Solid electrolyte material, preparation method thereof and solid-state battery

Abstract

The invention provides a solid-state electrolyte material, a preparation method thereof and a solid-state battery. The solid-state electrolyte material comprises Li < 6-z > MY < 5-z > X < 1 + z >, wherein M is one or more of V, Nb, Ta, Bi, Sb, As, Si, Ge, Sn and Pb; x is one or more of F, Cl, Br and I; y is one or more of S, O and Se; z is more than or equal to 0 and less than or equal to 2; according to the present invention, the M element and the X element are introduced to chemically replace the traditional solid electrolyte material Li6PS5X so as to form the new electrolyte material with the composition of Li < 6-z > MY < 5-z > X < 1 + z >, Y < 2-> is replaced with X <->, such that the interaction of lithium ions in the cage is weakened, the long-distance movement of the lithium ions in the whole structure is easily promoted, and the lithium ion battery performance is improved; and the proportion of the lithium element in the crystal lattice is increased along with the increase of the doping amount of the M element, so that the conductivity of the electrolyte is favorably improved. In addition, the novel electrolyte material is beneficial to inducing generation of Li-M alloy on a lithium metal negative electrode interface, so that the interface compatibility is improved, and the growth of lithium dendrites is inhibited.

Description

Technical Field

[0001] The present application relates to the technical field of solid electrolytes, and in particular to a solid electrolyte material, a preparation method thereof, and a solid-state battery. Background Art

[0002] With the rapid development of electronic devices, new energy vehicles, and energy storage systems, high-energy-density, high-safety secondary batteries have become a research hotspot. Lithium metal anodes, due to their extremely high theoretical capacity, are considered a key material for breaking the energy density bottleneck of traditional graphite anodes. However, lithium metal is prone to forming dendrites during cycling, which can cause battery short circuits and even thermal runaway, severely restricting its practical application.

[0003] In the related art, LPSC-type sulfide solid electrolytes are considered to be one of the promising sulfide electrolytes due to their high ionic conductivity.

[0004] However, the interfacial compatibility of LPSC solid electrolyte materials with the positive and negative electrodes is poor, which will lead to a large electrochemical impedance of the battery and make it difficult for the battery to operate stably at high rates. Summary of the Invention

[0005] The embodiments of the present application provide a solid electrolyte material, a preparation method thereof, and a solid-state battery, aiming to improve the technical problem in related technologies that solid electrolyte materials cannot have both high ionic conductivity and stable interface compatibility.

[0006] In a first aspect, an embodiment of the present application provides a solid electrolyte material, comprising:

[0007] Li 6-z MY 5-z X 1+z ;

[0008] in,

[0009] M is one or more of V, Nb, Ta, Bi, Sb, As, Si, Ge, Sn and Pb;

[0010] X is one or more of F, Cl, Br, and I;

[0011] Y is one or more of S, O and Se;

[0012] The value range of z is 0≤z≤2.

[0013] In one embodiment, M is one or more of V, Nb, and Ta; and / or

[0014] Said X is F or Cl; and / or

[0015] Said Y is S or O; and / or

[0016] The value range of z is 0<z≤1.

[0017] In one embodiment, the value range of z is 0<z≤0.7.

[0018] In one embodiment, the solid electrolyte material includes Li6VS4OCl, Li6NbS4OCl, Li6TaS4OCl, Li6V 0.4 Ta 0.6 One of S4OCl.

[0019] In one embodiment, the ionic conductivity of the solid electrolyte material is 4.1 mS / cm to 4.7 mS / cm; and / or

[0020] The first cycle discharge capacity of the solid electrolyte material is 184 mAh / g to 203 mAh / g; and / or

[0021] The first-cycle coulombic efficiency of the solid electrolyte material is 91.3% to 93.1%; and / or

[0022] The 100-cycle discharge capacity retention rate of the solid electrolyte material is 84.6% to 90.4%.

