阅读说明：本技术 一种预锂化石墨烯及其制备方法和应用 (Pre-lithiated graphene and preparation method and application thereof ) 是由 张振华 李长东 范霞 毛林林 阮丁山 于 2021-06-30 设计创作，主要内容包括：本发明电池材料技术领域,公开了一种预锂化石墨烯及其制备方法和应用,该预锂化石墨烯包括以下组分：锂的氧化物、锂的碳化物；锂的碳化物为Li-(2)CO-(3)、LiC-(x)、R-Li,其中,R为还原氧化石墨烯,1/6≤x≤1。本发明的预锂化石墨烯为石墨烯与锂、石墨烯与含锂化合物的复合物,该复合物中部分锂与石墨烯是以离子键相连,部分锂会形成其他含锂化合物均匀分布在石墨烯与锂的薄膜表面。(The invention discloses a pre-lithiated graphene and a preparation method and application thereof in the technical field of battery materials, wherein the pre-lithiated graphene comprises the following components: oxides of lithium, carbides of lithium; the carbide of lithium being Li 2 CO 3 、LiC x And R-Li, wherein R is reduced graphene oxide, and x is greater than or equal to 1/6 and less than or equal to 1. The pre-lithiated graphene is a compound of graphene and lithium and the graphene and a lithium-containing compound, wherein part of lithium and the graphene in the compound are connected by ionic bonds, and part of lithium can form other lithium-containing compounds which are uniformly distributed on the surfaces of the graphene and lithium films.)

1. A pre-lithiated graphene, comprising the following components: oxides of lithium, carbides of lithium; the carbide of lithium is Li₂CO₃、LiC_xAnd R-Li, wherein R is reduced graphene oxide, and x is greater than or equal to 1/6 and less than or equal to 1.

2. The prelithiated graphene according to claim 1, wherein the lithium oxide is lithium oxide.

3. The prelithiated graphene according to claim 1, wherein the prelithiated graphene has a specific surface area of 79.66-104m² g^-1The reversible specific capacity of the pre-lithiated graphene is 490-660mAh g^-1。

4. The method of preparing prelithiated graphene according to any of claims 1 to 3, comprising the steps of:

and mixing a lithium source, graphene oxide and an electron transfer carrier, adding a solvent, reacting, and drying to obtain the pre-lithiated graphene.

5. The production method according to claim 4, wherein the electron transfer carrier is at least one of tert-butylbenzene, tert-butylbenzo, and 4, 4-di-tert-butylbenzo.

6. The method according to claim 4, wherein the lithium source is elemental lithium.

7. The preparation method according to claim 4, wherein the mass ratio of the elemental lithium to the graphene oxide is (1-5): 100.

8. The preparation method of the graphene negative electrode is characterized by comprising the following steps:

mixing the pre-lithiated graphene, the adhesive and the solvent according to claims 1 to 3, coating the mixture on a copper foil, drying and carrying out heat treatment to obtain the graphene cathode, wherein the loading amount of the pre-lithiated graphene is 1.2-1.5mg cm^-2。

9. A graphene negative electrode, characterized by being prepared by the preparation method of claim 8.

10. A battery, comprising the following components: lithium metal foil, separator, graphene negative electrode according to claim 9, and electrolyte.

Technical Field

The invention belongs to the technical field of battery materials, and particularly relates to pre-lithiated graphene as well as a preparation method and application thereof.

Background

The graphene nanosheet has a unique structure, so that physical and electrical properties have great influence on energy storage equipment. In particular, in battery applications, the ultra-high conductivity and large specific surface area have prompted graphene to stand out among numerous carbon materials. Although graphene has excellent electrochemical properties, commercialization of graphene-based lithium ion batteries has not been completely achieved until now due to the lack of a scalable synthesis method to synthesize high-quality graphene. The current method for mass production of graphene is by oxidation-reduction.

