A negative electrode active material for a lithium slurry battery and a preparation method thereof

Abstract

The present invention discloses a negative electrode active material for a lithium slurry battery and a preparation method thereof. Using P123 as a structure-directing agent, organosilicon as a silicon source, and organic carbon as a carbon source, a gel-like silica / carbon precursor is obtained by a solvothermal method. Through high-temperature heat treatment, a rod-shaped silicon oxycarbide negative electrode active material is obtained. During the process of preparing silica using P123 as a structure-directing agent, a carbon source is introduced to obtain a silicon oxide material with both carbon coating and carbon reduction of silica, simplifying the process flow; through the selection of the carbon source, not only the problem that the carbon source is easily partially carbonized during hydrothermal treatment under acidic conditions is solved, but also the surface binding force and interface compatibility of the material are improved; by controlling the calcination temperature, a SiOx / C negative electrode material with a gradient distribution of silicon valence states is obtained, forming a mild stress gradient, a complete and strong carbon coating, and a gentle Si valence state gradient, promoting local stress release, ensuring a stable SEI film, and enhancing the kinetic diffusion of lithium ions.

Description

Technical Field

[0001] The present invention belongs to the technical field of slurry energy storage, and particularly relates to a negative silicon-carbon active material in a negative electrode slurry of a lithium slurry battery and a preparation method thereof. Background Art

[0002] The lithiation potential of silicon-based negative electrode materials is relatively low, and they have a high theoretical specific capacity, which can achieve a relatively high energy density and have been widely developed in lithium-ion battery negative electrode materials. Lithium slurry battery is a new type of energy storage technology with the advantages of independent output power and energy storage capacity, large energy density, low cost, good cycle performance, high battery system safety, etc. After long-term research and development and scale-up trial production by multiple scientific research institutions such as 24M Company, Kyocera, Institute of Electrical Engineering of Chinese Academy of Sciences, Dalian Institute of Chemical Physics, and Institute of Process Engineering, lithium slurry battery has become a new type of large-scale energy storage technology with great application prospects. It is of great significance to use silicon-based negative electrode materials in the negative electrode slurry of lithium slurry batteries.

[0003] Different from the fixed electrode structure of lithium-ion batteries, in slurry batteries, silicon-carbon materials are directly suspended in the electrolyte, and the active particles are in an unconstrained state. Volume expansion will bring problems such as changes in particle-to-particle contact, an increase in the contact area between the active material and the electrolyte, and an increase in side reactions. Summary of the Invention

[0004] Aiming at the crucial characteristics of constructing a stable suspension in the lithium slurry battery system and the problems of large volume expansion and poor conductivity of silicon-carbon materials themselves, the present invention provides a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states and a preparation method thereof, and applies the negative electrode active material as the negative electrode of a slurry battery to an energy storage battery. The silicon-carbon material suitable for the lithium slurry system proposed by the present invention can enhance the suspension stability of the lithium slurry system and the suspension stability of the silicon-carbon material in the slurry system.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A negative electrode active material for a lithium slurry battery, which is a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states, with a carbon coating on the outermost layer and silicon monoxide SiOx inside.

[0007] Further, the length of the SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states is 1 μm - 10 μm, and the diameter is 300 nm - 900 nm.

[0008] Further, the silicon monoxide SiOx has an amorphous structure, where 0.8 < x < 1.3, accounting for 85% - 95% wt of the negative electrode active material of the lithium slurry battery.

[0009] The present invention also provides a method for preparing a negative electrode active material of a lithium slurry battery. Using P123 as a structure-directing agent, organosilicon as a silicon source, and organic carbon as a carbon source, a method for obtaining the negative electrode active material by sol-hydrothermal-calcination specifically includes the following steps:

[0010] (1) Add P123 to a mixed solution of deionized water and hydrochloric acid, stir until P123 is completely dissolved, then add the silicon source, and stir for a period of time until the solution becomes sol-like to obtain system S1;

[0011] (2) Add the carbon source to system S1, continue stirring, and further solubilize to obtain system S2;

[0012] (3) Transfer system S2 to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a gel-like silica / carbon precursor;

[0013] (4) Wash and dry the product after the above hydrothermal reaction to obtain a silica / carbon precursor polymer;

[0014] (5) Calcinate the silica / carbon precursor polymer to obtain a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states.

