CN110265708B - Solid-phase synthesis method for synthesizing garnet-structured lithium lanthanum zirconium oxygen-based solid electrolyte material under synergistic action of quaternary ammonium hydroxide - Google Patents

Solid-phase synthesis method for synthesizing garnet-structured lithium lanthanum zirconium oxygen-based solid electrolyte material under synergistic action of quaternary ammonium hydroxide Download PDF

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CN110265708B
CN110265708B CN201910462865.2A CN201910462865A CN110265708B CN 110265708 B CN110265708 B CN 110265708B CN 201910462865 A CN201910462865 A CN 201910462865A CN 110265708 B CN110265708 B CN 110265708B
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邱越
郑卓群
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Anhui Benma Xianduan Science & Technology Co ltd
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Abstract

The invention discloses a solid phase synthesis method for realizing the industrial preparation of a LLZO solid electrolyte material by compounding and matching quaternary ammonium hydroxide and lithium carbonate according to a certain proportion as a lithium source compound, which can meet the basic requirement that a pure-phase LLZO solid electrolyte material can be directly prepared by high-temperature co-firing without prepressing the fully mixed raw materials into a block body, and gives consideration to the principles of high efficiency, environmental protection and safety in industrial synthesis.

Description

Solid-phase synthesis method for synthesizing lithium lanthanum zirconium oxygen-based solid electrolyte material with garnet structure under synergistic action of quaternary ammonium hydroxide
Technical Field
The invention belongs to the field of inorganic material synthesis, and particularly relates to a solid-phase synthesis method for synthesizing a lithium lanthanum zirconium oxygen (Li-La-Zr-O, LLZO) solid electrolyte material with a garnet structure under the synergistic action of quaternary ammonium hydroxide.
Background
At present, a variety of solid electrolyte materials have been widely paid attention and researched by researchers at home and abroad, including amorphous LiPON, and Li in oxide system 3x La 2/3-x TiO 3 (LLTO)、Li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP)、Li 1+ x Al x Ge 2-x (PO 4 ) 3 (LAGP)、Li 7 La 3 Zr 2 O 12 (LLZO), xLi of sulfide system 2 S-(1-x)P 2 S 5 、Li 10 GeP 2 S 12 (LGPS), polyethylene oxide in polymer systems (PEO), and the like. Among them, the oxide-type lithium ion conductor LLZO having a garnet structure is favored because of its advantages such as high lithium ion conductivity at room temperature, wide electrochemical window, and good stability to metallic lithium and ambient air.
Subject group of professor Weppner reports for the first time in non-patent document Angew. Chem. Int. Ed.,2007,46,7778-7781 a lithium ion conductor Li with garnet structure synthesized by solid phase reaction method 7 La 3 Zr 2 O 12 (LLZO) having a lithium ion conductivity of up to 3.0X 10 at 25 DEG C -4 S/cm, and an electrical conductivity activation energy of-0.30 eV at a temperature of 18 to 300 ℃. Also, in the chinese invention patent 'ion conductor having garnet structure' with application No. 200880023221.3, professor WeppnerThe related physical properties of chemically stable solid ion conductor materials with garnet structure such as LLZO and the like, and preparation methods thereof are disclosed formally, and the application thereof in batteries, storage batteries, electrochromic devices and other electrochemical cells is proposed. Thereafter, a great deal of research work was conducted on the LLZO system material by numerous researchers.
At present, the preparation methods for the LLZO-based solid electrolyte material are various, including a solid phase reaction method, a Pechini method, a glycine method, an EDTA method, a precipitation method, and the like. Wherein, the process equipment required by the high-temperature solid-phase reaction method is simpler, the preparation condition is easy to control, and the mass synthesis is easy to realize, thereby having the most industrial application value. When the solid-phase reaction is carried out, the lithium source compound used may be lithium oxide (Li) 2 O), anhydrous lithium hydroxide (LiOH), lithium hydroxide monohydrate (LiOH. H) 2 O), lithium carbonate (Li) 2 CO 3 ) Nitric acid (LiNO) 3 ) Lithium sulfate (Li) 2 SO 4 ) Lithium oxalate (Li) 2 C 2 O 4 ) Lithium acetate (CH) 3 COOLi), and the like. However, for reasons of cost, environmental protection, etc., it is more preferable to use lithium nickel cobalt manganese oxide (LiCoO) 2 ) Lithium iron phosphate (LiFePO) 4 ) Lithium titanate (Li) 4 Ti 5 O 12 ) Like the positive and negative electrode materials, lithium hydroxide monohydrate or lithium carbonate is used as a lithium source in industrial production for synthesis (other lithium source compounds including anhydrous lithium hydroxide are either much higher in cost or release polluting gases when participating in high-temperature solid-phase reaction, so that the lithium hydroxide is suitable for laboratory small-scale experiments and is not an ideal industrial synthesis raw material). Compared with the prior art, the lithium hydroxide monohydrate has lower melting point (462 ℃ below zero and 471 ℃ below zero) and higher activity, can play an effective sintering-assisting role in high-temperature solid-phase reaction with other raw materials, and can prepare an ideal target product at relatively lower reaction temperature; the melting point of the lithium carbonate is relatively high (723 ℃), so that the lithium carbonate has relatively poor reactivity in high-temperature solid-phase reaction, and the lithium carbonate is required to be treated at higher temperature or for longer time to obtain ideal lithium carbonateAnd (4) a target product. However, lithium hydroxide monohydrate is extremely alkaline and corrosive, and easily forms dust during batch processing, which causes burn and damage to human bodies; in addition, lithium hydroxide monohydrate is also prone to deterioration due to absorption of carbon dioxide in the air, and needs to be stored properly. In contrast, lithium carbonate is more stable and safer.