Generally, natural graphite is prepared as graphene oxide using Hummers' method. The reduction method includes thermal reduction, hydrothermal method, chemical method and the like. Although the preparation methods of graphene are numerous, the final graphene electrode causes capacity fading due to a high irreversible capacity. Irreversible capacity is associated with the large specific surface area of graphene, resulting in the consumption of large amounts of lithium ions by SEI film formation during initial discharge. In order to prevent the lithium ion concentration in the electrolyte from decreasing, a possible approach is prelithiation, which involves producing an SEI film by electrochemical reaction with lithium metal in the half cell, or introducing sacrificial lithium to the negative electrode by physical contact with lithium metal. The pre-formed SEI film reduces a space for forming an additional SEI film, thereby preventing the generation of an irreversible capacity. At the same time, the sacrificial lithium in the electrode complements the lithium loss resulting from the SEI film formation. In addition, the pre-lithiation electrode has lower voltage, and the voltage difference between the positive electrode and the negative electrode in the full battery is reduced, so that the energy density is improved. The previous prelithiation method then has some drawbacks: (1) electrochemical prelithiation has large time loss due to low current density; (2) electrical overload during the process can cause the batteries to catch fire and explode; (3) prelithiation using bulk lithium is inefficient.

Therefore, there is a need for a stable and efficient pre-lithiated graphene and a pre-lithiation method thereof.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. The pre-lithiated graphene is a compound of graphene and lithium and a compound containing lithium, wherein part of lithium and graphene in the compound are connected by ionic bonds, and part of lithium can form other compounds containing lithium and is uniformly distributed on the surfaces of films of the graphene and the lithium. The prepared pre-lithiated graphene has a large specific surface area, contains more micropore and mesopore defects, is beneficial to diffusion and migration of lithium ions, and simultaneously has a large specific surface area which is beneficial to compounding of Li, so that the lithium ions consumed in the charge-discharge process can be more effectively supplemented, and therefore, the pre-lithiated graphene has high reversible charge specific capacity, high cycling stability and high rate capability.

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

a pre-lithiated graphene comprising the following components: oxides of lithium, carbides of lithium; the carbide of lithium is Li₂CO₃、LiC_xAnd R-Li, wherein R is reduced graphene oxide, and x is greater than or equal to 1/6 and less than or equal to 1.

The reduced graphene oxide is prepared from graphene oxide and Li⁺(C₁₀H₁₄)^-And graphene oxide.

Preferably, the lithium oxide is lithium oxide.

Preferably, the specific surface area of the prelithiated graphene is 79.66-104m² g^-1The reversible specific capacity of the pre-lithiated graphene is 490-660mAh g^-1。

The invention also provides a preparation method of the pre-lithiated graphene, which comprises the following steps:

and mixing a lithium source, graphene oxide and an electron transfer carrier, adding a solvent, reacting, and drying to obtain the pre-lithiated graphene.

The reaction equation is as follows: li + C₁₀H₁₄→Li⁺(C₁₀H₁₄)^-，Li⁺(C₁₀H₁₄)^-+R-OH→LiO₂+Li₂CO₃+LiC_x+ R-Li. R is reduced graphene oxide.

Preferably, the electron transfer carrier is at least one of tert-butylbenzene, tert-butylbenzo, and 4, 4-di-tert-butylbenzo.

Preferably, the lithium source is elemental lithium.

Preferably, the mass ratio of the elementary lithium to the graphene oxide is (1-5): 100.

Preferably, the solvent is N-methylpyrrolidone.

Preferably, the temperature of the reaction is 30-100 ℃.

Preferably, the atmosphere of the reaction is argon or nitrogen.

Preferably, the stirring speed of the reaction is 100rpm to 400 rpm.

Preferably, the drying temperature is 80-90 ℃, and the drying time is 12-18 h.

The preparation principle of the pre-lithiated graphene is as follows:

lithium metal and an electron transfer carrier form a compound, the lithium metal is oxidized into lithium ions, the electron transfer carrier becomes negative active group anions, the active group ions react with oxygen-containing functional groups in graphene oxide, benzene rings in the active groups replace the oxygen-containing functional groups to recover a pi-pi structure of the graphene, so that the effect of reducing the graphene oxide is achieved, structural defects in the reduction process are inhibited, and the conductivity of the graphene is recovered. Lithium is also incorporated into the graphene to form a composite (lithium carbide, lithium carbonate, lithium oxide, etc.). The formed lithium compound not only can reduce the loss of lithium ions in the battery cycle process, but also has the function of lithium supplement. In addition, the formed substances such as lithium carbonate and lithium oxide can increase the interlayer spacing between the graphene, so that the deintercalation of lithium ions is promoted, and the reversible specific capacity and the cycling stability are improved.