[0023] In a second aspect, an embodiment of the present application provides a method for preparing a solid electrolyte material, the preparation method comprising the following steps:

[0024] According to Li 6-z MY 5-z X 1+z A lithium source, an M source, a Y source, and an X source are weighed and mixed in a stoichiometric ratio to obtain a precursor;

[0025] The precursor is calcined in an inert atmosphere, and the temperature is cooled to room temperature after the calcination is completed to obtain the solid electrolyte material.

[0026] In one embodiment, the lithium source includes one or more of Li2S2, Li2S, LiCl, LiBr, LiI, and LiF; and / or

[0027] One or more of the M source VCl5, V2O5, V2S5, NbCl5, TaCl5, VBr5, BiCl5, SbCl5; and / or

[0028] One or more of the Y source V2O5, V2S5, Li2O, Nb2O5; and / or

[0029] The X source is one or more of LiCl, LiBr, LiI, LiF, VCl5, NbCl5, and TaCl5.

[0030] In one embodiment, the Li 6-z MY 5-z X 1+z The lithium source, M source, Y source and X source are weighed in a stoichiometric ratio and mixed to obtain a precursor, including:

[0031] According to Li 6-z MY 5-z X 1+z A lithium source, an M source, a Y source, and an X source are weighed in a stoichiometric ratio and mixed to obtain a mixed powder;

[0032] The mixed powder is then ball-milled at a rotation speed of 300 rpm to 800 rpm for a time of 15 h to 60 h to obtain the precursor.

[0033] In one embodiment, during the ball milling process, the diameter of the grinding beads is 3 mm to 10 mm; and / or

[0034] The mass ratio of the grinding beads to the mixed powder is 5 to 40;

[0035] Preferably, the mass ratio of the grinding beads to the mixed powder is 20 to 30.

[0036] In one embodiment, the calcination temperature is 400° C. to 700° C.; and / or

[0037] The heating rate of the calcination is 1°C / min to 10°C / min; and / or

[0038] The cooling rate after the calcination is 0.5°C / min to 5°C / min; and / or

[0039] The calcination time is 2 hours to 12 hours.

[0040] In a third aspect, an embodiment of the present application provides a solid-state battery, comprising a positive electrode, a negative electrode, and an electrolyte layer, wherein the electrolyte layer comprises the solid-state electrolyte material as described above.

[0041] In one embodiment, the electrolyte layer is formed by pressing the solid electrolyte material;

[0042] Preferably, the pressing pressure is 500 MPa to 600 MPa.

[0043] Beneficial effects of the embodiments of the present application:

[0044] In the embodiment of the present application, the conventional solid electrolyte material Li6PS5X is chemically replaced by the introduction of M element and X element to form a new solid electrolyte material with the composition of Li 6-z MY 5-z X 1+zElectrolyte materials using X - Replace Y 2- , weakening the interaction between lithium ions in the "cage", helping to promote the long-distance movement of lithium ions in the entire structure, and the proportion of lithium elements in the lattice increases with the increase of the doping amount of M elements, which helps to improve the conductivity of the electrolyte. In addition, the new electrolyte material helps to induce the formation of Li-M alloy at the lithium metal negative electrode interface, thereby improving the interfacial compatibility and inhibiting the growth of lithium dendrites. In addition, the new electrolyte material also reduces the mass proportion of S, which is beneficial to inhibit the release of H2S, thereby improving air stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 is a flow chart of the preparation method of some embodiments of the present application;

[0047] Figure 2 1 is an XRD comparison chart of some embodiments of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; and "inside" and "outside" refer to the outline of the device.

[0049] With the widespread application of electronic devices, drones, and new energy vehicles, the requirements for battery energy density and safety are becoming increasingly higher, and there is an urgent need for energy storage batteries with high energy density.

[0050] All-solid-state batteries based on solid-state electrolytes are candidates for developing next-generation energy storage batteries with high energy density and safety. In addition, solid-state electrolytes significantly improve safety by replacing the flammable and volatile liquid electrolytes in traditional lithium-ion batteries.

[0051] The energy density of lithium-ion batteries using graphite as anode material is approaching its upper limit, but it still cannot meet the energy density and range requirements of users of the aforementioned devices. Therefore, replacing the graphite anode with a lithium metal anode material with a higher theoretical capacity, either partially or completely, is an effective way to increase battery energy density.

