A magnetically modified semi-solid fluid negative electrode and its preparation method and application

Abstract

The present invention discloses a magnetically modified semi-solid fluid negative electrode, and a preparation method and application thereof. A magnetically modified semi-solid fluid negative electrode comprises a composite material, a conductive agent and an electrolyte, wherein the composite material, the conductive agent and the electrolyte are mixed in a certain proportion to obtain a semi-solid fluid negative electrode; wherein the composite material is prepared by compounding a negative electrode active material, a superparamagnetic metal material and a carbon material. The present invention first prepares a composite material of a negative electrode active material, a carbon material and a superparamagnetic metal nanomaterial by a microwave method, and then mixes the composite material with a conductive agent and an electrolyte in a certain proportion to prepare a slurry as a semi-solid fluid negative electrode. This slurry electrode has good magnetic responsiveness and high electrical conductivity, and is used in semi-solid lithium-ion batteries. Under the action of a magnetic field, the specific capacity of the semi-solid fluid battery is improved. The preparation and control method of the magnetically modified semi-solid fluid negative electrode of the present invention can also be extended to other flowable electrochemical energy storage systems.

Description

Technical Field

[0001] The present invention belongs to the field of battery electrodes, and in particular relates to a magnetically modified semi-solid fluid negative electrode and a preparation method and application thereof. Background Art

[0002] Semi-solid flow batteries (SSFBs), a novel electrochemical energy storage technology, have attracted considerable attention in recent years due to their independently tunable energy storage capacity and power. They are expected to be used in large-scale energy storage applications. The electrode slurry in these batteries primarily consists of solid active materials, conductive agents, and electrolytes. The active materials, as the primary energy storage material, are a key factor influencing electrochemical performance. However, the preparation of most active materials is complex and time-consuming. Therefore, an efficient and convenient method is needed to prepare electrode materials with high specific capacity to increase the energy density of lithium-ion batteries.

[0003] High temperatures are an effective method for synthesizing materials such as metals, ceramics, and carbon compounds. However, traditional sintering furnaces have slow heating and cooling rates, low energy efficiency, and long heating times, making them unsuitable for the controlled synthesis of nanomaterials. However, high-temperature synthesis techniques based on carbon substrates offer the advantages of fast heating rates, high efficiency, and simplicity, making them suitable for the synthesis of carbon-supported nanoparticles.

[0004] For semi-solid-state lithium flow batteries, the core slurry has the problem of mutual constraints between conductivity, specific capacity and viscosity, which are related to the microstructure of the particles inside the electrode slurry. Therefore, starting from regulating the microstructure of the electrode slurry and finding a suitable method to prepare electrode slurry that takes into account both conductivity and fluidity is of great significance to improving the electrochemical performance of semi-solid-state batteries. Summary of the Invention

[0005] In order to solve the problem of mutual constraints among conductivity, specific capacity and viscosity in electrode slurry, the inventors conducted intensive research and designed a magnetically modified semi-solid fluid negative electrode and its preparation method and application. The magnetically modified composite material was prepared by a simple and efficient microwave method and prepared into a negative electrode slurry, which can effectively improve its electrical conductivity and improve the electrochemical performance of the semi-solid liquid flow battery under a magnetic field.

[0006] The technical solution adopted by the present invention to solve the above problems is:

[0007] According to one aspect of the present invention, a magnetically modified semi-solid fluid anode is provided, which comprises a composite material, a conductive agent, and an electrolyte, wherein the composite material, the conductive agent, and the electrolyte are mixed in a certain proportion to obtain a semi-solid fluid anode;

[0008] The composite material is prepared by compounding a negative electrode active material, a superparamagnetic metal material and a carbon material.

[0009] The present invention first prepares a composite material of anode active material, carbon material, and superparamagnetic metal nanomaterial using a microwave method, then prepares this composite material into anode slurry. Finally, the magnetic field is controlled to make the magnetism of this magnetic composite material reversible, thereby achieving the design and regulation of the slurry electrode microstructure. The semi-solid slurry can be efficiently magnetized under the action of a magnetic field, causing the active particles to align and contact closely, effectively shortening the electron transmission path and enhancing the conductivity of the electrode slurry. After the external magnetic field is removed, the active particles become non-magnetic due to zero remanence, thus dispersing and restoring fluidity. Therefore, the electrochemical performance of semi-solid flow batteries can be improved by independently adjusting the conductivity and fluidity of the slurry electrodes.

