CN114551987A - Preparation method of LLZO solid electrolyte and solid lithium battery with long cycle life - Google Patents
Preparation method of LLZO solid electrolyte and solid lithium battery with long cycle life Download PDFInfo
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- CN114551987A CN114551987A CN202111094070.4A CN202111094070A CN114551987A CN 114551987 A CN114551987 A CN 114551987A CN 202111094070 A CN202111094070 A CN 202111094070A CN 114551987 A CN114551987 A CN 114551987A
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- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
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- H—ELECTRICITY
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
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Abstract
The invention relates to the technical field of solid lithium batteries, in particular to a preparation method of a LLZO solid electrolyte and a solid lithium battery with long cycle life. A preparation method of LLZO solid electrolyte with long cycle life is characterized by comprising the following steps: (1) adding La (NO)3)3、ZrOCl2Adding lithium ions and a lithium atom substituting agent into an organic solvent, and stirring and mixing to obtain a mixed solution; (2) adding lithium ions with the molar weight of 10-12% of the lithium ions in the step one into the mixed solution, drying and calcining, naturally cooling to room temperature to obtain powder, mixing the powder with an organic solvent, and then carrying out ball milling to obtain a ball grinding material; (3) and cooling the ball grinding material powder, and then pressing the ball grinding material powder into a tablet to obtain the doped LLZO solid electrolyte membrane, namely the LLZO solid electrolyte with long cycle life. The LLZO solid electrolyte and the three-dimensional lithium composite negative plate are used for preparing a lithium battery, which can improve the ionic conductivity and reduce the ionic conductivityLow internal resistance of the solid lithium battery and prolonged cycle life.
Description
Technical Field
The invention relates to the technical field of solid lithium batteries, in particular to a preparation method of a LLZO solid electrolyte and a solid lithium battery with long cycle life.
Background
Solid lithium battery with high safety and high energyThe density becomes the main energy storage device in the existing energy field, people have higher and higher requirements on the safety and the conductivity of the solid lithium battery, and the garnet Li7La3Zr2O12(LLZO) has received extensive attention due to its high ionic conductivity, wide electrochemical stability window and good chemical stability, but poor interface contact between the solid electrolyte and the electrode used in solid lithium batteries is a bottleneck in the development of solid batteries, LLZO surface is spontanous, lithium dendrite precipitation occurs, especially, contaminants such as lithium hydroxide or lithium carbonate remaining on the surface hinder contact with metallic lithium, resulting in high interface impedance; compared with lithium metal, the interface impedance between the LLZO and the positive plate is more obvious, the interface compatibility between the LLZO and the lithium metal can be adjusted through surface treatment, and the impedance of the battery is reduced.
Chinese patent No. CN201910797734.X discloses a method for improving garnet type solid electrolyte, wherein an acidic substance or an ammonium salt substance is coated on the surface of the garnet type solid electrolyte, pollutants are removed after high-temperature reaction, and even the pollutants are converted into substances which are useful for uniform deposition of lithium metal, so that the electrochemical performance of the battery is improved, but the pollutants are removed only through surface treatment to improve the affinity of the lithium metal and LLZO, and the improvement degree of interface contact is limited; chinese patent CN112490445A discloses a preparation and application method of a modified lithium composite negative electrode material for improving the interface of a solid battery, wherein molten metal lithium is utilized to improve the surface wettability of the molten metal lithium to LLZO, the interface contact of the lithium metal and LLZO is improved, and the tight combination of the negative electrode and an electrolyte interface is realized, but under continuous charge and discharge, particularly high current density, the volume change generated in the circulation process can cause the interface clearance of a coating, even cause the separation of the lithium metal and LLZO, deteriorate the interface conductivity and reduce the cycle life of the battery.
Disclosure of Invention
In view of the above problems of the prior art, the present invention provides a LLZO solid electrolyte having a long cycle life, which plays a role in helping a solid lithium battery manufactured using the LLZO solid electrolyte to extend the cycle life; another object of the present invention is to provide a three-dimensional lithium composite negative electrode sheet with a long cycle life, which helps the solid lithium battery prepared from the three-dimensional lithium composite negative electrode sheet have a long cycle life; the invention also aims to provide a solid lithium battery with long cycle life, and the solid lithium battery prepared by the LLZO solid electrolyte or the three-dimensional lithium composite negative electrode sheet or the LLZO solid electrolyte and the three-dimensional lithium composite negative electrode sheet has long cycle life.