[0015] Further, the silicon source is an organosilicon of silicate esters, including but not limited to tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, etc.; the carbon source is an organic acid carbon source containing carboxyl groups, including but not limited to citric acid, tartaric acid, ascorbic acid, etc.

[0016] Further, in step (1), the stirring method is magnetic stirring in a water bath, the stirring speed is 70 rpm / min - 200 rpm / min; the pH of system S1 is 1 - 3; the stirring time after adding the silicon source is 3 h - 6 h; the silicon source addition rate is 0.5 ml / min - 1 ml / min.

[0017] Further, in step (1), the mass ratio of P123 to the silicon source is 1:1.5 - 1:3.

[0018] Further, in step (2), the stirring time after adding the carbon source is 22 h - 30 h; the mass ratio of the silicon source to the carbon source is 3:1 - 5:1; the carbon source addition rate is 0.5 ml / min - 1 ml / min.

[0019] Further, in step (3), the hydrothermal time is 20 h - 26 h, and the hydrothermal temperature is 100°C - 120°C.

[0020] Further, in step (4), the washing and drying method is rotary evaporation drying - vacuum drying.

[0021] Further, the rotary evaporation drying temperature is 60°C - 85°C, and the rotary evaporation drying time is 4h - 7h.

[0022] Further, the vacuum drying temperature is 120°C - 170°C, and the vacuum drying time is 15h - 25h.

[0023] Further, in the step (5), the calcination temperature is 650°C - 950°C, the calcination time is 2h - 5h, and the calcination atmosphere is a mixed gas of argon and hydrogen, where the volume fraction of hydrogen is 5%.

[0024] The present invention also provides a lithium slurry battery electrode prepared by using the above SiOx / C negative electrode material with a rod-like structure and a silicon valence gradient distribution as the negative electrode active material.

[0025] Compared with the prior art, the present invention prepares a silicon gradient material with both conductivity and slurry suspension stability, reduces the influence of the volume expansion of silicon-carbon materials on electrical properties in a slurry system without a tight binding environment, and the beneficial effects of the provided lithium slurry battery negative electrode active material are as follows:

[0026] 1) The present invention prepares silicon materials with spherical, rod-like, and hexahedral morphologies, studies the influence of morphology on the suspension stability of lithium slurry, and concludes that rod-like materials are most beneficial to the stability of lithium slurry suspension.

[0027] 2) In the past, a rod-like silica was first prepared using a P123 structure-directing agent, then the silica was reduced by magnesium thermal reduction to prepare nanosilicon, and then carbon-coated to obtain a rod-like silicon-carbon material. In this patent, a carbon source is directly introduced during the process of preparing silica using P123 as the structure-directing agent to obtain a silicon-oxygen material with both carbon coating and carbon reduction of silica, avoiding the complex process flow of using magnesium thermal reduction of silica and then carbon coating.

[0028] 3) Since the preparation of silica using P123 as the structure-directing agent is carried out under hydrothermal conditions in strong acid, most of the carbon source will be partially carbonized after hydrothermal treatment in strong acid, seriously affecting the subsequent carbon reduction and carbon coating effects. The present invention patent uses an organic carbon source containing carboxyl groups to solve the above problems. In addition, the carboxyl groups on the surface of the organic carbon source react with the surface of the silicon source to undergo further polyesterification under hydrothermal conditions, obtaining a carbon-coated silicon-oxygen material grafted by esterification reaction, which improves the surface binding force and interfacial compatibility of the material.

[0029] 4) The product after hydrothermal treatment is dried by rotary evaporation, which can protect the structural and compositional integrity of the hydrothermal product gel, and thus improve the carbon coating and reduction ability during the subsequent calcination process.

[0030] 5) By controlling the preparation process, a SiOx / C anode material with a gradient distribution of silicon valence states is obtained, which can disperse stress to a certain extent, reduce the damage to the material structure and SEI film, and improve the performance of the silicon-carbon material in a slurry system without a tightly bound environment. Description of the Drawings

[0031] Figure 1 XRD pattern of the anode active material in the present invention.

[0032] Figure 2 SEM image of the anode active material in the present invention.

[0033] Figure 3 Anode slurry prepared from the anode active material in the present invention.

[0034] Figure 4 Solution obtained after hydrothermal treatment of different carbon sources in Comparative Example 1 of the present invention.