[0010] The magnetically modified electrode composite material provided by the present invention is obtained by combining a negative electrode active material, a carbon material, and a superparamagnetic metal nanomaterial using a microwave method. The composite material is then mixed with a conductive agent and an electrolyte in a certain proportion to obtain a semi-solid fluid electrode. The preparation process of the composite material is simple and fast. When used as an electrode material to prepare a slurry electrode, it has the advantages of good magnetic response, high conductivity, and high specific capacity, thus completing the present invention.

[0011] Furthermore, the negative electrode active material in the composite material is selected from one or more of graphite, silicon or lithium titanate, and the negative electrode active material is preferably graphite (C).

[0012] Furthermore, the superparamagnetic material is selected from one or more of iron, cobalt, nickel, ferroferric oxide or ferrous oxide, preferably nickel (Ni).

[0013] Furthermore, the carbon material is selected from one or more of carbon nanotubes, nitrogen-doped graphene, carbon fiber and graphene oxide, and is preferably nitrogen-doped graphene (G).

[0014] Furthermore, the conductive agent is selected from one or more of Ketjen black, acetylene black, carbon fiber or carbon nanotube, preferably Ketjen black.

[0015] Furthermore, the electrolyte is lithium hexafluorophosphate and fluoroethylene carbonate dissolved in ethylene carbonate / diethyl carbonate / dimethyl carbonate (LiPF 6 +EC / DMC / DEC+5%FEC).

[0016] Furthermore, the semi-solid fluid electrode is a mixture of the composite material, the conductive agent and the electrolyte in a volume ratio of 3-5:5-20:30-50, preferably a uniform mixture in a volume ratio of 3:10:37.5.

[0017] According to a second aspect of the present invention, a method for preparing a magnetically modified semi-solid fluid anode is provided, wherein the magnetically modified semi-solid fluid anode comprises the aforementioned magnetically modified semi-solid fluid anode, and the preparation method comprises mixing a composite material, a conductive agent, and an electrolyte in a certain proportion to obtain a magnetically modified semi-solid fluid anode;

[0018] Also included is a method for preparing a magnetically modified composite material, the composite material preparation method comprising the following steps:

[0019] Step 1, preparing a suspension containing carbon material;

[0020] Preferably, the suspension containing the carbon material is a suspension of a carbon material such as graphene;

[0021] Step 2: mixing the negative electrode active material and a suspension containing a carbon material to obtain a negative electrode active material / carbon material composite material;

[0022] Step 3, preparing a superparamagnetic material salt solution;

[0023] Preferably, the superparamagnetic material salt solution comprises a metal nickel salt solution;

[0024] Step 4, mixing the sample mixed in step 2, i.e., the negative electrode active material / carbon material composite material, with the superparamagnetic material salt solution, such as the metal nickel salt solution, in step 3, and drying;

[0025] Step 5: The dried sample is subjected to microwave treatment.

[0026] Furthermore, in step 1, the volume ratio of the carbon material such as graphene to the solvent in the suspension containing the carbon material is 0.01-0.05 mg:5-20 ml, preferably 0.02-0.04 mg:10 ml, and more preferably 0.03 mg:10 ml.

[0027] Furthermore, in step 2, the mass ratio of the negative electrode active material to the carbon material such as graphene is 20-100:1, preferably 25-50:1, and more preferably 33:1.

[0028] Furthermore, in step 3, the concentration of the superparamagnetic material salt solution, such as the metal nickel salt solution, is 0.2-2.0 mol / L, preferably 0.2-1.0 mol / L, and more preferably 0.75 mol / L.

[0029] Furthermore, in step 4, the volume ratio of the composite material suspension to the superparamagnetic material salt solution, such as metal nickel salt solution, is 0.5-2.0:1, preferably 1:1.

[0030] In step 4, the mixed sample is centrifuged once, pre-frozen in a freeze dryer at -70°C to -40°C for 1-10 hours, then vacuumed, and carried out at -20°C to 0°C for 12-30 hours; further preferably, the freeze-drying is first pre-frozen at -60°C to -50°C for 2-8 hours, then vacuumed, and carried out at -10°C to 0°C for 12-20 hours.

[0031] Furthermore, in step 5, the frequency of the microwave treatment is 915-2450 MHz, more preferably 2450 MHz; the treatment time is 20-100 s, more preferably 45 s, and the power is 700 W.