[0052] In the related art, LPSC-type sulfide solid electrolytes are considered to be one of the promising sulfide electrolytes due to their high ionic conductivity. However, the interface compatibility between LPSC solid electrolyte materials and the positive and negative electrodes is poor, which will lead to a large electrochemical impedance of the battery and make it difficult for the battery to operate stably at a high rate. Secondly, there are grain boundary problems inside the solid electrolyte material, which makes the energy barrier for lithium ions to cross the grain boundaries large, resulting in low ionic conductivity of the solid electrolyte material. In addition, lithium dendrites tend to grow between the grain boundaries of the solid electrolyte, leading to battery failure. Therefore, the practical application of solid-state batteries must solve the interface compatibility problem and the grain boundary problem.

[0053] In view of this, the embodiments of the present application provide a solid electrolyte material, a preparation method thereof, and a solid-state battery, aiming to improve the technical problem in the related art that the sulfide solid electrolyte cannot have both high ionic conductivity and stable interface compatibility.

[0054] According to a first aspect of an embodiment of the present application, a solid electrolyte material is provided, which may include:

[0055] Li 6-z MY 5-z X 1+z ;

[0056] wherein M is one or more of V, Nb, Ta, Bi, Sb, As, Si, Ge, Sn, and Pb;

[0057] X is one or more of F, Cl, Br, and I;

[0058] Y is one or more of S, O and Se;

[0059] The value range of z is 0≤z≤2.

[0060] It is understandable that by introducing M and X elements, the traditional solid electrolyte material Li6PS5X is chemically replaced to form a new composition of Li 6-z MY 5-z X 1+z Electrolyte materials using X - Replace Y 2-, weakening the interaction between lithium ions in the "cage", helping to promote the long-distance movement of lithium ions in the overall structure of the electrolyte material, and the proportion of lithium elements in the lattice increases with the increase of the doping amount of the M element, which helps to improve the conductivity of the electrolyte. In addition, the new electrolyte material helps to induce the formation of Li-M alloy at the lithium metal negative electrode interface, thereby improving the interfacial compatibility and inhibiting the growth of lithium dendrites. In addition, the new electrolyte material also reduces the mass proportion of S, which is beneficial to inhibit the release of H2S, thereby improving air stability.

[0061] In some embodiments of the present application, M may be one or more of V, Nb, and Ta.

[0062] By adopting this approach, V, Nb, and Ta, with their larger atomic radii and suitable electronic structures, can expand lithium-ion transport channels, weaken the lattice constraints of lithium ions, help optimize lithium-ion migration paths, and further enhance long-range lithium-ion transport. Furthermore, the high melting points of V, Nb, and Ta help maintain the material's structural stability during high-temperature sintering and prevent abnormal grain growth.

[0063] In some embodiments of the present application, X is F or Cl.

[0064] By adopting this scheme, when Cl is selected as X, its moderate ionic radius helps weaken the lattice binding of Li+, thereby expanding the ion transport channel; while when F is selected as X, its smaller ionic radius helps enhance lattice stability. When F is doped in appropriate amounts, the local coordination environment is optimized, thus achieving a balance between ionic conductivity and structural stability.

[0065] In some embodiments of the present application, Y is S or O.

[0066] By adopting the above scheme, when Y is selected as S or O, it helps to improve the air stability of the electrolyte material, reduce the generation of H2S, and also ensure Li + Exercise better.

[0067] In some embodiments of the present application, the value range of z is 0<z≤1. Further, the value range of z is 0<z≤0.7. Exemplarily, the value range of z is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and any value between two adjacent values ​​mentioned above.

[0068] By adopting the above scheme, a suitable range of z helps to improve the ionic conductivity of the electrolyte material and ensures that the crystal phase of the electrolyte material is relatively stable. If the value of z is too large, the ionic conductivity of the electrolyte material will decrease and the crystal phase of the electrolyte will become increasingly unstable.

[0069] In some embodiments of the present application, the solid electrolyte material includes Li6VS4OCl, Li6NbS4OCl, Li6TaS4OCl, Li6V 0.4 Ta 0.6 One of S4OCl.