The invention is realized by the following technical scheme:
a preparation method of LLZO solid electrolyte with long cycle life comprises the following steps:
step one, La (NO)3)3、ZrOCl2Adding lithium ions and a lithium atom substituting agent into an organic solvent, stirring and mixing to obtain a mixed solution;
step two, adding lithium ions with the molar weight of 10-12% of that of the lithium ions in the step one into the mixed solution, drying and calcining, naturally cooling to room temperature to obtain powder, mixing the powder with an organic solvent, and then carrying out ball milling to obtain a ball grinding material;
and step three, the ball grinding material powder is cooled and then pressed into tablets to obtain the doped LLZO solid electrolyte membrane, namely the LLZO solid electrolyte with long cycle life.
The ion conductivity of LLZO is mainly related to a crystal structure, LLZO mainly has tetragonal and cubic polymorphic forms, the conductivity of cubic form is about 2 orders of magnitude higher than that of LLZO with tetragonal structure, so the cubic phase in LLZO needs to be stabilized, a certain amount of lithium vacancies can be formed by doping a lithium atom substituting agent at a lithium position, more cubic phase LLZO can be formed, the lithium ion conductivity is obviously improved, the ion conductivity of LLZO can be improved by doping the lithium atom substituting agent, the internal resistance of a solid battery is reduced, the polarization loss of the cycle life is reduced, and the cycle life of the battery is prolonged.
Preferably, the lithium ion refers to a lithium ion contained in a lithium salt, and the lithium salt is one of lithium nitrate, lithium carbonate and lithium hydroxide; the lithium atom substituting agent is one of aluminum inorganic salt, calcium inorganic salt, thallium inorganic salt, indium inorganic salt, niobium inorganic salt and tin inorganic salt; the organic solvent is one of isopropanol, propanol, n-butanol, acetone, butanone and ethyl acetate.
Preferably, La (NO) in step one3)3、ZrOCl2And the molar ratio of the lithium ions to the lithium atom substituting agent is 3:2:7: 0.05-0.09;
the mass fraction of the organic solvent is 50-65% of the mixed solution;
the stirring speed of the mixed solution is 60-120 r/min, and the time is 10-15 hours.
Preferably, the drying and calcining temperature is 900-;
the mass ratio of the powder to the organic solvent in the obtained mixture is 30-40: 5-10;
the working rotating speed of the ball mill is 120-180 r/min, and the ball milling time of the mixture is 3-6 h.
Preferably, the calcination temperature in the third step is 1000-.
Preferably, the method further comprises a fourth step of dissolving the polymer solid electrolyte in an organic solvent, mixing the solution with a mass ratio of 30-55%, infiltrating the two side surfaces of the doped LLZO solid electrolyte membrane prepared in the third step with the solution, drying the two side surfaces of the doped LLZO solid electrolyte membrane at 50-70 ℃ in vacuum, and depositing the dried polymer solid electrolyte on the two side surfaces of the doped LLZO solid electrolyte membrane to obtain the LLZO composite solid electrolyte with a soft interface layer;
the polymer solid electrolyte is one of polyethylene oxide (PEO) and derivatives thereof, polyvinylidene fluoride (PVDF) and derivatives thereof, Polyacrylonitrile (PAN) and derivatives thereof, and polymethyl methacrylate (PMMA) and derivatives thereof;
the organic solvent is one of acetonitrile, absolute ethyl alcohol, methanol, tetrahydrofuran, dimethyl formamide DMF and dimethyl sulfoxide.
The doped LLZO solid electrolyte with the soft interface is added, so that the damage of external mechanical load to the LLZO/positive and negative electrode interfaces can be effectively buffered, and the actual service life of the solid battery is prolonged.
A solid lithium battery prepared from the LLZO solid electrolyte obtained by the preparation method according to claim 1, comprising a positive plate, a negative plate and a doped LLZO solid electrolyte membrane tightly attached between the positive and negative plates.
