Porous carbon composite material, preparation method thereof, negative electrode sheet and solid-state battery

Abstract

The application relates to the technical field of battery materials, in particular to a porous carbon composite material, a preparation method thereof, a negative electrode sheet and a solid-state battery. The preparation method of the porous carbon composite material comprises the following steps: preparing a metal ion salt solution A containing a lithium source, a lanthanum source and a zirconium source, and preparing a precipitant solution B containing a precipitant; mixing the metal ion salt solution A, the precipitant solution B and a porous carbon material, so that the lithium source, the lanthanum source and the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material to obtain a precursor solution C; through a co-precipitation method, the lithium source, the lanthanum source and the zirconium source react with the precipitant to generate lithium lanthanum zirconium oxide and deposit in the pores of the porous carbon material to obtain the porous carbon composite material. After the porous carbon composite material prepared by the application is made into a negative electrode sheet and assembled into a solid-state battery, the solid-state battery shows the advantages of high discharge capacity, good cycle performance, low interface resistance and high safety, which is beneficial to the large-scale industrial application of the solid-state battery.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery materials, in particular to a porous carbon composite material, a preparation method thereof, a negative electrode sheet and a solid-state battery. BACKGROUND

[0002] Lithium ion batteries have many advantages such as high rated voltage, high energy density, long cycle life and low self-discharge, and have been widely used in electric vehicles, energy storage systems, electronic products and other fields. At the same time, the performance requirements of lithium ion batteries are also getting higher and higher. Among them, the solid-state battery is a kind of lithium ion battery using solid-state electrode material and solid-state electrolyte material, which has attracted widespread attention due to its high safety, large energy density and long cycle life. However, the poor ion conductivity of the solid-state battery limits its performance in practical application.

[0003] Traditional technologies mainly improve the preparation method of the solid-state electrolyte to improve the ion conductivity of the solid-state battery, such as introducing specific additives into the solid-state electrolyte or optimizing the structure of the solid-state electrolyte. In addition, there are also some technologies that optimize the positive electrode material or the negative electrode material to improve the overall performance of the solid-state battery. However, the traditional method can only improve the battery performance to a certain extent, but cannot fundamentally solve the defect of poor ion conductivity, and may even have a negative impact on the energy density, cycle stability and interface resistance of the solid-state battery. SUMMARY

[0004] Therefore, it is necessary to provide a porous carbon composite material, a preparation method thereof, a negative electrode sheet and a solid-state battery to solve the problem that the traditional method cannot fundamentally solve the defect of poor ion conductivity, and may even have a negative impact on the energy density, cycle stability and interface resistance of the solid-state battery.

[0005] The above-mentioned purpose of the application is achieved by the following technical solutions:

[0006] In a first aspect, the application provides a preparation method of a porous carbon composite material, comprising the following steps:

[0007] Preparation of a metal ion salt solution A containing a lithium source, a lanthanum source and a zirconium source, and preparation of a precipitant solution B containing a precipitant;

[0008] Mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material, so that the lithium source, the lanthanum source and the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material, to obtain a precursor solution C;

[0009] The lithium source, the lanthanum source and the zirconium source are reacted with the precipitant to form lithium lanthanum zirconium oxide by co-precipitation and deposit in the pores of the porous carbon material, to obtain the porous carbon composite material.

[0010] In one of the embodiments, the mass ratio of the lithium lanthanum zirconium oxide and the porous carbon material is (0.01-0.3):1.

[0011] In one of the embodiments, the porous carbon material includes one or more of activated carbon, mesoporous carbon, porous carbon sphere, carbon nanotube, carbon molecular sieve and carbon aerogel.

[0012] In one of the embodiments, the specific surface area of the porous carbon material is 100 m 2 / g-500 m 2 / g.

[0013] In one of the embodiments, the particle size of the porous carbon material is 1 μm-100 μm.

[0014] In one of the embodiments, the pore size of the porous carbon material is 10 nm-50 nm.

[0015] In one of the embodiments, the volume ratio of the pores of the porous carbon material is 80%-98%.

[0016] In one of the embodiments, the molar ratio of lithium element in the lithium source, lanthanum element in the lanthanum source and zirconium element in the zirconium source is (5-8):(2-4):(1-3).

[0017] In one of the embodiments, the lithium source includes one or more of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium dihydrogen phosphate and lithium hydrogen phosphate.

[0018] In one of the embodiments, the lanthanum source includes one or more of lanthanum nitrate, lanthanum chloride, lanthanum sulfate and lanthanum acetate.

[0019] In one of the embodiments, the zirconium source includes one or more of zirconium nitrate, zirconium chloride, zirconium sulfate and zirconium acetate.

[0020] In one of the embodiments, the concentration of the lithium source in the metal ion salt solution A is 0.05 g / mL-0.3 g / mL.

[0021] In one of the embodiments, the precipitant includes one or more of ammonia water, ammonium bicarbonate and ammonium carbonate.

[0022] In one of the embodiments, the molar ratio of lithium element in the lithium source and the precipitant is (0.1-1):(0.5-2).