[0070] In some embodiments of the present application, the ionic conductivity of the solid electrolyte material is 4.1 mS / cm to 4.7 mS / cm.

[0071] In some embodiments of the present application, the first cycle discharge capacity of the solid electrolyte material is 184 mAh / g to 203 mAh / g.

[0072] In some embodiments of the present application, the first-cycle coulombic efficiency of the solid electrolyte material is 91.3% to 93.1%.

[0073] In some embodiments of the present application, the 100-cycle discharge capacity retention rate of the solid electrolyte material is 84.6% to 90.4%.

[0074] By adopting the above solution, the solid electrolyte material of the present embodiment has a high ionic conductivity, significantly higher than that of traditional sulfide solid electrolytes, which helps the battery operate stably at high current densities. Moreover, the high ionic conductivity of the solid electrolyte material helps reduce the migration resistance of lithium ions at low temperatures, thereby widening the operating temperature range of the battery.

[0075] The solid electrolyte material of the embodiment of the present application has a large first-cycle discharge capacity, can support batteries with higher energy density, and can be used as an electrolyte material for energy storage batteries. Moreover, the first-cycle coulombic efficiency of the electrolyte material is close to that of the graphite negative electrode system, indicating that the side reaction of the electrolyte with the lithium metal negative electrode in the first cycle is effectively suppressed, thereby reducing irreversible capacity loss. In addition, the capacity retention rate of the solid electrolyte material is significantly better than that of the traditional sulfide system, which helps to show that the electrolyte effectively suppresses lithium dendrite growth and interfacial side reactions.

[0076] According to a second aspect of the embodiment of the present application, a method for preparing a solid electrolyte material is provided, referring to Figure 1 , the preparation method comprises the following steps:

[0077] S100, according to Li 6-z MY 5-z X 1+z A lithium source, an M source, a Y source, and an X source are weighed and mixed in a stoichiometric ratio to obtain a precursor;

[0078] S200, calcining the precursor under an inert atmosphere, and cooling the temperature to room temperature after calcination to obtain a solid electrolyte material.

[0079] By adopting the above scheme, according to Li 6-z MY 5-z X 1+z The raw materials are weighed in a stoichiometric ratio and then the mixed raw materials are calcined. The preparation process is simple and convenient, and the ionic conductivity, cycle stability and air stability of the prepared sulfide solid electrolyte are significantly improved.

[0080] In some embodiments of the present application, the lithium source may include one or more of Li2S2, Li2S, LiCl, LiBr, LiI, LiF, etc.; preferably, the lithium source may include Li2S2, Li2S or LiCl.

[0081] In some embodiments of the present application, the M source may include one or more of VCl5, V2O5, V2S5, NbCl5, TaCl5, VBr5, BiCl5, SbCl5, etc.

[0082] In some embodiments of the present application, the Y source may include one or more of V2O5, V2S5, Li2O, Nb2O5, etc.; preferably, the Y source may include V2O5 or V2S5.

[0083] In some embodiments of the present application, the X source may include one or more of LiCl, LiBr, LiI, LiF, VCl5, NbCl5, TaCl5, etc.; preferably, the X source may include LiCl.

[0084] In some embodiments of the present application, in step S100, according to Li 6-z MY 5-z X 1+z The lithium source, M source, Y source and X source are weighed in a stoichiometric ratio and mixed to obtain a precursor, including:

[0085] S110, according to Li 6-z MY 5-z X 1+z Lithium source, M source, Y source and X source are weighed in a stoichiometric ratio and ground to obtain a mixed powder;

[0086] S120, ball milling the mixed powder at a rotation speed of 300 rpm to 800 rpm for 15 h to 60 h to obtain a precursor.

[0087] By adopting the above scheme, the mixing process includes manual grinding and mechanical ball milling. Manual grinding helps to preliminarily mix the raw materials, and mechanical ball milling helps to fully mix the mixed powders, laying the foundation for subsequent calcination to prepare high-performance sulfide solid electrolytes.