Preferably, the negative electrode sheet is prepared by the following processes:
heating and stirring lithium, a lithium ion regulator and a reinforcing material at a molar ratio of 25-40:3-10:5-15 in an argon atmosphere, then heating and stirring, and rolling the obtained composite material into a foil at room temperature to obtain the three-dimensional lithium composite negative plate with the thickness of 50-250 mu m.
Preferably, the lithium ion regulator is one of boron, carbon, silicon carbide, boron carbide, yttrium oxide, magnesium oxide and magnesium disilicide; the reinforcing material is one of aluminum, silver, chromium, iron and zinc;
the temperature after heating is 300-400 ℃, and the holding time is 30-60 minutes;
the temperature after the temperature rise is 500 ℃ and 550 ℃, and the holding time is 30-60 minutes;
the stirring speed is 100-250 r/min;
the pressing pressure is 10-20 MPa.
Introducing a lithium ion regulator into the metal lithium cathode, wherein on one hand, lithium and the lithium ion regulator can form a solid solution, the structure of the solid solution is similar to that of metal lithium, so that the structural integrity and stability in the charging and discharging process can be maintained, and on the other hand, the lithium ion regulator can regulate the introduction flux of lithium ions, so that the concentration gradient of the lithium ions in the cathode in the embedding process is reduced; in the three-dimensional lithium composite negative plate, the lithium element needs to be excessive, so that a small amount of lithium (not less than 15-20% of the total amount of lithium) still remains in the composite negative plate after discharging (namely, negative pole lithium removal) and the composite negative plate and a lithium ion regulator continue to form a solid solution to keep the stability of the structure; the introduction of the reinforcing material can enhance the mechanical strength of the frame, the cathode does not have obvious volume change in the charging and discharging process, and the cathode is always kept in close contact with the LLZO, so that the increase of the interface internal resistance is avoided, the higher the battery internal resistance is, the more serious the battery polarization is, the polarization loss can be caused in the circulating process, and the quick reduction of the battery circulating life is caused; the three-dimensional lithium composite negative plate after partial discharge and lithium removal can be used as an effective carrier even under long-term circulation and high current density because the rest lithium in the composite negative electrode and the lithium-lithium ion regulator skeleton provide a continuous path for lithium ions and electrons, thereby prolonging the cycle life of the solid lithium battery.
Preferably, the preparation method of the solid lithium battery with long cycle life comprises the following steps:
pressing the positive plate and the negative plate on two sides of the doped LLZO solid electrolyte under the pressure of 10-30 MPa; or pressing the positive plate and the three-dimensional lithium composite plate on two sides of the doped LLZO solid electrolyte under 10-30 MPa; the solid lithium battery with long cycle life is obtained.
The invention has the beneficial effects that: (1) an atom substituting agent is doped on the LLZO film, a steady electron-ion double-conductivity frame is constructed on the interface of high-elasticity LLZO and metal lithium, so that the risk of lithium dendrite precipitation is reduced, and the structure and electrochemical stability of the LLZO/metal lithium interface under continuous charge and discharge and large current density are improved; (2) a soft interface layer is further added on the surface of the LLZO, so that the interface compatibility of the LLZO and the positive plate is improved, the simultaneous optimization of the solid electrolyte and the positive and negative electrode interfaces is realized, and the cycle life of the all-solid battery is obviously prolonged; (3) the lithium ion regulator and the mechanical reinforcing element for the three-dimensional lithium composite negative plate are used for enhancing the mechanical strength of the negative plate and maintaining the structural stability, and the cycle life of the solid lithium battery is effectively prolonged.