A preparation method of a graphene negative electrode comprises the following steps:

subjecting the prelithiated stone to a heat treatmentMixing graphene, an adhesive and a solvent, coating the mixture on a copper foil, drying and carrying out heat treatment to obtain the graphene negative electrode, wherein the loading capacity of the pre-lithiated graphene is 1.2-1.5mg cm^-2。

Preferably, the mass ratio of the pre-lithiated graphene to the adhesive is (90-95) to (5-10).

Preferably, the adhesive is styrene butadiene rubber.

Preferably, the solvent is N-methylpyrrolidone.

Preferably, the drying temperature is 90-100 ℃, the drying time is 0.5-2h, and the drying atmosphere is argon atmosphere or nitrogen.

Preferably, the heat treatment temperature is 100-120 ℃, and the heat treatment time is 10-12 h.

The graphene negative electrode is prepared by the preparation method.

A battery comprising the following components: lithium metal foil, a diaphragm, a graphene negative electrode and electrolyte.

Preferably, the separator is a polypropylene film.

Preferably, the electrolyte is LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Further preferably, the LiPF₆The concentration of (2) is 1 mol/L.

Further preferably, the volume ratio of the ethylene carbonate, the dimethyl carbonate and the diethyl carbonate is 1:1: 1.

Compared with the prior art, the invention has the following beneficial effects:

1. the pre-lithiated graphene is a compound of graphene and lithium and the graphene and a lithium-containing compound, wherein part of lithium and the graphene in the compound are connected by ionic bonds, and part of lithium can form other lithium-containing compounds which are uniformly distributed on the surfaces of the graphene and lithium films. The prepared pre-lithiated graphene has a large specific surface area, contains more micropore and mesopore defects, is beneficial to diffusion and migration of lithium ions, and simultaneously has a large specific surface area which is beneficial to compounding of Li, so that the lithium ions consumed in the charge-discharge process can be more effectively supplemented, and therefore, the pre-lithiated graphene has high reversible charge specific capacity, high cycling stability and high rate capability.

2. Compared with the conventional pre-lithiation method for embedding lithium between graphene layers, the chemical method for synthesizing the pre-lithiated graphene has the advantages that the loss of lithium in the electrolyte is reduced more effectively, the reduction and the pre-lithiation of the graphene oxide can be completed in one step, simplicity and high efficiency are realized, and a direction is provided for large-scale preparation of the graphene for the negative electrode.

3. According to the invention, a lithium simple substance rather than a lithium salt or other compounds is selected as a lithium source of the pre-lithiated graphene, so that the efficiency of reducing the graphene oxide is further improved because the lithium simple substance can effectively react with an electron transfer carrier, and more lithium carbide can be formed, and the lithium source is more beneficial to the improvement of reversible capacity compared with lithium carbonate or lithium oxide and the like.

Drawings

The invention is further described with reference to the following figures and examples, in which:

fig. 1 is an SEM image of prelithiated graphene of example 2 of the present invention;

fig. 2 is a high resolution C1s plot in X-ray photoelectron spectroscopy analysis of pre-lithiated graphene of example 2 of the present invention;

fig. 3 is a plot of high resolution Li1s in X-ray photoelectron spectroscopy analysis of pre-lithiated graphene of example 2 of the present invention;

FIG. 4 is N of pre-lithiated graphene of example 2 of the present invention₂Adsorption and desorption constant temperature curve chart;

fig. 5 is a pore size distribution plot for pre-lithiated graphene of example 2 of the present invention.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

The prelithiated graphene of this example includes the following components: LiO₂、Li₂CO₃、LiC_xR-Li, wherein R is reduced graphene oxide, and x is not less than 1/6 and not more than 1; the specific surface area of the prelithiated graphene is 81.18m² g^-1The reversible specific capacity of the prelithiated graphene is 540mAh g^-1。

In addition, the different mass ratios of lithium and graphene oxide lead to different contents of lithium carbide generated by reaction, so that the different reversible specific capacities are caused, in addition, the prelithiation and the reduction of the graphene oxide are synchronously completed, and different Li ratios lead to different reduction degrees, so that different defects are caused, so that the specific surface areas are different.