[0088] In some embodiments of the present application, in step S120, during the ball milling process, the diameter of the grinding beads is 3 mm to 10 mm. Exemplarily, the diameter of the grinding beads is 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, and any value between two adjacent values ​​mentioned above.

[0089] In some embodiments of the present application, in step S120, the mass ratio of the grinding beads to the mixed powder is 5 to 40. Further, the mass ratio of the grinding beads to the mixed powder is 20 to 30. Exemplarily, the mass ratio of the grinding beads to the mixed powder is 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, and any value between two adjacent values.

[0090] In some embodiments of the present application, the calcination temperature may be 400° C. to 700° C. Further, the calcination temperature may be 450° C. to 575° C. For example, the calcination temperature may be 450° C., 475° C., 500° C., 525° C., 550° C., 575° C., and any value between two adjacent values.

[0091] In some embodiments of the present application, the heating rate of calcination is 1°C / min to 10°C / min. Further, the heating rate of calcination is 1°C / min to 4°C / min. Exemplarily, the heating rate of calcination is 1°C / min, 2°C / min, 3°C / min, 4°C / min, and any value between two adjacent values.

[0092] By adopting the above scheme, a suitable heating rate helps to ensure that the calcination temperature increases gradually, making the calcination process uniform and stable, thereby ensuring the stability of the crystal phase of the electrolyte material after calcination.

[0093] In some embodiments of the present application, the cooling rate after calcination is 0.5°C / min to 5°C / min. Further, the cooling rate after calcination is 1°C / min to 3°C / min. Exemplarily, the cooling rate after calcination is 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, and any value between two adjacent values.

[0094] By adopting the above solution, a suitable cooling rate helps to ensure the stability of the crystal phase of the electrolyte material, thereby preventing the crystal phase of the electrolyte material from being uneven due to an excessively fast cooling rate.

[0095] In some embodiments of the present application, the calcination time may be 2 hours to 12 hours. Further, the calcination time may be 4 hours to 8 hours. Exemplarily, the calcination time may be 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and any value between two adjacent values.

[0096] According to a third aspect of an embodiment of the present application, a solid-state battery is provided. The solid-state battery may include a positive electrode, a negative electrode, and an electrolyte layer, wherein the electrolyte layer includes the solid-state electrolyte material as described above.

[0097] By adopting the above scheme, since the solid electrolyte material of the embodiment of the present application has high ionic conductivity, first-cycle discharge capacity, first-cycle coulombic efficiency and 100-cycle discharge capacity retention rate, the energy density, cycle life and safety of the solid-state battery of the embodiment of the present application are comprehensively improved.

[0098] In some embodiments of the present application, the positive electrode is made of LiCoO2, LiFePO4, LiNiO2, LiNi x Co y Mn 1-x-y O2、LiNi x Co y Al 1-x-y O2, Li3V2(PO4)3, LiMn2O4, LiNi 0.5 Mn 1.5 O4、LiFe x Mn 1-x A mixture of one or more of PO4, xLi2MnO3·(1-x)LiMO2 (M=Ni, Co, Mn, etc.).

[0099] In some embodiments of the present application, the electrolyte layer is formed by pressing a solid electrolyte material.

[0100] In some embodiments of the present application, the pressing pressure is 500 MPa to 600 MPa. Further, the pressing pressure is 520 MPa to 580 MPa. Exemplarily, the pressing pressure can be 520 MPa, 530 MPa, 540 MPa, 550 MPa, 560 MPa, 570 MPa, 580 MPa, 590 MPa, 600 MPa, and any value between two adjacent values.

[0101] By adopting the above solution, the electrolyte layer prepared under the above pressure range has better density and ductility.

[0102] The present invention is described in detail below by means of specific examples, which are only some examples of the present invention and are not intended to limit the present invention. The raw materials used in the following examples, unless otherwise specified, are all commercially available products.

