An interface-stable bilayer halide electrolyte, its preparation method, and an all-solid-state battery

Abstract

This invention discloses an interface-stable bilayer halide electrolyte, its preparation method, and an all-solid-state battery, relating to the field of battery technology. The bilayer halide electrolyte includes an electrolyte layer and a negative electrode protective layer, wherein the electrolyte layer is Li. a M b X c Cl d Or Na a M b X c Cl d The negative electrode protective layer is Li e Y f N g Z h Cl i Or Na e Y f N g Z h Cl i Y represents yttrium; M and N are at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB; and X and Z are at least one element from I, Br, F, O, S, and N. This invention selects yttrium-based halides with good compatibility and low reduction potential to replace sulfides as the negative electrode protective layer. Combined with a halide solid electrolyte with high ionic conductivity, a bilayer halide structure is formed, which solves the problems of irreversible reaction between the halide solid electrolyte and the sulfide protective layer, as well as instability at the negative electrode.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to an interface-stable bilayer halide electrolyte, its preparation method, and an all-solid-state battery. Background Technology

[0002] The frequent occurrence of safety incidents such as spontaneous combustion and explosions of lithium batteries makes the safety of power batteries, especially lithium batteries, a long-term challenge in their electrification development. Furthermore, commercially available lithium-ion batteries based on graphite anodes and transition metal oxide cathodes have essentially reached their energy density ceiling (300 Wh / kg), making the development of next-generation transformative energy storage technologies to overcome safety and energy density bottlenecks an urgent priority. Therefore, replacing liquid organic electrolytes with lithium metal anodes—which pose explosion and fire risks—with solid electrolytes possessing ideal mechanical modulus, high ionic conductivity, and a wide voltage window holds promise for simultaneously addressing the specific energy, cycle life, and safety challenges faced by traditional lithium-ion batteries. This aligns with the future development direction of large-capacity rechargeable batteries and represents an ideal power source for electric vehicles and large-scale energy storage.

[0003] All-solid-state lithium batteries mainly consist of three parts: the positive electrode, the solid electrolyte, and the lithium metal negative electrode. The solid electrolyte material is the core component of a solid-state battery, and it is generally desirable for the solid electrolyte to have high ionic conductivity (>10). -3 S / cm), extremely low electronic conductivity (<10 S / cm), -12 Solid-state lithium batteries possess excellent electrochemical properties (>5.5 V), a wide electrochemical window, good thermal stability, chemical stability, and good interfacial compatibility. Therefore, the essence of all-solid-state lithium batteries lies in developing superior solid electrolytes. Currently, solid electrolyte materials mainly fall into two categories: polymer solid electrolytes and inorganic solid electrolytes. Inorganic electrolytes include oxide solid electrolytes, sulfide solid electrolytes, borohydride solid electrolytes, and halide solid electrolytes. Among these, halide electrolytes have simple synthesis conditions, low grain boundary resistance, high room-temperature ionic conductivity, stable electrochemical performance, and good plasticity, meeting most of the requirements for high-performance solid electrolytes and making them a highly promising electrolyte material.

[0004] Based on recent research, although halide solid electrolytes have achieved high ionic conductivity to meet the needs of practical applications, the stability of the halide electrolyte / electrode interface remains a major obstacle to the practical application of all-solid-state lithium batteries. The compatibility and operational stability of the electrolyte / electrode interface determine the selection of positive and negative electrode materials for all-solid-state batteries, thus affecting their mass / volume energy density. Simultaneously, it influences the ion conduction rate within the solid-state battery, thereby determining its output power density. Common electrode / electrolyte interface problems mainly manifest in three aspects: physical contact, chemical compatibility, and electrochemical stability. In 2021, researchers including Jürgen Janek from the University of Münster, Germany, used lithium metal sputtering deposition combined with in-situ X-ray photoelectron spectroscopy to reveal chemical information changes at the Li3InCl6-lithium metal interface, demonstrating that lithium metal induces In at the interface. 3+ Continuous reduction reactions lead to the ongoing degradation of the solid electrolyte. The products of the interfacial reduction reaction cannot completely block electron exchange, inducing the continuous reduction and degradation of transition metal cations in the electrolyte. This results in thermodynamic instability at the interface between the metal chloride solid electrolyte and the lithium or lithium-indium anode, preventing the formation of a self-limiting interfacial passivation layer during cycling. The anode interface continues to deteriorate, ultimately leading to battery failure. Therefore, to improve interfacial stability, a protective layer is added between the halide solid electrolyte and the metal or alloy anode to form a bilayer structure. Most common anode protective layers in these structures are composed of sulfides.

[0005] Recent research has revealed significant electrochemical incompatibility between sulfide anode protective layers and halide solid electrolyte systems. Studies indicate that while the bilayer electrolyte improves capacity retention and suppresses interfacial resistance growth, in-depth characterization of the buried interface using time-of-flight secondary ion mass spectrometry combined with focused ion beam scanning electron microscopy (FAST) confirmed the occurrence of irreversible chemical decomposition reactions at the interface by detecting indium sulfide-rich regions at the halide-sulfide contact area. Further investigation by altering the central metal revealed the chemical reactivity between sulfide Li6PS5Cl and the halide solid electrolyte, and its impact on the performance of bilayer batteries. In-situ electrochemical impedance spectroscopy, temperature-dependent X-ray diffraction, ectopic X-ray photoelectron spectroscopy, and differential scanning calorimetry were used to quantify the reactivity between sulfides and halides. The results suggest that the reaction kinetics are indeed determined by the central metal ion of the halide. Li3InCl6 and Li2ZrCl6 exhibit high reactivity with Li6PS5Cl, and the formation of intermediate products leads to a significant decrease in the ionic conductivity of the bilayer structure, negatively impacting battery performance. Meanwhile, metal sulfides are expensive and unstable in air, producing toxic hydrogen sulfide gas. Therefore, it is crucial to develop new anode protective layers to replace sulfide protective layers, while simultaneously improving the stability of halide electrolyte layers and metal or alloy anodes.