[0023] In one of the embodiments, the method of mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material comprises one or more of the following: a soaking method, a stirring method and an ultrasonic method.

[0024] In one of the embodiments, the mixing of the metal ion salt solution A, the precipitant solution B and the porous carbon material comprises the following steps:

[0025] The metal ion salt solution A and the precipitant solution B are mixed to obtain a mixed solution.

[0026] The porous carbon material is soaked in the mixed solution for 12-36 hours, stirred at 400-1200 rpm for 2-8 hours, and ultrasonically treated for 2-8 hours.

[0027] In one of the embodiments, the co-deposition method comprises the following steps: the precursor solution C is heated to 600-1200 °C at a heating rate of 2-7 °C / min in a protective gas atmosphere, and is kept at the temperature for 8-16 hours.

[0028] In the second aspect, the application provides a porous carbon composite material prepared by the method described above.

[0029] In the third aspect, the application provides a negative electrode sheet comprising the porous carbon composite material described above.

[0030] In the fourth aspect, the application provides a solid-state battery comprising the negative electrode sheet described above.

[0031] The application has at least the following advantages:

[0032] The lithium source, the lanthanum source, the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material, and the lithium lanthanum zirconium oxide solid-state electrolyte is deposited in the pores of the porous carbon material by the co-deposition method to prepare the porous carbon composite material. The composition uniformity, the purity and the grain growth quality of the lithium lanthanum zirconium oxide solid-state electrolyte are good, and the process is simple, which is conducive to reducing the preparation cost of the battery. At the same time, the porous carbon material has excellent electrical conductivity, which can greatly improve the ion conductivity of the porous carbon composite material, and is conducive to increasing the migration rate of lithium ions. Compared with the traditional method of coating the solid-state electrolyte on the graphite negative electrode, the porous carbon material has the advantages of large specific surface area and high porosity, which not only increases the loading amount of the lithium lanthanum zirconium oxide solid-state electrolyte, but also improves the interface contact between the lithium lanthanum zirconium oxide solid-state electrolyte and the porous carbon material, and reduces the interface resistance. After the porous carbon composite material prepared by the application is made into a negative electrode sheet and assembled into a solid-state battery, the solid-state battery has the advantages of high discharge capacity, good cycle performance, low interface resistance and high safety, which is conducive to the large-scale industrial application of the solid-state battery. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its beneficial effects, the attached drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the attached drawings in the following description are only some embodiments of the present application, and other attached drawings can be obtained by those skilled in the art without any creative effort based on these attached drawings.

[0034] Figure 1 A flowchart of a preparation method of a porous carbon composite material in an embodiment;

[0035] Figure 2 A structural schematic diagram of a porous carbon composite material in an embodiment;

[0036] Figure 3 A needle-punching experiment result diagram of a solid-state battery of Embodiment 1. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present application, the present application will be further described in detail in combination with specific embodiments. However, the present application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein only for the purpose of describing specific embodiments of the present application, and is not intended to limit the present application.

[0039] In the present application, the meaning of "and / or" is any and all combinations of one or more relevant listed items. The meaning of "at least one" is more than one, such as one, two, and more than two. The meaning of "a plurality of" or "several" is at least two, such as two, three, and the like, and the meaning of "a plurality of layers" is at least two layers, such as two layers, three layers, and the like, unless otherwise specifically limited. In the description of the present application, the meaning of "several" is at least one, such as one, two, and the like, unless otherwise specifically limited.

[0040] When a numerical range is disclosed in the present application, the above range is considered to be continuous, and includes the minimum value and the maximum value of the range, and every value between such minimum value and maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in the present application should be understood to include any and all sub-ranges included therein.

[0041] If not otherwise specified, all steps of the present application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0042] In the present application, "above" or "below" includes the number itself. For example, 1 below includes 1.

[0043] In the present application, the temperature parameter, if not otherwise specified, allows for constant temperature treatment, and also allows for fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy range controlled by the instrument. Fluctuations within a range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0044] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: 23°C ± 2°C, 25°C ± 5°C or 20°C ± 5°C.

[0045] Although solid-state batteries have the advantages of high safety, high energy density and long cycle life, there are still some deficiencies that need to be solved at the present stage, among which the most prominent one is the poor ionic conductivity of solid-state electrolyte. Specifically, compared with liquid electrolyte, the migration rate of lithium ions in solid-state electrolyte is slower, which affects the charging and discharging speed and power performance of the battery. In addition, it is difficult to form good interface contact between the solid-state electrolyte and the electrode, resulting in high interface impedance, low lithium ion transmission flux at the interface and low utilization rate of active materials.

[0046] Traditional technologies mainly improve the preparation method of solid-state electrolyte to improve the ionic conductivity of solid-state battery, such as introducing specific additives into solid-state electrolyte and optimizing the structure of solid-state electrolyte. Some technologies are to optimize the positive electrode material or negative electrode material to improve the overall performance of the solid-state battery. However, these methods not only have complex process and increase the preparation cost of the solid-state battery, but also can only improve the battery performance to a certain extent, and cannot fundamentally solve the problem of poor ionic conductivity. Even it may have a negative impact on other performances of the battery, such as reducing the energy density or cycle stability. It has been reported that solid-state electrolyte is used to coat graphite negative electrode, but there are still problems of poor interface contact and high interface impedance between solid-state electrolyte and negative electrode.