[0103] Example 1

[0104] A solid-state battery comprising a positive electrode, a negative electrode, and an electrolyte layer;

[0105] The positive electrode uses LiNi 0.8 Co 0.1 Mn 0.1 O2;

[0106] The negative electrode uses a metallic lithium negative electrode;

[0107] The electrolyte layer was prepared by the following steps:

[0108] S100. Raw materials were weighed according to a molar ratio of Li2S:V2S5:V2O5:VCl5=3:0.2:0.2:0.2, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0109] S200, placing the precursor into an alumina crucible, and then placing the alumina crucible into a muffle furnace for sintering at a sintering temperature of 550°C, a sintering time of 10 hours, a heating rate of 1°C / min, and then naturally cooling to room temperature with the furnace at a cooling rate of 0.5°C / min to obtain a solid electrolyte material Li6VS4OCl;

[0110] S300, then pressing the solid electrolyte material under a pressure of 580 MPa and maintaining the pressure for 3 minutes to obtain an electrolyte layer;

[0111] S400, encapsulating the positive electrode, electrolyte layer and negative electrode by preheating, vacuuming, hot pressing in stages and cold pressing to shape.

[0112] Example 2

[0113] A solid-state battery differs from Example 1 in that the electrolyte layer is prepared in a different manner. The electrolyte layer in this embodiment is prepared using the following steps:

[0114] S100. Raw materials were weighed according to a molar ratio of Li2S:Nb2S5:Nb2O5:NbCl5=3:0.2:0.2:0.2, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0115] S200, placing the precursor into an alumina crucible, and then placing the alumina crucible into a muffle furnace for sintering at a sintering temperature of 550°C, a sintering time of 10 hours, a heating rate of 1°C / min, and then naturally cooling to room temperature with the furnace at a cooling rate of 0.5°C / min to obtain a solid electrolyte material Li6NbS4OCl;

[0116] S300, then the solid electrolyte material is pressed at a pressure of 580 MPa and maintained at this pressure for 3 minutes to obtain an electrolyte layer.

[0117] Example 3

[0118] A solid-state battery differs from Example 1 in that the electrolyte layer is prepared in a different manner. The electrolyte layer in this embodiment is prepared using the following steps:

[0119] S100. Raw materials were weighed according to a molar ratio of Li2S:Ta2S5:Ta2O5:TaCl5=3:0.2:0.2:0.2, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0120] S200, placing the precursor into an alumina crucible, and then placing the alumina crucible into a muffle furnace for sintering at a sintering temperature of 550°C, a sintering time of 10 hours, a heating rate of 1°C / min, and then naturally cooling to room temperature with the furnace at a cooling rate of 0.5°C / min to obtain a solid electrolyte material Li6TaS4OCl;

[0121] S300, then the solid electrolyte material is pressed at a pressure of 580 MPa and maintained at this pressure for 3 minutes to obtain an electrolyte layer.

[0122] Example 4

[0123] A solid-state battery differs from Example 1 in that the electrolyte layer is prepared in a different manner. The electrolyte layer in this embodiment is prepared using the following steps:

[0124] S100. Raw materials were weighed according to a molar ratio of Li2S:V2S5:Ta2O5:VCl5:Ta2S5=3:0.1:0.2:0.2:0.1, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0125] S200, the precursor is placed in an alumina crucible, and then the alumina crucible is placed in a muffle furnace for sintering at a temperature of 550 ° C, a sintering time of 10 hours, a heating rate of 1 ° C / min, and then naturally cooled to room temperature with the furnace, and a cooling rate of 0.5 ° C / min to obtain a solid electrolyte material Li6V 0.4 Ta 0.6 S4OCl;

[0126] S300, then the solid electrolyte material is pressed at a pressure of 580 MPa and maintained at this pressure for 3 minutes to obtain an electrolyte layer.

[0127] Comparative Example 1

[0128] A solid-state battery differs from Example 1 in that the electrolyte layer is prepared in a different manner. The electrolyte layer in this embodiment is prepared using the following steps:

[0129] S100. Raw materials were weighed according to a molar ratio of Li2S:P2S5:LiCl = 2.5:0.5:1, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0130] S200, placing the precursor into an alumina crucible, and then placing the alumina crucible into a muffle furnace for sintering at a sintering temperature of 550°C, a sintering time of 10 hours, a heating rate of 1°C / min, and then naturally cooling to room temperature with the furnace at a cooling rate of 0.5°C / min to obtain a solid electrolyte material Li6PS5Cl;

[0131] S300, then the solid electrolyte material is pressed at a pressure of 580 MPa and maintained at this pressure for 3 minutes to obtain an electrolyte layer.