For the synthesis of the LLZO-based solid electrolyte material, according to the descriptions in a large number of non-patent documents such as angew.chem. int.ed.,2007,46,7778-7781, inorg.chem.,2011,50,1089-1097, etc., if lithium carbonate is used as a lithium source, lithium carbonate powder is required to be fully and uniformly mixed with other raw materials including lanthanum source compounds, zirconium source compounds, doping element compounds, etc., and is pre-pressed into a block body and then is subjected to high-temperature co-firing to obtain the cubic-phase LLZO-based solid electrolyte material, otherwise, if the mixed powder is directly subjected to high-temperature co-firing, an insulating lanthanum zirconate phase is generated; and if lithium hydroxide monohydrate (or anhydrous lithium hydroxide) is used as a lithium source, the lithium hydroxide monohydrate is fully mixed with other raw materials and directly co-fired at high temperature to prepare the cubic-phase LLZO solid electrolyte material.
For industrial large-scale synthesis, the operation mode of pre-pressing various raw materials which are uniformly mixed into a block body for high-temperature solid-phase reaction, and then grinding the sintered block body (usually with extremely high hardness) into powder is undoubtedly very complicated and costly, so lithium carbonate is not suitable for being directly used as an industrial raw material for synthesizing the LLZO-based solid electrolyte material; in the case of using lithium hydroxide monohydrate as a lithium source for the industrial production of the LLZO-based solid electrolyte material, a series of handling and storage issues must be carefully handled in order to prevent injury to workers or deterioration thereof, in view of its strong basicity, strong corrosiveness and instability.
The quaternary ammonium base is an organic strong base, the alkalinity of the quaternary ammonium base is equivalent to that of KOH and NaOH, the quaternary ammonium base has extremely wide application in the field of industrial scientific research, can be used as a catalyst in the aspect of organic silicon synthesis, can be used as a template agent for synthesizing zeolite and molecular sieve, can be used as a gas chromatography pretreatment agent, a phase transfer catalyst for chemical reaction, a titrant of organic acid, can be used as an etching agent of a printed circuit board, a cleaning agent in the manufacture of microelectronic chips and the like, the research on the quaternary ammonium base is mostly limited to short-chain quaternary ammonium base at home and abroad at present, and has a fresh report on the research on the long-chain quaternary ammonium base, and the long-chain quaternary ammonium base not only maintains the strong alkalinity of the traditional short-chain quaternary ammonium base, but also has surface activity, so the quaternary ammonium base can be simultaneously used as the organic strong base and the surface active agent, and the application field of the quaternary ammonium base is wider than the traditional short-chain quaternary ammonium base. The present inventors tried for the first time to apply quaternary ammonium hydroxide to the synthesis of a solid electrolyte material of LLZO system.
Disclosure of Invention
In the industrial synthesis of the LLZO-based solid electrolyte material, lithium hydroxide monohydrate (LiOH. H) is used alone 2 O) or lithium carbonate (Li) 2 CO 3 ) The invention provides a solid phase synthesis method for realizing the industrial preparation of the LLZO solid electrolyte material by compounding and matching quaternary ammonium hydroxide and a lithium source according to a certain proportion, which can meet the basic requirement that pure-phase LLZO solid electrolyte material can be directly prepared by high-temperature co-firing without prepressing the fully mixed raw materials into blocks and gives consideration to the principles of high efficiency, environmental protection and safety in industrial synthesis.
According to the solid-phase synthesis method for synthesizing the LLZO solid electrolyte material with the garnet structure under the synergistic effect of the quaternary ammonium hydroxide, the lithium source adopted in the synthesis is mainly lithium carbonate, and the quaternary ammonium hydroxide is compounded and matched according to a certain proportion, wherein the molar ratio of the quaternary ammonium hydroxide to the lithium carbonate is as follows: 0.05. The molecular structural formula of the quaternary ammonium hydroxide is as follows:
Figure RE-GDA0002115244850000041
wherein, R1, R2, R3 and R4 are respectively and independently selected from hydrogen, alkyl, alkenyl, alkynyl, phenyl or aryl; or R1, R2, R3 and R4 are respectively and independently selected from at least one element group of boron, silicon, nitrogen, phosphorus, oxygen, sulfur, fluorine, chlorine, bromine and iodine; r1, R2, R3 and R4 are independent substituent groups, or two adjacent groups are combined to form a ring.
Preferably, in the molecular structural formula of the quaternary ammonium hydroxide, R1, R2, R3 and R4 are independent substituent groups, and R1, R2, R3 and R4 are respectively hydrogen or alkyl with 1-18 carbon atoms.
The quaternary ammonium base is an organic strong base, the alkalinity of the quaternary ammonium base is equivalent to that of KOH and NaOH, and the quaternary ammonium base is compounded with lithium carbonate and can exert the activity similar to lithium hydroxide; in particular, long-chain quaternary ammonium hydroxide not only maintains strong basicity of the traditional short-chain quaternary ammonium hydroxide, but also has surface activity, so that the long-chain quaternary ammonium hydroxide can be used as an organic strong base and a surfactant at the same time. The molar ratio of the quaternary ammonium hydroxide to the lithium carbonate is as follows: 0.05. The proportion of quaternary ammonium base is too high, and the cost is increased; the proportion of quaternary ammonium base is too low, and the coordination effect is not obvious.
Preferably, the LLZO-based solid electrolyte material is specifically Li of a cubic phase garnet structure 7 La 3 Zr 2 O 12 And derivatives Li obtained by variously doping and modifying the same 7-δ C z La 3-y B y Zr 2-z A x O 12 (wherein, A is one or more of Ta, nb, sb, W, Y, V, sc, bi, si, ti, te, hf, ge, zn, sn and the like, B is one or more of Mg, ca, sr, ba, ce, pr, nd, sm, pm, eu and the like, C is one or more of Al, ga, B, in, tl and the like, x, Y and z are more than or equal to 0 and less than or equal to 1, Y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 0.5, and x + Y + z is less than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 0.5>0) Including but not limited to Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 、 Li 6.28 Al 0.24 La 3 Zr 2 O 12 、Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 、Li 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 、 Li 6.6 La 3 Zr 1.6 Sb 0.4 O 12 、Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Ga 0.25 La 3 Zr 2 O 12 And the like.