[0035] Figure 5 Electrochemical performance of Example 1 of the present invention. Detailed Description of the Invention

[0036] The present invention will be further described below with reference to examples, but it should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] The preparation method of the anode active material of the lithium slurry battery in this example is as follows:

[0039] (1) Add a certain amount of P123 to deionized water and hydrochloric acid (2M) solution, adjust the pH to 2, stir magnetically until P123 is completely dissolved, control the stirring speed at 100 rpm / min, and then add tetraethyl orthosilicate at a rate of 0.7 ml / min according to 2 times the mass of P123, and continue to stir for 4 h to obtain system S1.

[0040] (2) Slowly add a citric acid aqueous solution to system S1, with the mass ratio of tetraethyl orthosilicate to citric acid being 3:1, control the dropping rate at 0.5 ml / min, and continue to stir for 24 h for further sol-gelation to obtain system S2.

[0041] (3) Transfer system S2 to a reaction kettle, with a hydrothermal temperature of 105 °C and a hydrothermal time of 24 h, and naturally cool to room temperature after hydrothermal treatment to obtain a gel-like silica / carbon precursor.

[0042] (4) Spin-dry the hydrothermal product to remove the excess solvent, with a rotary evaporation temperature of 80 °C and a rotary evaporation time of 5 h, and then place the round-bottom flask in a vacuum drying oven, with a drying temperature of 150 °C and a drying time of 24 h, to obtain a silica / carbon precursor polymer.

[0043] (5) Calcinate the silicon dioxide / carbon precursor polymer. The calcination atmosphere is a mixed gas of argon and hydrogen, the calcination temperature is 750 °C, and the calcination time is 2 h to obtain a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states.

[0044] Use this material as the negative electrode active material of the lithium slurry battery to prepare a slurry electrode. The preparation process is as follows: Mix 10% active material, 0.5% single-walled carbon nanotube powder, and 89.5% conventional electrolyte evenly with a defoamer to obtain a negative electrode slurry. Conduct slurry suspension stability and electrochemical performance tests respectively. Put the negative electrode slurry into a graduated test tube for suspension stability testing. The obtained slurry has no sedimentation in 14 days and has good fluidity. Use a lithium metal sheet as the counter electrode to assemble a battery for electrochemical performance testing of the negative electrode suspension. The test conditions are 0.005 V - 2 V, the test current is 0.1 C, and after 20 cycles, the capacity retention rate is 89%.

[0045] Example 2

[0046] The preparation method of the negative electrode active material of the lithium slurry battery in this example is as follows:

[0047] (1) Add a certain amount of P123 to deionized water and hydrochloric acid (2 M) solution, adjust the pH to 1, stir magnetically until P123 is completely dissolved, control the stirring speed at 70 rpm / min, and then add tetraethyl orthosilicate at a rate of 0.5 ml / min according to 1.5 times the mass of P123, and continue stirring for 6 h to obtain system S1.

[0048] (2) Slowly add a citric acid aqueous solution to system S1. The mass ratio of tetraethyl orthosilicate to citric acid is 3:1. Control the dropping rate at 0.5 ml / min and continue stirring for 28 h for further sol-gelation to obtain system S2.

[0049] (3) Transfer system S2 to a reaction kettle, the hydrothermal temperature is 120 °C, the hydrothermal time is 20 h, and after hydrothermal treatment, it is naturally cooled to room temperature to obtain a gel-like silicon dioxide / carbon precursor.

[0050] (4) Spin-dry the hydrothermal product to remove excess solvent. The rotary evaporation temperature is 85 °C, the rotary evaporation time is 4 h, and then put the round-bottom flask into a vacuum drying oven. The drying temperature is 160 °C, and the drying time is 20 h to obtain a silicon dioxide / carbon precursor polymer.

[0051] (5) Calcinate the silicon dioxide / carbon precursor polymer. The calcination atmosphere is a mixed gas of argon and hydrogen, the calcination temperature is 850 °C, and the calcination time is 2 h to obtain a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states.

[0052] The material was used as the negative electrode active material of the lithium slurry battery to prepare a slurry electrode. The negative electrode slurry was put into a graduated test tube for suspension stability testing. The obtained slurry showed no sedimentation in 14 days and had good fluidity. Using a lithium metal sheet as the counter electrode, a battery was assembled to conduct electrochemical performance testing on the negative electrode suspension. The testing conditions were 0.005V - 2V, the testing current was 0.1C, and after 20 cycles, the capacity retention rate was 87%.