[0132] Comparative Example 2

[0133] A solid-state battery differs from Example 1 in that the electrolyte layer is prepared in a different manner. The electrolyte layer in this embodiment is prepared using the following steps:

[0134] S100. Raw materials were weighed according to a molar ratio of Li2S:P2S5:P2O5:BiCl5=3:0.2:0.2:0.2, mixed, and ground for 20 minutes to obtain a mixed powder; the mixed powder was then ball-milled in a zirconia ball mill at a speed of 700 r / min, with the direction of the ball milling changed every 10 minutes for 20 hours, and the interior of the zirconia ball mill was scraped once every hour to obtain a precursor; wherein the mass ratio of the mixed powder to the grinding balls with a diameter of 3 mm was 1:10, the mass ratio of the mixed powder to the grinding balls with a diameter of 5 mm was 1:10, and the mass ratio of the mixed powder to the grinding balls with a diameter of 10 mm was 1:10;

[0135] S200, the precursor is placed in an alumina crucible, and then the alumina crucible is placed in a muffle furnace for sintering at a temperature of 550 ° C, a sintering time of 10 hours, a heating rate of 1 ° C / min, and then naturally cooled to room temperature with the furnace, and a cooling rate of 0.5 ° C / min to obtain a solid electrolyte material Li6P 0.8 Bi 0.2 S4OCl;

[0136] S300, then the solid electrolyte material is pressed at a pressure of 580 MPa and maintained at this pressure for 3 minutes to obtain an electrolyte layer.

[0137] Performance test: Electrochemical impedance spectroscopy was performed using an electrochemical workstation. The ionic conductivity of the solid electrolyte was calculated using the following formula:

[0138] σ=L / (RS)

[0139] Wherein, L is the thickness of the solid electrolyte, S is the area facing the stainless steel sheet, and R is the measured electrolyte body impedance.

[0140] Normal temperature cycle test:

[0141] Place the battery at room temperature of 25°C, charge it at a constant current of 0.7C to 3.9V, then charge it at a constant voltage of 3.9V with a cut-off current of 0.05C, and then discharge it at a constant current of 1C to 1.5V. Repeat this cycle for 100 cycles.

[0142] First-week coulombic efficiency = ratio of discharge capacity in the second week to discharge capacity in the first week;

[0143] Calculate the 100-cycle capacity retention rate = discharge capacity at the 100th cycle / average discharge capacity of the 1st to 3rd cycle × 100%.

[0144] The test results are shown in Table 1

[0145] Table 1

[0146]

[0147] Compared with Example 1 and Comparative Examples 1-2, the formula of Example 1 is added with V element and X element to prepare a new electrolyte material Li 6-z MY 5-z X 1+z , while the comparative example 1 is not doped with M element and is a traditional LPSC electrolyte structure, the M element in the comparative example 2 partially replaces the P element, and the O element partially replaces the S element. Combined with the test results in Table 1, it can be seen that compared with the comparative examples 1-2, the ionic conductivity, first-week discharge capacity, first-week coulombic efficiency and 100-week discharge capacity retention rate of the solid-state battery of Example 1 are higher, which shows that the use of X - Replace Y 2- , weakening the interaction between lithium ions in the "cage", helping to promote the long-distance movement of lithium ions in the overall structure of the electrolyte material. Moreover, the proportion of lithium elements in the lattice increases with the increase of the doping amount of the M element, which helps to improve the conductivity of the electrolyte. In addition, the new electrolyte material helps to induce the formation of Li-M alloy at the lithium metal negative electrode interface, thereby improving the interfacial compatibility and inhibiting the growth of lithium dendrites.

[0148] Compared with Example 1, Example 2-4 changes the type of doped M element. The M element is at least one of V, Nb, and Ta. As shown in Table 2, the ionic conductivity, first-cycle discharge capacity, first-cycle coulombic efficiency, and 100-cycle discharge capacity retention rate of the solid electrolyte membrane doped with at least one of the above three M elements are maintained at a high level. Figure 2 It can be seen from the XRD crystal phase spectrum that the battery has excellent stability in the 100-week cycle test.