Preferably, the solid phase synthesis method comprises the following steps:
(1) Weighing and mixing the lithium source and quaternary ammonium hydroxide compound, the lanthanum source compound, the zirconium source compound and the corresponding raw material compounds of other doping elements according to the molar ratio in the molecular formula of the target product LLZO solid electrolyte material (wherein the mixed lithium source needs to be excessive by 2-15 wt% to compensate volatility loss in the subsequent high-temperature treatment process), and simultaneously adding a proper amount of mixing solvent and carrying out ball milling for 6-24 hours. Under the action of quaternary ammonium base, especially under the action of long carbon chain quaternary ammonium base, the compound of lithium source and quaternary ammonium base can be fully mixed with lanthanum source compound, zirconium source compound and other corresponding raw material compounds of doping elements, thereby promoting the complete solid phase reaction at high temperature.
(2) And separating the fully mixed and ground raw material mixture powder from the mixing solvent by a certain technical means, thereby obtaining fully dried solid-phase reaction raw material mixture powder.
(3) And filling the fully dried solid-phase reaction raw material mixture powder into a crucible or a sagger, and reacting at high temperature for 6-24 hours to obtain the target product LLZO solid electrolyte material.
Preferably, the lanthanum source compound is one or a mixture of more of lanthanum oxide, lanthanum hydroxide, lanthanum carbonate, lanthanum acetate, lanthanum oxalate, lanthanum nitrate, lanthanum sulfate and the like, and is preferably lanthanum oxide, and the lanthanum oxide is roasted at 800-950 ℃ for 1-24 hours before use; the zirconium source compound is one or a mixture of more of zirconia, zirconium hydroxide, zirconyl nitrate, zirconium acetate, zirconium nitrate, zirconium carbonate, zirconium sulfate and the like, preferably zirconia, and the zirconia is roasted at 120-600 ℃ for 1-24 hours before use; the corresponding raw material compound of the other doping elements is one or a mixture of more of oxide, hydroxide, carbonate, nitrate and the like of the doping elements, preferably the oxide of the doping elements, such as tantalum oxide, aluminum oxide, niobium oxide, antimony oxide, tungsten oxide and the like, and the oxide of the doping elements is roasted at 120-600 ℃ for 1-24 hours before use.
Preferably, the mixing solvent is one of absolute ethyl alcohol, industrial alcohol, isopropanol, acetone and deionized water.
Preferably, the means for separating the sufficiently mixed and milled raw material mixture powder from the kneading solvent is one of techniques such as spray drying, centrifugal separation, distillation, suction filtration, and freeze drying.
Preferably, the high-temperature reaction process is carried out at a high temperature of 850-1000 ℃, preferably 900-950 ℃; the atmosphere of the high-temperature reaction can be ambient air, and can also be flowing air or oxygen atmosphere; the heating rate before the high-temperature reaction is 1-10 ℃/min, and the cooling rate after the reaction is finished is 1-5 ℃/min.
Preferably, after the high-temperature reaction is completed and the temperature is reduced, the particle size of the target product LLZO-based solid electrolyte material can be further controlled to a level required for subsequent application by means of ball milling, sand milling and the like.
The invention has the beneficial effects that:
preferably, when the quaternary ammonium hydroxide and lithium source composite is used in the preparation process of the LLZO-based solid electrolyte material, compared with the case of using lithium carbonate alone as a lithium source, a complicated operation mode that the raw material mixture powder which is fully mixed must be pre-pressed into a block and then subjected to a high-temperature solid-phase reaction, and then the block with extremely high hardness after sintering is ground into powder again can be fundamentally avoided, and meanwhile, the potential safety and quality hazards caused by the disadvantages of strong basicity, strong corrosivity, instability and the like of lithium hydroxide monohydrate can be fully reduced compared with the case of using lithium hydroxide monohydrate alone as a lithium source.
Preferably, except that quaternary ammonium base is used as a synergist, the other preparation procedures are not obviously different from the traditional solid phase synthesis method, so that the preparation process is simple, the operation condition is mild, and the industrial popularization is easy to realize.
Drawings
FIG. 1 is an X-ray diffraction pattern of a LLZO-based solid electrolyte material synthesized in each example of the present invention and comparative example.
FIG. 2 is a scanning electron micrograph of a cross section of a LLZO-based solid electrolyte material synthesized in some examples of the present invention and comparative examples after sintering into a dense mass: a) Example 1; b) Example 2; c) Example 3; d) Example 4; e) Comparative example 1; f) Comparative example 3.
FIG. 3 is Li synthesized in example 2 of the present invention 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Solid electrolyte material: a) Alternating current impedance spectra measured at different temperatures and b) arrhenius curves.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples, which however are only intended to illustrate and not to limit the invention.
The invention mainly provides a solid phase synthesis method for preparing a LLZO solid electrolyte material by using lithium carbonate and quaternary ammonium hydroxide compound as a lithium source, which comprises the following specific steps:
(1) Mixing lithium carbonate and quaternary ammonium base with lanthanum source compound (such as lanthanum oxide, lanthanum hydroxide, etc.), zirconium source compound (such as zirconium oxide), and other corresponding material compounds (such as tantalum oxide, aluminum oxide, niobium oxide, etc.) of other doping elements at a certain ratio according to target product Li 7 La 3 Zr 2 O 12 Or Li 7-δ C z La 3-y B y Zr 2-z A x O 12 (wherein A is one or more of elements such as Ta, nb, sb, W, Y, V, sc, bi, si, ti, te, hf, ge, zn, sn and the like, B is one or more of elements such as Mg, ca, sr, ba, ce, pr, nd, sm, pm, eu and the like, C is one or more of elements such as Al, ga, B, in, tl and the like, x, Y and z meet the condition that x is more than or equal to 0 and less than or equal to 1, Y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 0.5, and x + Y + z is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 0.5>0) Mixing at the stoichiometric ratio in (1). In order to compensate the volatility loss of lithium in the subsequent high-temperature treatment process, the dosage of the lithium source needs to be excessive by 2-15 wt% as appropriate. Then adding a proper amount of mixing solvent (such as absolute ethyl alcohol, industrial alcohol, isopropanol, acetone, deionized water and the like) and grinding medium (such as zirconia beads), and performing ball milling (planetary or roller ball milling) for 6-24 hours to ensure that various raw material powders are fully and uniformly mixed.
