Inorganic halide solid electrolyte, method for producing the same, and all-solid battery

Abstract

The application belongs to the technical field of new energy materials, and specifically discloses an inorganic halide solid electrolyte, a preparation method thereof and a full solid battery. The application first grinds and mixes LiCl, InCl3 and HfCl4 under a protective atmosphere to obtain a mixture; keeps the protective atmosphere, and sequentially performs ball milling and tablet pressing on the mixture to obtain a precursor tablet; then vacuum seals and sinter the precursor tablet to obtain the inorganic halide solid electrolyte Li 2.7 In 0.7 Hf 0.3 Cl6. The application introduces a higher valence Hf 4+ Into the crystal lattice of Li3InCl6, generates a certain Li + Defect vacancy, and provides more migration paths for Li + Transmission. The introduction of Hf 4+ Greatly improves the ion conductivity of the solid electrolyte, and the electrochemical performance and stability of the assembled full solid battery are also greatly improved.

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to an inorganic halide solid electrolyte, its preparation method, and an all-solid-state battery. Background Technology

[0002] In recent years, with the increasing demand for high-energy-density and high-safety energy storage systems, all-solid-state lithium batteries (ASSBs) that use non-flammable solid electrolytes to replace flammable liquid electrolytes have become a research focus in the new energy field. Among many inorganic solid electrolytes, halide solid electrolytes have shown great commercial application potential due to their wide electrochemical window, excellent high-voltage oxidation resistance, and good interfacial compatibility with high-voltage layered oxide cathodes. In the halide solid electrolyte system, lithium indium chloride (Li3InCl6) has attracted much attention due to its unique crystal structure and relatively good environmental tolerance. Compared with traditional yttrium-based halides (such as Li3YCl6), Li3InCl6 can even be synthesized using a simple liquid-phase method, greatly reducing production costs and process barriers. However, despite the above advantages of Li3InCl6, the following unresolved technical bottlenecks still exist in its commercial application: (1) The room temperature ionic conductivity is still insufficient: The room temperature ionic conductivity of pure phase Li3InCl6 is usually around 10. -4 The value is on the order of S / cm. While this is competitive among inorganic solid-state electrolytes, it is still insufficient to meet the kinetic requirements of all-solid-state batteries under fast charging and discharging (high rate) and low-temperature environments. The limitations of the ion transport channels restrict the development of Li... + Rapid migration.

[0003] (2) Structural and interface degradation during long-term cycling: During the long-term charge-discharge cycle of all-solid-state batteries, the lattice structure of pure-phase Li3InCl6 is prone to micro-stress and structural degradation due to repeated lithium ion insertion and extraction. At the same time, the electrochemical stability at the interface between the electrolyte and the positive and negative electrodes is difficult to maintain under long-term cycling, which easily leads to a continuous increase in interface impedance, and thus manifests as rapid decay of the full battery capacity and shortened cycle life.

[0004] To improve the ionic conductivity of inorganic solid electrolytes, heterovalent element doping is considered an effective modification strategy. By introducing high-valence metal cations to replace existing lattice sites, lithium vacancies can be artificially introduced into the lattice, thereby widening ion transport channels and reducing migration barriers. However, due to differences in the ionic radius, electronegativity, and bonding characteristics of dopants, not all high-valence elements can simultaneously improve conductivity and maintain crystal structure stability. Introducing unsuitable dopants into Li3InCl6 not only fails to effectively improve conductivity but may also induce the formation of impurity phases, further deteriorating the battery's cycle performance. Furthermore, precise control of the doping amount is crucial to overcoming the shortcomings of existing technologies. If the doping amount of high-valence elements is too low, the concentration of lithium vacancies introduced into the lattice is insufficient to form a continuous three-dimensional ion transport network, making it difficult to achieve a substantial leap in room-temperature ionic conductivity. Conversely, if the doping amount is too high, excessive heterovalent ions will induce severe lattice stress and distortion, exceeding the solid solution limit of the material, leading to framework structure collapse or the formation of a large number of insulating impurity phases. These impurity phases not only become physical obstacles to ion transport, but also exacerbate side reactions at the electrolyte-electrode interface during long-term cycling, leading to a sharp increase in interfacial impedance.

