Oxyhalide solid-state electrolyte, preparation method therefor, and battery

Abstract

An oxyhalide solid-state electrolyte, a preparation method therefor, and a battery. The general formula of the oxyhalide solid-state electrolyte is Li 2a+bM bO aX' cX" d, wherein M is selected from Ta, In, or Zr, X is selected from the halogens, 0.5≤a≤1.6, 1≤b≤1.5, 5≤c+d≤7.5, and both c and d are numbers greater than or equal to 0. In a humid environment, the ionic conductivity of the oxyhalide solid-state electrolyte is reduced by very little in comparison to when same is in a dry environment, and the oxyhalide solid-state electrolyte still has good ionic conductivity.

Description

Oxyhalide solid electrolyte, preparation method thereof, and battery Technical Field

[0001] The present application relates to the field of electrolyte technology, and in particular to an oxyhalide solid electrolyte, a preparation method thereof, and a battery. Background Art

[0002] Lithium-ion batteries have undergone extensive research and development over the past few decades. Lithium-ion batteries primarily consist of a positive electrode, a negative electrode, an electrolyte, and a separator. The electrolyte is a crucial component of lithium-ion batteries, serving as a barrier to electronic conduction while establishing an ion conduction pathway between the positive and negative electrodes within the battery. Therefore, the electrochemical performance of a battery is closely related to the properties of the electrolyte.

[0003] Solid-state electrolyte (SSE) is a solid ion conductor electrolyte with the characteristics of high safety, no leakage of toxic organic liquids, low flammability, non-volatility, high mechanical stability, high thermal stability, easy processing, and low self-discharge rate. It is used to replace liquid electrolytes in lithium-ion batteries. Technical issues

[0004] However, the moisture resistance of existing solid electrolytes is poor and needs to be further improved. Technical Solutions

[0005] In view of this, the present application provides an oxyhalide solid electrolyte, aiming to improve the problem of poor moisture resistance of existing solid electrolytes.

[0006] The embodiment of the present application is implemented as follows: an oxyhalide solid electrolyte, the general formula of which is Li 2a+b M b O a X' c X” d , wherein M is selected from Ta, In or Zr, X is selected from halogen, wherein 0.5≤a≤1.6, 1≤b≤1.5, 5≤c+d≤7.5, and c and d are both numbers greater than 0.

[0007] Optionally, in some embodiments, the halogen includes one or more of F, Cl, and Br.

[0008] Optionally, in some embodiments, the range of a is 0.5≤a≤0.8; and / or

[0009] The range of b is 1≤b≤1.2; and / or

[0010] The range of c+d is 5≤c+d≤6.8.

[0011] Optionally, in some embodiments, the general formula of the oxyhalide solid electrolyte is Li 2.5 Ta 1.1 O 0.7 Cl 6.1 F 0.5 、Li2TaO 0.5 Cl 5.6 F 0.4 、Li 3.2 Zr 1.2 One or more of OCl5Br, Li4Zr2OCl8F2.

[0012] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 10.7 to 11.8 mS / cm when the relative humidity is 0%.

[0013] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 9.1 to 10.9 mS / cm at a relative humidity of 5%.

[0014] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 10.5 to 10.7 mS / cm at a relative humidity of 10%.

[0015] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 8.0 to 10.1 mS / cm at a relative humidity of 15%.

[0016] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 7.1 to 10.0 mS / cm at a relative humidity of 20%.

[0017] Optionally, in some embodiments, the ionic conductivity of the oxyhalide solid electrolyte is in the range of 5.9 to 7.5 mS / cm at a relative humidity of 30%.

[0018] Accordingly, the present application also provides a method for preparing an oxyhalide solid electrolyte, comprising the following steps:

[0019] A first metal halide, a second metal halide, a third metal halide, and lithium oxide are mixed to obtain a mixture, wherein the chemical formula of the first metal halide is LiX', and the chemical formula of the second metal halide is MX' m , the chemical formula of the third metal halide is MX" n , X' and X" are each independently selected from halogen, and X' and X" are different, M is selected from Ta, In or Zr, and m and n are each independently selected from any integer from 1 to 5;

[0020] ball milling the mixture to obtain an oxyhalide solid electrolyte precursor;

[0021] The oxyhalide solid electrolyte precursor is annealed to obtain an oxyhalide solid electrolyte.