[0047] Based on this, the first aspect of the application provides a porous carbon composite material to solve the problem that the traditional method cannot fundamentally solve the poor ion conductivity, and even may have a negative impact on the energy density, cycle stability and interface resistance of the solid-state battery.

[0048] Please refer to Figure 1 , which is a flowchart of the preparation method of the porous carbon composite material in an embodiment. As shown in Figure 1 , the preparation method of the porous carbon composite material comprises the following steps:

[0049] S100: preparing a metal ion salt solution A containing a lithium source, a lanthanum source and a zirconium source, and preparing a precipitant solution B containing a precipitant;

[0050] S200: mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material, so that the lithium source, the lanthanum source and the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material, to obtain a precursor solution C;

[0051] S300: by co-precipitation method, the lithium source, the lanthanum source and the zirconium source react with the precipitant to generate lithium lanthanum zirconium oxide and deposit in the pores of the porous carbon material, to obtain the porous carbon composite material.

[0052] The application first uniformly distributes the lithium source, the lanthanum source, the zirconium source and the precipitant in the pores of the porous carbon material, and then deposits the lithium lanthanum zirconium oxide solid electrolyte in the pores of the porous carbon material by co-precipitation method to prepare the porous carbon composite material. The composition uniformity of the lithium lanthanum zirconium oxide solid electrolyte is good, the purity is high and the grain growth quality is good, and the process is simple, which is conducive to reducing the preparation cost of the battery. At the same time, the porous carbon material has excellent conductivity, which can greatly improve the ion conductivity of the porous carbon composite material, and is conducive to increasing the migration rate of lithium ions. Compared with the traditional method of coating the solid electrolyte on the graphite negative electrode, the porous carbon material has the advantages of large specific surface area and high porosity, which not only increases the loading capacity of the lithium lanthanum zirconium oxide solid electrolyte, but also improves the interface contact between the lithium lanthanum zirconium oxide solid electrolyte and the porous carbon material, and reduces the interface resistance. After the porous carbon composite material prepared by the application is made into a negative electrode sheet and assembled into a solid-state battery, the solid-state battery shows the advantages of high discharge capacity, good cycle performance, low interface resistance and high safety, which is conducive to the large-scale industrial application of the solid-state battery.

[0053] The preparation method of the porous carbon composite material is described in detail in the following step-by-step manner.

[0054] S100: preparing a metal ion salt solution A containing a lithium source, a lanthanum source and a zirconium source, and preparing a precipitant solution B containing a precipitant;

[0055] Optionally, the molar ratio of lithium element in the lithium source, lanthanum element in the lanthanum source and zirconium element in the zirconium source is (5-8):(2-4):(1-3), and further optionally 7:3:2. As an example, the molar ratio of lithium element in the lithium source and lanthanum element in the lanthanum source can be 5:2, 5:3, 5:4, 6:2, 6:3, 6:4, 7:2, 7:3, 7:4, 8:2, 8:3 or 8:4; the molar ratio of lithium element in the lithium source and zirconium element in the zirconium source can be 5:1, 5:2, 5:3, 6:1, 6:2, 6:3, 7:1, 7:2, 7:3, 8:1, 8:2 or 8:3; and the molar ratio of lanthanum element in the lanthanum source and zirconium element in the zirconium source can be 2:1, 2:2, 2:3, 3:1, 3:2, 3:3, 4:1, 4:2 or 4:3.

[0056] Optionally, the lithium source comprises one or more of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium dihydrogen phosphate and lithium hydrogen phosphate, and further lithium hydroxide.

[0057] Optionally, the lanthanum source comprises one or more of lanthanum nitrate, lanthanum chloride, lanthanum sulfate and lanthanum acetate, and further lanthanum nitrate.

[0058] Optionally, the zirconium source comprises one or more of zirconium nitrate, zirconium chloride, zirconium sulfate and zirconium acetate, and further zirconium nitrate.

[0059] Optionally, the metal ion salt solution A further contains a dopant; wherein the dopant comprises one or more of oxide, hydroxide, nitrate, carbonate, sulfate and hydrochloride of M element, and the M element comprises one or more of aluminum, calcium, iron, niobium, titanium, antimony, magnesium, zinc, gallium and tantalum, and further one or more of aluminum and tantalum.

[0060] It can be understood that the compounds of the lithium source, the lanthanum source, the zirconium source and the dopant can be compounds without combined water, such as anhydrous lithium carbonate, or compounds with combined water, such as lithium hydroxide monohydrate. Meanwhile, in order to promote the lithium source, the lanthanum source, the zirconium source and the dopant to be fully and uniformly distributed in the pores in the porous carbon material, the lithium source, the lanthanum source, the zirconium source and the dopant selected in the present application have good solubility and can be dissolved in the solvent of the metal ion salt solution A.