[0005] Therefore, finding a suitable doping element to lattice-control Li3InCl6, which can effectively introduce lithium vacancies, significantly improve its room temperature ionic conductivity, stabilize its crystal structure, and suppress interfacial side reactions, thereby significantly improving the long-cycle stability and overall electrochemical performance of all-solid-state batteries, is a key unsolved technical problem in the field of halide solid electrolytes. Summary of the Invention

[0006] In view of this, the present invention provides an inorganic halide solid electrolyte and its preparation method and an all-solid-state battery, to solve the technical defects of existing Li3InCl6 solid electrolytes, such as low room temperature ionic conductivity and easy structural degradation and increased interfacial impedance during long-term cycling of all-solid-state batteries, which leads to excessively rapid capacity decay.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An inorganic halide solid electrolyte, wherein the chemical formula of the inorganic halide solid electrolyte is Li 2.7 In 0.7 Hf 0.3 Cl6.

[0008] Another object of the present invention is to provide a method for preparing an inorganic halide solid electrolyte, comprising the following steps: 1) LiCl, InCl3, and HfCl4 were ground and mixed under a protective atmosphere to obtain a mixture; 2) Maintaining a protective atmosphere, the mixture is sequentially ball-milled and compressed to obtain precursor tablets; 3) Vacuum seal the precursor sheet, and then sinter the vacuum-sealed precursor sheet to obtain an inorganic halide solid electrolyte.

[0009] Preferably, the molar ratio of LiCl, InCl3, and HfCl4 in step 1) is 2.7:0.7:0.3; The grinding and mixing time is 15-30 minutes.

[0010] Preferably, the conditions for ball milling in step 2) include: a ball milling speed of 300~500 rpm, a ball milling time of 5~10 h, a ball milling medium of zirconia beads with a diameter of 5~10 mm, and a ball-to-material ratio of 20~30:1.

[0011] Preferably, the pressure of the tablet compression in step 2) is 8~10MPa.

[0012] Preferably, the sintering temperature in step 3) is 300~500℃ and the sintering time is 5~10h.

[0013] Preferably, the protective atmosphere described in steps 1) and 2) independently includes one or more of argon atmosphere, helium atmosphere and nitrogen atmosphere.

[0014] Another object of the present invention is to provide an all-solid-state battery, comprising a positive electrode, a negative electrode, and an electrolyte; The electrolyte is the aforementioned inorganic halide solid electrolyte; The method for preparing the all-solid-state battery includes: An inorganic halide solid electrolyte is placed in a solid-state battery mold and pressed into a sheet to serve as the electrolyte. Then, a positive electrode material is placed on the surface of the pressed solid electrolyte and pressed into a sheet to prepare the positive electrode. A lithium indium metal sheet is then placed on the other surface of the solid electrolyte and pressed into a sheet to prepare the negative electrode, thus obtaining an all-solid-state battery.

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. This invention introduces Hf into the Li3InCl6 lattice. 4+ Replace part In 3+ By utilizing the charge compensation mechanism of heterovalent doping, a large number of uniformly distributed lithium-ion vacancies (V`Li) were introduced into the crystal lattice. This not only broadened the three-dimensional transport channels of lithium ions but also lowered the ion migration energy barrier, thereby increasing the room-temperature ionic conductivity of the solid electrolyte to 1.25 × 10⁻⁶. -3 The S / cm ratio is nearly three times higher than that of undoped pure phase materials.