[0032] According to the third aspect of the present invention, there is provided an application of the magnetically modified semi-solid fluid negative electrode or the preparation method as described above. Under the control of a magnetic field, the magnetically modified semi-solid fluid negative electrode is suitable for improving battery performance and application.

[0033] The beneficial effects of the present invention include:

[0034] 1) The composite material provided by the present invention uses a micron-sized negative electrode active material as a matrix, which can be used directly after purchase; a metal nanomaterial with superparamagnetism is selected and composited with a carbon material and an active material with good electrical conductivity to obtain a magnetically modified composite material with good magnetic response and good electrical conductivity;

[0035] 2) The method for preparing a magnetically modified composite material provided by the present invention uses a simple microwave method to directly generate superparamagnetic nanoparticles on the surface of the active material through carbothermal reduction. The nanometer size facilitates their stable and uniform coating on the surface of the active material, so that the active material obtains uniform magnetism and has a good magnetic response effect.

[0036] 3) The magnetically modified composite material provided by the present invention, when prepared into a semi-solid fluid negative electrode, has the advantages of high conductivity, good stability and high specific capacity;

[0037] 4) The magnetically modified semi-solid fluid anode provided by the present invention exhibits a favorable magnetic response to magnetic fields, allowing the composite material particles to be tightly packed during charge and discharge, shortening the electron transport path and thereby improving the conductivity of the electrode slurry. After the external magnetic field is removed, the composite material particles, lacking magnetism, disperse and regain fluidity, resulting in an electrode slurry with high conductivity and fluidity.

[0038] 5) The preparation and application of the magnetically modified semi-solid fluid anode provided by this invention can produce an electrode slurry with high conductivity and fluidity, improving the electrochemical performance of the battery. This dual-functional semi-solid electrode, characterized by both fluidity and superparamagnetism, can provide guidance and theoretical basis for the design of novel semi-solid slurry electrodes and can be extended to other flowable energy storage systems, with potential applications in large-scale energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 shows the XRD pattern of the graphite-graphene-nickel composite material in Example 1;

[0040] Figure 2 The SEM and mapping images of the graphite-graphene-nickel composite material in Example 1 are shown;

[0041] Figure 3 Graph showing the magnetic response effect of the graphite-graphene-nickel composite material in Example 1;

[0042] Figure 4 The conductivity diagram of the semi-solid slurry prepared from the graphite-graphene-nickel composite material in Example 2 is shown;

[0043] Figure 5 The graph shows the rate performance of the semi-solid-state battery assembled with the graphite-graphene-nickel composite material in Example 2 with (M) and without a magnetic field. DETAILED DESCRIPTION

[0044] The present invention will be described in further detail below with reference to the accompanying drawings and examples, through which the features and advantages of the present invention will become more clearly understood.

[0045] In some embodiments, a magnetically modified semi-solid fluid negative electrode is provided, which includes a composite material, a conductive agent and an electrolyte. The composite material, the conductive agent and the electrolyte are mixed in a certain proportion to obtain a semi-solid fluid negative electrode; wherein the composite material is prepared by compounding a negative electrode active material, a superparamagnetic metal material and a carbon material.

[0046] The present invention provides a magnetically modified composite material obtained by combining a negative electrode active material, a carbon material, and a superparamagnetic metal nanomaterial using a microwave method. The composite material has a simple and fast preparation process. When used as an electrode material to prepare a slurry electrode, it exhibits excellent magnetic response, high conductivity, and high specific capacity.

[0047] The magnetically modified semi-solid fluid anode of the present invention exhibits a favorable magnetic response to magnetic fields, allowing the composite material particles to align closely during charge and discharge, shortening the electron transport path and thereby improving the conductivity of the electrode slurry. Upon removal of the external magnetic field, the composite material particles, lacking magnetism, disperse and regain fluidity, resulting in an electrode slurry with both high conductivity and fluidity.

[0048] In a preferred embodiment, the negative electrode active material is selected from one or more of graphite, silicon or lithium titanate, and the negative electrode material is preferably graphite (C).

[0049] The negative electrode active material is preferably graphite, because graphite has a high theoretical capacity (~372 mAh / g) and a low operating voltage (~0.2 V vs. Li / Li+), and has the advantages of abundant reserves, low price, high stability, and good electronic conductivity.