[0053] Example 3

[0054] The preparation method of the negative electrode active material of the lithium slurry battery in this example is as follows:

[0055] (1) A certain amount of P123 was added to deionized water and hydrochloric acid (2M) solution, the pH was adjusted to 2, and magnetic stirring was carried out until P123 was completely dissolved. The stirring speed was controlled at 200 rpm / min, and then tetrapropyl orthosilicate was added dropwise at a rate of 0.5 ml / min according to 1.5 times the mass of P123, and stirring was continued for 3 h to obtain system S1.

[0056] (2) An aqueous citric acid solution was slowly added to system S1. The mass ratio of tetrapropyl orthosilicate to citric acid was 3:1. The dropping rate was controlled at 0.5 ml / min, and stirring was continued for 22 h for further sol-gelation to obtain system S2.

[0057] (3) System S2 was transferred to a reaction kettle, the hydrothermal temperature was 100 °C, the hydrothermal time was 26 h, and after hydrothermal treatment, it was naturally cooled to room temperature to obtain a gel-like silica / carbon precursor.

[0058] (4) The hydrothermal product was spin-dried to remove the excess solvent. The rotary evaporation temperature was 65 °C, and the rotary evaporation time was 7 h. Then the round-bottom flask was placed in a vacuum drying oven, the drying temperature was 130 °C, and the drying time was 25 h to obtain a silica / carbon precursor polymer.

[0059] (5) The silica / carbon precursor polymer was calcined. The calcination atmosphere was a mixed gas of argon and hydrogen, the calcination temperature was 850 °C, and the calcination time was 4 h to obtain a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states.

[0060] (6) The material was used as the negative electrode active material of the lithium slurry battery to prepare a slurry electrode. The negative electrode slurry was put into a graduated test tube for suspension stability testing. The obtained slurry showed no sedimentation in 14 days and had good fluidity. Using a lithium metal sheet as the counter electrode, a battery was assembled to conduct electrochemical performance testing on the negative electrode suspension. The testing conditions were 0.005V - 2V, the testing current was 0.1C, and after 20 cycles, the capacity retention rate was 91%.

[0061] Example 4

[0062] The preparation method of the negative electrode active material of the lithium slurry battery in this embodiment is as follows:

[0063] (1) Add a certain amount of P123 to deionized water and hydrochloric acid (2M) solution, adjust the pH to 2, stir magnetically until P123 is completely dissolved, control the stirring speed at 150 rpm / min, then add tetraethyl orthosilicate at a rate of 0.7 ml / min according to 3 times the mass of P123, and continue stirring for 3 h to obtain system S1.

[0064] (2) Slowly add tartaric acid aqueous solution to system S1, the mass ratio of tetraethyl orthosilicate to tartaric acid is 5:1, control the dropping rate at 0.7 ml / min, and continue stirring for 22 h for further sol-gelation to obtain system S2.

[0065] (3) Transfer system S2 to a reaction kettle, with a hydrothermal temperature of 105 °C and a hydrothermal time of 24 h, and naturally cool to room temperature after hydrothermal treatment to obtain a gel-like silica / carbon precursor.

[0066] (4) Spin-dry the hydrothermal product to remove the excess solvent, with a rotary evaporation temperature of 75 °C and a rotary evaporation time of 6 h, then put the round-bottom flask into a vacuum drying oven, with a drying temperature of 160 °C and a drying time of 24 h to obtain a silica / carbon precursor polymer.

[0067] (5) Calcinate the silica / carbon precursor polymer, with a calcination atmosphere of argon-hydrogen mixed gas, a calcination temperature of 900 °C, and a calcination time of 3 h to obtain a SiOx / C negative electrode material with a rod-like structure and a gradient distribution of silicon valence states.

[0068] (6) Use this material as the negative electrode active material of the lithium slurry battery to prepare a slurry electrode, put the negative electrode slurry into a graduated test tube for suspension stability testing, the obtained slurry has no sedimentation in 14 days and has good fluidity. Use a lithium metal sheet as the counter electrode to assemble a battery for electrochemical performance testing of the negative electrode suspension. The test conditions are 0.005V - 2V, the test current is 0.1C, and after 20 cycles, the capacity retention rate is 88%.