[0061] Optionally, the solvent of the metal ion salt solution A comprises water, which can be tap water, distilled water, reverse osmosis water, deionized water, pure water and ultrapure water, and further deionized water or pure water.

[0062] Optionally, the concentration of the lithium source in the metal ion salt solution A is 0.05 g / mL to 0.3 g / mL, further optionally 0.08 g / mL to 0.24 g / mL. As an example, the concentration of the lithium source in the metal salt solution can be 0.05 g / mL, 0.08 g / mL, 0.1 g / mL, 0.12 g / mL, 0.15 g / mL, 0.18 g / mL, 0.2 g / mL, 0.22 g / mL, 0.25 g / mL, 0.28 g / mL, or 0.3 g / mL.

[0063] Optionally, the metal ion salt solution A of the lithium source, the lanthanum source, and the zirconium source is prepared by the following steps: adding the lithium source, the lanthanum source, and the zirconium source in a solvent, heating to 60 °C to 80 °C, and stirring at 400 rpm to 1200 rpm for 8 h to 36 h. As an example, the temperature after heating can be 60 °C, 62 °C, 65 °C, 68 °C, 70 °C, 72 °C, 75 °C, 78 °C, or 80 °C, further optionally 70 °C to 76 °C; the stirring speed can be 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, or 1200 rpm, further optionally 800 rpm to 1000 rpm; and the stirring time can be 8 h, 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, or 36 h, further optionally 8 h to 12 h.

[0064] Optionally, the precipitant includes one or more of ammonia water, ammonium bicarbonate, and ammonium carbonate, further optionally ammonia water.

[0065] Optionally, the concentration of the precipitant in the precipitant solution is 1 mol / L to 5 mol / L, further optionally 2.5 mol / L to 3.5 mol / L. As an example, the concentration of the precipitant in the precipitant solution can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L.

[0066] Optionally, the molar ratio of the lithium source to the precipitant is (0.1 to 1):(0.5 to 2). As an example, the molar ratio of the lithium source to the precipitant can be 0.1:0.5, 0.1:1, 0.1:1.5, 0.1:2, 0.2:0.5, 0.2:1, 0.2:1.5, 0.2:2, 0.4:0.5, 0.4:1, 0.4:1.5, 0.4:2, 0.6:0.5, 0.6:1, 0.6:1.5, 0.6:2, 0.8:0.5, 0.8:1, 0.8:1.5, 0.8:2, 1:0.5, 1:1, 1:1.5, or 1:2.

[0067] S200: mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material, so that the lithium source, the lanthanum source and the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material, to obtain a precursor solution C.

[0068] Optionally, the porous carbon material comprises one or more of activated carbon, mesoporous carbon, porous carbon sphere, carbon nanotube, carbon molecular sieve and carbon aerogel, and further optionally one or more of activated carbon, mesoporous carbon and porous carbon sphere.

[0069] Optionally, the specific surface area of the porous carbon material is 100 m 2 / g~500 m 2 / g, including but not limited to 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, 300 m 2 / g, 350 m 2 / g, 400 m 2 / g, 450 m 2 / g or 500 m 2 / g, and further optionally 100 m 2 / g~300 m 2 / g.

[0070] Optionally, the particle size of the porous carbon material is 1 μm~100 μm, including but not limited to 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, and further optionally 40 μm~80 μm.

[0071] Optionally, the pore size of the porous carbon material is 10 nm~50 nm, including but not limited to 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, and further optionally 30 nm~50 nm.

[0072] Optionally, the volume ratio of the pores of the porous carbon material is 80%~98%, including but not limited to 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96% or 98%.

[0073] Optionally, the distance between two adjacent pores of the porous carbon material is 1.5 nm~2 nm. It can be understood that the distance between two adjacent pores refers to the shortest distance between the edges of the two adjacent pores.

[0074] The specific surface area of the porous carbon material has an influence on the loading amount of lithium lanthanum zirconium oxide, and the specific surface area of the porous carbon material is controlled to be 100 m 2 / g~500m 2 / g is conducive to obtaining high load of lithium lanthanum zirconium oxide and more excellent electrical performance. The particle size, pore size and porosity of the porous carbon material jointly determine the size of the specific surface area. The smaller the particle size, the larger the pore size, the more the number of pores and the higher the porosity, the larger the specific surface area of the porous carbon material, and the more lithium lanthanum zirconium oxide is deposited.

[0075] Optionally, the mass ratio of the porous carbon material and the lithium source is 1:(0.05-0.2), including but not limited to: 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.12, 1:0.14, 1:0.16, 1:0.18, 1:0.2, and further optionally 1:(0.08-0.15).

[0076] Optionally, the method for mixing the precursor solution A and the porous carbon material includes one or more of the following: immersion method, stirring method and ultrasonic method.

[0077] Optionally, the mixing of the metal ion salt solution A, the precipitant solution B and the porous carbon material includes the following steps:

[0078] Mixing the metal ion salt solution A and the precipitant solution B to obtain a mixed solution;

[0079] Placing the porous carbon material in the mixed solution for immersion for 12h-36h, stirring at 400rpm-1200rpm for 2h-8h, and ultrasonic treatment for 2h-8h.