[0006] Yttrium-based halides possess low reduction potentials, stabilizing metal or alloy anodes. Furthermore, they are compatible with other high-ionic-conductivity halide solid electrolytes, exhibiting no chemical reactions, thus holding promise as a protective layer for both the electrolyte and the anode. Currently, Li3YCl6 has been successfully used as an anode protective layer in all-solid-state lithium-ion batteries, paired with a halide oxide solid electrolyte, maintaining a 90.7% retention rate after 2400 cycles at 2C. However, Li3YCl6 currently exhibits a high ion diffusion barrier and low room-temperature ionic conductivity, typically 2 × 10⁻⁶. -4The low S / cm ratio limits its widespread application in solid-state batteries. Further optimization of synthesis conditions, control of vacancy concentration and disorder of cation and anion sites can further improve the ionic conductivity and anode stability of yttrium-based halides. Atomic substitution is considered one of the most effective modification strategies. Whether it's equivalent or heterovalent ion substitution, the resulting structural changes affect the migration path of lithium / sodium ions, potentially leading to lower migration barriers and faster ion conduction. Introduced metal ions tend to occupy the original metal ion sites, resulting in disorder and the creation of more vacancies for lithium / sodium ion migration, thus improving ionic conductivity at room temperature. Introducing metal ions with lower reduction potentials can further increase anode stability. Introducing anions can improve anode stability, possibly because the products formed in contact with lithium metal can better fill vacancies and defects at relevant interfaces, forming a denser intermediate layer (such as LiF or Li3N), making Li... + It can be deposited uniformly, resulting in a denser interface, thereby preventing the formation of further reactions and improving the stability of halides to the negative electrode and cycle stability. Summary of the Invention

[0007] The purpose of this invention is to at least solve one of the technical problems existing in the prior art. This invention provides an interface-stable bilayer halide electrolyte, its preparation method, and an all-solid-state battery. This invention aims to solve four key problems. First, it has been confirmed that there is an irreversible chemical decomposition reaction between halide solid electrolytes and sulfide anode layers. By designing and selecting a halide anode protective layer with chemical compatibility with the electrolyte, a bilayer halide structure is formed, achieving interface stability with the electrolyte. Second, most halide solid electrolytes are thermodynamically unstable with metal or alloy anodes. By selecting a halide anode protective layer with a low reduction potential, the compatibility between the bilayer halide structure and the anode is improved. Third, the precursor metal sulfides for synthesizing sulfide solid electrolytes are expensive. By designing a bilayer halide structure, all precursors are metal halides, reducing the problem of excessively high costs due to raw materials and processes. Fourth, the problem of toxic hydrogen sulfide gas produced by sulfides. This invention designs and selects yttrium-based halides with low reduction potential to replace sulfides as the negative electrode protective layer material, and combines them with a halide solid electrolyte with high ionic conductivity to form a bilayer halide structure. When applied to all-solid-state batteries, it forms a stable interface between the electrolyte-negative electrode protective layer and the bilayer halide structure-negative electrode, thereby achieving high energy density and long-cycle stability in all-solid-state battery applications. Its bilayer halide structure exhibits high room temperature ionic conductivity, interface stability, and excellent metal negative electrode interface compatibility. When assembled into a lithium / sodium-ion all-solid-state battery, the battery exhibits high specific capacity, safety, and stable cycle performance.

[0008] This invention selects yttrium-based halides, which are compatible with halide electrolytes and have low reduction potentials, as the negative electrode protective layer. Combined with other halide solid electrolytes with high ionic conductivity, a bilayer halide structure is formed for application in all-solid-state batteries. A series of yttrium-based halides with different elemental doping are synthesized using a combination of mechanical ball milling and high-temperature solid-state methods, achieving the optimal composition that balances ionic conductivity and negative electrode stability. By adjusting the anion / cation doping levels, the ionic conductivity, negative electrode stability, and cycle stability of the yttrium-based halides are improved. A series of halide solid electrolyte materials with high ionic conductivity are synthesized using a combination of mechanical ball milling and high-temperature solid-state methods, improving the battery's specific capacity, rate performance, and cycle performance. This bilayer halide structure design enhances the stability of the electrolyte-negative electrode protective layer and the bilayer halide structure-negative electrode interface, thereby enabling high-energy-density, long-cycle-stable all-solid-state battery applications.

[0009] The technical solution of the present invention is as follows: A first aspect of the present invention provides an interface-stable bilayer halide electrolyte, comprising an electrolyte layer and a negative electrode protective layer, wherein the electrolyte layer is Li a M b X c Cl d Or Na a M b X c Cl d The negative electrode protective layer is Li e Y f N g Z h Cl i Or Na e Y f N g Z h Cl i ; Wherein, Y is element yttrium, M and N are at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB, X and Z are at least one element from I, Br, F, O, S, and N, and 0.1 <a≤6,0.1≤b≤1,0≤c≤0.9,0<d≤6,0.1<e≤6,0.1≤f≤0.9,0.1≤g≤1,0≤h≤0.9,0<i≤6。

[0010] Optionally, M and N are at least one of Ta, In, Hf, Nd, Sc, La, Zr, Sm, Al, Er, Ho, Ce, Nd, Eu, Tb, Dy, Gd, Tm, Yb, and Lu.

[0011] Optionally, the chemical formula of the electrolyte layer satisfies a+b×ε1=c×ε2+d, where ε1 and ε2 are the valences of M and X, respectively; The chemical formula of the negative electrode protective layer satisfies e+3f+g×ε3=h×ε4+i, where ε3 and ε4 are the valences of N and Z, respectively.

[0012] Optionally, the electrolyte layer Li a M b X c Cl d Electrical conductivity ≥ 2 × 10 -3 S / cm, the electrolyte layer Na a M b X c Cl d Electrical conductivity ≥ 5 × 10 -4 S / cm.

[0013] A second aspect of the present invention provides a method for preparing a bilayer halide electrolyte, comprising the following steps: An electrolyte layer is synthesized by using lithium halide salts or sodium halide salts and halide salts of at least one element from groups IIIA, IIIB, IVA, IVB, VA and VB as raw materials, through mechanical ball milling combined with high-temperature solid-phase method. A negative electrode protective layer is synthesized by using lithium halogen salts or sodium halogen salts, yttrium chloride and halogen salts of at least one element from groups IIIA, IIIB, IVA, IVB, VA and VB as raw materials, through mechanical ball milling combined with high-temperature solid-phase method. The electrolyte layer and the negative electrode protective layer are stacked to obtain a double-layer halide electrolyte.

[0014] Optionally, the preparation method includes the following specific steps: S1. Under an inert gas atmosphere, a lithium halide salt or a sodium halide salt is mixed with a halide salt of at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB, and then ball-milled with ZrO2 ball milling beads to obtain a first mixed powder; under an inert gas atmosphere, the first mixed powder is sieved, and the sieved first mixed powder is pressed into a tablet to obtain a first tablet; the first tablet is sintered under vacuum conditions to obtain an electrolyte layer; S2. Under an inert gas atmosphere, a lithium halide salt or a sodium halide salt, yttrium chloride, and a halide salt of at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB are mixed and ball-milled with ZrO2 ball milling beads to obtain a second mixed powder. Under an inert gas atmosphere, the second mixed powder is sieved and then pressed into a tablet to obtain a second tablet. The second tablet is sintered under vacuum to obtain a negative electrode protective layer. S3. The electrolyte layer and the negative electrode protective layer are stacked to obtain a double-layer halide electrolyte.