[0069] Example 5

[0070] The preparation method of the negative electrode active material of the lithium slurry battery in this embodiment is as follows:

[0071] (1) Add a certain amount of P123 to deionized water and hydrochloric acid (2M) solution, adjust the pH to 2, stir magnetically until P123 is completely dissolved, control the stirring speed at 100 rpm / min, then add tetraethyl orthosilicate at a rate of 1 ml / min according to 2 times the mass of P123, and continue stirring for 3 h to obtain system S1.

[0072] (2) Slowly add an aqueous citric acid solution to the S1 system. The mass ratio of tetraethyl orthosilicate to citric acid is 4:1. Control the dropping rate at 1 ml / min and continue stirring for 24 h for further sol-gelation to obtain system S2.

[0073] (3) Transfer system S2 to a reaction kettle. The hydrothermal temperature is 105 °C and the hydrothermal time is 24 h. After hydrothermal treatment, it is naturally cooled to room temperature to obtain a gel-like silica / carbon precursor.

[0074] (4) Spin-dry the hydrothermal product to remove the excess solvent. The rotary evaporation temperature is 85 °C and the rotary evaporation time is 4 h. Then place the round-bottom flask in a vacuum drying oven. The drying temperature is 160 °C and the drying time is 24 h to obtain a silica / carbon precursor polymer.

[0075] (5) Calcinate the silica / carbon precursor polymer. The calcination atmosphere is a mixed gas of argon and hydrogen. The calcination temperature is 950 °C and the calcination time is 5 h to obtain a SiOx / C anode material with a rod-like structure and a gradient distribution of silicon valence states.

[0076] (6) Use this material as the anode active material of a lithium slurry battery to prepare a slurry electrode. Place the negative electrode slurry in a graduated test tube for suspension stability testing. The obtained slurry shows no sedimentation in 14 days and has good flow performance. Use a lithium metal sheet as the counter electrode to assemble a battery for electrochemical performance testing of the negative electrode suspension. The test conditions are 0.005 V - 2 V, the test current is 0.1 C. After 20 cycles, the capacity retention rate is 91%.

[0077] Comparative Example 1

[0078] Compared with Example 1, in step (2), the carbon source citric acid is replaced with sucrose or chitosan or phenolic resin or asphalt or polyvinyl alcohol. The remaining steps are the same as those in Example 1. The main purpose of this Comparative Example 1 is to investigate the influence of the type of carbon source on the carbon coating and carbon reduction effects. The experimental results show that when using non-acidic carbon sources such as sucrose or chitosan or phenolic resin or asphalt or polyvinyl alcohol, the system S2 is black or dark brown after hydrothermal treatment, and the color of the material after calcination is light gray. When assembling a battery for electrochemical performance testing of the negative electrode suspension, the specific capacity is less than 100 mAh. After 20 cycles, the capacity retention rate is less than 20%. The reason for this phenomenon is that when non-acidic carbon sources are hydrothermally treated under acidic conditions, partial carbonization will occur, affecting subsequent carbon coating and carbon reduction. Moreover, when using P123 as a template method to prepare rod-like silica, it is synthesized under acidic hydrothermal conditions. Therefore, if other non-acidic carbon sources are selected, it is impossible to obtain a rod-like silicon-carbon material with carbon coating and carbon reduction through a one-step method.

[0079] Comparative Example 2

[0080] Compared with Example 1, in which step (4) is to remove the excess solvent of the gel-like silica / carbon precursor by centrifugation or suction filtration. The remaining steps are the same as those in Example 1. The main purpose of this Comparative Example 2 is to investigate the effect of the treatment method of the gel-like silica / carbon precursor on the material properties. The experimental results show that when the excess solvent of the gel-like silica / carbon precursor is removed by centrifugation or suction filtration, the color of the obtained product remains white after drying and calcination, indicating that carbon reduction has not occurred.

[0081] Comparative Example 3

[0082] Compared with Example 1, in which step (1) is to replace tetraethyl orthosilicate as the silicon source with propyltriethylsilane. The remaining steps are the same as those in Example 1. The main purpose of this Comparative Example 2 is to investigate the effect of the type of silicon source on the material properties. The experimental results show that when propyltriethylsilane is used as the silicon source, the product obtained after hydrothermal treatment is still in a flowing solution state and the excess solvent cannot be removed by rotary evaporation. After vacuum drying, it is still a viscous flowing system.