[0016] 2. The introduction of Hf element in this invention effectively stabilizes the anionic framework structure of Li3InCl6, alleviating volume expansion and lattice stress during charge and discharge. Simultaneously, this electrolyte maintains good chemical and electrochemical interfacial stability with the positive and negative electrode materials, suppressing interfacial side reactions. The all-solid-state battery assembled using this electrolyte retains a capacity of 74.3% after 100 cycles at 0.1C, more than twice that of pure-phase materials (capacity retention of 32% after 100 cycles at 0.1C), demonstrating excellent long cycle life. It is particularly important to note that the superior long cycle life and structural stability achieved in this invention are highly dependent on the amount of specific elements introduced and their atomic stoichiometry (Li... 2.7 In 0.7 Hf 0.3 Cl6). From a microscopic perspective, Hf 4+ Replace In 3+ This method involves heterovalent substitution, and based on a charge compensation mechanism, this specific stoichiometric ratio induces an optimal concentration of lithium-ion vacancies in the crystal lattice, thereby constructing the most efficient three-dimensional ion transport network. If the amount of Hf introduced is too low, the concentration of lithium vacancies generated in the crystal lattice will be insufficient, failing to overcome the bottleneck of ionic conductivity. Conversely, if the amount of Hf introduced is too high, excessive heterovalent cations will cause severe lattice stress and local structural distortion, not only destroying the intrinsic stability of the anionic framework but also easily inducing impurity phase precipitation, thereby exacerbating interfacial side reactions and leading to a precipitous decline in cycle life. Therefore, the specific atomic stoichiometric ratio of Hf 0.3, In 0.7, and Li 2.7 in this invention is precisely at the golden balance point between widening ion channels and maintaining high lattice stability, which is the key to achieving high capacity retention after 100 cycles at 0.1C.

[0017] 3. The preparation method of the present invention, which combines mechanical ball milling and high-temperature sintering, is simple to operate, has low requirements for equipment, uses relatively inexpensive raw materials, and has good prospects for industrial application and large-scale production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 Li, as in Example 1 2.7 In 0.7 Hf 0.3XRD comparison of Cl6 inorganic halide solid electrolyte and pure phase Li3InCl6 inorganic halide solid electrolyte; Figure 2 XRD patterns of inorganic halide solid electrolytes for Comparative Examples 1 and 2; Figure 3 Li, as in Example 1 2.7 In 0.7 Hf 0.3 Electrochemical impedance spectroscopy of Cl6 inorganic halide solid electrolyte and pure phase Li3InCl6 inorganic halide solid electrolyte; Figure 4 Electrochemical impedance spectroscopy (EIS) spectra of inorganic halide solid electrolytes from Comparative Examples 1 and 2 are shown. Figure 5 Long-cycle performance of an all-solid-state battery assembled with a pure-phase Li3InCl6 inorganic halide solid electrolyte; Figure 6 Li, as in Example 1 2.7 In 0.7 Hf 0.3 Long-cycle performance of an all-solid-state battery assembled with Cl6 inorganic halide solid electrolyte; Figure 7 Li, for Comparative Example 1 2.8 In 0.8 Hf 0.2 Long-cycle performance of an all-solid-state battery assembled with Cl6 inorganic halide solid electrolyte; Figure 8 Li for Comparative Example 2 2.6 In 0.6 Hf 0.4 Long-cycle performance of an all-solid-state battery assembled with Cl6 inorganic halide solid electrolyte. Detailed Implementation

[0020] This invention provides an inorganic halide solid electrolyte, wherein the chemical formula of the inorganic halide solid electrolyte is Li. 2.7 In 0.7 Hf 0.3 Cl6. Through extensive research, this invention has strictly limited the doping amount. This specific doping ratio can maximize the widening of ion transport channels while perfectly maintaining and stabilizing the structural integrity of the anion framework, which is the key to achieving long-cycle stability and high ionic conductivity in all-solid-state batteries.

[0021] This invention also provides a method for preparing an inorganic halide solid electrolyte, comprising the following steps: 1) LiCl, InCl3, and HfCl4 were ground and mixed under a protective atmosphere to obtain a mixture; 2) Maintaining a protective atmosphere, the mixture is sequentially ball-milled and compressed to obtain precursor tablets; 3) Vacuum seal the precursor sheet, and then sinter the vacuum-sealed precursor sheet to obtain an inorganic halide solid electrolyte.

