Solid electrolyte silicon-based modified negative electrode material as well as preparation method and application thereof

Abstract

According to the preparation method of the solid-state electrolyte silicon-based modified negative electrode material provided by the invention, the solid-state electrolyte required to be added and the SWCNT difficult to disperse are compounded on the silicon-carbon negative electrode material in advance when the negative electrode plate is pulped, so that the addition amount of the solid-state electrolyte and the dispersion difficulty of the SWCNT are reduced, and meanwhile, the performance of the negative electrode plate and the battery is ensured; the solid-state electrolyte silicon-based modified negative electrode material and the preparation method thereof have the advantages that the solid-state electrolyte silicon-based modified negative electrode material is simple in preparation process, the cost is obviously reduced, good electrochemical performance including relatively high first efficiency and reversible specific capacity is shown, and the invention also provides the solid-state electrolyte silicon-based modified negative electrode material, an electrode plate and a battery applying the solid-state electrolyte silicon-based modified negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state lithium-ion batteries, in particular to a solid-state electrolyte silicon-based modified negative electrode material and a preparation method and application thereof. Background Art

[0002] Solid-state lithium-ion batteries have higher safety and energy density than traditional liquid lithium-ion batteries. The electrolyte inside solid-state batteries uses solid materials instead of traditional electrolytes. With the increasing demand for battery safety and energy density, solid-state batteries are gradually becoming the focus of research and development of batteries and technologies.

[0003] However, in actual applications, the large amount of solid electrolyte added leads to high costs. The difficulty in dispersing SWCNT in slurries containing solid electrolytes made of conventional materials leads to large internal resistance, which greatly limits the application of solid-state batteries.

[0004] In view of this, the inventors specially designed a solid electrolyte silicon-based modified negative electrode material and its preparation method and application, which resulted in this case. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing a solid electrolyte silicon-based modified negative electrode material, which has a simple preparation process. The prepared solid electrolyte silicon-based modified negative electrode material does not need to be added with a solid electrolyte or a small amount of solid electrolyte when it is subsequently applied to a solid-state lithium-ion battery, which significantly reduces the cost and improves the energy density. At the same time, it exhibits good electrochemical properties, including high first efficiency, reversible specific capacity and good rate performance.

[0006] The invention also proposes a solid electrolyte silicon-based modified negative electrode material.

[0007] The invention also provides an electrode plate.

[0008] The invention also provides a battery.

[0009] A method for preparing a solid electrolyte silicon-based modified negative electrode material provided by the present invention comprises: 1) Dispersing the silicon-carbon negative electrode, single-walled carbon nanotubes, and carbon source in a certain proportion and a solvent in a certain solid content to obtain a mixed slurry A; 2) Drying the uniformly mixed and dispersed slurry A under an inert atmosphere to obtain powder A; 3) Carbonizing powder A at a certain temperature under an inert atmosphere to obtain powder B; 4) Dispersing the sulfide solid electrolyte and powder B in a certain proportion and solvent 2 in a certain solid content under an inert atmosphere to obtain a mixed slurry B; 5) Drying the uniformly mixed and dispersed slurry B under an inert atmosphere to obtain powder C; 6) The powder C is subjected to heat treatment at a certain temperature under an inert atmosphere to obtain a solid electrolyte silicon-based modified negative electrode material.

[0010] The preparation process of the present invention compounds the solid electrolyte that needs to be added when the negative electrode sheet is slurried and the difficult-to-disperse SWCNT onto the silicon-carbon negative electrode material in advance, thereby reducing the amount of solid electrolyte added and the difficulty of SWCNT dispersion, while ensuring the performance of the negative electrode sheet and the battery; the preparation process is simple, the cost is significantly reduced, and good electrochemical properties are exhibited, including higher first efficiency and reversible specific capacity.

[0011] In some embodiments of the present invention, in step 2) and step 5), the drying treatment used is rapid spray drying or reduced pressure rapid drying or vacuum drying; for example, vacuum freeze drying and the like.