[0022] Optionally, in some embodiments, the molar ratio of the lithium oxide, the first metal halide, the second metal halide, and the third metal halide is (0.01-2):(0.01-2):(0.1-1.5):(0.1-1.5).

[0023] Optionally, in some embodiments, the mass ratio of the ball milling beads to the mixture is in the range of (8-20):1.

[0024] Optionally, in some embodiments, the halogen includes F, Cl or Br.

[0025] Optionally, in some embodiments, the equipment used for ball milling is a planetary ball mill.

[0026] Optionally, in some embodiments, the ball milling speed is 500-700 rpm; and / or

[0027] The effective ball milling time is 70 to 200 hours.

[0028] Optionally, in some embodiments, the ratio of the ball milling rest time to the ball milling time is (0.1-1):1.

[0029] Optionally, in some embodiments, the annealing temperature is 100-300° C., and the annealing time is 30-180 min.

[0030] Optionally, in some embodiments, the mixing is performed under a protective atmosphere, and the gas in the protective atmosphere includes one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0031] Correspondingly, the present application also provides a battery comprising the oxyhalide solid electrolyte. Beneficial effects

[0032] The oxyhalide solid electrolyte described in the present application has good moisture resistance due to the synergistic effect of the elements and element ratios in the oxyhalide solid electrolyte. In this way, the ionic conductivity of the oxyhalide solid electrolyte in a humid environment decreases very little compared to that in a dry environment, while still having good ionic conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0034] FIG1 is a flow chart of a method for preparing an oxyhalide solid electrolyte provided in an embodiment of the present application;

[0035] FIG2 is an electrochemical impedance spectroscopy diagram of a battery prepared using the oxyhalide solid electrolyte of Example 1 of the present application;

[0036] FIG3 is an electrochemical impedance spectroscopy diagram of a battery prepared using the oxyhalide solid electrolyte of Example 8 of the present application;

[0037] FIG4 is an electrochemical impedance spectroscopy diagram of a battery prepared using the oxyhalide solid electrolyte of Example 10 of the present application;

[0038] FIG5 is an electrochemical impedance spectroscopy diagram of a battery prepared using the oxyhalide solid electrolyte of Comparative Example 1 of the present application;

[0039] FIG6 is an electrochemical impedance spectrum of a battery prepared from an oxyhalide solid electrolyte in Comparative Example 2 of the present application.

[0040] FIG7 is an electrochemical impedance spectroscopy diagram of a battery prepared using the oxyhalide solid electrolyte of Comparative Example 8 of the present application;

[0041] FIG8 is an XRD diagram of the oxyhalide solid electrolyte of Example 1 of the present application.

[0042] Implementation Methods of the Application

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0044] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in actual use or operation, specifically in the drawing directions of the accompanying drawings; whereas "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "including" means "including but not limited to." Terms such as first, second, and third are used merely as labels and do not impose numerical requirements or establish a sequence.

[0045] In this application, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0046] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0047] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0048] Existing solid electrolytes include oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes. Oxide solid electrolytes offer extremely high ionic conductivity and electrochemical windows, but struggle to balance mechanical properties. High-temperature sintering during actual battery fabrication can easily lead to unexpected adverse interfacial reactions. Sulfide solid electrolytes also offer extremely high ionic conductivity, but their poor air stability and environmental toxicity limit their rapid development and application. Furthermore, sulfide solid electrolytes are difficult to pair with currently popular high-voltage oxide cathode materials. Halide solid electrolytes, which are currently attracting renewed attention, offer high ionic conductivity, excellent mechanical properties, and good interfacial stability with ternary materials, making them promising candidates for high-energy-density, high-safety solid-state lithium batteries. However, existing halide solid electrolytes have poor moisture resistance, and their ionic conductivity decreases significantly in humid environments. In addition, the production process of halide solid electrolytes generally relies on high-energy ball milling and annealing processes. However, in order to achieve ideal physical and chemical properties, the ball milling equipment that provides mechanochemical reactions is often extremely expensive, and non-specific phase halides are often unstable after annealing, showing low ionic conductivity and repeatability.