Detailed Description
Example 1
Preparing the LLZO solid electrolyte doped with the lithium atom substitute: adding La (NO)3)3、ZrOCl2、Al(NO3)3、LiNO3Adding into Isopropanol (IPA) at a stoichiometric ratio of 3:2:7:0.07, wherein the mass ratio of IPA in the mixed solution is 50%, stirring and mixing thoroughly at room temperature for 10 hr, and adding LiNO3LiOH. H with a molar ratio of 12%2O to compensate for the loss of lithium volatilization, the above mixed material was dried and calcined in air at 1000 c and held for 12 hours. And naturally cooling to room temperature, mixing the obtained powder with a small amount of IPA, placing the mixture into a high-energy vibration ball mill for ball milling for 5 hours, wherein the mass ratio of the powder to the IPA is 30:8, finally calcining the mixture at 1100 ℃ for 9 hours, cooling to room temperature, and pressing the granules into tablets by using 200MPa pressure to obtain the Al-doped LLZO solid electrolyte membrane Al-LLZO with the thickness of 50 microns.
Example 2
Preparing the LLZO solid electrolyte doped with the lithium atom substitute: adding La (NO)3)3、ZrOCl2、Al(NO3)3、LiNO3Adding into Isopropanol (IPA) at a stoichiometric ratio of 3:2:7:0.05, wherein the mass ratio of IPA in the mixed solution is 65%, stirring and mixing thoroughly at room temperature for 11 hr, and adding LiNO3LiOH. H with a molar ratio of 10%2O to compensate for the loss of lithium volatilization, the above mixed material was dried and calcined in air at 1000 c for 10 hours. And naturally cooling to room temperature, mixing the obtained powder with a small amount of IPA, placing the mixture into a high-energy vibration ball mill for ball milling for 5 hours, wherein the mass ratio of the powder to the IPA is 35:10, finally calcining the mixture at 1100 ℃ for 9 hours, cooling to room temperature, and pressing the granules into tablets by using 200MPa pressure to obtain the Al-doped LLZO solid electrolyte membrane Al-LLZO with the thickness of 100 mu m.
Example 3
Preparing the LLZO solid electrolyte doped with the lithium atom substitute: adding La (NO)3)3、ZrOCl2、Al(NO3)3、LiNO3Adding into Isopropanol (IPA) at a stoichiometric ratio of 3:2:7:0.09, wherein the mass ratio of IPA in the mixed solution is 57.5%, stirring and mixing thoroughly at room temperature for 12 hr, and adding LiNO3LiOH. H with a molar ratio of 11%2O to compensate for the loss of lithium volatilization, the above mixed material was dried and calcined in air at 1000 c and held for 12 hours. And naturally cooling to room temperature, mixing the obtained powder with a small amount of IPA, placing the mixture into a high-energy vibration ball mill for ball milling for 6 hours, wherein the mass ratio of the powder to the IPA is 35:6, finally calcining the mixture at 1000 ℃ for 9 hours, cooling to room temperature, and pressing the granules into tablets by using 200MPa pressure to obtain the Al-doped LLZO solid electrolyte membrane Al-LLZO with the thickness of 100 mu m.
Example 4
Adopting the Al-LLZO solid electrolyte membrane Al-LLZO prepared in example 1, dissolving PEO solid electrolyte in an organic solvent, mixing to form a solution with the mass ratio of 30%, infiltrating the two side surfaces of the Al-doped LLZO solid electrolyte membrane, and drying in vacuum at 50 ℃ to obtain the LLZO composite solid electrolyte.
Example 5
Adopting the Al-LLZO solid electrolyte membrane Al-LLZO prepared in the example 2, dissolving PVDF solid electrolyte in an organic solvent, mixing into a solution with the mass ratio of 42.5%, infiltrating the two side surfaces of the Al-doped LLZO solid electrolyte membrane, and drying in vacuum at the temperature of 60 ℃ to obtain the LLZO composite solid electrolyte.
Example 6
The Al-LLZO solid electrolyte membrane Al-LLZO prepared in example 3 was used, PAN solid electrolyte was dissolved in an organic solvent, mixed into a solution of 55% by mass, infiltrated into both side surfaces of the Al-doped LLZO solid electrolyte membrane, and vacuum-dried at 70 ℃ to obtain a LLZO composite solid electrolyte.