[0012] In some embodiments of the present invention, in step 1), the silicon-carbon negative electrode is any one of sub-silicon, sand-ground silicon-carbon, gas-phase silicon-carbon, porous silicon, and micron silicon, or a combination of any two or more thereof; the carbon source is any one of asphalt, glucose, and phenolic resin, or a combination of any two or more thereof.

[0013] In some embodiments of the present invention, in step 1), the silicon-carbon negative electrode is 95%-99.8%, the single-walled carbon nanotubes are 0.01%-0.2%, the carbon source is 0-5%, and the solvent is added at a certain solid content, and the solid content is 5-30%.

[0014] In some embodiments of the present invention, in step 3), the carbonization temperature is 450°C-1000°C.

[0015] In some embodiments of the present invention, in step 4), in step 1), the solvent 1 is an organic solvent, which is any one of water, methanol, and ethanol; The second solvent is any one of anhydrous hydrazine, n-heptane, toluene, anisole, xylene, ethylene glycol dimethyl ether, diethyl ether or other organic solvents, or a combination of any two or more thereof; In some embodiments of the present invention, in step 4), the sulfide solid electrolyte is 0.1%-10%, the powder B is 90-99.9%; the solvent 2 is added at a certain solid content, and the solid content is 5-30%.

[0016] In some embodiments of the present invention, in step 4), the sulfide solid electrolyte is any one of LPSC (lithium phosphorus sulfur chloride), LGPS (lithium gallium phosphide) and LPS (lithium phosphorus sulfide).

[0017] In some embodiments of the present invention, in step 6), the heat treatment temperature is 150°C-300°C.

[0018] According to the present invention, a solid electrolyte silicon-based modified negative electrode material is provided, and the solid electrolyte silicon-based modified negative electrode material is prepared by a preparation method.

[0019] According to an electrode plate provided by the present invention, a solid electrolyte silicon-based modified negative electrode material is made into an electrode plate by pulping, coating, applying, compacting and drying; wherein, during the pulping, the conductive agent accounts for 0.1%-2%, the adhesive accounts for 2%-5%, the solid electrolyte accounts for 0-30%, and the solid electrolyte is any one of LPSC (lithium phosphorus sulfur chloride), LGPS (lithium gallium phosphide) or LPS (lithium phosphorus sulfide); the rest is solid electrolyte silicon-based modified negative electrode material, after coating, a layer of solid electrolyte layer is coated on the surface and then compacted, the formula of the solid electrolyte layer is: solid electrolyte: SBS=97:3, the compaction density of the electrode plate is 1.0g / cm³-1.7 g / cm³, and the drying temperature is 100°C to 200°C; the conductive agent is any one of conductive carbon black, carbon nanotubes, and graphene, or a combination of any two or more thereof; the adhesive is at least one of NBR and SBS.

[0020] A battery provided by the present invention uses a battery pole piece, and the counter electrode is a lithium sheet or one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, and a ternary material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] in: Figure 1 This is a SEM test image of the solid electrolyte silicon-based modified negative electrode material prepared in Example 1 of the present invention; Figure 2 This is a SEM test image of the solid electrolyte silicon-based modified negative electrode material prepared in Example 2 of the present invention; Figure 3 This is a SEM test image of the solid electrolyte silicon-based modified negative electrode material prepared in Example 3 of the present invention; Figure 4 This is a SEM test image of the solid electrolyte silicon-based modified negative electrode material prepared in Example 4 of the present invention; Figure 5 This is a SEM test image of the solid electrolyte silicon-based modified negative electrode material prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example

