Preparation method and application of pre-lithiated lithium battery negative electrode material

Abstract

The invention relates to the technical field of lithium battery materials, in particular to a preparation method and application of a pre-lithiated lithium battery negative electrode material.The preparation method comprises the steps that graphene oxide is dissolved in deionized water, and ultrasonic treatment is conducted to obtain graphene oxide turbid liquid; transferring the ferric nitrate solution and the lithium nitrate solution into the graphene oxide turbid liquid, and performing ultrasonic treatment; then putting the mixed solution into a vacuum oven, and drying; grinding the dried sample; and putting the ground sample into heating equipment, heating, and stopping heating after the temperature is raised to 300 DEG C, so as to obtain the pre-lithiated lithium battery negative electrode material. According to the invention, pre-lithiation is adopted to make up the lithium source consumed by forming an SEI film through first charging, the first efficiency of the battery is improved, and the capacity and energy density of the battery are improved to a certain extent. The preparation method provided by the invention is simple and effective, and the lithium battery negative electrode material with high performance and high coulombic efficiency can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery materials, and in particular to a preparation method and application of a pre-lithiated lithium battery negative electrode material. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, long cycle life, high operating voltage, low self-discharge rate, and wide operating temperature range, and are considered to be one of the most promising energy storage devices. However, during the first charging process of lithium-ion batteries, the organic electrolyte is reduced and decomposed on the surface of the negative electrode material to form a layer of solid electrolyte interface film (SEI), and the formation of this SEI film will cause the consumption of lithium in the positive electrode. This process is irreversible. At the same time, the formation and consumption of the SEI film require the consumption of lithium in the positive electrode, resulting in a low coulombic efficiency in the first cycle, which reduces the capacity and energy density of lithium-ion batteries. Summary of the invention

[0003] In order to solve the problem that the lithium in the positive electrode is consumed during the first charging process of a lithium-ion battery, resulting in low efficiency and reduced capacity and energy density of the lithium-ion battery, the present invention provides a method for preparing a pre-lithiated lithium battery negative electrode material and its application.

[0004] The present invention is achieved through the following technical solution: A method for preparing a pre-lithiated lithium battery negative electrode material, comprising the following steps: Step 1): dissolving graphene oxide in deionized water and subjecting the mixture to ultrasonic treatment to obtain a graphene oxide suspension; Step 2): Dissolve ferric nitrate and lithium nitrate in deionized water to prepare solution A and solution B respectively; Step 3): Move solution A and solution B into the graphene oxide suspension prepared in step 1) and perform ultrasonic treatment; Step 4): Then put the mixed solution obtained in step 3) into a vacuum oven for drying; Step 5): Grind the dried sample; then put the ground sample into a heating device, heat it, and stop heating after the temperature reaches 300 °C to obtain a pre-lithiated lithium battery negative electrode material.

[0005] As a further improvement of the technical solution of the preparation method of the present invention, the ferric nitrate can be replaced by a mixture of one or more of cobalt nitrate, nickel nitrate, copper nitrate and cerium nitrate in any proportion.

[0006] As a further improvement of the technical solution of the preparation method of the present invention, the concentration of the graphene oxide suspension is 10 mg / mL.

[0007] As a further improvement of the technical solution of the preparation method of the present invention, the mass percentage of metallic iron in the pre-lithiated lithium battery negative electrode material is 5% to 30%.

[0008] As a further improvement of the technical solution of the preparation method of the present invention, the mass ratio of the lithium nitrate to the graphene oxide is 1-5:100.

[0009] As a further improvement of the technical solution of the preparation method of the present invention, the heating equipment is a tubular furnace or a muffle furnace.

[0010] As a further improvement of the technical solution of the preparation method of the present invention, the atmosphere in the heating equipment is air, nitrogen or argon.

[0011] The present invention further provides a method for preparing a pre-lithiated lithium battery negative electrode material, and uses the obtained pre-lithiated lithium battery negative electrode material as an electrode material in a lithium ion battery.

[0012] The present invention provides a lithium ion battery, which is composed of a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode material used in the negative electrode is a pre-lithiated lithium battery negative electrode material prepared by the above-mentioned method for preparing a pre-lithiated lithium battery negative electrode material.

[0013] The method for preparing a pre-lithiated lithium battery negative electrode material provided by the present invention has the following advantages compared with the prior art: The present invention adopts pre-lithiation to make up for the lithium source consumed by the formation of SEI film during the first charge, the first efficiency of the battery will be improved, and the capacity and energy density of the battery will be improved to a certain extent. In addition, the preparation method provided by the present invention is simple and effective, and can obtain a lithium battery negative electrode material with high performance and high coulomb efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 The figure is the rate performance test curve of Example 1 and Comparative Example 1.