[0022] In this invention, the molar ratio of LiCl, InCl3, and HfCl4 in step 1) is 2.7:0.7:0.3.

[0023] In this invention, the grinding and mixing time is 15-30 min, specifically 16 min, 18 min, 20 min, 22 min, 25 min, or 28 min.

[0024] In this invention, the ball milling conditions in step 2) include: a ball milling speed of 300-500 rpm, specifically 320 rpm, 350 rpm, 380 rpm, 400 rpm, 420 rpm, 450 rpm, or 480 rpm; a ball milling time of 5-10 h, specifically 6 h, 7 h, 8 h, or 9 h; a ball milling medium of zirconia beads with a diameter of 5-10 mm, specifically 6 mm, 7 mm, 8 mm, or 9 mm; and a ball-to-material ratio of 20-30:1, preferably 25-30:1, and more preferably 30:1.

[0025] In this invention, the pressing pressure in step 2) is 8~10MPa, specifically 8.2MPa, 8.4MPa, 8.5MPa, 8.6MPa, or 8.8MPa. The purpose of pressing in this invention is to form the electrolyte into a dense sheet, which is then placed in a Pyrex tube and sealed for sintering, ensuring uniform heating.

[0026] In this invention, the tablet is preferably formed into an electrolyte tablet using a hydraulic press under the above pressure, and then left to stand for 3 to 5 minutes, specifically 3.2 minutes, 3.5 minutes, 3.8 minutes, 4 minutes, 4.2 minutes, 4.5 minutes, or 4.8 minutes.

[0027] In this invention, the sintering temperature in step 3) is 300~500℃, specifically 320℃, 350℃, 380℃, 400℃, 420℃, 450℃, or 480℃; the sintering time is 5~10h, specifically 6h, 7h, 8h, or 9h.

[0028] In this invention, the protective atmosphere described in steps 1) and 2) independently includes one or more of argon atmosphere, helium atmosphere and nitrogen atmosphere.

[0029] The present invention also provides an all-solid-state battery, comprising a positive electrode, a negative electrode and an electrolyte; wherein the electrolyte is the aforementioned inorganic halide solid electrolyte.

[0030] In this invention, the method for preparing the all-solid-state battery includes: An inorganic halide solid electrolyte is placed in a solid-state battery mold and pressed into a sheet to serve as the electrolyte. Then, a positive electrode material is placed on the surface of the pressed solid electrolyte and pressed into a sheet to prepare the positive electrode. A lithium indium metal sheet is then placed on the other surface of the solid electrolyte and pressed into a sheet to prepare the negative electrode, thus obtaining an all-solid-state battery.

[0031] In this invention, the cathode material is preferably a commercial NCM811 cathode material.

[0032] In this invention, the mass ratio of the inorganic halide solid electrolyte to the positive electrode material and the negative electrode material is preferably 80~120mg:10~15mg:1~2mg, more preferably 90~110:11~14:1.2~1.8, and even more preferably 100:12:1.5; the negative electrode material refers to lithium indium metal sheet.

[0033] In this invention, the pressing pressure of the inorganic halide solid electrolyte is preferably 8~10 MPa, specifically 8.2 MPa, 8.5 MPa, 8.8 MPa, 9 MPa, 9.2 MPa, 9.5 MPa, or 9.8 MPa; the pressing pressure of the positive electrode material is preferably 6~8 MPa, specifically 6.2 MPa, 6.5 MPa, 6.8 MPa, 7 MPa, 7.2 MPa, 7.5 MPa, or 7.8 MPa; and the pressing pressure of the lithium indium metal sheet is preferably 2~3 MPa, specifically 2.2 MPa, 2.5 MPa, or 2.8 MPa.

[0034] In this invention, after the all-solid-state battery is assembled, it is preferably left to stand for 5 to 12 hours, specifically 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 11 hours.