(2) After various raw material powders are fully and uniformly mixed by ball milling, the separation of the mixed material solvent and the raw material mixture powder is realized by technical means such as spray drying, centrifugal separation, distillation, suction filtration or freeze drying. In each example and comparative example of the invention, the separation process of the mixing solvent and the raw material mixture powder is realized by a spray drying mode.
(3) And filling the solid-phase reaction raw material mixture powder which is fully separated from the mixed material solvent into a crucible or a saggar, and reacting at the high temperature of 850-1000 ℃ for 6-24 hours to obtain the target product LLZO solid electrolyte material.
(4) The LLZO solid electrolyte material prepared by high-temperature reaction can be further finely ground to D through ball milling, sand grinding and other means 50 Is powder of several micrometers or even hundreds of nanometers.
The basic physical properties of the finally prepared LLZO-based solid electrolyte powder were measured and analyzed by an X-ray diffraction diffractometer, a laser particle size analyzer, an ac impedance spectroscopy, and the like. In order to test the lithium ion conductivity of the LLZO solid electrolyte material, the prepared LLZO solid electrolyte powder is pressed and molded into a LLZO solid electrolyte wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100Mpa, and the LLZO solid electrolyte wafer is sintered at the high temperature of 1050-1230 ℃ for 10-36 hours to form a compact block. In order to avoid the phase change of the material (generation of an insulating lanthanum zirconate phase) caused by the volatilization of lithium during high-temperature sintering as much as possible, it is necessary to bury the LLZO-based solid electrolyte wafer with the base powder and sinter the wafer (after sintering, lanthanum zirconate is generally generated as a hetero phase in the buried base powder, and the LLZO-based solid electrolyte bulk is hardly generated as a hetero phase by virtue of the protection of the base powder). The atmosphere used in sintering can be ambient air or flowing air or oxygen atmosphere, the heating rate before sintering is generally 1-10 ℃/min, and the cooling rate after sintering is 1-5 ℃/min. The density of the sintered LLZO solid electrolyte block can be observed by a scanning electron microscope. After sintering, properly grinding the surface and the side edges of the LLZO solid electrolyte block to completely remove the possible impure phases such as lanthanum zirconate and the like at the edges, then measuring the diameter and the thickness of the sheet LLZO solid electrolyte block, uniformly coating a layer of gold slurry on the two surfaces of the LLZO solid electrolyte block, drying, carrying out high-temperature heat treatment at 800-950 ℃ for 0.5-2 hours, cooling, connecting a silver net and a lead wire for AC impedance spectroscopy test, and obtaining the lithium ion conductivity sigma of the LLZO solid electrolyte block according to the following formula (1)
Figure RE-GDA0002115244850000091
In the formula (1), t and d are the thickness and diameter of the sheet-like LLZO-based solid electrolyte block, respectively, R g And R gb The grain resistance and the grain boundary resistance of the impedance spectrum respectively correspond to the intercept of a semi-arc in a Nyquist curve of the measured impedance spectrum on a real axis at a high frequency band and a low frequency band.
Further, the relationship between the lithium ion conductivity σ of the LLZO-based solid electrolyte material and the absolute temperature T satisfies Arrhenius equation shown in the following formula (2)
Figure RE-GDA0002115244850000092
In the formula (2), σ 0 Is a pre-exponential factor, E a Is the lithium ion conductivity activation energy of the LLZO solid electrolyte material, and R is an ideal gas constant. Therefore, the lithium ion conductivity sigma of the LLZO system solid electrolyte block material at different temperatures can be measured by using an alternating current impedance spectrum, then the ln (sigma T) is used as a vertical axis, 1000/T is used as a horizontal axis to be plotted, and the slope of the obtained straight line is-E a The lithium ion conductivity activation energy E of the LLZO solid electrolyte bulk material can be calculated by the calculation method of/1000R a 。
Example 1
The LLZO-based solid electrolyte material synthesized in example 1 was Li 6.28 Al 0.24 La 3 Zr 2 O 12 The lithium source complex is quaternary ammonium base (tetramethylammonium hydroxide): li 2 CO 3 1 (molar ratio) = 0.8.
Li 6.28 Al 0.24 La 3 Zr 2 O 12 Synthesis of materials:(1) La is preliminarily formed 2 O 3 Calcining the powder at 900 deg.C for 12 hr to remove Al 2 O 3 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Separately weighing Li according to molecular formula 2 CO 3 (excess amount of Li: 5%), al 2 O 3 、La 2 O 3 、ZrO 2 And putting the quaternary ammonium hydroxide powder into a ball milling tank, adding a proper amount of isopropanol and zirconia beads, and carrying out ball milling on the mixture for 24 hours in a roller ball mill; (3) After the ball milling is finished, removing and recycling isopropanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 900 ℃ at the speed of 3 ℃/min, roasting for 12 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) Further performing ball milling to obtain Li after solid phase reaction 6.28 Al 0.24 La 3 Zr 2 O 12 Grinding the powder to D 50 Is fine powder of 3 microns, and the related physical property characterization is carried out.
Li 6.28 Al 0.24 La 3 Zr 2 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction of the prepared Li 6.28 Al 0.24 La 3 Zr 2 O 12 The phase of the powder is characterized, and the result is shown in figure 1, which is an ideal cubic garnet structure; (2) By laser particle size analyzer on the prepared Li 6.28 Al 0.24 La 3 Zr 2 O 12 The particle size and specific surface of the powder were tested and the results are shown in table 1; (3) The obtained Li 6.28 Al 0.24 La 3 Zr 2 O 12 Pressing the powder into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with mother powder, putting the wafer into a corundum crucible, heating to 1150 ℃ at the speed of 3 ℃/min, sintering for 10 hours in a flowing air atmosphere, then cooling to room temperature at the speed of 3 ℃/min, and carrying out scanning electron microscope on the sintered Li 6.28 Al 0.24 La 3 Zr 2 O 12 The compactness of the wafer is observed, and the result is shown in figure 2a, the compactness is still good, but a small amount of closed pores still exist; (4) Li after sintering and grinding 6.28 Al 0.24 La 3 Zr 2 O 12 The two sides of the wafer are evenly coated with a layer of gold paste, the wafer is dried and then is subjected to heat treatment at 900 ℃ for 2 hours, after the wafer is cooled to room temperature, the conductivity test is carried out, the measured alternating current impedance spectrogram under the condition of room temperature (25 ℃) is shown in the table 1, and the room temperature lithium ion conductivity calculated by combining the formula (1) is further included.