The preparation method of the prelithiated graphene of this embodiment includes the following steps:

weighing lithium metal and graphene oxide with the mass ratio of 2 wt% and placing the lithium metal and the graphene oxide into a container, adding tert-butyl benzene and tert-butyl benzene to obtain a mixture, pouring N-methyl pyrrolidone serving as a solvent into the mixture in the container to obtain slurry, introducing nitrogen to remove air in a beaker, magnetically stirring the slurry at the rotation speed of 300rpm and the reaction temperature of 70 ℃, stirring for 2 hours, washing and filtering the slurry with water, placing the filtered slurry in a vacuum drying oven, and performing vacuum drying at the temperature of 80 ℃ for 15 hours to obtain the pre-lithiated graphene.

The preparation principle of the pre-lithiated graphene is as follows:

lithium metal and an electron transfer carrier form a compound, the lithium metal is oxidized into lithium ions, the electron transfer carrier becomes negative active group anions, the active group ions react with oxygen-containing functional groups in graphene oxide, benzene rings in the active groups replace the oxygen-containing functional groups to recover a pi-pi structure of the graphene, so that the effect of reducing the graphene oxide is achieved, structural defects in the reduction process are inhibited, and the conductivity of the graphene is recovered. Lithium is also incorporated into the graphene to form a composite (lithium carbide, lithium carbonate, lithium oxide, etc.). The formed lithium compound not only can reduce the loss of lithium ions in the battery cycle process, but also has the function of lithium supplement. In addition, the formed substances such as lithium carbonate and lithium oxide can increase the interlayer spacing between the graphene, so that the deintercalation of lithium ions is promoted, and the reversible specific capacity and the cycling stability are improved.

A preparation method of a graphene negative electrode comprises the following steps:

putting 90 wt% of active material and 10 wt% of styrene butadiene rubber adhesive into an N-methyl pyrrolidone solvent, stirring, coating slurry on a copper foil, performing the coating process in a glove box filled with argon, drying for 1h at 90 ℃ in an argon atmosphere to obtain a pole piece, placing the pole piece under a vacuum condition, performing heat treatment at 100 ℃ for 12h, removing the residual solvent and the unreacted electron transfer carrier added previously to obtain a graphene cathode, wherein the loading amount of pre-lithiated graphene is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mAg by using an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The rate capability is 50-1000mAg at current density^-1And (4) measuring.

Example 2

The prelithiated graphene of this example includes the following components: LiO₂、Li₂CO₃、LiC_xR-Li, wherein R is reduced graphene oxide, and x is not less than 1/6 and not more than 1; the specific surface area of the prelithiated graphene is 103.21m² g^-1The reversible specific capacity of the prelithiated graphene is 651mAh g^-1。

The preparation method of the prelithiated graphene of this embodiment includes the following steps:

weighing 4 wt% of lithium metal and graphene oxide, placing the lithium metal and the graphene oxide into a container, adding tert-butyl benzene and tert-butyl benzene to obtain a mixture, pouring N-methyl pyrrolidone serving as a solvent into the mixture in the container to obtain slurry, introducing nitrogen to remove air in a beaker, magnetically stirring the slurry at the rotating speed of 300rpm and the reaction temperature of 70 ℃, stirring for 2 hours, washing and filtering the slurry with water, placing the filtered slurry in a vacuum drying oven, and performing vacuum drying at the temperature of 80 ℃ for 15 hours to obtain the pre-lithiated graphene.

A preparation method of a graphene negative electrode comprises the following steps:

putting 90 wt% of active material and 10 wt% of styrene butadiene rubber adhesive into an N-methyl pyrrolidone solvent, stirring, coating slurry on a copper foil, performing the coating process in a glove box filled with argon, drying for 1h at 90 ℃ in an argon atmosphere to obtain a pole piece, placing the pole piece under a vacuum condition, performing heat treatment at 100 ℃ for 12h, removing the residual solvent and the unreacted electron transfer carrier added previously to obtain a graphene cathode, wherein the loading amount of pre-lithiated graphene is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mAg by using an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The rate capability is 50-1000mAg at current density^-1And (4) measuring.

