attaching the material for electrode prelithiation to a battery electrode sheet, and hot rolling the material for electrode prelithiation and the battery electrode sheet at 50-100 °C; during the rolling process, enabling the Li element in the material for electrode prelithiation to be embedded in the battery electrode sheet, and simultaneously migrating the dense protective layer in the material for electrode prelithiation to the surface of the battery electrode sheet to form an electrode protective layer.

2. The method for prelithiation treatment of an electrode according to claim 1, characterized in that, The dense protective layer includes LiNO 3 , Li 3 N, LiN x O y (0 ≤ x ≤ 3, 0 ≤ y ≤ 3) and Li 3 Bi, at least one of them.

3. The method for prelithiation treatment of an electrode according to claim 1, characterized in that, it further comprises a passivation layer covering the surface of the dense protective layer, and the passivation layer comprises hexamine.

4. The method for prelithiation treatment of an electrode according to claim 1, characterized in that, the step of bringing the lithium substrate into contact with the reaction solution to form a dense protective layer on the surface of the lithium substrate comprises: immersing the lithium substrate in the reaction solution or showering the lithium substrate with the reaction solution to form a dense protective layer on the surface of the lithium substrate.

5. The method according to claim 1, characterized in that, the method further comprises: spraying hexamine on the surface of the dense protective layer to form a passivation layer.

6. The method according to claim 1, characterized in that, the concentration of the bismuth nitrate solution is 0.5-2%; the immersion duration of the lithium substrate in the reaction solution or the showering duration of the reaction solution on the lithium substrate is 5-20 minutes.

7. A lithium-ion battery, characterized in that, the lithium-ion battery comprises an electrode obtained by using the method for prelithiation treatment of an electrode according to any one of claims 1-6.

8. A vehicle, characterized in that, the vehicle comprises the lithium-ion battery according to claim 7.