[0080] It can be understood that after mixing the metal ion salt solution A and the precipitant solution B, the lithium source, the lanthanum source and the zirconium source can coexist with the precipitant because the precipitation temperature has not been reached. As an example, the immersion time of the porous carbon material in the mixed solution can be 12h, 15h, 18h, 21h, 24h, 27h, 30h, 33h or 36h, and further optionally 24h; the stirring speed can be 400rpm, 600rpm, 800rpm, 1000rpm or 1200rpm, and further optionally 800rpm; and the ultrasonic treatment time can be 2h, 3h, 4h, 5h, 6h, 7h or 8h, and further optionally 4h.

[0081] S300: generating lithium lanthanum zirconium oxide by the co-precipitation method, and depositing the lithium lanthanum zirconium oxide in the pores of the porous carbon material to obtain a porous carbon composite material.

[0082] Optionally, the co-precipitation method includes the following steps: heating the precursor solution C to 600℃-1200℃ at a heating rate of 2℃ / min-7℃ / min in a protective gas atmosphere, and maintaining the temperature for 8h-10h.

[0083] The precipitation temperature of the co-precipitation method directly affects the deposition rate of the solid-state electrolyte and the grain size of the solid-state electrolyte. If the precipitation temperature is too high, impurities will be introduced, causing abnormal grain growth; if the precipitation temperature is too low, the deposition rate will be slow, causing uneven grain growth. The precipitation temperature in the present application is controlled at 600-1200℃, which can achieve fast deposition of the solid-state electrolyte, ensure uniform grain growth, and avoid the introduction of impurities.

[0084] As an example, the heating rate can be 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min or 7℃ / min, further optionally 5℃ / min; the precipitation temperature of the co-precipitation method can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃ or 1200℃, further optionally 600-800℃; the holding time of the co-precipitation method can be 8h, 8.5h, 9h, 9.5h or 10h, further optionally 8h.

[0085] Optionally, the protective gas includes one or more of nitrogen, helium, neon, argon and xenon, further optionally nitrogen.

[0086] Optionally, after the co-precipitation method, the following steps are further included: washing and drying the product of the co-precipitation method to remove residual raw materials and impurities.

[0087] Optionally, the mass ratio of lithium lanthanum zirconium oxide and porous carbon material is (0.01-0.3):1, including but not limited to: 0.01:1, 0.05:1, 0.1:1, 0.12:1, 0.15:1, 0.18:1, 0.2:1, 0.22:1, 0.25:1, 0.28:1 or 0.3:1, further optionally (0.1-0.3):1.

[0088] Optionally, the grain size of the lithium lanthanum zirconium oxide is 100-700nm. It can be understood that the grain size of the lithium lanthanum zirconium oxide can be observed by morphology characterization of a scanning electron microscope. As an example, the grain size of the lithium lanthanum zirconium oxide can be 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm or 700nm.

[0089] Thanks to the high specific surface area and high porosity of the porous carbon material, the loading amount of the lithium lanthanum zirconium oxide in the porous carbon composite material is higher, and has a relatively uniform grain size, while not causing negative effects on the specific capacity, energy density, cycle performance and interface resistance of the porous carbon composite material.

[0090] In a second aspect, the present application provides a porous carbon composite material prepared by the method described above.

[0091] See Figure 2 , which is a schematic diagram of the structure of the porous carbon composite material in an embodiment. As shown in Figure 2 , the porous carbon composite material includes a porous carbon material 21 and a solid-state electrolyte 23 deposited in the pores 22 of the porous carbon material 21; wherein the solid-state electrolyte 23 includes one or more of lithium lanthanum zirconium oxide and lithium lanthanum zirconium oxide doped with an M element; the expression of the lithium lanthanum zirconium oxide is Li a La b Zr c O 12 , a = 5-8, b = 2-4, c = 1-3, and further optionally Li7La3Zr2O 12 ; the M element includes one or more of aluminum, calcium, iron, niobium, titanium, antimony, magnesium, zinc, gallium, and tantalum, and further optionally one or more of aluminum and tantalum.

[0092] In a third aspect, the present application provides a negative electrode tab including the porous carbon composite material described above.

[0093] Optionally, the negative electrode tab includes a negative electrode current collector and a negative electrode active layer covering at least one surface of the negative electrode current collector.

[0094] Optionally, the negative electrode current collector includes a metal foil or a composite current collector, the metal foil in the negative electrode current collector can be selected from a copper foil, the composite current collector includes a polymer substrate and a metal layer formed on the polymer substrate, the material of the polymer substrate can be polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE), and the material of the metal layer can be aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.

[0095] Optionally, the raw materials of the negative electrode active layer include the porous carbon composite material described above, a binder, a conductive agent, and a solvent. The binder includes at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), sodium carboxymethyl cellulose (CMC), and carboxymethyl chitosan (CMCS); the conductive agent includes at least one of conductive carbon, superconducting carbon, acetylene black, carbon black, ketjen black, carbon quantum dots, carbon nanotubes, graphene, and carbon nanofibers; and the solvent includes water.