[0015] Optionally, the ball milling conditions in steps S1 and S2 include: the diameter of the ZrO2 grinding balls is 3 mm and 5 mm, the mass ratio of ZrO2 grinding balls to raw materials is 10:1-40:1; the ball milling is first performed at a low speed of 80 rpm to 120 rpm for 20 min to 40 min, and then at a speed of 450 rpm to 550 rpm for 1.5 h to 20 h. The tableting conditions in steps S1 and S2 include: a tableting pressure of 100 MPa-400 MPa and a holding time of 30 s-10 min; The sintering conditions in steps S1 and S2 include: sintering temperature of 100℃-600℃, heating rate of 0.1℃ / min-10℃ / min, and sintering time of 0.5h-36h. In step S3, the electrolyte layer and the negative electrode protective layer are laminated by cold pressing or hot pressing.

[0016] A third aspect of the present invention provides an all-solid-state battery comprising the bilayer halide electrolyte or the bilayer halide electrolyte obtained by the preparation method described above.

[0017] Optionally, the all-solid-state battery further includes a positive electrode and a negative electrode, with the bilayer halide electrolyte disposed between the positive electrode and the negative electrode.

[0018] Optionally, the all-solid-state battery is an all-solid-state lithium-ion battery or an all-solid-state sodium-ion battery.

[0019] This invention has at least one of the following beneficial effects: This invention addresses the challenges of irreversible reactions between the halide solid electrolyte and the sulfide protective layer, as well as instability at the negative electrode, by selecting yttrium-based halides with low reduction potentials that are compatible with halide electrolytes and to replace sulfides as the negative electrode protective layer. This strategy, combined with a halide solid electrolyte with high ionic conductivity, forms a bilayer halide structure. The specific advantages of this invention are: 1) The design of yttrium-based halides as the protective layer ensures chemical compatibility with the halide solid electrolyte, preventing other irreversible reactions and stabilizing the electrolyte-negative electrode protective layer interface in the bilayer structure; 2) By selecting yttrium-based halides with low reduction potentials, the compatibility of the protective layer with the negative electrode is improved, achieving a stable bilayer structure and negative electrode interface; 3) The raw materials are metal halides, and high-energy ball milling combined with sintering significantly reduces raw material and process costs. Attached Figure Description

[0020] Figure 1 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li2.5 Y 0.5 Hf 0.5 SEM image of the Cl6 double-layer halide structure.

[0021] Figure 2 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 SEM image of the Cl6 bilayer halide structure.

[0022] Figure 3 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 XRD pattern of the Cl6 double halide structure.

[0023] Figure 4 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Ionic conductivity diagram of Cl6 bilayer halide structure.

[0024] Figure 5 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Rate performance curve of all-solid-state lithium-ion battery with Cl6 double-layer halide structure.

[0025] Figure 6 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Cycle performance curves of all-solid-state lithium-ion batteries with a Cl6 bilayer halide structure.

[0026] Figure 7 The Li obtained in Embodiment 1 of this invention 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5Y 0.5 Hf 0.5 The limiting current density curve of a symmetrical cell with a Cl6 bilayer halide structure.

[0027] Figure 8 Na obtained in Example 3 of this invention 2.5 Y 0.5 Hf 0.5 Ionic conductivity diagram of Cl6 negative electrode protective layer material particles.

[0028] Figure 9 Na obtained in Example 3 of this invention 1.8 Ta 0.6 In 0.4 Cl6||Na 2.5 Y 0.5 Hf 0.5 SEM image of the Cl6 bilayer halide structure.

[0029] Appendix Figure 10 The Li obtained in Comparative Example 1 of this invention 1.6 Ta 0.7 In 0.3 The limiting current density curve of a symmetric cell with a Cl6 monolayer halide structure.

[0030] Appendix Figure 11 The Li obtained in Comparative Example 2 of this invention 1.6 Ta 0.7 In 0.3 Cycle life curve of all-solid-state lithium-ion battery with Cl6||LPSCl halide-sulfide structure. Detailed Implementation

[0031] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] An embodiment of the present invention provides an interface-stable bilayer halide electrolyte, comprising an electrolyte layer and a negative electrode protective layer, wherein the electrolyte layer is Li a M b X c Cl d Or Na a M b X c Cl d The negative electrode protective layer is Li e Y f N g Z h Cl i Or Nae Y f N g Z h Cl i ; Wherein, Y is element yttrium, M and N are at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB, X and Z are at least one element from I, Br, F, O, S, and N, and 0.1 <a≤6,0.1≤b≤1,0≤c≤0.9,0<d≤6,0.1<e≤6,0.1≤f≤0.9,0.1≤g≤1,0≤h≤0.9,0<i≤6。

[0033] This invention replaces sulfides with yttrium-based halides, which have good compatibility and low reduction potential, as the negative electrode protective layer, and combines them with a halide solid electrolyte with high ionic conductivity to form a bilayer halide electrolyte structure. The yttrium-based halides of this invention are stable to metal or alloy negative electrodes and do not react with the electrolyte layer, thus solving the problems of irreversible reactions between the halide solid electrolyte and the sulfide protective layer, as well as instability at the negative electrode. This bilayer halide structure design improves the stability of the electrolyte-negative electrode protective layer and the bilayer halide structure-negative electrode interface, thereby enabling high-energy-density, long-cycle-stable all-solid-state battery applications.

[0034] In some embodiments, M and N are at least one of Ta, In, Hf, Nd, Sc, La, Zr, Sm, Al, Er, Ho, Ce, Nd, Eu, Tb, Dy, Gd, Tm, Yb, and Lu.

[0035] In some embodiments, for the electrolyte layer, its chemical formula satisfies a+b×ε1=c×ε2+d, where ε1 and ε2 are the valences of M and X, respectively; For the negative electrode protective layer, its chemical formula satisfies e+3f+g×ε3=h×ε4+i, where ε3 and ε4 are the valences of N and Z, respectively.

[0036] In some embodiments, the halide material used as the electrolyte layer has high ionic conductivity, and the electrolyte layer Li a M b X c Cl d Its electrical conductivity is not less than 2×10 -3 S / cm, the electrolyte layer Na a M b X c Cl d The electrical conductivity is not less than 5×10 - 4 S / cm.