[0017] Figure 2 The cycle performance curves of Example 1 and Comparative Example 1 at a high current density of 2 A / g.

[0018] Figure 3 The impedance performance diagram of Example 3 and Comparative Example 3. DETAILED DESCRIPTION

[0019] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] The present invention provides a specific embodiment of a method for preparing a pre-lithiated lithium battery negative electrode material, comprising the following steps: Step 1): dissolving graphene oxide in deionized water and subjecting the mixture to ultrasonic treatment to obtain a graphene oxide suspension; Step 2): Dissolve ferric nitrate and lithium nitrate in deionized water to prepare solution A and solution B respectively; Step 3): Move solution A and solution B into the graphene oxide suspension prepared in step 1) and perform ultrasonic treatment; Step 4): Then put the mixed solution obtained in step 3) into a vacuum oven for drying; Step 5): Grind the dried sample; then put the ground sample into a heating device, heat it, and stop heating after the temperature reaches 300 °C to obtain a pre-lithiated lithium battery negative electrode material.

[0022] In one embodiment provided by the present invention, the iron nitrate can be replaced by a mixture of one or more of cobalt nitrate, nickel nitrate, copper nitrate and cerium nitrate in any proportion.

[0023] In another embodiment provided by the present invention, the concentration of the graphene oxide suspension is 10 mg / mL.

[0024] In one embodiment provided by the present invention, the mass percentage of metallic iron in the pre-lithiated lithium battery negative electrode material is 5% to 30%.

[0025] In another embodiment provided by the present invention, the mass ratio of the lithium nitrate to the graphene oxide is 1-5:100.

[0026] In one embodiment provided by the present invention, the heating device is a tubular furnace or a muffle furnace.

[0027] In another embodiment provided by the present invention, the atmosphere in the heating device is air, nitrogen or argon.

[0028] The present invention also provides a method for preparing a pre-lithiated lithium battery negative electrode material, and application of the prepared pre-lithiated lithium battery negative electrode material as an electrode material in a lithium ion battery.

[0029] Specifically, the lithium-ion battery is composed of a positive electrode, a negative electrode, an electrolyte and a separator, and is characterized in that the negative electrode material used in the negative electrode is the pre-lithiated lithium battery negative electrode material prepared by the above-mentioned preparation method of the pre-lithiated lithium battery negative electrode material.

[0030] The specific embodiments of the present invention are described in detail below. Example 1

[0031] Weigh 100 mg of graphene oxide and dissolve it in 10 mL of deionized water, ultrasonically treat it for 1 h, and prepare a 10 mg / mL graphene oxide suspension. Weigh 75.9 mg of iron nitrate (Fe(NO3)3·9H2O) and 2 mg of lithium nitrate and dissolve them in 5 mL of deionized water, respectively, to prepare solution A and solution B. Transfer solution A and solution B into the graphene oxide suspension, ultrasonically treat it for 30 min, and then put the resulting mixture into a vacuum oven at 80 °C and dry it for 12 h; put the dried sample into a mortar and grind it evenly, put it in a quartz crucible with a lid, put it in a tube furnace, and heat it to 300 °C at a heating rate of 10 °C / min in an air atmosphere, then stop heating, and collect the lithium battery negative electrode material in the crucible after the tube furnace cools down. Among them, the mass percentage of metallic iron in the lithium battery negative electrode material is 5 wt%. Example 2

[0032] The preparation method of Example 2 is different from that of Example 1 in that cobalt nitrate is used instead of iron nitrate. Example 3

[0033] The preparation method of Example 3 is different from that of Example 1 in that nickel nitrate is used instead of iron nitrate. Example 4

[0034] The preparation method of Example 4 is different from that of Example 1 in that copper nitrate is used instead of iron nitrate. Comparative Example 1

[0035] Comparative Example 1 is a negative electrode material for a lithium battery. Compared with Example 1, the difference is that lithium nitrate is not added, and the rest is the same. Comparative Example 2

[0036] Comparative Example 2 is a negative electrode material for a lithium battery. Compared with Example 2, the difference is that lithium nitrate is not added, and the rest is the same. Comparative Example 3

[0037] Comparative Example 3 is a negative electrode material for a lithium battery. Compared with Example 3, the difference is that lithium nitrate is not added, and the rest is the same. Comparative Example 4

[0038] Comparative Example 4 is a negative electrode material for a lithium battery. Compared with Example 4, the difference is that lithium nitrate is not added, and the rest is the same.