[0149] The above is a detailed introduction to the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A solid electrolyte material, characterized in that The solid electrolyte material comprises: Li 6-z MY 5-z X 1+z ; in, M is one or more of V, Nb, Ta, Bi, Sb, As, Si, Ge, Sn and Pb; X is one or more of F, Cl, Br, and I; Y is one or more of S, O and Se; The value range of z is 0≤z≤2.

2. The solid electrolyte material according to claim 1, characterized in that The M is one or more of V, Nb, and Ta; and / or Said X is F or Cl; and / or Said Y is S or O; and / or The value range of z is 0<z≤1.

3. The solid electrolyte material according to claim 2, characterized in that The value range of z is 0<z≤0.

7.

4. The solid electrolyte material according to claim 2, characterized in that The solid electrolyte material includes Li6VS4OCl, Li6NbS4OCl, Li6TaS4OCl, Li6V 0.4 Ta 0.6 One of S4OCl.

5. The solid electrolyte material according to any one of claims 1 to 4, characterized in that The ionic conductivity of the solid electrolyte material is 4.1 mS / cm to 4.7 mS / cm; and / or The first cycle discharge capacity of the solid electrolyte material is 184 mAh / g to 203 mAh / g; and / or The first-cycle coulombic efficiency of the solid electrolyte material is 91.3% to 93.1%; and / or The 100-cycle discharge capacity retention rate of the solid electrolyte material is 84.6% to 90.4%.

6. A method for preparing a solid electrolyte material, characterized in that: The preparation method comprises the following steps: According to Li 6-z MY 5-z X 1+z A lithium source, an M source, a Y source, and an X source are weighed and mixed in a stoichiometric ratio to obtain a precursor; The precursor is calcined in an inert atmosphere, and the temperature is cooled to room temperature after the calcination is completed to obtain the solid electrolyte material.

7. The method for preparing a solid electrolyte material according to claim 6, wherein: The lithium source includes one or more of Li2S2, Li2S, LiCl, LiBr, LiI, and LiF; and / or One or more of the M source VCl5, V2O5, V2S5, NbCl5, TaCl5, VBr5, BiCl5, SbCl5; and / or One or more of the Y source V2O5, V2S5, Li2O, Nb2O5; and / or The X source is one or more of LiCl, LiBr, LiI, LiF, VCl5, NbCl5, and TaCl5.

8. The method for preparing a solid electrolyte material according to claim 6, wherein: According to Li 6-z MY 5-z X 1+z The lithium source, M source, Y source and X source are weighed in a stoichiometric ratio and mixed to obtain a precursor, including: According to Li 6-z MY 5-z X 1+z Lithium source, M source, Y source and X source are weighed in a stoichiometric ratio and ground to obtain a mixed powder; The mixed powder is then ball-milled at a rotation speed of 300 rpm to 800 rpm for a time of 15 h to 60 h to obtain the precursor.

9. The method for preparing a solid electrolyte material according to claim 8, wherein: During the ball milling process, the diameter of the grinding beads is 3 mm to 10 mm; and / or The mass ratio of the grinding beads to the mixed powder is 5 to 40; Preferably, the mass ratio of the grinding beads to the mixed powder is 20 to 30.

10. The method for preparing a solid electrolyte material according to claim 6, wherein: The calcination temperature is 400°C to 700°C; and / or The heating rate of the calcination is 1°C / min to 10°C / min; and / or The cooling rate after the calcination is 0.5°C / min to 5°C / min; and / or The calcination time is 2 hours to 12 hours.

11. A solid-state battery, characterized in that: The solid-state battery includes a positive electrode, a negative electrode, and an electrolyte layer, and the electrolyte layer includes the solid-state electrolyte material according to any one of claims 1 to 5.

12. The solid-state battery according to claim 11, characterized in that The electrolyte layer is formed by pressing the solid electrolyte material; Preferably, the pressing pressure is 500 MPa to 600 MPa.

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