[0037] Another embodiment of the present invention provides a method for preparing a bilayer halide electrolyte, comprising the following steps: An electrolyte layer is synthesized by using lithium halide salts or sodium halide salts and halide salts of at least one element from groups IIIA, IIIB, IVA, IVB, VA and VB as raw materials, through mechanical ball milling combined with high-temperature solid-phase method. A negative electrode protective layer is synthesized by using lithium halogen salts or sodium halogen salts, yttrium chloride and halogen salts of at least one element from groups IIIA, IIIB, IVA, IVB, VA and VB as raw materials, through mechanical ball milling combined with high-temperature solid-phase method. The electrolyte layer and the negative electrode protective layer are stacked to obtain a double-layer halide electrolyte.

[0038] This invention employs a combination of mechanical ball milling and high-temperature solid-state processing to synthesize a series of yttrium-based halides doped with different elements, achieving optimal composition that balances ionic conductivity and anode stability. By adjusting the anion / cation doping levels, the ionic conductivity, anode stability, and cycle stability of the yttrium-based halides are improved. The use of mechanical ball milling combined with high-temperature solid-state processing synthesizes a series of halide solid electrolyte materials with high ionic conductivity, thereby improving the battery's specific capacity, rate performance, and cycle performance.

[0039] In some embodiments, the preparation method includes: using lithium chloride (LiCl), lithium fluoride (LiF), lithium bromide (LiBr), lithium iodide (LiI), sodium chloride (NaCl), sodium fluoride (NaF), sodium bromide (NaBr), sodium iodide (NaI), yttrium chloride (YCl3), and a halide salt of at least one element from groups IIIA, IIIB, IVA, IVB, VA, or VB (such as scandium chloride (ScCl3), hafnium chloride (HfCl4), tantalum chloride (TaCl5), etc.) as raw materials, and synthesizing them by mechanical ball milling combined with high-temperature solid-phase method.

[0040] In some embodiments, the preparation method includes the following specific steps: S1. Under an inert gas atmosphere, lithium halide salts or sodium halide salts are weighed and mixed with halide salts of at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB according to the stoichiometric ratio of the general formula. ZrO2 ball milling beads are added for ball milling to obtain a first mixed powder. If the first mixed powder obtained using lithium halide salts as raw materials (Li...) a M y N z Cl b The ionic conductivity is less than 2 × 10⁻⁶. -3 S / cm or the first mixed powder obtained from sodium halide salts (Na) a M y Nz Cl b The ionic conductivity is less than 5 × 10⁻⁶. -4 If S / cm, then proceed to the next step of tableting and sintering; if the first mixed powder Li a M y N z Cl b Its ionic conductivity is not less than 2×10 -3 S / cm or Na a M y N z Cl b Its ionic conductivity is not less than 5×10 -4 If the value is S / cm, then use it directly.

[0041] Under an inert gas atmosphere, the first mixed powder is sieved, and the sieved first mixed powder is pressed into a tablet to obtain a first tablet; the first tablet is sintered under vacuum conditions to obtain an electrolyte layer. S2. Under an inert gas atmosphere, a lithium halide salt or a sodium halide salt, yttrium chloride, and a halide salt of at least one element from groups IIIA, IIIB, IVA, IVB, VA, and VB are mixed, and then ball-milled with ZrO2 ball milling beads to obtain a second mixed powder; if the second mixed powder obtained using a lithium halide salt as a raw material (Li e Y f N g Z h Cl i The ionic conductivity is less than 8 × 10⁻⁶. -4 S / cm or a second mixed powder (Na) obtained from sodium halide salts. e Y f N g Z h Cl i The ionic conductivity is less than 2 × 10⁻⁶. -4 If S / cm, then proceed to the next step of tableting and sintering; if the second mixed powder Li a M y N z Cl b Its ionic conductivity is not less than 8×10 -4 S / cm or Na a M y N z Cl b Its ionic conductivity is not less than 2×10 -4 If the value is S / cm, then use it directly.

[0042] Under an inert gas atmosphere, the second mixed powder is sieved and then pressed into a tablet to obtain a second tablet; the second tablet is sintered under vacuum to obtain a negative electrode protective layer. S3. The electrolyte layer and the negative electrode protective layer are stacked to obtain a double-layer halide electrolyte.

[0043] In some embodiments, the ball milling conditions in steps S1 and S2 include: the diameter of the ZrO2 grinding balls is 3 mm and 5 mm; the mass ratio of ZrO2 grinding balls to raw material is 10:1-40:1; during ball milling, the balls are first rotated at a low speed of 80 rpm to 120 rpm for 20 min to 40 min, and then rotated at a speed of 450 rpm to 550 rpm for 10 h to 16 h; preferably, the mass ratio of ZrO2 grinding balls to raw material is 20:1-40:1; during ball milling, the balls are first rotated at a low speed of 90 rpm to 110 rpm for 25 min to 35 min, and then rotated at a speed of 480 rpm to 520 rpm for 12 h to 16 h. More preferably, the mass ratio of ZrO2 grinding balls to raw material is 30:1-40:1; during ball milling, the balls are first rotated at a low speed of 100 rpm for 30 min, and then rotated at a speed of 500 rpm for 15 h.

[0044] The tableting conditions in steps S1 and S2 include: a tableting pressure of 100 MPa-400 MPa and a holding time of 30 s-10 min; preferably, a tableting pressure of 200 MPa-400 MPa and a holding time of 30 s-5 min; more preferably, a tableting pressure of 250 MPa-350 MPa and a holding time of 30 s-2 min.

[0045] The sintering conditions in steps S1 and S2 include: a sintering temperature of 100℃-600℃, a heating rate of 0.1℃ / min-10℃ / min, and a sintering time of 0.5h-36h; preferably, a sintering temperature of 200℃-500℃, a heating rate of 1℃ / min-10℃ / min, and a sintering time of 1h-20h; more preferably, a sintering temperature of 300℃-400℃, a heating rate of 3℃ / min-7℃ / min, and a sintering time of 3h-10h.

[0046] In step S3, the electrolyte layer and the negative electrode protective layer are laminated by cold pressing or hot pressing.

[0047] In some embodiments, the particle diameter of the bilayer halide electrolyte described in step S3 is 0.1 μm-20 μm to meet the application requirements of lithium / sodium ion solid-state batteries.

[0048] A third aspect of the present invention provides an all-solid-state battery comprising the bilayer halide electrolyte or the bilayer halide electrolyte obtained by the preparation method described above.