[0050] In a preferred embodiment, the superparamagnetic material is selected from one or more of iron, cobalt, nickel, ferroferric oxide or ferrous oxide, more preferably nickel (Ni).

[0051] The superparamagnetic material is preferably nickel. This is because the oxidation potential of nickel is low. If it is loaded on the surface of the positive electrode active material, the nickel will be continuously oxidized and lost during the battery charging process. However, it does not react within the negative electrode potential, so it is suitable for negative electrode active materials.

[0052] In a preferred embodiment, the carbon material is selected from one or more of carbon nanotubes, nitrogen-doped graphene, carbon fibers and graphene oxide, more preferably nitrogen-doped graphene (G).

[0053] In the embodiments of the present invention, the addition of superparamagnetic metal materials and carbon materials is crucial for preparing superparamagnetic composite materials and improving their magnetic response and electrochemical properties. On the one hand, the active material alone does not have magnetism, and the addition of superparamagnetic materials gives the composite material a good magnetic response. On the other hand, most active materials have poor electrical conductivity on their own, and their electrochemical properties as lithium-ion battery electrode materials are poor. Compounding with conductive metal and carbon materials can enhance their conductivity and improve the electrochemical performance of the composite material.

[0054] In a preferred embodiment, the conductive agent is selected from one or more of Ketjen black, acetylene black, carbon fiber or carbon nanotube, preferably Ketjen black.

[0055] In a preferred embodiment, the electrolyte is lithium hexafluorophosphate and fluoroethylene carbonate dissolved in ethylene carbonate / diethyl carbonate / dimethyl carbonate (LiPF 6 +EC / DMC / DEC+5% FEC).

[0056] In a preferred embodiment, the composite material, the conductive agent and the electrolyte are mixed in a volume ratio of 3-5:5-20:30-50, preferably in a volume ratio of 3:10:37.5.

[0057] In some embodiments, a method for preparing the aforementioned magnetically modified semi-solid fluid negative electrode is also provided, the preparation method comprising mixing a composite material, a conductive agent, and an electrolyte in a certain proportion to obtain a magnetically modified semi-solid fluid negative electrode.

[0058] The preparation method also includes a method for preparing a magnetically modified composite material, and the composite material preparation method includes the following steps:

[0059] Step 1, preparing a suspension containing carbon material;

[0060] The suspension containing the carbon material may be, for example, a suspension of a carbon material such as graphene.

[0061] Specifically, four portions of 0.03 g of graphene were weighed, added to ethanol respectively, and ultrasonicated for 30 minutes to uniformly disperse the graphene.

[0062] Step 2: Mixing the negative electrode active material and a carbon material suspension such as graphene to obtain a negative electrode active material / carbon material composite material.

[0063] Specifically, four portions of 1.0 g of graphite were weighed and mixed with the graphene suspension, and ultrasonically and magnetically stirred for 30 minutes to uniformly disperse the graphite.

[0064] Step 3, preparing a superparamagnetic material salt solution;

[0065] The superparamagnetic material salt solution may be, for example, a metal nickel salt solution.

[0066] Specifically, 0.648 g, 1.296 g, 1.944 g, and 2.592 g of NiCl 2 were weighed and dissolved in ethanol until the NiCl 2 was completely dissolved, to prepare CG-NiCl 2 solutions with NiCl 2 concentrations of 0.25 mol / L, 0.5 mol / L, 0.75 mol / L, and 1.0 mol / L. The solutions were then adjusted to pH 5 with NaOH solution and set aside.

[0067] Step 4, mixing the sample mixed in step 2 with a metal nickel salt solution and drying;

[0068] Specifically, the graphite-graphene suspension is added to the above-mentioned NiCl2 solution of different concentrations, and the mixed suspension is sonicated for 10 minutes and magnetically stirred for 10 minutes, alternating back and forth three times for a total of 1 hour to obtain a uniformly mixed suspension. The mixed suspension is centrifuged once at 8000 rpm for 5 minutes, the supernatant is discarded, and then pre-frozen in a freeze dryer at -70°C to -40°C for 1-10 hours, then vacuumized, and continued at -20°C to 0°C for 12-30 hours. More preferably, the freeze-drying is first pre-frozen at -60°C to -50°C for 2-8 hours, then vacuumized, and continued at -10°C to 0°C for 12-20 hours. Even more preferably, the freeze-drying is first pre-frozen at -50°C for 5 hours, then vacuumized, and continued at 0°C for 16 hours.