Fig. 1 is an SEM image of prelithiated graphene of example 2 of the present invention; from fig. 1, lithium complexes with uniform graphene film surface distribution can be obtained.

FIG. 2Is a high resolution C1s plot in X-ray photoelectron spectroscopy analysis of the pre-lithiated graphene of example 2 of the present invention; fig. 3 is a plot of high resolution Li1s in X-ray photoelectron spectroscopy analysis of pre-lithiated graphene of example 2 of the present invention; FIGS. 2 and 3 demonstrate LiCO₃，Li₂The existence of O, C-Li shows that the graphene oxide is not only prelithiated but also effectively reduced, and the generated lithium compound is similar to SEI film components, so that the formation of an SEI film in the charge and discharge process can be effectively inhibited.

FIG. 4 is N of pre-lithiated graphene of example 2 of the present invention₂Adsorption and desorption constant temperature curve chart (nitrogen relative pressure); fig. 5 is a pore size distribution plot for pre-lithiated graphene of example 2 of the present invention; fig. 4 and 5 illustrate that the pore size of the pre-lithiated graphene is mainly distributed in the range of 60-160nm, and the pore structures facilitate lithium ion diffusion on the surface and in the graphene.

Example 3

The prelithiated graphene of this example includes the following components: LiO₂、Li₂CO₃、LiC_xR-Li, wherein R is reduced graphene oxide, and x is not less than 1/6 and not more than 1; the specific surface area of the prelithiated graphene is 94.7m² g^-1The reversible specific capacity of the prelithiated graphene is 572mAh g^-1。

The preparation method of the prelithiated graphene of this embodiment includes the following steps:

weighing 6 wt% of lithium metal and graphene oxide, placing the lithium metal and the graphene oxide into a container, adding tert-butyl benzene and tert-butyl benzene to obtain a mixture, pouring N-methyl pyrrolidone serving as a solvent into the mixture in the container to obtain slurry, introducing nitrogen to remove air in a beaker, magnetically stirring the slurry at the rotating speed of 300rpm and the reaction temperature of 70 ℃, stirring for 2 hours, washing and filtering the slurry with water, placing the filtered slurry in a vacuum drying oven, and performing vacuum drying at the temperature of 80 ℃ for 15 hours to obtain the pre-lithiated graphene.

A preparation method of a graphene negative electrode comprises the following steps:

adding 90 wt% of active material and 10 wt% of styrene-butadiene rubber adhesive into N-methyl pyrrolidone solvent, stirring, and coating the slurry on copper foilAnd performing the coating process in a glove box filled with argon, drying for 1h at 90 ℃ in an argon atmosphere to obtain a pole piece, placing the pole piece under a vacuum condition, performing heat treatment at 100 ℃ for 12h, removing the residual solvent and the unreacted electron transfer carrier added before to obtain the graphene negative electrode, wherein the loading amount of the pre-lithiated graphene is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mA g by an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The multiplying power performance is that the current density is 50-1000mA g^-1And (4) measuring.

Example 4

The prelithiated graphene of this example includes the following components: LiO₂、Li₂CO₃、LiC_xR-Li, wherein R is reduced graphene oxide, and x is not less than 1/6 and not more than 1; the specific surface area of the prelithiated graphene is 79.66m² g^-1The reversible specific capacity of the prelithiated graphene is 493mAh g^-1。

The preparation method of the prelithiated graphene of this embodiment includes the following steps:

weighing lithium metal and graphene oxide with the mass ratio of 8 wt% and placing the lithium metal and the graphene oxide into a container, adding tert-butyl benzene and tert-butyl benzene to obtain a mixture, pouring N-methyl pyrrolidone serving as a solvent into the mixture in the container to obtain slurry, introducing nitrogen to remove air in a beaker, magnetically stirring the slurry at the rotation speed of 300rpm and the reaction temperature of 70 ℃, stirring for 2 hours, washing and filtering the slurry with water, placing the filtered slurry in a vacuum drying oven, and performing vacuum drying at the temperature of 80 ℃ for 15 hours to obtain the pre-lithiated graphene.