[0049] This invention selects yttrium-based halides, which have good compatibility with halide electrolytes and low reduction potential, as the negative electrode protective layer. It is combined with other halide solid electrolytes with high ionic conductivity to form a bilayer halide structure, which is applied to all-solid-state batteries. Through this bilayer halide structure design, the stability of the electrolyte-negative electrode protective layer and the bilayer halide structure-negative electrode interface is improved, thereby realizing the application of high energy density and long cycle stability all-solid-state batteries.

[0050] Optionally, the all-solid-state battery further includes a positive electrode and a negative electrode, with the bilayer halide electrolyte disposed between the positive electrode and the negative electrode.

[0051] Optionally, the all-solid-state battery is an all-solid-state lithium-ion battery or an all-solid-state sodium-ion battery.

[0052] Optionally, the negative electrode is selected from at least one of lithium metal, lithium-indium alloy, lithium-silicon alloy, lithium-magnesium alloy, lithium-aluminum alloy, sodium metal, sodium-tin alloy, and other composite sodium metals. The positive electrode active material includes, but is not limited to, at least one of LiCoO2, LiFePO4, NCM ternary materials, lithium-rich phase lithium manganese oxide and lithied layered oxides, and lithied layered sulfides. The conductive agent may include at least one of graphite, carbon black, acetylene black, Ketjen black, and carbon fiber.

[0053] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following specific embodiments.

[0054] Example 1 This embodiment provides a Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 The preparation method of Cl6 bilayer halide all-solid-state battery, the specific preparation steps are as follows: (1) Mixing: LiCl, TaCl5 and InCl3 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 1.6:0.7:0.3, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of about 40:1. Planetary ball milling was carried out in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 15 h to obtain mixed powder.

[0055] (2) Tableting: The ball-milled mixed powder was sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder was placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa was applied for 1 min to obtain an electrolyte tablet.

[0056] (3) Sintering: The above electrolyte sheet was sintered under vacuum at 300℃, with a heating rate of 5℃ / min and a sintering time of 5h, to obtain Li 1.6 Ta 0.7 In 0.3 Cl6 electrolyte layer material.

[0057] (4) Mixing: LiCl, YCl3, and HfCl4 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 2.5:0.5:0.5, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of approximately 40:1. Planetary ball milling was performed in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 15 h to obtain a mixed powder.

[0058] (5) Tableting: The ball-milled mixed powder is sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder is placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa is applied for 1 min to obtain an electrolyte tablet.

[0059] (6) Sintering: The above electrolyte sheet was sintered under vacuum at 400℃, with a heating rate of 5℃ / min and a sintering time of 3h, to obtain Li. 2.5 Y 0.5 Hf 0.5 Cl6 halide anode protective layer material.

[0060] (7) Ionic conductivity test: 100 mg of the halide electrolyte layer and negative electrode protective layer powder samples prepared in the above examples were accurately weighed and placed into an insulating cylindrical mold with an inner diameter of 10 mm. The samples were then cold-pressed under a pressure of 300 MPa to prepare test pieces. The pressed materials were subjected to AC impedance spectroscopy (EIS) and thickness tests in sequence. The ionic conductivity of the halide material was calculated using the obtained impedance values ​​and the Arrhenius equation. The test results are as follows: Figure 4 As shown. Electrolyte layer Li 1.6 Ta 0.7 In 0.3 The ionic conductivity of Cl6 is 4.5 × 10⁻⁶. -3 S / cm, negative electrode protective layer Li 2.5 Y 0.5 Hf 0.5 The ionic conductivity of Cl6 is 0.8 × 10⁻⁶.-3 S / cm.

[0061] (8) Double-layer halide structure: 60 mg of halide electrolyte Li was added to an insulating cylindrical mold with a diameter of 10 mm. 1.6 Ta 0.7 In 0.3 Cl6 was then pressurized to 300 MPa to obtain a solid electrolyte layer; subsequently, 50 mg of Li was added. 2.5 Y 0.5 Hf 0.5 The Cl6 negative electrode protective layer material is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure. The Li obtained in this embodiment... 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 SEM image of the Cl6 double halide structure is shown below. Figures 1-2 As shown in the figure, the bilayer halide forms a dense solid electrolyte layer with a tight contact interface. The XRD pattern is shown below. Figure 3 As shown, by Figure 3 This indicates that the material synthesis was successful.

[0062] (9) Performance testing: In an argon glove box, NCM 811 positive electrode active material, Li3InCl6 solid electrolyte, and VGCF were weighed in a mass ratio of 80:20:5, and then thoroughly ground in a mortar to obtain a composite positive electrode material; in the above embodiment, Li 1.6 Ta 0.7 In 0.3 5 mg of composite cathode material was added to the Cl6 side and pressurized at 300 MPa; in the Li of the above embodiment 2.5 Y 0.5 Hf 0.5 A lithium-indium alloy with a diameter of 10 mm and a thickness of 200 μm was placed on the Cl6 side as the negative electrode, and a pressure of 200 MPa was applied to obtain a mold battery. The rate performance of the assembled solid-state battery was tested under the following conditions: current density of 0.1–1 C and voltage range of 2.7–4.3 V (Li... + / Li), the test results are as follows Figure 5 As shown. Cyclic performance testing was performed on the assembled solid-state battery under the following conditions: current density of 0.5C and voltage range of 2.7–4.3V (Li). + / Li), the test results are as follows Figure 6 As shown.

[0063] (10) In an argon glove box, to verify the compatibility of the bilayer halide structure prepared in the above embodiments with the lithium indium alloy anode, a LiIn / bilayer electrolyte / LiIn symmetric cell was assembled for limiting current density testing. First, 60 mg of Li was subjected to a pressure of 300 MPa using an insulating cylindrical mold with an inner diameter of 10 mm. 1.6 Ta 0.7 In 0.3 Cl6 electrolyte is pressed into a 0.4 mm thick disc, and then 50 mg of the negative electrode protective layer material Li prepared in the above example is added to both sides of the electrolyte. 2.5 Y 0.5 Hf 0.5 Cl6 is stacked and pressurized at 300 MPa to obtain a bilayer electrolyte structure; two 10 mm diameter, 200 μm thick lithium-indium alloy sheets are bonded to both sides of the bilayer electrolyte and pressurized at 100 MPa to obtain a LiIn / bilayer electrolyte / LiIn symmetrical mold battery, with an efficiency of 0.05-10 mA / cm². 2 The limiting current density was tested under the surface current condition, and the test results are as follows: Figure 7 As shown.

[0064] Example 2 This embodiment provides a Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.25 Nd 0.33 The preparation method of Cl6 bilayer halide all-solid-state battery, the specific preparation steps are as follows: (1) Mixing: LiCl, TaCl5 and InCl3 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 1.6:0.7:0.3, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of about 40:1. Planetary ball milling was carried out in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 15 h to obtain mixed powder.