TABLE 1 basic physical properties of LLZO-based solid electrolyte materials synthesized in some examples of the present invention and comparative examples
Figure RE-GDA0002115244850000101
Example 2
The LLZO-based solid electrolyte material synthesized in example 2 was Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The lithium source complex is quaternary ammonium base (tetramethylammonium hydroxide): li 2 CO 3 1 (molar ratio).
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Synthesis of materials: (1) La is preliminarily formed 2 O 3 Calcining the powder at 900 deg.C for 12 hr to obtain Nb 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Separately weighing Li according to molecular formula 2 CO 3 (excess amount of Li: 3%), al 2 O 3 、La 2 O 3 、Nb 2 O 5 、ZrO 2 And putting the quaternary ammonium hydroxide powder into a ball milling tank, adding a proper amount of absolute ethyl alcohol and zirconia beads, and ball milling for 24 hours on a roller ball mill; (3) After the ball milling is finished, removing and recycling the anhydrous ethanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 900 ℃ at the speed of 3 ℃/min, roasting for 12 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) Further ball-milling the Li obtained after the solid phase reaction 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Grinding the powder to D 50 Fine powder of 3 μmAnd (5) carrying out related physical property characterization.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction on the Li produced 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The phase of the powder is characterized, and the result is shown in figure 1 and is an ideal cubic garnet structure; (2) By laser particle size analyzer on the prepared Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The particle size and specific surface of the powder were tested and the results are shown in table 1; (3) The obtained Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Pressing the powder into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with mother powder, putting the wafer into a corundum crucible, heating to 1150 ℃ at the speed of 2 ℃/min, sintering for 10 hours in a flowing oxygen atmosphere, then cooling to room temperature at the speed of 3 ℃/min, and carrying out scanning electron microscope on the sintered Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The compactness of the wafer is observed, and the result is shown in figure 2b, so that the compactness is better; (4) Li after sintering and grinding 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Uniformly coating a layer of gold paste on two surfaces of the wafer, drying, carrying out heat treatment at 900 ℃ for 1 hour, carrying out conductivity test after cooling to room temperature, and further combining an alternating current impedance spectrogram under the condition of room temperature (25 ℃) and the room temperature lithium ion conductivity calculated by the formula (1) to be listed in the table 1; (5) Further, li was measured at 20 ℃, 30 ℃, 40 ℃,50 ℃, 60 ℃ and the like 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The AC impedance spectrum of the wafer is shown in FIG. 3a, and Arrhenius curve obtained by further combining the formula (2) with ln (σ T) as the vertical axis and 1000/T as the horizontal axis is shown in FIG. 3b, from which the Li produced can be estimated 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The lithium ion conductivity activation energy of the material is 0.348eV.
Example 3
LLZO-based solid synthesized in example 3The electrolyte material is Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The lithium source is LiOH. H 2 O and Li 2 CO 3 ，Li 2 CO 3 Is composed of lithium salt (80 wt.%) and quaternary ammonium hydroxide (Li) 2 CO 3 1 (molar ratio) = 0.3.
Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 Synthesis of materials: (1) La beforehand 2 O 3 Calcining the powder at 900 deg.C for 12 hr to obtain Ta 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Respectively weighing LiOH and H according to molecular formula 2 O and Li 2 CO 3 (excess value of Li: 10%), la 2 O 3 、Ta 2 O 5 、ZrO 2 And putting the quaternary ammonium hydroxide powder into a ball milling tank, adding a proper amount of isopropanol and zirconia beads, and carrying out ball milling on the mixture for 18 hours in a roller ball mill; (3) After the ball milling is finished, removing and recycling isopropanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 950 ℃ at the speed of 4 ℃/min, roasting for 10 hours under the condition of ambient air, and then cooling to room temperature at the speed of 3 ℃/min; (5) Further performing ball milling to obtain Li after solid phase reaction 6.5 La 3 Zr 1.5 Ta 0.5 O 12 Grinding the powder to D 50 Is fine powder with the particle size of 3 microns, and is subjected to related physical property characterization.
Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction of the prepared Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The phase of the powder is characterized, and the result is shown in figure 1 and is an ideal cubic garnet structure; (2) By laser particle size analyzer on the prepared Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The particle size and specific surface of the powder were tested and the results are shown in table 1; (3) Li to be prepared 6.5 La 3 Zr 1.5 Ta 0.5 O 12 Powder bodyPressing into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with the mother powder, putting the wafer into a corundum crucible, heating to 1150 ℃ at the speed of 3 ℃/min, sintering for 12 hours in a flowing oxygen atmosphere, then cooling to room temperature at the speed of 3 ℃/min, and carrying out scanning electron microscope on the sintered Li through 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The compactness of the wafer is observed, and the result is shown in figure 2c, so that the compactness is better; (4) Li after sintering and grinding 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The two sides of the wafer are evenly coated with a layer of gold paste, the wafer is dried and then is subjected to heat treatment at 900 ℃ for 2 hours, after the wafer is cooled to room temperature, the conductivity test is carried out, the measured alternating current impedance spectrogram under the condition of room temperature (25 ℃) is shown in the table 1, and the room temperature lithium ion conductivity calculated by combining the formula (1) is further included.
Example 4
The LLZO-based solid electrolyte material synthesized in example 4 was Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 The lithium source is LiOH. H 2 O and Li 2 CO 3 ，Li 2 CO 3 Is composed of 60% (by weight) of lithium salt, and quaternary ammonium base (hexadecyl trimethyl ammonium hydroxide) Li 2 CO 3 1 (molar ratio) = 0.1.
Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 Synthesis of materials: (1) La (OH) 3 Calcining the powder at 200 deg.C for 2 hr to remove Al 2 O 3 、Nb 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Respectively weighing LiOH and H according to molecular formula 2 O、Li 2 CO 3 (excess Li of 8%), al 2 O 3 、La(OH) 3 、Nb 2 O 5 、ZrO 2 And quaternary ammonium hydroxide, putting the powder into a ball milling tank, adding a proper amount of deionized water and zirconia beads, and ball milling for 24 hours on a roller ball mill; (3) After the ball milling is finished, removing deionized water by using open spray drying equipment to obtain dry raw material mixture powder;(4) Putting the raw material mixture powder into a sagger, heating to 900 ℃ at the speed of 3 ℃/min, roasting for 12 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) Further milling the obtained Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 Grinding the powder to D 50 Is fine powder with the particle size of 3 microns, and is subjected to related physical property characterization.
Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction on the Li produced 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 The phase of the powder is characterized, and the result is shown in figure 1 and is an ideal cubic garnet structure; (2) By laser particle size analyzer on the prepared Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 The particle size and specific surface of the powder were tested and the results are shown in table 1; (3) Li to be prepared 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 Pressing the powder into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with mother powder, putting the wafer into a corundum crucible, heating to 1150 ℃ at the speed of 3 ℃/min, sintering for 12 hours in a flowing argon atmosphere, then cooling to room temperature at the speed of 3 ℃/min, and carrying out scanning electron microscope on the sintered Li 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 The compactness of the wafer is observed, and the result is shown in figure 2d, so that the compactness is better; (4) Li after sintering and grinding 6.15 Al 0.2 La 3 Zr 1.75 Nb 0.25 O 12 Two surfaces of the wafer are evenly coated with a layer of gold paste, heat treatment is carried out for 1 hour at 900 ℃ after drying, conductivity test is carried out after cooling to room temperature, the measured alternating current impedance spectrogram under the room temperature (25 ℃) condition is further combined with the room temperature lithium ion conductivity calculated by the formula (1) and is listed in the table 1.
Example 5
LLZO-based solid electrolyte material synthesized in example 5Is Li 6.6 La 3 Zr 1.6 Sb 0.4 O 12 The lithium source is LiOH. H 2 O and Li 2 CO 3 ，Li 2 CO 3 85% (by weight) of lithium salt as main component, and compounding with quaternary ammonium base (tetramethylammonium hydroxide), wherein the quaternary ammonium base is Li 2 CO 3 1 (molar ratio) = 0.5.
Li 6.6 La 3 Zr 1.6 Sb 0.4 O 12 Synthesis and characterization of materials: (1) La is preliminarily formed 2 O 3 The powder is roasted for 12 hours at 900 ℃, and Sb is added 2 O 3 Calcining the powder at 150 ℃ for 2 hours to obtain ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Respectively weighing LiOH. H according to molecular formula 2 O、Li 2 CO 3 、La 2 O 3 、Sb 2 O 3 And ZrO 2 And putting the quaternary ammonium hydroxide powder into a ball milling tank, adding a proper amount of absolute ethyl alcohol and zirconia beads, and carrying out ball milling on a planetary ball mill for 12 hours; (3) After the ball milling is finished, removing and recycling the anhydrous ethanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 950 ℃ at the speed of 3 ℃/min, roasting for 10 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) By means of X-ray diffraction on the Li produced 6.6 La 3 Zr 1.6 Sb 0.4 O 12 The phase of the powder was characterized, and the result is an ideal cubic garnet structure as shown in fig. 1.
Example 6
The LLZO-based solid electrolyte material synthesized in example 6 was Li 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 The lithium source is LiOH. H 2 O and Li 2 CO 3 ，Li 2 CO 3 Is mainly lithium salt accounting for 90 percent (mass percent) and is compounded with quaternary ammonium base (tetramethylammonium hydroxide), wherein the quaternary ammonium base is Li 2 CO 3 1 (molar ratio) = 0.8.
Li 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 Synthesis and characterization of materials: (1) La (OH) 3 Calcining the powder at 200 deg.C for 2 hr to remove Ca (OH) 2 Calcining the powder at 150 deg.C for 2 hr to obtain Nb 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) Respectively weighing LiOH and H according to molecular formula 2 O、Li 2 CO 3 、La(OH) 3 、Ca(OH) 2 、 Nb 2 O 5 、ZrO 2 And putting the quaternary ammonium hydroxide powder into a ball milling tank, adding a proper amount of isopropanol and zirconia beads, and carrying out ball milling on a planetary ball mill for 18 hours; (3) After the ball milling is finished, removing and recovering isopropanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 900 ℃ at the speed of 2.5 ℃/min, roasting for 12 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) By means of X-ray diffraction on the Li produced 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 The phase of the powder was characterized, and as a result, the powder had an ideal cubic garnet structure as shown in fig. 1.
Comparative example 1
The LLZO-based solid electrolyte material synthesized in comparative example 1 was Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The lithium source is LiOH. H 2 Excess of O, li was 3%.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Synthesis of materials: (1) La is preliminarily formed 2 O 3 The powder is roasted for 12 hours at 900 ℃, and Nb is added 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) 291.75 g of LiOH. H were weighed out separately 2 O, 488.71 g La 2 O 3 33.23 g Nb 2 O 5 And 215.64 g ZrO 2 Putting the powder into a ball milling tank, adding a proper amount of absolute ethyl alcohol and zirconia beads, and ball milling for 24 hours on a roller ball mill; (3) After the ball milling is finished, removing and recycling the anhydrous ethanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Loading the raw material mixture powder into a sagger at a speed of 3 deg.C/minHeating to 900 ℃, roasting for 12 hours under the condition of ambient air, and then cooling to room temperature at the speed of 3 ℃/min; (5) Further performing ball milling to obtain Li after solid phase reaction 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Grinding the powder to D 50 Is fine powder of 3 microns, and the related physical property characterization is carried out.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction of the prepared Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The phase of the powder is characterized, and the result is shown in figure 1 and is an ideal cubic garnet structure; (2) By laser particle size analyzer on the prepared Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The particle size and specific surface of the powder were tested and the results are shown in table 1; (3) Li to be prepared 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Pressing the powder into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with mother powder, putting the wafer into a corundum crucible, heating to 1150 ℃ at the speed of 2 ℃/min, sintering for 10 hours in a flowing oxygen atmosphere, then cooling to room temperature at the speed of 3 ℃/min, and carrying out scanning electron microscope on the sintered Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The compactness of the wafer is observed, and the result is shown in figure 2e, so that the compactness is better; (4) Li after sintering and grinding 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Two surfaces of the wafer are evenly coated with a layer of gold paste, heat treatment is carried out for 1 hour at 900 ℃ after drying, conductivity test is carried out after cooling to room temperature, the measured alternating current impedance spectrogram under the room temperature (25 ℃) condition is further combined with the room temperature lithium ion conductivity calculated by the formula (1) and is listed in the table 1.