[0069] Step 5: The dried sample is subjected to microwave treatment.

[0070] The freeze-dried sample was placed in a crucible inside a glass bottle. A balloon was placed over the bottle neck in a glove box to expose the sample to an argon atmosphere. Finally, the glass bottle was placed in a turntable microwave oven and microwave-treated at a frequency of 2450 MHz, a treatment time of 45 seconds, and a power of 700 W to produce the CG-Ni composite material.

[0071] It should be understood that when other types of carbon materials or superparamagnetic materials are used, the preparation method of the composite material has the same or similar principles and operating methods, which will not be described in detail here.

[0072] In some embodiments, the application of a magnetically modified semi-solid fluid anode or preparation method is also provided. Under magnetic field control, the magnetically modified semi-solid fluid anode is suitable for improving battery performance and application. The magnetically modified semi-solid fluid anode has good magnetic response effect and high conductivity. When applied to batteries, it has the advantage of high specific capacity under magnetic field control. For example, a semi-solid lithium-ion half-battery obtained by mixing a CG-Ni composite material with a conductive agent and an electrolyte in a volume ratio of 3:10:37.5 effectively improves rate performance under magnetic field control.

[0073] To fully illustrate the relevant performance of the magnetically modified semi-solid fluid anode provided by the present application and facilitate understanding of the present invention, the present application has conducted multiple sets of experimental verifications. The present invention will be further described below with reference to specific examples.

[0074] Example 1

[0075] Weigh four portions of 0.03g graphene and add them to ethanol. Ultrasonicate for 30 minutes to evenly disperse the graphene. Weigh four portions of 1.0g graphite and mix them with the suspension. Ultrasonicate and magnetically stir for 30 minutes to evenly disperse the graphene. Weigh 0.648g, 1.296g, 1.944g, and 2.592g of NiCl₂, respectively, and dissolve them in ethanol until the NiCl₂ is completely dissolved. CG-NiCl₂ solutions with NiCl₂ concentrations of 0.25mol / L, 0.5mol / L, 0.75mol / L, and 1.0mol / L are prepared. These solutions are then adjusted to pH 5 with NaOH solution. The graphite-graphene suspensions are then added to the NiCl₂ solutions of varying concentrations. The mixed suspensions are ultrasonicated for 10 minutes and magnetically stirred for 10 minutes, alternating between three cycles for a total of 1 hour to obtain a uniformly mixed suspension.

[0076] The mixed suspension was centrifuged once at 8000 rpm for 5 min, the supernatant was discarded, and then pre-frozen in a freeze dryer at -50°C for 5 h, and then vacuum-dried and kept at 0°C for 16 h.

[0077] The above sample was placed in a crucible placed in a glass bottle, and a balloon was placed on the mouth of the glass bottle in a glove box to place the sample in an argon atmosphere. Finally, the glass bottle was placed in a turntable microwave oven for microwave treatment to generate a CG-Ni composite material.

[0078] Figure 1 The XRD patterns of the CG-Ni composite material from Example 1 show that the characteristic peaks of C are well preserved in samples with varying concentrations. Furthermore, the intensity of the Ni diffraction peak increases with increasing NiCl₂ precursor concentration, indicating a higher Ni content. However, when the NiCl₂ precursor concentration reaches 1.0 mol / L, impurities such as NiCl₂ (PDF#71-2032) and NiO (PDF#71-1179) are present. Therefore, considering the purity of the sample and the need for both conductivity and magnetic properties, the CG-Ni composite material prepared with a NiCl₂ precursor concentration of 0.75 mol / L was selected for electrode fabrication.

[0079] Figure 2 The following are SEM images and mapping images of the CG-Ni composite material in Example 1. The SEM image shows spherical carbon particles coated with small spherical particles, representing elemental nickel. Curled sheets adjacent to the graphite are graphene. The mapping image shows that carbon comes from carbon, and nickel comes from nickel. The mapping image demonstrates a uniform distribution of nickel on the carbon. Besides carbon and nickel, the composite material is free of oxygen and chloride impurities, indicating the preparation of a pure CG-Ni composite material.