[0065] (2) Tableting: The ball-milled mixed powder was sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder was placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa was applied for 1 min to obtain an electrolyte tablet.

[0066] (3) Sintering: The above electrolyte sheet was sintered under vacuum at 300℃, with a heating rate of 5℃ / min and a sintering time of 5h, to obtain Li 1.6 Ta 0.7 In0.3 Cl6 electrolyte layer material.

[0067] (4) Mixing: LiCl, YCl3, NdCl3, and HfCl4 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 2.5:0.5:0.25:0.33, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of approximately 40:1. Planetary ball milling was performed in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 15 h to obtain a mixed powder.

[0068] (5) Tableting: The ball-milled mixed powder is sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder is placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa is applied for 1 min to obtain an electrolyte tablet.

[0069] (6) Sintering: The above electrolyte sheet was sintered under vacuum at 300°C with a heating rate of 5°C / min for 3 hours to obtain Li. 2.5 Y 0.5 Hf 0.25 Nd 0.33 Cl6 halide anode protective layer material.

[0070] (7) Ionic conductivity test: Accurately weigh 100 mg of the halide negative electrode protective layer powder sample prepared in the above examples, place it into a cylindrical mold with an inner diameter of 10 mm, and cold press it under a pressure of 300 MPa to prepare a test piece. The pressed negative electrode protective layer was subjected to AC impedance spectroscopy (EIS) and thickness testing in sequence. The ionic conductivity of the halide negative electrode protective layer material was calculated using the obtained impedance values ​​and the Arrhenius equation. Electrolyte layer Li 1.6 Ta 0.7 In 0.3 The ionic conductivity of Cl6 is 4.5 × 10⁻⁶. -3 S / cm, negative electrode protective layer Li 2.5 Y 0.5 Hf 0.25 Nd 0.33 The ionic conductivity of Cl6 is 1.2 × 10⁻⁶. - 3 S / cm.

[0071] (8) Double-layer halide structure: 60 mg of halide electrolyte Li was added to an insulating cylindrical mold with a diameter of 10 mm. 1.6 Ta 0.7 In 0.3Cl6 was then pressurized to 300 MPa to obtain a solid electrolyte layer; subsequently, 50 mg of Li was added. 2.5 Y 0.5 Hf 0.25 Nd 0.33 The Cl6 negative electrode protective layer material is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure.

[0072] (9) Performance testing: In an argon glove box, NCM 811 positive electrode active material, Li3InCl6 solid electrolyte, and VGCF were weighed in a ratio of 80:20:5, and then thoroughly ground using a mortar and pestle to obtain a composite positive electrode material; in the above embodiment, Li 1.6 Ta 0.7 In 0.3 5 mg of composite cathode material was added to the Cl6 side and pressurized at 300 MPa; in the Li of the above embodiment 2.5 Y 0.5 Hf 0.25 Nd 0.33 On the Cl6 side, a lithium-indium alloy with a diameter of 10 mm and a thickness of 200 μm was placed as the negative electrode, and a pressure of 200 MPa was applied to obtain a mold battery. The rate performance of the assembled solid-state battery was tested under the following conditions: current density of 0.1–1 C and voltage range of 2.7–4.3 V (Li... + / Li). Cyclic performance tests were performed on the assembled solid-state battery under the following conditions: current density of 0.5C and voltage range of 2.7–4.3V (Li). + / Li).

[0073] (10) In an argon glove box, to verify the compatibility of the bilayer halide structure prepared in the above embodiments with the lithium indium alloy anode, a LiIn / bilayer electrolyte / LiIn symmetric cell was assembled for limiting current density testing. First, 60 mg of Li was subjected to a pressure of 300 MPa using an insulating cylindrical mold with an inner diameter of 10 mm. 1.6 Ta 0.7 In 0.3 Cl6 electrolyte is pressed into a 0.4 mm thick disc. Then, 50 mg of the negative electrode protective layer material prepared in the above example is added to both sides of the electrolyte, and the disc is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure. Two 10 mm diameter, 200 μm thick lithium-indium alloy sheets are bonded to both sides of the double-layer electrolyte and pressurized at 100 MPa to obtain a LiIn / electrolyte / LiIn symmetrical mold battery with an efficiency of 0.05-10 mA / cm². 2 The limiting current density was tested under surface current conditions.

[0074] Example 3 This embodiment prepared a Na 1.8 Ta 0.6 In 0.4 Cl6|| Na 2.5 Y 0.5 Hf 0.5 The preparation method of Cl6 bilayer halide all-solid-state battery, the specific preparation steps are as follows: (1) Mixing: NaCl, InCl3, and TaCl5 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 1.8:0.4:0.6, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of approximately 40:1. Planetary ball milling was performed in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 2 h to obtain a mixed powder.

[0075] (2) Tableting: The ball-milled mixed powder was sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder was placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa was applied for 1 min to obtain an electrolyte tablet.

[0076] (3) Sintering: The above electrolyte sheet was sintered under vacuum at 300°C, with a heating rate of 5°C / min and a sintering time of 5h, to obtain Na. 1.8 Ta 0.6 In 0.4 Cl6 electrolyte layer material.

[0077] (4) Mixing: Under an inert gas atmosphere, weigh NaCl, YCl3 and HfCl4 according to the stoichiometric ratio of 2.5:0.5:0.5 of the general formula, and then add them into a high-energy ball milling jar. Add zirconia grinding balls with diameters of 3 mm and 5 mm, with a material ratio of about 40:1. Perform planetary ball milling under an argon atmosphere. First, rotate at a low speed of 100 rpm for 30 min, and then rotate at a speed of 500 rpm for 4 h to obtain mixed powder.

[0078] (5) Tableting: The ball-milled mixed powder is sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder is placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa is applied for 1 min to obtain an electrolyte tablet.

[0079] (6) Sintering: The above electrolyte sheet is sintered under vacuum at 400℃, with a heating rate of 5℃ / min and a sintering time of 3h to obtain Na. 2.5 Y 0.5 Hf 0.5 Cl6 halide anode protective layer material.

[0080] (7) Ionic conductivity test: 100 mg of the halide electrolyte layer and negative electrode protective layer powder samples prepared in the above examples were accurately weighed and placed into a cylindrical mold with an inner diameter of 10 mm. The samples were then cold-pressed under a pressure of 300 MPa to prepare test pieces. The pressed negative electrode protective layer was subjected to AC impedance spectroscopy (EIS) and thickness tests in sequence. The ionic conductivity of the halide negative electrode protective layer material was calculated using the obtained impedance values ​​and the Arrhenius equation. The test results are as follows: Figure 8 As shown. Electrolyte layer Na 1.8 Ta 0.6 In 0.4 The ionic conductivity of Cl6 is 1×10⁻⁶. -3 S / cm. Negative electrode protective layer Na 2.5 Y 0.5 Hf 0.5 The ionic conductivity of Cl6 is 0.6 × 10⁻⁶. -3 S / cm.