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] LiCl, InCl3, and HfCl4 were weighed according to a stoichiometric ratio of 2.7:0.7:0.3 and ground in an agate mortar for 15 minutes. The mixture was then transferred to a ball mill jar, and 5mm diameter zirconia beads were added at a ball-to-material ratio of 30:1. The mixture was ball-milled at 500 rpm for 5 hours. The milled precursor material was then pressed into precursor sheets using a hydraulic press under a pressure of 10 MPa and allowed to stand for 5 minutes. The pressed sheets had a diameter of 10mm. The precursor sheets were then vacuum-sealed in Pyrex tubes and placed in a muffle furnace for high-temperature sintering. The specific process parameters were: heating from room temperature to 350℃ at a rate of 5℃ / min, maintaining the temperature for 5 hours, and then naturally cooling to room temperature to obtain LiCl. 2.7 In 0.7 Hf 0.3 Cl6 is an inorganic halide solid electrolyte. All the above operations were performed in a glove box filled with argon gas.

[0038] The Li obtained in this embodiment 2.7 In 0.7 Hf 0.3 The XRD comparison diagrams of Cl6 inorganic halide solid electrolyte and pure phase Li3InCl6 inorganic halide solid electrolyte are shown below. Figure 1 As shown, through Figure 1 It can be seen that the doped Li 2.7 In 0.7 Hf 0.3 The main characteristic diffraction peaks of Cl6 and pure phase Li3InCl6 are highly coincident and have sharp peak shapes. Figure 1 No obvious new impurity peaks were observed; this fully demonstrates that high-valence Hf ions have successfully entered the crystal lattice and replaced some In ions, forming a uniform solid solution; this specific doping ratio perfectly preserves the high crystallinity and structural stability of the material without destroying the original anionic framework structure of the crystal or inducing the precipitation of insulating impurity phases.

[0039] Comparative Example 1

[0040] The only difference between this comparative example and Example 1 is that the stoichiometric ratio of LiCl, InCl3, and HfCl4 is adjusted to 2.8:0.8:0.2, resulting in the preparation of Li 2.8 In 0.8 Hf 0.2 Cl6 is an inorganic halide solid electrolyte.

[0041] Comparative Example 2

[0042] The only difference between this comparative example and Example 1 is that the stoichiometric ratio of LiCl, InCl3, and HfCl4 is adjusted to 2.6:0.6:0.4, resulting in the preparation of Li... 2.6 In 0.6 Hf0.4 Cl6 is an inorganic halide solid electrolyte.

[0043] The XRD patterns of the inorganic halide solid electrolytes obtained in Comparative Examples 1 and 2 are shown below. Figure 2 As shown, through Figure 2 It can be seen that when the doping amount of Hf element is low (i.e., Li in Comparative Example 1), 2.8 In 0.8 Hf 0.2 Cl6), its XRD diffraction pattern is similar to that of Example 1, with no obvious impurity peaks, indicating that the material can still maintain its original anionic framework structure under low doping levels; however, when the Hf doping level is too high (i.e., Li in Comparative Example 2), 2.6 In 0.6 Hf 0.4 In the XRD diffraction pattern of Cl6, in addition to the characteristic peaks of the main phase, obvious diffraction peaks of unknown impurities or HfCl4 byproducts also appeared. Simultaneously, the intensity of the main phase diffraction peaks decreased or broadened. This indicates that excessive heterovalent ion doping exceeded the solid solution limit of the crystal lattice, not only failing to maintain stable solid solution within the lattice but also inducing structural distortion and leading to the precipitation of insulating impurities. This comparative result further confirms, from a crystal structure perspective, the Li in Example 1... 2.7 In 0.7 Hf 0.3 The stoichiometric ratio of Cl6 is the optimal ratio for maintaining a highly stable framework and suppressing the formation of impurity phases.

[0044] Example 2

[0045] Take 80 mg of the inorganic halide solid electrolyte prepared in Example 1, place it in a solid battery mold, and press it into a sheet under a hydraulic press at 10 MPa; then, lay 10 mg of commercial NCM811 positive electrode material on the top layer of the electrolyte sheet, and press it under a hydraulic press at 6 MPa; then place the cut Li-In metal discs on the bottom layer of the electrolyte sheet, press them at 2 MPa, and fix all the screws of the solid electrolyte mold; let it stand for 10 hours to obtain the assembled all-solid-state battery. All the above operations were carried out in an argon-filled glove box.