[0096] Optionally, the method for preparing the negative electrode sheet comprises the following steps: dispersing the porous carbon composite material, the binder and the conductive agent in a solvent to prepare a negative electrode slurry; covering the negative electrode slurry on at least one surface of the negative electrode current collector, and performing drying, rolling and cutting to obtain the negative electrode sheet.

[0097] In a fourth aspect, the present application provides a solid-state battery comprising the negative electrode sheet as described above.

[0098] Optionally, the solid-state battery comprises a positive electrode sheet, the negative electrode sheet as described above and a separator.

[0099] Optionally, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer covering at least one surface of the positive electrode current collector.

[0100] Optionally, the positive electrode current collector comprises a metal foil or a composite current collector. The metal foil can be an aluminum foil. The composite current collector in the positive electrode current collector is substantially the same as the composite current collector in the negative electrode current collector, which will not be described herein again.

[0101] Optionally, the raw materials of the positive electrode active layer comprise a positive electrode active material, a binder, a conductive agent and a solvent. The positive electrode active material is a positive electrode active material known in the art for use in a solid-state battery. As an example, the positive electrode active material can be at least one of lithium transition metal oxides and olivine structure lithium-containing phosphates. The lithium transition metal oxides include but are not limited to: lithium cobalt oxide such as LiCoO2; lithium nickel oxide such as LiNiO2; lithium manganese oxide such as LiMnO2or LiMn2O4; lithium nickel cobalt oxide; lithium manganese cobalt oxide; lithium nickel manganese oxide; lithium nickel cobalt manganese oxide such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ); and lithium nickel cobalt aluminum oxide such as LiNi 0.8 Co 0.15 Al 0.05O2; and modified compounds of the above lithium transition metal oxides. Lithium-containing phosphates of olivine structure include, but are not limited to: lithium iron phosphate, such as LiFePO4 (LFP); a composite of lithium iron phosphate and carbon; lithium manganese phosphate, such as LiMnPO4; a composite of lithium manganese phosphate and carbon; lithium manganese iron phosphate; a composite of lithium manganese iron phosphate and carbon; and modified compounds of the above lithium-containing phosphates of olivine structure. The modified compounds of each material can be at least one of a doping modification and a surface coating modification. The binder includes at least one of polyvinylidene fluoride (PVDF), sodium alginate (SA), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), hydrogenated nitrile rubber (HNBR), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA). The conductive agent includes at least one of conductive carbon, super conductive carbon, acetylene black, carbon black, ketjen black, carbon quantum dots, carbon nanotubes, graphene, and carbon nanofibers. The solvent includes N-methyl pyrrolidone (NMP).

[0102] Optionally, the method for preparing the positive electrode sheet includes the following steps: dispersing the positive electrode active material, the binder, and the conductive agent in an organic solvent to prepare a positive electrode slurry; covering the positive electrode slurry on at least one surface of the positive electrode current collector, and performing drying, rolling, and cutting processes to obtain the positive electrode sheet.

[0103] It can be understood that the separator can be a porous separator with good chemical stability and mechanical stability; at the same time, the separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation. Optionally, the material of the separator includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0104] Optionally, the positive electrode sheet, the negative electrode sheet, and the separator can be prepared into a solid-state battery through a winding process or a stacking process.

[0105] The following will be further described in combination with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples can be sourced from the market if not specifically stated. The instruments used can be sourced from the market if not specifically stated. The processes involved can be routinely selected by those skilled in the art if not specifically stated.

[0106] Example 1

[0107] Please refer to Table 1. The method for preparing the porous carbon composite material of the present embodiment is as follows:

[0108] (1) Take lithium hydroxide monohydrate, lanthanum nitrate and zirconium nitrate, add them to 500 mL of deionized water, heat to 60°C, and then magnetically stir at a speed of 500 rpm for 8 hours to obtain a metal salt ion solution A. Dilute concentrated ammonia water with deionized water to obtain a precipitant solution B. The molar ratio of lithium, lanthanum and zirconium in the metal salt ion solution A is 7:3:2, the concentration of lithium is 14 mol / L, the concentration of ammonia monohydrate in the precipitant solution B is 3 mol / L, and the molar ratio of lithium to ammonia monohydrate is 1:1.

[0109] (2) Mix the metal ion solution A and the precipitant solution B to obtain a mixed solution; take 300 g of activated carbon material (specific surface area 150 m 2 / g, particle size 40 μm, pore size 50 nm, pore volume ratio 96%, and the distance between adjacent two pores is about 1.8 nm), place it in the mixed solution, soak for 24 hours, then magnetically stir at a speed of 800 rpm for 4 hours, and then ultrasonic for 4 hours, so that lithium, lanthanum and zirconium and ammonia monohydrate are uniformly distributed in the pores of the activated carbon material, to obtain a precursor solution C.

[0110] (3) Under the protection of nitrogen, heat the precursor solution C to 700°C at a heating rate of 5°C / min, and keep the temperature for 8 hours, so that lithium, lanthanum and zirconium in the precursor solution C react with ammonia monohydrate to generate lithium lanthanum zirconium oxide and deposit in the pores of the activated carbon material; by washing and drying, the unreacted raw materials and impurities are removed, to obtain a porous carbon composite material with a mass ratio of lithium lanthanum zirconium oxide to porous carbon material of 0.1:1.