A preparation method of a graphene negative electrode comprises the following steps:

putting 90 wt% of active material and 10 wt% of styrene butadiene rubber adhesive into an N-methyl pyrrolidone solvent, stirring, coating slurry on a copper foil, performing the coating process in a glove box filled with argon, drying for 1h at 90 ℃ in an argon atmosphere to obtain a pole piece, placing the pole piece under a vacuum condition, performing heat treatment at 100 ℃ for 12h, removing the residual solvent and the unreacted electron transfer carrier added previously to obtain a graphene cathode, wherein the loading amount of pre-lithiated graphene is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mA g by an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The multiplying power performance is that the current density is 50-1000mA g^-1And (4) measuring.

Comparative example 1

The preparation method of the graphene negative electrode of the comparative example comprises the following steps:

putting 90 wt% of graphene oxide and 10 wt% of styrene butadiene rubber adhesive into an N-methyl pyrrolidone solvent, stirring, coating slurry on a copper foil, performing the coating process in a glove box filled with argon, drying for 1h at 90 ℃ under the atmosphere of argon to obtain a pole piece, placing the pole piece under a vacuum condition, and performing heat treatment at 100 ℃ for 12h to obtain a graphene cathode, wherein the loading amount of the graphene oxide is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and diethyl carbonate.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mA g by an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The multiplying power performance is that the current density is 50-1000mA g^-1And (4) measuring.

Comparative example 2

The preparation method of the reduced graphene oxide of the comparative example includes the following steps:

weighing graphene oxide, putting the graphene oxide into a container, adding hydrazine hydrate, magnetically stirring for 12 hours at 80 ℃, filtering slurry, performing vacuum drying for 10 hours at 90 ℃, putting the dried solid into a tubular furnace, and performing heat treatment for 6 hours at 150 ℃ in a mixed gas of argon and hydrogen in a ratio of 4:1 to obtain reduced graphene oxide.

A preparation method of a graphene negative electrode comprises the following steps:

putting 90 wt% of reduced graphene oxide and 10 wt% of styrene butadiene rubber adhesive into an N-methyl pyrrolidone solvent, stirring, coating slurry on a copper foil, performing the coating process in a glove box filled with argon, drying for 1h at the temperature of 90 ℃ in the atmosphere of argon to obtain a pole piece, placing the pole piece under a vacuum condition, performing heat treatment at the temperature of 100 ℃ for 12h, removing the residual solvent and the unreacted electron transfer carrier added before to obtain a graphene cathode, wherein the loading amount of the reduced graphene oxide is 1.2mg cm^-2。

A battery comprising the following components: lithium metal foil, polypropylene film, graphene negative electrode and LiPF₆Ethylene carbonate, dimethyl carbonate and di-carbonic acidAnd (4) ethyl ester.

Preparing a battery: 1mol/L LiPF₆The electrolyte is prepared by dissolving the electrolyte in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1:1:1, and then the coin-type half-cell is formed by taking a lithium metal foil as a positive electrode, a polypropylene film as a diaphragm and a graphene negative electrode.

The coin-type half cell is subjected to electrochemical performance detection, charging and discharging and cycling stability at a current density of 30mA g by an electrochemical workstation^-1Voltage 0.01-3.0V (vs. Li/Li)⁺) The following measurements were made. The multiplying power performance is that the current density is 50-1000mA g^-1And (4) measuring.

Physical and chemical properties:

table 1 shows the specific surface area of the samples prepared in examples 1, 2, 3, 4 compared to comparative examples 1, 2, and it was found that the specific surface area of the pre-lithiated graphene is significantly higher than that of the comparative examples, especially the specific surface area of example 2 is the largest.

TABLE 1 specific surface areas of the prelithiated graphene of examples 1-4 to the graphene oxide of comparative examples 1-2

Electrochemical performance:

table 2 shows the comparison of the electrochemical properties of the samples prepared in examples 1, 2, 3 and 4 and comparative examples 1 and 2, and it is found that the reversible charge specific capacity, the cycling stability and the rate capability of the pre-lithiated graphene samples prepared in examples 1 to 4 of the present invention are higher than those of the samples prepared in comparative examples 1 and 2, and especially the electrochemical property of example 2 is significantly superior.

Table 2 electrochemical performance test data for pre-lithiated graphene and comparative samples

The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.