[0039] The negative electrode material is used as the electrode active material, and is mixed with conductive carbon black Super P and binder PVDF in a mass ratio of 7:2:1, poured into an agate mortar and ground continuously for 10 min, N-methylpyrrolidone (NMP) is added, and a magnetic rotor is placed, and stirred at a speed of 550 r / min for 3 h to obtain a slurry with uniform distribution and moderate viscosity. The fully mixed slurry is evenly coated on the copper foil and placed in a vacuum oven at 120 °C for 12 h. The dried copper foil is taken out and cut into small discs with a diameter of 12 mm using a cutting machine. Select the appropriate pole piece and weigh it, and put it into the transition chamber for washing, vacuum wash three times continuously to completely remove the oxygen and moisture in the material, and then put it into a glove box filled with argon. Take out the negative electrode shell, and then put in the lithium sheet, diaphragm, drip electrolyte, put in the gasket and gasket, and cover the positive electrode shell in this order to complete the battery assembly. The lithium sheet is used as the positive electrode of the half-cell, the diaphragm is a polypropylene diaphragm, the electrolyte is a mixed solution of LiPF6, the volume ratio of ethylene carbonate / dimethyl carbonate in the mixed solution is 1:1, and the concentration of LiPF6 is 1.0 M.

[0040] The electrical performance test was carried out using the blue electric test system. The test results are shown in Table 1: Table 1 project 0.2A / g current density first charge specific capacity (mAh / g) 0.2A / g current density first discharge specific capacity (mAh / g) First charge and discharge efficiency (%) Example 1 1472 2086 70.6 Example 2 1674 2407 69.5 Example 3 1488 2082 71.5 Example 4 856 1128 75.9 Comparative Example 1 999 1630 61.3 Comparative Example 2 1133 1769 64.0 Comparative Example 3 783 1193 65.6 Comparative Example 4 335 538 62.3 It can be seen from Table 1 that the pre-lithiated lithium battery negative electrode material prepared by the present invention has a significantly improved first discharge efficiency compared with the non-pre-lithiated negative electrode material, and has a more excellent charge and discharge specific capacity.

[0041] Figure 1 The rate performance test curves of Example 1 and Comparative Example 1 are as follows: Figure 1 It can be seen that as the current density gradually increases, the cycle reversible capacity of the two negative electrode materials decreases. When the discharge specific capacity is restored to 0.2 A / g, it can basically be restored to the initial discharge capacity, showing the good cycle reversibility of the negative electrode materials in Example 1 and Comparative Example 1. Compared with Comparative Example 1, the rate performance of the negative electrode material in Example 1 is greatly improved, indicating that the pre-lithiation negative electrode material has excellent stability and rate performance.

[0042] Figure 2 The cycle performance curves of Example 1 and Comparative Example 1 at a high current density of 2 A / g are shown. The cycle data show that after 700 cycles at a current density of 2.0 A / g, the capacity of Example 1 remains at 736.9 mAh / g, and the capacity retention rate is as high as 95.4%, which is better than 90.9% of Comparative Example 1, showing excellent cycle stability.

[0043] Figure 3 3 is the impedance performance diagram of Example 3 and Comparative Example 3. From the AC impedance fitting data, it can be seen that the electrode of Example 1 has a smaller charge transfer impedance and a faster ion diffusion rate, and therefore has good reaction kinetics behavior.

[0044] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A method for preparing a pre-lithiated lithium battery negative electrode material, characterized in that: The steps include: Step 1): dissolving graphene oxide in deionized water and subjecting the mixture to ultrasonic treatment to obtain a graphene oxide suspension; Step 2): Dissolve ferric nitrate and lithium nitrate in deionized water to prepare solution A and solution B respectively; Step 3): Move solution A and solution B into the graphene oxide suspension prepared in step 1) and perform ultrasonic treatment; Step 4): Then put the mixed solution obtained in step 3) into a vacuum oven for drying; Step 5): Grind the dried sample; then put the ground sample into a heating device, heat it, and stop heating after the temperature reaches 300 °C to obtain a pre-lithiated lithium battery negative electrode material.

2. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The iron nitrate may be replaced by a mixture of one or more of cobalt nitrate, nickel nitrate, copper nitrate and cerium nitrate in any proportion.

3. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The concentration of the graphene oxide suspension is 10 mg / mL.

4. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The mass percentage of metallic iron in the pre-lithiated lithium battery negative electrode material is 5% to 30%.

5. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The mass ratio of the lithium nitrate to the graphene oxide is 1-5:

100.

6. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The heating device is a tubular furnace or a muffle furnace.

7. The method for preparing a pre-lithiated lithium battery negative electrode material according to claim 1, characterized in that: The atmosphere in the heating device is air, nitrogen or argon.

8. Use of the pre-lithiated lithium battery negative electrode material prepared by the method for preparing a pre-lithiated lithium battery negative electrode material according to any one of claims 1 to 7 as an electrode material in a lithium ion battery.

9. A lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte and a separator, characterized in that: The negative electrode material used in the negative electrode is a pre-lithiated lithium battery negative electrode material prepared by the method for preparing a pre-lithiated lithium battery negative electrode material as described in any one of claims 1 to 7.

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