Example 7
Preparing a three-dimensional lithium composite negative plate: putting lithium, boron and magnesium into an iron crucible according to the mass ratio of 40:10:15, heating to 400 ℃ under argon atmosphere, vigorously stirring for 60 minutes at 250 revolutions per minute, continuously heating to 550 ℃, and vigorously stirring for 60 minutes at 250 revolutions per minute, so that the raw materials are fully mixed and reacted by a two-step method. Subsequently, the composite material obtained was rolled at room temperature under 10MPa to a foil having a thickness of 200. mu.m.
Example 8
Preparing a three-dimensional lithium composite negative plate: putting lithium, boron and magnesium into an iron crucible according to the mass ratio of 32.5:6.5:10, then heating to 350 ℃ under the argon atmosphere, violently stirring for 45 minutes at 175 rpm, continuously heating to 525 ℃, and violently stirring for 45 minutes, and fully mixing and reacting the raw materials by a two-step method; subsequently, the composite material obtained was rolled at room temperature under 15MPa to a foil having a thickness of 150. mu.m.
Example 9
Preparing a three-dimensional lithium composite negative plate: putting lithium, boron and magnesium into an iron crucible according to a molar ratio of 25:3:5, heating to 300 ℃ under argon atmosphere, violently stirring at 100 rpm for 30 minutes, then heating to 500 ℃, violently stirring at 100 rpm for 30 minutes, fully mixing and reacting the raw materials by a two-step method, and rolling the obtained composite material into a foil with the thickness of 50 microns at room temperature of 20 MPa.
Example 10
Preparing a positive plate: placing lithium iron phosphate, ketjen black, LLZO solid electrolyte and PVDF binder in a high-energy vibration ball mill according to the mass ratio of 55:3.5:7.5:4.5, ball-milling for 45 minutes, placing the uniformly mixed powder in a molybdenum-based mold, and pressing into a positive plate with the thickness of 100 mu m under 300 standard atmospheric pressures;
the positive electrode sheet and the pure lithium sheet were pressed at 10MPa on both sides of the LLZO composite solid electrolyte in example 1.
Example 11
The positive electrode sheet was prepared as in example 10;
the positive electrode sheet and the three-dimensional lithium composite negative electrode sheet in example 7 were pressed at 20MPa on both sides of the LLZO composite solid electrolyte in example 1.
Example 12
The positive electrode sheet was prepared as in example 10;
the positive electrode sheet and the three-dimensional lithium composite negative electrode sheet in example 7 were pressed at 30MPa on both sides of the LLZO composite solid electrolyte in example 4.
Example 13
The positive electrode sheet was prepared as in example 10;
the positive electrode sheet and the three-dimensional lithium composite negative electrode sheet in example 8 were pressed at 30MPa on both sides of the LLZO composite solid electrolyte in example 5.
Example 14
The positive electrode sheet was prepared as in example 10;
the positive electrode sheet and the three-dimensional lithium composite negative electrode sheet in example 9 were pressed at 20MPa on both sides of the LLZO composite solid electrolyte in example 6.
Example 15
The positive electrode sheet was prepared as in example 10;
the positive electrode sheet and the pure lithium sheet were pressed at 30MPa on both sides of the LLZO composite solid electrolyte in example 4.
Comparative example 1
Unlike example 12, the LLZO solid electrolyte used was free of any doping, and the remaining conditions were the same as example 12.
Comparative example 2
Unlike example 12, the LLZO solid electrolyte used was free of any doping, and the negative electrode sheet used was a pure lithium sheet, and the rest of the conditions were the same as example 12.
Comparative example 3
Preparation of lithium-magnesium alloy sheet: heating lithium and magnesium to 400 ℃ in an argon atmosphere at a molar ratio of 40:15, stirring at 250 rpm for 60 minutes, heating to 550 ℃, stirring vigorously at 250 rpm for 60 minutes, fully mixing and reacting the raw materials by a two-step method, and rolling the obtained composite material into a foil with the thickness of 200 mu m at the room temperature of 10 MPa;
except for using a lithium-magnesium alloy sheet as a negative electrode sheet in example 12, the other conditions were the same as in example 12.