[0081] (5) Double-layer halide structure: 60 mg of halide electrolyte Na was added to an insulating cylindrical mold with a diameter of 10 mm. 1.8 Ta 0.6 In 0.4 Cl6 was then pressurized to 300 MPa to obtain a solid electrolyte layer; subsequently, 50 mg of Na was added. 2.5 Y 0.5 Hf 0.5 Cl6 negative electrode protective layer material is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure, Na 1.8 Ta 0.6 In 0.4 Cl6||Na 2.5 Y 0.5 Hf 0.5 SEM image of the Cl6 double halide structure is shown below. Figure 9 As shown.

[0082] (6) Performance testing: In an argon glove box, NaCrO2 positive electrode active material and Na 1.8 Ta 0.6 In 0.4 Cl6 solid electrolyte and VGCF were weighed in a ratio of 80:20:5, and then thoroughly ground in a mortar to obtain a composite cathode material; Na... 1.8 Ta 0.6 In 0.4 5 mg of composite cathode material was added to the Cl6 side and pressurized at 300 MPa; in the Na... 2.5 Y 0.5 Hf 0.5A sodium-tin alloy with a diameter of 10 mm and a thickness of 200 μm was placed on the side of the Cl6 negative electrode protective layer as the negative electrode, and a pressure of 200 MPa was applied to obtain a mold battery. The rate performance of the assembled solid-state battery was tested under the following conditions: current density of 0.1-1C and voltage range of 2.5-4.0V (Na... + / Na). Cyclic performance testing was performed on the assembled solid-state battery under the following conditions: current density of 0.5C and voltage range of 2.5–4.0V (Na). + / Na).

[0083] (7) In an argon glove box, to test the Na prepared in the above examples 1.8 Ta 0.6 In 0.4 Cl6||Na 2.5 Y 0.5 Hf 0.5 The compatibility of Cl6 bilayer halides with sodium-tin alloy anodes was investigated. A NaSn / bilayer electrolyte / NaSn symmetric cell was assembled for limiting current density testing. First, 60 mg of solid electrolyte NaSn was added to the cell under a pressure of 300 MPa using an insulating cylindrical mold with an inner diameter of 10 mm. 1.8 Ta 0.6 In 0.4 Cl6 was pressed into 0.35 mm thick discs, and then 50 mg of Na prepared in the above example was added to both sides of the electrolyte. 2.5 Y 0.5 Hf 0.5 Cl6 negative electrode protective layer material is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure; two sodium-tin alloy sheets with a diameter of 10 mm and a thickness of 200 μm are bonded to both sides of the above double-layer electrolyte and pressurized at 100 MPa to obtain a symmetrical mold battery containing NaSn / electrolyte / NaSn, with an efficiency of 0.05-10 mA / cm². 2 The limiting current density was tested under surface current conditions.

[0084] Example 4 This embodiment provides Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 The preparation method of the bilayer halide all-solid-state battery, the specific preparation steps are as follows: (1) Mixing: LiCl, TaCl5 and InCl3 were weighed in an inert gas atmosphere according to the stoichiometric ratio of 1.6:0.7:0.3, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm were added, with a material ratio of about 40:1. Planetary ball milling was carried out in an argon atmosphere. First, the mixture was rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 15 h to obtain mixed powder.

[0085] (2) Tableting: The ball-milled mixed powder was sieved under an inert gas atmosphere to obtain a 200-mesh mixed powder; and the obtained mixed powder was placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa was applied for 1 min to obtain an electrolyte tablet.

[0086] (3) Sintering: The above electrolyte sheet was sintered under vacuum at 300℃, with a heating rate of 5℃ / min and a sintering time of 5h, to obtain Li 1.6 Ta 0.7 In 0.3 Cl6 electrolyte layer material.

[0087] (4) Mixing: LiCl, LiBr, YCl3, and HfCl4 are weighed in an inert gas atmosphere according to the stoichiometric ratio of 2:0.5:0.5:0.5, and then added to a high-energy ball milling jar. Zirconia grinding balls with diameters of 3 mm and 5 mm are added, with a material ratio of approximately 40:1. Planetary ball milling is performed in an argon atmosphere. First, the mixture is rotated at a low speed of 100 rpm for 30 min, and then at a speed of 500 rpm for 10 h to obtain a mixed powder.

[0088] (5) Tableting: The powder after ball milling is sieved under an inert gas atmosphere, and the mixed powder obtained above is placed in a tableting mold under an inert gas atmosphere and a pressure of 300 MPa is applied for 1 min to obtain electrolyte tablets.

[0089] (6) Sintering: The above electrolyte sheet was sintered under vacuum at 400℃, with a heating rate of 5℃ / min and a sintering time of 3h, to obtain Li. 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 Halogenated negative electrode protective layer material.

[0090] (7) Ionic conductivity test: Accurately weigh 100 mg of the halide negative electrode protective layer powder sample prepared in the above examples, place it into a cylindrical mold with an inner diameter of 10 mm, and cold press it under a pressure of 300 MPa to prepare a test piece. The pressed negative electrode protective layer was subjected to AC impedance spectroscopy (EIS) and thickness testing in sequence. The ionic conductivity of the halide oxide negative electrode protective layer material was calculated using the obtained impedance values ​​and the Arrhenius equation. Electrolyte layer Li 1.6 Ta 0.7 In 0.3 The ionic conductivity of Cl6 is 4.5 × 10⁻⁶. -3 S / cm. Negative electrode protective layer Li 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 Its ionic conductivity is 1.5 × 10⁻⁶. -3 S / cm.

[0091] (8) Double-layer halide structure: 60 mg of halide electrolyte Li was added to an insulating cylindrical mold with a diameter of 10 mm. 1.6 Ta 0.7 In 0.3 Cl6 was then pressurized to 300 MPa to obtain a solid electrolyte layer; subsequently, 50 mg of Li was added. 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 The negative electrode protective layer material is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure.