[0024] This embodiment 1 provides a solid electrolyte silicon-based modified negative electrode material method, an electrode and a battery containing the solid electrolyte silicon-based modified negative electrode material, comprising the following steps: 1) Sand-ground silicon carbon, single-walled carbon nanotubes, and asphalt are mixed and dispersed evenly with water at a solid content of 20% in a ratio of 99.6:0.06:0.34 to obtain slurry A; 2) The uniformly mixed and dispersed slurry A was spray-dried under a nitrogen atmosphere to obtain a powder A; 3) Carbonizing powder A at 850°C in a nitrogen atmosphere to obtain powder B; 4) Dispersing the sulfide solid electrolyte and powder B in a ratio of 3:97 and anhydrous hydrazine solvent at a solid content of 20% under a nitrogen atmosphere to obtain a mixed slurry B; 5) The uniformly mixed and dispersed slurry B is spray-dried under a nitrogen atmosphere to obtain powder C; 6) heat treating the powder C at 200° C. in a nitrogen atmosphere to obtain a solid electrolyte silicon-based modified negative electrode material; 7) The product obtained in step (6) is sieved with 400 mesh, and then slurried and coated according to the formula of solid electrolyte silicon-based modified negative electrode material: solid electrolyte: SBS: CCB (conductive carbon black) = 91.5: 5: 3: 0.5, and a solid electrolyte layer with a formula of solid electrolyte: SBS = 97: 3 is coated on the electrode after coating, and finally rolled at a compaction density of 1.55 g / cm³ to produce an electrode containing a solid electrolyte silicon-based modified negative electrode material; The product of step (7) is assembled into a battery under an inert atmosphere, wherein the counter electrode of the battery is a lithium sheet, thereby obtaining a battery containing a solid electrolyte silicon-based modified negative electrode material. Example

[0025] The difference between this embodiment and embodiment 1 is that in step (1) of this embodiment, the ratio of sand-ground silicon carbon, single-walled carbon nanotubes, and asphalt is 99.46:0.2:0.34, and the rest is consistent with embodiment 1. Example

[0026] The difference between this embodiment and embodiment 1 is that in this embodiment, the ratio of sand-ground silicon carbon, single-walled carbon nanotubes, and asphalt is 99.8:0.2:0, and the rest is consistent with embodiment 1. Example

[0027] The present embodiment is different from the embodiment 1 in that the silicon-carbon material in step (1) is silicon-carbon prepared by vapor deposition, the carbon source is glucose, and the carbonization temperature in step (3) is 450° C. The rest is the same as the embodiment 1. Example

[0028] The difference between this embodiment and embodiment 1 is that in step (1) of this embodiment, the sand-ground silicon carbon, single-walled carbon nanotubes, and asphalt are mixed and dispersed uniformly in water at a ratio of 94.9:0.1:5 at a solid content of 10%, and the carbonization temperature in step (3) is 1000° C. The rest is the same as in embodiment 1.

[0029] Comparative Example 1 In this comparative example, the unmodified high-capacity silicon-carbon negative electrode material of the present invention is selected as the silicon-carbon raw material, and then slurry coating is performed according to the formula of sand-ground silicon-carbon: CB: SWCNT: SBS: solid electrolyte = 65.44: 1.5: 0.06: 3: 30, and a solid electrolyte layer with a formula of solid electrolyte: SBS = 97: 3 is coated on the electrode after coating, and finally rolled at a compaction density of 1.55 g / cm³ to produce an electrode containing a solid electrolyte silicon-based modified negative electrode material.

[0030] The results of the above tests are shown in Table 1 below: Example First discharge specific capacity mAh / g First coulombic efficiency% 1 1610 89.5 2 1611 89.4 3 1590 88.9 4 1830 93.2 5 1530 88.9 Comparative Example First discharge specific capacity mAh / g First coulombic efficiency% 1 1430 78 It can be seen from Table 1 above that the solid electrolyte silicon-based modified negative electrode materials, electrode sheets and batteries prepared in the above embodiments and comparative examples have higher initial specific capacity and initial coulombic efficiency, showing better electrochemical performance; furthermore, from the SEM test images of the solid electrolyte silicon-based modified negative electrode materials prepared in Examples 1, 2, 3, 4 and 5, it can be seen that the single-walled carbon nanotubes are evenly distributed on the prepared solid electrolyte silicon-based modified negative electrode materials and the surface of the silicon-carbon material is coated with a layer of solid electrolyte.