[0046] Li prepared with pure phase Li3InCl6 and Comparative Example 1 respectively 2.8 In 0.8 Hf 0.2 Li prepared from Cl6 and Comparative Example 2 2.6 In 0.6 Hf 0.4 Cl6, as an inorganic halide solid electrolyte, was used in the same manner to prepare the corresponding solid-state battery.

[0047] Performance testing: Li obtained in Example 1 2.7 In 0.7 Hf 0.3 The electrochemical impedance spectroscopy spectra of Cl6 inorganic halide solid electrolyte and pure-phase Li3InCl6 inorganic halide solid electrolyte are as follows: Figure 3 As shown, through Figure 2 It can be seen that the inorganic halide solid electrolyte Li prepared in Example 1 2.7 In 0.7 Hf 0.3 The ionic conductivity of Cl6 differs significantly from that of the pure-phase inorganic halide solid electrolyte Li3InCl6, reaching 1.25 × 10⁻⁶ at room temperature. -3 The S / cm ratio indicates good performance. The electrochemical impedance spectroscopy spectra of Comparative Example 1 and Comparative Example 2 are shown below. Figure 4 As shown, through Figure 4 It can be seen that the Li prepared in Comparative Example 1 2.8 In 0.8 Hf 0.2 Li prepared from Cl6 and Comparative Example 2 2.6 In 0.6 Hf 0.4 Cl6, their ionic conductivity is 0.99×10 -3 S / cm and 1.18×10 -3 Compared to pure Li3InCl6, the ionic conductivity was improved to varying degrees in terms of S / cm, but it was still lower than that of Li prepared under the optimal stoichiometric ratio. 2.7 In 0.7 Hf 0.3 For Cl6, their ionic conductivity is further reduced. Specifically, in Comparative Example 1, due to the low Hf doping concentration, the concentration of lithium vacancies induced within the crystal lattice is insufficient, failing to fully construct a continuous and efficient ion transport network, resulting in a higher material impedance. In Comparative Example 2, the excessive Hf doping exceeds the solid solution limit, causing lattice distortion and the precipitation of insulating impurities that block the lithium-ion transport channels, leading to an increase in impedance. This electrochemical impedance behavior further confirms at the electrochemical performance level that only under a specific stoichiometric ratio can the optimal balance be achieved between maximizing ion channel widening and maintaining structural stability, thereby obtaining the lowest impedance and the highest room-temperature ionic conductivity.

[0048] The pure-phase Li3InCl6 inorganic halide solid electrolyte was used to assemble an all-solid-state battery according to the above method. Its long-cycle performance is shown in the figure below. Figure 5 As shown, the long-cycle performance diagram of the all-solid-state battery corresponding to the inorganic halide solid electrolyte in Example 1 is as follows. Figure 6 As shown in the figure, the long-cycle performance of the all-solid-state battery corresponding to the inorganic halide solid electrolyte of Comparative Example 1 is as follows: Figure 7As shown in the figure, the long-cycle performance of the all-solid-state battery corresponding to the inorganic halide solid electrolyte in Comparative Example 2 is as follows: Figure 8 As shown. (Through) Figures 5-8 It can be seen that the all-solid-state battery assembled from the inorganic halide solid electrolyte prepared in Example 1 and the pure-phase inorganic halide solid electrolyte exhibits significant differences in cycle performance. The all-solid-state battery corresponding to Example 1 retains 74% of its initial capacity after 100 cycles, while the capacity retention rates of Comparative Examples 1 and 2 after 100 cycles are only 60.16% and 22.43%, respectively, and the capacity retention rate of the pure-phase material is only about 32%. This significant data comparison intuitively shows that when the doping amount is too low, sufficient interconnected and efficient ion channels are not formed inside the electrolyte, resulting in limited kinetic performance of the all-solid-state battery during long-term cycling, and the capacity decays accordingly. When the doping amount is too high, severe lattice distortion and the precipitation of insulating impurity phases greatly damage the interfacial stability between the solid electrolyte and the positive and negative electrodes, leading to a continuous surge in interfacial impedance and a precipitous decline in cycle capacity. Its long-term cycle performance is even worse than that of the undoped pure-phase material. In summary, the macroscopic test data of long-cycle performance confirms that the specific atomic stoichiometry defined in Example 1 of this invention is the optimal critical point that balances high ionic conductivity and excellent interface stability, and has irreplaceable core significance for achieving long cycle life of all-solid-state batteries.