[0111] (4) Preparation of solid-state battery:

[0112] Take the porous carbon composite material as the negative active material, disperse the porous carbon composite material, super-p conductive carbon black (SP), carboxymethyl cellulose sodium (CMC) and styrene butadiene rubber (SBR) in deionized water according to a mass ratio of 94:2:1.5:2.5, vacuum stir in a blender to disperse, and prepare a uniform and bubble-free negative electrode slurry; uniformly coat the negative electrode slurry on a copper foil, dry, roll and cut to obtain a negative electrode sheet.

[0113] Take lithium nickel cobalt manganese oxide as the positive active material, disperse lithium nickel cobalt manganese oxide, polyvinylidene fluoride (PVDF), super-p conductive carbon black (SP) and carbon nanotubes (CNT) in N-methyl pyrrolidone (NMP) according to a mass ratio of 96:2:1:1, vacuum stir in a blender to disperse, and prepare a uniform and bubble-free positive electrode slurry; uniformly coat the positive electrode slurry on an aluminum foil, dry, roll and cut to obtain a positive electrode sheet.

[0114] The negative electrode sheet with deposited solid electrolyte (for the comparative example without deposition: the solid electrolyte is coated on the surface of the negative electrode to form a film) and the positive electrode sheet are stacked through the solid electrolyte layer to obtain a solid battery composite sheet, and then the solid battery composite sheet is isostatically pressed to obtain a solid battery. The electrodes are on the same side, and the tabs are welded together with the current collector by using an ultrasonic welding machine, and then packaged with an aluminum plastic film. After baking the battery, it is subjected to formation and capacity test to prepare a solid battery with a capacity of 4 Ah.

[0115] Example 2

[0116] This example is basically the same as Example 1, except that in step (2), the specific surface area of the activated carbon material is 100 m 2 / g, the particle size is 50 μm, the pore size is 30 nm, the pore volume ratio is 95.4%, and the distance between adjacent two pores is about 1.7 nm.

[0117] Example 3

[0118] This example is basically the same as Example 1, except that in step (2), the porous carbon material is mesoporous carbon with a specific surface area of 150 m 2 / g, the particle size is 80 μm, the pore size is 50 nm, the pore volume ratio is 94.9%, and the distance between adjacent two pores is about 2 nm.

[0119] Example 4

[0120] This example is basically the same as Example 1, except that in step (2), the amount of activated carbon material is 200 g.

[0121] Example 5

[0122] This example is basically the same as Example 1, except that in step (2), the amount of activated carbon material is 500 g.

[0123] Example 6

[0124] This example is basically the same as Example 1, except that in step (3), the co-precipitation treatment conditions are: heating the precursor solution B to 600 ℃ at a heating rate of 4 ℃ / min, and keeping the temperature for 10 h.

[0125] Example 7

[0126] This example is basically the same as Example 1, except that in step (3), the chemical vapor deposition conditions are: heating the precursor solution B to 1200 ℃ at a heating rate of 5 ℃ / min, and keeping the temperature for 8 h.

[0127] Example 8

[0128] This example is basically the same as Example 1, except that in step (1), the precursor solution A is further added with a dopant, aluminum hydroxide.

[0129] Comparative Example 1

[0130] This example is basically the same as Example 1, except that the porous carbon composite material in the negative electrode sheet is replaced with an equal amount of active carbon material, and lithium lanthanum zirconium oxide is made into a solid electrolyte coated on the surface of the negative electrode sheet, and then the negative electrode sheet and the positive electrode sheet are assembled into a solid-state battery by lamination.

[0131] Comparative Example 2

[0132] This example is basically the same as Example 1, except that the porous carbon material in step (2) is replaced with a graphite material without a porous structure, and a graphite composite material with lithium lanthanum zirconium oxide coated on the surface of the graphite is prepared; the graphite composite material is used as a negative electrode active material to prepare a negative electrode sheet, and a solid-state battery is assembled by lamination with a positive electrode sheet.

[0133] Test Example

[0134] The solid-state batteries or cells in each example and each comparative example are tested as follows:

[0135] 1. Normal temperature cycle performance:

[0136] (1) At 25℃±3℃, the cell is charged at 0.5C constant current and constant voltage to 4.2V, and the cutoff current is 0.05C;

[0137] (2) Standby for 30min;

[0138] (3) At 25℃±3℃, the cell is discharged at 1C constant current to 3.0V, and the capacity D1 at this time is recorded;

[0139] (4) Standby for 30min;

[0140] (5) Cycle steps (1)~(4), record the cycle number and the final discharge capacity D2, and calculate the capacity retention rate of the cell D=D2 / D1x100%, the results are shown in Table 1.