The synthesis scheme of comparative example 1 is identical to that of example 2 except that the lithium source complex used is different, and the synthesis and test conditions are the same, and from the comparison of the results associated with table 1, fig. 2 and fig. 3, li synthesized by the two schemes 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The basic properties of (A) are very close. Therefore, the solid-phase synthesis method for preparing the LLZO solid electrolyte material by using the lithium carbonate/quaternary ammonium hydroxide compound can obtain the synthesis effect equivalent to that when lithium hydroxide monohydrate is used as a lithium source, but can fully reduce the potential safety and quality hazards caused by the defects of strong basicity, strong corrosivity, instability and the like of the lithium hydroxide monohydrate.
Comparative example 2
The LLZO-based solid electrolyte material synthesized in comparative example 2 was Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The lithium source used is Li 2 CO 3 The excess value of Li is 3%.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Synthesis and characterization of materials: (1) La beforehand 2 O 3 The powder is roasted for 12 hours at 900 ℃, and Nb is added 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) 25.68 g of Li were weighed out separately 2 CO 3 48.87 g La 2 O 3 3.32 g Nb 2 O 5 And 21.56 g ZrO 2 Putting the powder into a ball milling tank, adding a proper amount of absolute ethyl alcohol and zirconia beads, and carrying out ball milling on the powder for 24 hours on a planet ball mill; (3) After the ball milling is finished, removing and recycling the anhydrous ethanol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Putting the raw material mixture powder into a sagger, heating to 900 ℃ at the speed of 3 ℃/min, roasting for 12 hours under the ambient air condition, and then cooling to room temperature at the speed of 3 ℃/min; (5) By means of X-ray diffraction of the prepared Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The phase of the powder was characterized, and the results are shown in fig. 1, and it can be seen that Li having a cubic garnet structure was not obtained 6.75 La 3 Zr 1.75 Nb 0.25 O 12 And only the complex phase such as lanthanum zirconate exists in the product.
Comparative example 3
The LLZO-based solid electrolyte material synthesized in comparative example 3 wasLi 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The lithium source used is Li 2 CO 3 The excess value of Li is 3%.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Synthesis of materials: (1) La beforehand 2 O 3 The powder is roasted for 12 hours at 900 ℃, and Nb is added 2 O 5 And ZrO 2 Roasting the powder at 600 ℃ for 5 hours; (2) 25.68 g of Li were weighed out separately 2 CO 3 48.87 g La 2 O 3 3.32 g Nb 2 O 5 And 21.56 g ZrO 2 Putting the powder into a ball milling tank, adding a proper amount of absolute ethyl alcohol and zirconia beads, and carrying out ball milling on the powder for 24 hours on a planetary ball mill; (3) After the ball milling is finished, removing and recovering the absolute ethyl alcohol by using organic solvent spray drying equipment to obtain dry raw material mixture powder; (4) Pressing the raw material mixture powder into a wafer with the diameter of 22mm and the thickness of 3mm under the pressure of 100MPa, putting the wafer into a crucible, heating the wafer to 900 ℃ at the speed of 3 ℃/min, roasting the wafer for 12 hours under the ambient air condition, and then cooling the wafer to room temperature at the speed of 3 ℃/min; (5) After the temperature is reduced, putting the calcined wafer block into an agate mortar to be ground into powder, and further grinding the powder to D 50 Is fine powder with the particle size of 3 microns, and is subjected to related physical property characterization.
Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Physical property characterization of the material: (1) By means of X-ray diffraction on the Li produced 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The phase of the powder is characterized, and the result is shown in figure 1, the powder is an ideal cubic garnet structure, and no complex phases such as lanthanum zirconate exist; (2) By laser particle size analyzer for the prepared Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The particle size and specific surface of the powder were tested, and the results are shown in table 1; (3) The obtained Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 Pressing the powder into a wafer with the diameter of 15mm and the thickness of 1mm under the pressure of 100MPa, burying the wafer with the mother powder, putting the wafer into a corundum crucible, and raising the wafer at the speed of 2 ℃/minThe temperature is increased to 1150 ℃, the mixture is sintered for 10 hours in the flowing oxygen atmosphere, then the temperature is reduced to the room temperature at the speed of 3 ℃/min, and the sintered Li is processed by a scanning electron microscope 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The compactness of the wafer is observed, and the result is shown in figure 2f, so that the compactness is better; (4) Li after sintering and grinding 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The two sides of the wafer are evenly coated with a layer of gold paste, the wafer is dried and then is subjected to heat treatment at 900 ℃ for 1 hour, after the wafer is cooled to room temperature, the conductivity test is carried out, the measured alternating current impedance spectrogram under the condition of room temperature (25 ℃) is shown in the table 1, and the room temperature lithium ion conductivity calculated by further combining the formula (1) is shown in the table 1.
Li in comparative examples 3 and 2 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The synthesis conditions of the powder are basically the same, but in comparative example 3, the raw material mixture powder after mixed grinding is pre-pressed and then subjected to high-temperature roasting treatment, and finally, the pure Li with the cubic phase garnet structure is successfully prepared 6.75 La 3 Zr 1.75 Nb 0.25 O 12 The material of comparative example 2, which was not subjected to the preliminary pressing treatment, was prepared by synthesizing a hetero phase such as lanthanum zirconate, and it was found that when the LLZO-based solid electrolyte material was synthesized by using lithium carbonate as a lithium source, the preliminary pressing treatment was required for the raw material mixture powder before the high-temperature solid-phase reaction. In the embodiment of the invention, when the quaternary ammonium hydroxide with a proper proportion is added and used, the solid electrolyte material is prepared under almost the same synthesis conditions, the powder with excellent performance can be successfully prepared without secondary prepressing treatment, and therefore, the superiority of the scheme provided by the invention applied to the solid phase synthesis scheme of the LLZO solid electrolyte material is fully proved.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.