Comparative example 4
Preparation of lithium-boron alloy sheet: putting lithium and boron into an iron crucible according to the mass ratio of 40:10, heating to 400 ℃ under the argon atmosphere, keeping for 60 minutes under the condition of vigorous stirring at 250 revolutions per minute, continuously heating to 550 ℃, keeping for 60 minutes under the condition of vigorous stirring at 250 revolutions per minute, and fully mixing and reacting the raw materials by a two-step method. Then, rolling the obtained composite material into a foil with the thickness of 200 mu m at room temperature and under 10 MPa;
except for using a lithium-boron alloy sheet as a negative electrode sheet in example 12, the other conditions were the same as in example 12.
The solid lithium batteries of the examples and the comparative examples are tested for performance:
testing the internal resistance of the battery: the electrochemical performance of the cells was tested at 30 ℃. The internal resistance of the battery is tested by using an alternating current impedance spectroscopy EIS, and the frequency range is 0.1-106HZ, the amplitude of the applied voltage is 5-10 mV;
and (3) testing the cycle life: the cycle life of the battery is tested at 30 ℃ by taking 0.2C as the charge-discharge multiplying power and within the voltage range of 3.0-4.1V, and when the battery has obvious short circuit (the voltage drop speed is more than or equal to 5mV/s), the cycle test is considered to be stopped when the service life is terminated.
The data of the performance test of the solid lithium batteries of the respective examples and comparative examples are shown in the following table 1:
TABLE 1 test results of solid-state batteries prepared under different conditions
| Group of | Internal resistance of battery (omega) | Cycle life |
| Example 10 | 102.4 | 196 |
| Example 11 | 68.2 | 420 |
| Example 12 | 68.9 | 456 |
| Example 13 | 69.8 | 448 |
| Example 14 | 71.9 | 442 |
| Example 15 | 86.9 | 273 |
| Comparative example 1 | 69.5 | 423 |
| Comparative example 2 | 116.9 | 157 |
| Comparative example 3 | 69.5 | 416 |
| Comparative example 4 | 78.4 | 386 |
As can be seen from the data in table 1, the doped LLZO solid electrolytes with the three-dimensional lithium composite negative electrode sheet and the soft interface layer in examples 12 to 14 are different only in preparation value, wherein the battery obtained in example 12 has relatively low internal resistance and longest cycle life; example 10 only uses doped LLZO solid electrolyte, and pure lithium sheet is used as the negative plate without soft interface layer, the internal resistance of the battery is much higher than that of other examples, and the cycle life is much shorter than that of other examples; in the embodiment 11, the three-dimensional lithium composite negative plate and the doped LLZO solid electrolyte without the soft interface layer have small influence on the internal resistance of the battery, but the cycle life is shorter than that of the embodiment 12-14; example 15, a pure lithium sheet is used as a negative electrode sheet, only the doped LLZO solid electrolyte with the soft interface layer is used, the internal resistance of the battery is smaller than that of example 10, and is larger than that of other examples, the cycle life is also smaller than that of example 10, and is larger than that of other examples, the resistance of the negative electrode sheet is significantly higher than that of each example, the cycle life is significantly lower than that of each example under the conditions of long-time discharge and high temperature, and the structural stability is far lower than that of each example adopting the three-dimensional lithium composite negative electrode sheet; the LLZO solid electrolyte adopted in the comparative example 1 is not doped with aluminum, the contact internal resistance between the battery electrolyte and the pole piece is not affected, but the conductivity of the undoped LLZO electrolyte body is reduced, and the cycle life is reduced; comparative example 2 using a pure lithium sheet as a negative electrode sheet and a LLZO solid electrolyte without doping and a soft interface layer, the battery had higher internal resistance and lower cycle life than example 10 using a pure lithium sheet without a soft interface layer and a doped LLZO solid electrolyte; the negative electrode sheet of comparative example 3 had no reinforcing material and had a slightly lower cycle life than each example; the negative plate of the comparative example 4 has no lithium ion regulator, the internal resistance of the negative plate is obviously increased, the cycle life is reduced, and the structural stability of the negative plate is reduced.