[0083] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A negative electrode active material for a lithium slurry battery, characterized in that: The negative electrode active material for the lithium slurry battery is a SiOx / C negative electrode material with a rod-like structure and a silicon valence state gradient distribution. The outermost layer is coated with carbon, and the inside is silicon monoxide SiOx; The length of the SiOx / C negative electrode material is 1 μm - 10 μm, and the diameter is 300 nm - 900 nm; The silicon monoxide SiOx is an amorphous structure, where 0.8 < x < 1.3, accounting for 85% - 95% wt of the negative electrode active material for the lithium slurry battery; The preparation method of the negative electrode active material for the lithium slurry battery includes the following steps: (1) Add P123 to a mixed solution of deionized water and hydrochloric acid, stir until P123 is completely dissolved, then add a silicon source, and stir for a period of time until the solution becomes a sol to obtain system S1; (2) Add a carbon source to system S1, continue stirring, and further solubilize to obtain system S2; (3) Transfer system S2 to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a gel-like silicon dioxide / carbon precursor; (4) Dry the gel-like silicon dioxide / carbon precursor to obtain a silicon dioxide / carbon precursor polymer; (5) Calcinate the silicon dioxide / carbon precursor polymer to obtain a SiOx / C negative electrode material with a rod-like structure and a silicon valence state gradient distribution; In step (1), the silicon source is an organosilicon of silicate esters, including tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate; In step (2), the carbon source is an organic acid carbon source, including citric acid, tartaric acid, and ascorbic acid; In step (4), the washing and drying method is rotary evaporation drying - vacuum drying.

2. A preparation method of a negative electrode active material for a lithium slurry battery as described in claim 1, characterized in that it includes the following steps: (1) Add P123 to a mixed solution of deionized water and hydrochloric acid, stir until P123 is completely dissolved, then add a silicon source, and stir for a period of time until the solution becomes a sol to obtain system S1; (2) Add a carbon source to system S1, continue stirring, and further solubilize to obtain system S2; (3) Transfer system S2 to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a gel-like silicon dioxide / carbon precursor; (4) Dry the gel-like silicon dioxide / carbon precursor to obtain a silicon dioxide / carbon precursor polymer; (5) Calcinate the silicon dioxide / carbon precursor polymer to obtain a SiOx / C negative electrode material with a rod-like structure and a silicon valence state gradient distribution.

3. The preparation method of a negative electrode active material for a lithium slurry battery as described in claim 2, characterized in that: In step (1), the silicon source is an organosilicon of silicate esters, including tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate; the stirring time after adding the silicon source is 3 h - 6 h; the silicon source addition rate is 0.5 ml / min - 1 ml / min; the stirring speed is 70 rpm / min - 200 rpm / min; the pH of system S1 is 1 - 3.

4. The preparation method of a negative electrode active material for a lithium slurry battery as described in claim 2, characterized in that: The addition amount of the silicon source in the step (1) is 1.5 to 3 times the mass of P123.

5. The method for preparing the negative electrode active material of the lithium slurry battery according to claim 2, characterized in that: in the step (2), the carbon source is an organic acid carbon source, including citric acid, tartaric acid, ascorbic acid, the stirring time after adding the carbon source is 22h - 30h; the carbon source addition rate is 0.5 ml / min - 1ml / min; the mass ratio of the silicon source to the carbon source is 3:1 - 5:

1.

6. The method for preparing the negative electrode active material of the lithium slurry battery according to claim 2, characterized in that: in the step (3), the hydrothermal time is 20h - 26h, and the hydrothermal temperature is 100°C - 120°C.

7. The method for preparing the negative electrode active material of the lithium slurry battery according to claim 2, characterized in that: in the step (5), the calcination temperature is 650°C - 950°C, the calcination time is 2h - 5h, and the calcination atmosphere is an argon-hydrogen mixed gas, wherein the volume fraction of hydrogen is 5%.

8. A lithium slurry battery electrode, characterized in that, it is prepared by using the SiOx / C negative electrode material with a rod-shaped structure and a gradient distribution of silicon valence states described in claim 1 as the negative electrode active material.

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