[0141] 2. Needle test:

[0142] (1) At 25℃±3℃, the cell is charged at 0.5C constant current and constant voltage to 4.2V, and the cutoff current is 0.05C;

[0143] (2) Standby for 30min;

[0144] (3) using a high-temperature-resistant steel needle with a diameter of Φ3mm-Φ5mm (the conical angle of the needle tip is 45°-60°, the surface of the needle is smooth, free of rust, oxidation layer and oil stains), at a speed of (25±5) mm / s from the direction perpendicular to the electrode plate, and the penetration position is preferably close to the geometric center of the punctured surface, and the steel needle stays in the battery cell;

[0145] (4) observe for 60min; the needle puncture test result graph of the solid-state battery of example 1 is shown in Figure 3 ;

[0146] (5) if the battery does not explode or catch fire, it is a test pass, and the results are shown in table 1.

[0147] 3. Internal resistance:

[0148] By applying a small current signal of 1000Hz to the battery, the feedback voltage value is measured, and the internal resistance of the battery is measured by the ratio of voltage to current.

[0149] As shown in table 2, the porous carbon composite material prepared by examples 1-8 as the negative active material, the solid-state battery is obviously superior to comparative examples 1-2 in terms of first discharge specific capacity D1, capacity retention rate after 500 cycles and internal resistance, and can pass the needle puncture test, and has high safety.

[0150] Table 1. Parameters of negative active material

[0151]

[0152] Table 2. Performance of solid-state battery

[0153]

[0154] Each technical feature of the above-described embodiments can be combined arbitrarily, and to make the description simple, not all possible combinations of each technical feature in the above-described embodiments are described, however, as long as the combination of these technical features does not exist contradictory, it should be considered as the scope of the present application.

[0155] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the protection scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for producing a porous carbon composite material, characterized by, The method comprises the following steps: Preparation of a metal ion salt solution A containing a lithium source, a lanthanum source and a zirconium source, and preparation of a precipitant solution B containing a precipitant; Mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material, so that the lithium source, the lanthanum source and the zirconium source and the precipitant are uniformly distributed in the pores of the porous carbon material, to obtain a precursor solution C; Through a co-precipitation method, the lithium source, the lanthanum source and the zirconium source react with the precipitant to generate lithium lanthanum zirconium oxide and deposit in the pores of the porous carbon material, to obtain the porous carbon composite material; The mass ratio of the lithium lanthanum zirconium oxide to the porous carbon material is (0.01-0.3):1; The specific surface area of the porous carbon material is 100 m 2 / g~500 m 2 / g; The pore size of the porous carbon material is 10-50 nm.

2. The method for producing a porous carbon composite material according to claim 1, wherein The porous carbon material comprises one or more of activated carbon, mesoporous carbon, porous carbon spheres, carbon nanotubes, carbon molecular sieves and carbon aerogels.

3. The method for producing a porous carbon composite material according to claim 2, wherein One or more of the following conditions are met: (1) The particle size of the porous carbon material is 1-100 μm; (2) The volume percentage of the pores of the porous carbon material is 80%-98%.

4. The method for producing a porous carbon composite material according to any one of claims 1 to 3, characterized by, The molar ratio of lithium in the lithium source, lanthanum in the lanthanum source and zirconium in the zirconium source is (5-8):(2-4):(1-3).

5. The method for producing a porous carbon composite material according to claim 4, wherein One or more of the following conditions are met: (1) The lithium source comprises one or more of lithium hydroxide, lithium carbonate, lithium chloride, lithium nitrate, lithium dihydrogen phosphate and lithium hydrogen phosphate; (2) The lanthanum source comprises one or more of lanthanum nitrate, lanthanum chloride, lanthanum sulfate and lanthanum acetate; (3) The zirconium source comprises one or more of zirconium nitrate, zirconium chloride, zirconium sulfate and zirconium acetate; (4) The concentration of lithium in the metal ion salt solution A is 0.05-0.3 g / mL; (5) The precipitant comprises one or more of ammonia water, ammonium bicarbonate and ammonium carbonate; (6) The molar ratio of lithium in the lithium source to the precipitant is (0.1-1):(0.5-2).

6. The method for producing a porous carbon composite material according to any one of claims 1 to 3, wherein The method for mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material comprises one or more of infiltration, stirring and ultrasonic methods.

7. The method for producing a porous carbon composite material according to claim 6, wherein Mixing the metal ion salt solution A, the precipitant solution B and the porous carbon material comprises the following steps: Mixing the metal ion salt solution A and the precipitant solution B to obtain a mixed solution; Infiltrating the porous carbon material in the mixed solution for 12-36 h, stirring at 400-1200 rpm for 2-8 h and ultrasonic treatment for 2-8 h.

8. The method for producing a porous carbon composite material according to any one of claims 1 to 3, characterized by, The co-precipitation method comprises the following steps: In a protective gas atmosphere, the precursor solution C is heated to 600-1200 ℃ at a heating rate of 2-7 ℃ / min and held for 8-16 h.

9. A porous carbon composite material, characterized by, The porous carbon composite material is prepared by the method of any one of claims 1-8.

10. A negative electrode sheet characterized by comprising: The porous carbon composite material of claim 9 is included.

11. A solid state battery, characterized by The negative electrode sheet of claim 10 is included.

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