Claims (10)

1. The solid-phase synthesis method for synthesizing the lithium lanthanum zirconium oxygen solid electrolyte material with the garnet structure under the synergistic action of quaternary ammonium hydroxide is characterized by comprising the following steps of: the method comprises the following steps:
(1) Weighing and mixing the compound of the quaternary ammonium hydroxide and a mixed lithium source and corresponding raw material compounds of a lanthanum source compound, a zirconium source compound and other doping elements according to the molar ratio in the molecular formula of a target product lithium lanthanum zirconium oxygen solid electrolyte material, wherein the mixed lithium source needs to be excessive by 2-15 wt% to compensate volatility loss in the subsequent high-temperature treatment process, and simultaneously adding a proper amount of mixing solvent and performing ball milling for 6-24 hours;
(2) Separating the fully mixed and ground raw material mixture powder from the mixing solvent to obtain fully dried solid-phase reaction raw material mixture powder;
(3) Filling the fully dried solid-phase reaction raw material mixture powder into a crucible or a sagger, and reacting for 6-24 hours at the high temperature of 850-1000 ℃ to obtain the target product lithium lanthanum zirconium oxygen-based solid electrolyte material; the mixed lithium source comprises lithium carbonate and is compounded with quaternary ammonium base according to a certain proportion, wherein the molar ratio of the quaternary ammonium base to the lithium carbonate is as follows: 0.05 to 1, wherein the molecular structural formula of the quaternary ammonium base is as follows:
Figure FDA0003886856400000011
wherein, R1, R2, R3 and R4 are respectively and independently selected from hydrogen, alkyl, alkenyl, alkynyl, phenyl or aryl; or R1, R2, R3 and R4 are respectively and independently selected from at least one element group of boron, silicon, nitrogen, phosphorus, oxygen, sulfur, fluorine, chlorine, bromine and iodine; r1, R2, R3 and R4 are independent substituent groups, or two adjacent groups are combined to form a ring.
2. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material with a garnet structure under the synergistic effect of a quaternary ammonium hydroxide according to claim 1, wherein R1, R2, R3 and R4 in the molecular structural formula of the quaternary ammonium hydroxide are independent substituent groups, and R1, R2, R3 and R4 are hydrogen or alkyl with a carbon number of 1-18 respectively.
3. The solid-phase synthesis method of lithium lanthanum zirconium oxide-based solid electrolyte material of garnet structure under the synergistic effect of quaternary ammonium hydroxide according to claim 1, characterized in that the molar ratio of the quaternary ammonium hydroxide to the lithium carbonate is: 0.1.
4. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure under the synergistic action of a quaternary ammonium hydroxide according to claim 1, characterized in that: the lithium lanthanum zirconium oxygen system solid electrolyte material is Li7La3Zr2O12 with a cubic phase garnet structure.
5. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure under the synergistic action of a quaternary ammonium hydroxide according to claim 1, characterized in that: the lithium lanthanum zirconium oxygen system solid electrolyte material comprises Li6.5La3Zr1.5Ta0.5O12, li6.28Al0.24La3Zr2O12, li6.15Al0.2La3Zr1.75Nb0.25O12, li6.8 La 2.9 Ca0.05Zr1.75Nb0.25O12, li6.6La3Zr1.6Sb0.4O12, li6.75La3Zr1.75Nb0.25O12 and Li6.25Ga0.25La3Zr2O12.
6. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure according to claim 1 under the synergistic effect of a quaternary ammonium hydroxide, characterized in that: the lanthanum source compound is one or a mixture of more of lanthanum oxide, lanthanum hydroxide, lanthanum carbonate, lanthanum acetate, lanthanum oxalate, lanthanum nitrate and lanthanum sulfate, the zirconium source compound is one or a mixture of more of zirconium oxide, zirconium hydroxide, zirconyl nitrate, zirconium acetate, zirconium nitrate, zirconium carbonate and zirconium sulfate, and the corresponding raw material compound of other doping elements is one or a mixture of more of oxide, hydroxide, carbonate and nitrate of the doping element.
7. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure according to claim 6 under the synergistic effect of a quaternary ammonium hydroxide, characterized in that: the lanthanum source compound is lanthanum oxide, and the lanthanum oxide is roasted for 1 to 24 hours at the temperature of 800 to 950 ℃ before use; the zirconium source compound is zirconia, and the zirconia is roasted for 1 to 24 hours at the temperature of between 120 and 600 ℃ before use; the corresponding raw materials of the other doping elements are one or a mixture of more of tantalum oxide, aluminum oxide, niobium oxide, antimony oxide and tungsten oxide, and the oxides of the doping elements are roasted for 1 to 24 hours at the temperature of between 120 and 600 ℃ before use.
8. The solid-phase synthesis method of lithium lanthanum zirconium oxygen-based solid electrolyte material of garnet structure under the synergistic effect of quaternary ammonium hydroxide according to claim 1, characterized in that: the mixed solvent is one of absolute ethyl alcohol, industrial alcohol, isopropanol, acetone and deionized water.
9. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure under the synergistic action of a quaternary ammonium hydroxide according to claim 1, characterized in that: the technical means of separating the fully mixed and ground raw material mixture powder from the mixed material solvent is one of spray drying, centrifugal separation, distillation, suction filtration and freeze drying technologies.
10. The solid-phase synthesis method of a lithium lanthanum zirconium oxygen-based solid electrolyte material of a garnet structure under the synergistic action of a quaternary ammonium hydroxide according to claim 1, characterized in that: and filling the fully dried solid-phase reaction raw material mixture powder into a crucible or a saggar, and reacting for 6-24 hours at the high temperature of 900-950 ℃, wherein the atmosphere of the high-temperature reaction is ambient air, the temperature rising rate before the high-temperature reaction is 1-10 ℃/min, and the temperature lowering rate after the reaction is finished is 1-5 ℃/min.
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