Claims (10)
1. A preparation method of LLZO solid electrolyte with long cycle life is characterized by comprising the following steps:
step one, La (NO)3)3、ZrOCl2Adding lithium ions and a lithium atom substituting agent into an organic solvent, stirring and mixing to obtain a mixed solution;
step two, adding lithium ions with the molar weight of 10-12% of that of the lithium ions in the step one into the mixed solution, drying and calcining, naturally cooling to room temperature to obtain powder, mixing the powder with an organic solvent, and then carrying out ball milling to obtain a ball grinding material;
and step three, calcining and cooling the ball-milled material, and then pressing into tablets to obtain the doped LLZO solid electrolyte membrane, namely the LLZO solid electrolyte with long cycle life.
2. The method according to claim 1, wherein the lithium ions are lithium ions contained in a lithium salt, and the lithium salt is one of lithium nitrate, lithium carbonate and lithium hydroxide;
the lithium atom substituting agent is one of aluminum inorganic salt, calcium inorganic salt, thallium inorganic salt, indium inorganic salt, niobium inorganic salt and tin inorganic salt;
the organic solvent is one of isopropanol, propanol, n-butanol, acetone, butanone and ethyl acetate.
3. The method of claim 1, wherein La (NO) is added in the first step3)3、ZrOCl2And the molar ratio of the lithium ions to the lithium atom substituting agent is 3:2:7: 0.05-0.09；
The mass fraction of the organic solvent is 50-65% of the mixed solution;
the stirring speed of the mixed solution is 60-120 r/min, and the time is 10-15 hours.
4. The method as claimed in claim 1, wherein the temperature of the dry calcination in step two is 900-1000 ℃ for 10-20 hours;
the mass ratio of the powder to the organic solvent in the obtained mixture is 30-40: 5-10;
the working rotating speed of the ball mill is 120-180 r/min, and the ball milling time of the mixture is 3-6 h.
5. The method as claimed in claim 1, wherein the calcination temperature in step three is 1000-1200 ℃ and the calcination time is 8-12 hours;
the pressing pressure is 100-300 MPa.
6. The method of claim 1, wherein the method further comprises a fourth step of dissolving the polymer solid electrolyte in an organic solvent, mixing the solution into a solution with a mass ratio of 30-55%, infiltrating the two side surfaces of the doped LLZO solid electrolyte membrane prepared in the third step with the solution, and vacuum-drying the impregnated membrane at 50-70 ℃ to obtain a LLZO composite solid electrolyte with a soft interface layer;
the polymer solid electrolyte is one of polyethylene oxide (PEO) and derivatives thereof, polyvinylidene fluoride (PVDF) and derivatives thereof, Polyacrylonitrile (PAN) and derivatives thereof, and polymethyl methacrylate (PMMA) and derivatives thereof;
the organic solvent is one of acetonitrile, absolute ethyl alcohol, methanol, tetrahydrofuran, dimethyl formamide DMF and dimethyl sulfoxide.
7. A solid lithium battery comprising the LLZO solid electrolyte obtained by the method according to claim 1, wherein the LLZO solid electrolyte comprises a positive electrode sheet, a negative electrode sheet and a doped LLZO solid electrolyte membrane tightly adhered between the positive and negative electrode sheets.
8. The solid lithium battery according to claim 7, wherein the negative electrode sheet is manufactured by:
heating and stirring lithium, a lithium ion regulator and a reinforcing material at a molar ratio of 25-40:3-10:5-15 in an argon atmosphere, then heating and stirring, and rolling the obtained composite material into a foil at room temperature to obtain the three-dimensional lithium composite negative plate with the thickness of 50-250 mu m.
9. The solid lithium battery of claim 8: the lithium ion regulator is characterized in that the lithium ion regulator is one of boron, carbon, silicon carbide, boron carbide, yttrium oxide, magnesium oxide and magnesium disilicide; the reinforcing material is one of aluminum, silver, chromium, iron and zinc;
the temperature after heating is 300 ℃ and 400 ℃, and the holding time is 30-60 minutes;
the temperature is 500-550 ℃ after the temperature rise, and the holding time is 30-60 minutes;
the stirring speed is 100-250 r/min;
the pressing pressure is 10-20 MPa.
10. The solid lithium battery according to claim 7, 8 or 9, wherein the positive electrode tab and the negative electrode tab are pressed at 10 to 30MPa on both sides of the doped LLZO solid electrolyte.
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