[0049] In addition, through Figures 5-8 It can be seen that, in terms of initial capacity, the first-cycle capacity of Example 1 is significantly higher than that of the pure phase and slightly higher than that of Comparative Examples 1 and 2. The assembly conditions and active material loading of all batteries in this invention are strictly consistent, and the differences in initial capacity can be directly attributed to the improvement of electrolyte kinetics by appropriate doping. Appropriate doping can optimize the crystal structure to build a highly efficient and interconnected three-dimensional ion transport network, significantly improving ionic conductivity and reducing initial interface polarization, allowing the positive electrode active material to be fully utilized, thereby achieving peak capacity in the first cycle. Excessive doping, on the other hand, will cause lattice distortion and precipitation of insulating impurities, disrupting solid-solid interface stability, leading to a surge in interface impedance and hindering lithium-ion transport kinetics, ultimately causing capacity decay in the first cycle.

[0050] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0051] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inorganic halide solid electrolyte, characterized in that, The inorganic halide solid electrolyte has the chemical formula Li 2.7 In 0.7 Hf 0.3 Cl6.

2. The method for preparing an inorganic halide solid electrolyte according to claim 1, characterized in that, Includes the following steps: 1) LiCl, InCl3, and HfCl4 were ground and mixed under a protective atmosphere to obtain a mixture; 2) Maintaining a protective atmosphere, the mixture is sequentially ball-milled and compressed to obtain precursor tablets; 3) Vacuum seal the precursor sheet, and then sinter the vacuum-sealed precursor sheet to obtain an inorganic halide solid electrolyte.

3. The method for preparing an inorganic halide solid electrolyte according to claim 2, characterized in that, The molar ratio of LiCl, InCl3, and HfCl4 mentioned in step 1) is 2.7:0.7:0.3; The grinding and mixing time is 15-30 minutes.

4. The method for preparing an inorganic halide solid electrolyte according to claim 3, characterized in that, The conditions for ball milling described in step 2) include: a ball milling speed of 300~500 rpm, a ball milling time of 5~10 h, a ball milling medium of zirconia beads with a diameter of 5~10 mm, and a ball-to-material ratio of 20~30:

1.

5. The method for preparing an inorganic halide solid electrolyte according to claim 4, characterized in that, The pressure for tablet compression in step 2) is 8~10MPa.

6. A method for preparing an inorganic halide solid electrolyte according to any one of claims 2 to 4, characterized in that, The sintering temperature in step 3) is 300~500℃, and the sintering time is 5~10h.

7. The method for preparing an inorganic halide solid electrolyte according to claim 6, characterized in that, The protective atmosphere described in steps 1) and 2) independently includes one or more of argon atmosphere, helium atmosphere and nitrogen atmosphere.

8. An all-solid-state battery, characterized in that, Includes positive electrode, negative electrode, and electrolyte; The electrolyte is the inorganic halide solid electrolyte as described in claim 1; The method for preparing the all-solid-state battery includes: An inorganic halide solid electrolyte is placed in a solid-state battery mold and pressed into a sheet to serve as the electrolyte. Then, a positive electrode material is placed on the surface of the pressed solid electrolyte and pressed into a sheet to prepare the positive electrode. A lithium indium metal sheet is then placed on the other surface of the solid electrolyte and pressed into a sheet to prepare the negative electrode, thus obtaining an all-solid-state battery.

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