[0080] Figure 3 The following image shows the magnetic response of the CG-Ni composite material. In the absence of an applied magnetic field, the black particles of the composite material accumulate at the bottom of the bottle due to gravity. However, when a magnetic field is applied from one side, the composite particles quickly converge toward the magnetic side and move with the movement of the magnet, demonstrating the material's excellent magnetic response.

[0081] Example 2

[0082] from Figure 4 It can be seen from the figure that the electronic conductivity of CG-Ni slurry is significantly greater than that of C slurry. The former (2.02mS / cm) is about 2.2 times that of the latter (0.93mS / cm). This is because the conductive metal Ni is evenly coated on the graphite surface, which increases the conductivity of the composite material. In addition, the graphene in the composite material has excellent conductive properties and plays a good conductive role, which together increase the electronic conductivity of the CG-Ni composite material.

[0083] The rate performance test of the lithium-ion semi-solid half-battery assembled in Example 2 was carried out under the following test conditions: the test voltage was 0.01-3.00 V, and the test was carried out at 0.1C, 0.2C, 0.5C, 1C and 2C respectively. The test results are shown in FIG. Figure 5 shown.

[0084] from Figure 5 It can be seen that under the action of a magnetic field, the semi-solid lithium-ion half-battery prepared from this composite material has a higher capacity, and its rate performance is significantly improved compared with that of CG-Ni and C batteries in the absence of a magnetic field.

[0085] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the present invention and do not constitute any limitation on the scope of protection of the present invention. Various improvements, equivalent substitutions, or modifications may be made to the technical content of the present invention and its embodiments without departing from the spirit and scope of protection of the present invention, and all of these fall within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the appended claims.

Claims

1. Application of a magnetically modified semi-solid fluid negative electrode, characterized in that: The invention comprises a composite material, a conductive agent and an electrolyte, wherein the composite material, the conductive agent and the electrolyte are mixed in a certain proportion to obtain a semi-solid fluid negative electrode; wherein the composite material is made by compounding a negative electrode active material, a superparamagnetic metal material and a carbon material, which is then prepared into a negative electrode slurry, and finally the magnetism of the composite material is made reversible by magnetic field control. The semi-solid slurry is magnetized under the action of the magnetic field, so that the active particles are neatly arranged and in close contact. After the external magnetic field is removed, the active particles have no magnetism due to zero remanence, thereby dispersing and recovering fluidity; The negative electrode active material is graphite; The preparation of the composite material comprises the following steps: Step 1, preparing a carbon material suspension, wherein the carbon material suspension includes a graphene suspension; Step 2: mixing the negative electrode active material and the carbon material suspension, adding graphite to the graphene suspension, mixing, and stirring to obtain a graphite / graphene composite material; Step 3, preparing a salt solution corresponding to a superparamagnetic metal material, wherein the superparamagnetic metal material is nickel, and the salt solution is a nickel chloride solution, and adjusting the pH value thereof to an appropriate value; Step 4, loading the superparamagnetic material onto the surface of the negative electrode active material, mixing the graphite / graphene composite material in Step 2 with the nickel chloride solution in Step 3, stirring, and freeze-drying; Step 5: subjecting the dried sample to microwave treatment at a frequency of 2450 MHz, a treatment time of 45 s, and a power of 700 W to obtain a composite material loaded with superparamagnetic metal nanoparticles for later use.

2. The use of a magnetically modified semi-solid fluid negative electrode according to claim 1, characterized in that: The carbon material is nitrogen-doped graphene.

3. The use of a magnetically modified semi-solid fluid negative electrode according to claim 1, characterized in that: The conductive agent is Ketjen black.

4. The use of a magnetically modified semi-solid fluid negative electrode according to claim 1, characterized in that: The composite material, the conductive agent and the electrolyte are mixed in a volume ratio of 3:10:37.

5.

5. The use of a magnetically modified semi-solid fluid negative electrode according to claim 1, characterized in that: In step 1, the volume ratio of the carbon material mass to the solvent in the graphene suspension is 0.03 mg:10 ml; In step 2, the mass ratio of the negative electrode active material to the carbon material is 33:

1.

6. The use of a magnetically modified semi-solid fluid negative electrode according to claim 1, characterized in that: In step 3, the concentration of the salt solution corresponding to the superparamagnetic metal material is 0.75 mol / L; In step 4, the volume ratio of the negative electrode active material / carbon material composite material to the superparamagnetic material salt solution is 1:1.

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