[0031] In summary, the preparation process of the present invention compounds the solid electrolyte and the difficult-to-disperse SWCNT that need to be added when the negative electrode sheet is pulped to the silicon-carbon negative electrode material in advance, reducing the amount of solid electrolyte added and the difficulty of SWCNT dispersion, while ensuring the performance of the negative electrode sheet and the battery; specifically, when designing the material, the solid electrolyte and the single-walled carbon nanotube are compounded to the material to obtain a sea urchin-shaped solid electrolyte silicon-based modified negative electrode material with uniform single-walled tube dispersion and solid electrolyte wrapping, which can be added without single-walled carbon nanotubes in the subsequent pulping process, solving the problem of uneven dispersion of single-walled carbon nanotubes during solid-state battery pulping; reducing the amount of solid electrolyte added, significantly reducing costs, and improving the capacity and first effect of silicon-carbon negative electrode materials. Therefore, the preparation process of the present invention is simple, the cost is significantly reduced, and good electrochemical properties are exhibited, including higher first effect and reversible specific capacity.

[0032] It is worth noting that the raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the field; the methods used in the present invention, unless otherwise specified, are all conventional methods in the field.

[0033] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0034] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for preparing a solid electrolyte silicon-based modified negative electrode material, characterized in that: include: 1) Dispersing the silicon-carbon negative electrode, single-walled carbon nanotubes, and carbon source uniformly with the solvent to obtain a mixed slurry A; 2) Drying the uniformly mixed and dispersed slurry A under an inert atmosphere to obtain powder A; 3) Carbonizing powder A under an inert atmosphere to obtain powder B; 4) Dispersing the sulfide solid electrolyte, powder B and solvent 2 uniformly under an inert atmosphere to obtain a mixed slurry B; 5) Drying the uniformly mixed and dispersed slurry B under an inert atmosphere to obtain powder C; 6) The powder C is heat treated in an inert atmosphere to obtain a solid electrolyte silicon-based modified negative electrode material.

2. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In steps 2) and 5), the drying treatment adopted is rapid spray drying, reduced pressure rapid drying or vacuum drying.

3. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In step 1), the silicon-carbon negative electrode is any one of sub-silicon, sand-ground silicon-carbon, gas-phase silicon-carbon, porous silicon, and micron silicon, or a combination of any two or more thereof; the carbon source is any one of asphalt, glucose, and phenolic resin, or a combination of any two or more thereof.

4. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In step 1), the silicon-carbon negative electrode is 95%-99.8%, the single-walled carbon nanotube is 0.01%-0.2%, the carbon source is 0-5%, and the solvent is added at a certain solid content, and the solid content is 5-30%.

5. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In step 3), the carbonization temperature is 450°C-1000°C.

6. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In step 1), the first solvent is an organic solvent, which is any one of water, methanol and ethanol; In step 4), the second solvent is any one of anhydrous hydrazine, n-heptane, toluene, anisole, xylene, ethylene glycol dimethyl ether, and diethyl ether, or a combination of any two or more thereof.

7. The method for preparing a solid electrolyte silicon-based modified negative electrode material according to claim 1, characterized in that: In step 4), the sulfide solid electrolyte is 0.1%-10%, the powder B is 90-99.9%; the solvent 2 is added at a certain solid content, and the solid content is 5-30%.

8. A solid electrolyte silicon-based modified negative electrode material, characterized in that: The solid electrolyte silicon-based modified negative electrode material is prepared by the method as described in any one of claims 1-7.

9. An electrode plate, characterized in that: The solid electrolyte silicon-based modified negative electrode material is made into an electrode plate through pulping, coating, coating, compacting and drying processes, wherein during the pulping, the conductive agent accounts for 0.1%-2%, the adhesive accounts for 2%-5%, the solid electrolyte accounts for 0-30%, and the rest is the solid electrolyte silicon-based modified negative electrode material. After coating, a layer of solid electrolyte layer is coated on the surface and then compacted. The formula of the solid electrolyte layer is: solid electrolyte: SBS=97:3, and the compaction density of the electrode plate is 1.0g / cm³-1.7 g / cm³; the conductive agent is any one of conductive carbon black, carbon nanotubes, and graphene, or a combination of any two or more thereof; the adhesive is at least one of NBR and SBS.

10. A battery, characterized in that: The battery pole piece according to claim 9 is used, and the counter electrode is a lithium sheet or one of lithium cobalt oxide, lithium manganese oxide, lithium ferrous phosphate, lithium manganese iron phosphate, and a ternary material.

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