[0092] (9) Performance testing: In an argon glove box, NCM 811 positive electrode active material, Li3InCl6 solid electrolyte, and VGCF were weighed in a ratio of 80:20:5, and then thoroughly ground using a mortar and pestle to obtain a composite positive electrode material; in the above embodiment, Li 1.6 Ta 0.7 In 0.3 5 mg of composite cathode material was added to the Cl6 side and pressurized at 300 MPa; in the Li of the above embodiment 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 On the side, a lithium-indium alloy with a diameter of 10 mm and a thickness of 200 μm was placed as the negative electrode, and a pressure of 200 MPa was applied to obtain a mold battery. The rate performance of the assembled solid-state battery was tested under the following conditions: current density of 0.1–1 C and voltage range of 2.7–4.3 V (Li... + / Li). Cyclic performance tests were performed on the assembled solid-state battery under the following conditions: current density of 0.5C and voltage range of 2.7–4.3V (Li). + / Li).

[0093] (10) In an argon glove box, to verify the compatibility of the bilayer halide structure prepared in the above embodiments with the lithium indium alloy anode, a LiIn / bilayer electrolyte / LiIn symmetric cell was assembled for limiting current density testing. First, 50-80 mg of Li was injected into the cell using an insulating cylindrical mold with an inner diameter of 10 mm at a pressure of 300 MPa. 1.6 Ta 0.7 In 0.3 Cl6 electrolyte is pressed into a 0.4 mm thick disc. Then, 50 mg of the negative electrode protective layer material prepared in the above example is added to both sides of the electrolyte, and the disc is stacked and pressurized at 300 MPa to obtain a double-layer electrolyte structure. Two 10 mm diameter, 200 μm thick lithium-indium alloy sheets are bonded to both sides of the double-layer electrolyte and pressurized at 100 MPa to obtain a LiIn / electrolyte / LiIn symmetrical mold battery with an efficiency of 0.05-10 mA / cm². 2 The limiting current density was tested under surface current conditions.

[0094] Comparative Example 1 This comparative example prepared Li 1.6 Ta 0.7 In 0.3 The Cl6 monolayer halide all-solid-state battery was constructed using the same steps as in Example 1, except for the absence of a negative electrode protective layer. The limiting current density indicates a polarization voltage as high as 5V, as shown in the test results. Figure 10 As shown.

[0095] Comparative Example 2 This comparative example prepared Li 1.6 Ta 0.7 In 0.3 A solid-state battery with a Cl6||LPSCl halide-sulfide structure was used, but the negative electrode protective layer was replaced with LPSCl sulfide; other steps were the same as in Example 1. Due to interface instability, the cycle life curve showed a retention rate of only 4.6% after 500 cycles. The test results are as follows. Figure 11 As shown.

[0096] Table 1 shows the battery stability test results and limiting current density results of the bilayer halide all-solid-state batteries in Examples 1-4.

[0097] Table 1 As can be seen from Table 1, the bilayer halide all-solid-state batteries prepared in Examples 1-4 have high specific capacity, cycle life and limiting current density, which shows that the present invention can improve interface stability and all-solid-state battery stability through the design of bilayer halide structure.

[0098] As can be seen from the comparison of Comparative Examples 1-2 and Example 1 above, compared with single-layer halide all-solid-state batteries and halide-sulfide structure all-solid-state batteries, the all-solid-state battery designed by the present invention with a double-layer halide structure is stable at high current density for the negative electrode, and has long cycle stability when assembling an all-solid-state battery with a positive electrode. This indicates that the design of the double-layer halide structure is the preferred solution to improve interface stability and the stability of all-solid-state batteries.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An interface-stable bilayer halide electrolyte, characterized in that, The double-layer halide electrolyte is an electrolyte layer and a negative electrode protective layer. The bilayer halide electrolyte is Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Cl6, Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.25 Nd 0.33 Cl6, Na 1.8 Ta 0.6 In 0.4 Cl6||Na 2.5 Y 0.5 Hf 0.5 Cl6 or Li 1.6 Ta 0.7 In 0.3 Cl6||Li 2.5 Y 0.5 Hf 0.5 Cl 5.5 Br 0.5 ; The electrolyte layer Li 1.6 Ta 0.7 In 0.3 The conductivity of Cl6 is ≥2×10⁻⁶. -3 S / cm, the electrolyte layer Na 1.8 Ta 0.6 In 0.4 The conductivity of Cl6 is ≥5×10⁻⁶. -4 S / cm; The preparation method of the bilayer halide electrolyte includes the following steps: S1. Under an inert gas atmosphere, a lithium halide or sodium halide is mixed with a Ta halide and an In halide, and ZrO2 ball milling beads are added for ball milling to obtain a first mixed powder; under an inert gas atmosphere, the first mixed powder is sieved, and the sieved first mixed powder is pressed into a tablet to obtain a first tablet; the first tablet is sintered under vacuum to obtain an electrolyte layer. S2. Under an inert gas atmosphere, a lithium halide salt or a sodium halide salt, yttrium chloride and a Hf halide salt or a Hf halide salt and a Nd halide salt are mixed, and ZrO2 ball milling beads are added for ball milling to obtain a second mixed powder; under an inert gas atmosphere, the second mixed powder is sieved, and the sieved second mixed powder is pressed into a tablet to obtain a second tablet; the second tablet is sintered under vacuum conditions to obtain a negative electrode protective layer; S3. The electrolyte layer and the negative electrode protective layer are stacked to obtain a double-layer halide electrolyte; In steps S1 and S2, the ball mill is first rotated at a low speed of 80 rpm to 120 rpm for 20 min to 40 min, and then rotated at a speed of 450 rpm to 550 rpm for 1.5 h to 20 h. In steps S1 and S2, the sintering temperature is 100℃-600℃, the heating rate is 0.1℃ / min-10℃ / min, and the sintering time is 0.5h-36h.

2. The bilayer halide electrolyte according to claim 1, characterized in that, The conditions for ball milling in steps S1 and S2 include: the diameter of the ZrO2 ball milling beads is 3 mm and 5 mm, and the mass ratio of ZrO2 ball milling beads to raw materials is 10:1-40:1; The tableting conditions in steps S1 and S2 include: a tableting pressure of 100 MPa-400 MPa and a holding time of 30 s-10 min; In step S3, the electrolyte layer and the negative electrode protective layer are laminated by cold pressing or hot pressing.

3. An all-solid-state battery, characterized in that, Includes the bilayer halide electrolyte as described in any one of claims 1 to 2.

4. The all-solid-state battery according to claim 3, characterized in that, The all-solid-state battery also includes a positive electrode and a negative electrode, and the bilayer halide electrolyte is disposed between the positive electrode and the negative electrode.

5. The all-solid-state battery according to claim 4, characterized in that, The all-solid-state battery is either an all-solid-state lithium-ion battery or an all-solid-state sodium-ion battery.

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