[0049] The technical solution of this application is as follows:

[0050] In the first aspect, the present invention provides an oxyhalide solid electrolyte having the general formula Li 2a+b M b O a X' c X” d , wherein M is selected from Ta, In or Zr, X is selected from halogen, wherein 0.5≤a≤1.6, 1≤b≤1.5, 5≤c+d≤7.5, and c and d are both numbers greater than 0.

[0051] It can be understood that in some embodiments, one of c and d can be 0. In this case, the oxyhalide solid electrolyte includes only one halogen.

[0052] The halogen includes but is not limited to one or more of F, Cl, and Br.

[0053] In some embodiments, a may be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, etc. In at least one preferred embodiment, a is in the range of 0.5≤a≤0.8.

[0054] In some embodiments, b may be 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, etc. In at least one preferred embodiment, the range of b is 1≤a≤1.2.

[0055] In some embodiments, c+d may be 5, 5.2, 5.5, 5.6, 5.8, 6, 6.2, 6.4, 6.5, 6.7, 6.8, 7, 7.2, 7.4, 7.5, etc. In at least one preferred embodiment, the range of c+d is 5≤c+d≤6.8.

[0056] As an example, in some embodiments, the general formula of the oxyhalide solid electrolyte is Li 2.5 Ta 1.1 O 0.7 Cl 6.1 F 0.5 、Li2TaO 0.5 Cl 5.6 F 0.4 、Li 3.2 Zr 1.2 One or more of OCl5Br, Li4Zr2OCl8F2.

[0057] The ionic conductivity of the oxyhalide solid electrolyte is in the range of 10.7 to 11.8 mS / cm when the relative humidity (RH) is 0%.

[0058] The ionic conductivity of the oxyhalide solid electrolyte at a relative humidity (RH) of 5% ranges from 9.1 to 10.9 mS / cm, for example, 9.1 mS / cm, 8.5 mS / cm, 9.8 mS / cm, 10.0 mS / cm, 10.2 mS / cm, 10.5 mS / cm, 10.9 mS / cm, etc.

[0059] The ionic conductivity of the oxyhalide solid electrolyte at a relative humidity (RH) of 10% is in the range of 10.5 to 10.7 mS / cm, for example, 10.5 mS / cm, 10.6 mS / cm, 10.7 mS / cm, etc.

[0060] The ionic conductivity of the oxyhalide solid electrolyte at a relative humidity (RH) of 15% ranges from 8.0 to 10.1 mS / cm, for example, 8.0 mS / cm, 8.2 mS / cm, 8.5 mS / cm, 8.8 mS / cm, 9.0 mS / cm, 9.2 mS / cm, 9.5 mS / cm, 9.8 mS / cm, 10.0 mS / cm, 10.1 mS / cm, etc.

[0061] The ionic conductivity of the oxyhalide solid electrolyte at a relative humidity (RH) of 20% is in the range of 7.1 to 10.0 mS / cm, for example, 7.1 mS / cm, 7.2 mS / cm, 7.5 mS / cm, 7.6 mS / cm, 7.8 mS / cm, 8.0 mS / cm, 8.5 mS / cm, 8.6 mS / cm, 9.0 mS / cm, 9.2 mS / cm, 9.4 mS / cm, 9.6 mS / cm, 9.8 mS / cm, 10.0 mS / cm, etc.

[0062] The ionic conductivity of the oxyhalide solid electrolyte at a relative humidity (RH) of 30% ranges from 5.9 to 7.5 mS / cm, for example, 5.9 mS / cm, 6.0 mS / cm, 6.2 mS / cm, 6.4 mS / cm, 6.5 mS / cm, 6.6 mS / cm, 6.8 mS / cm, 7.0 mS / cm, 7.2 mS / cm, 7.3 mS / cm, 7.5 mS / cm, etc.

[0063] The oxyhalide solid electrolyte described in the present application has good moisture resistance due to the synergistic effect of the elements and element ratios in the oxyhalide solid electrolyte. In this way, the ionic conductivity of the oxyhalide solid electrolyte in a humid environment decreases very little compared to that in a dry environment, while still having good ionic conductivity.

[0064] In the second aspect, referring to FIG1 , the present embodiment further provides a method for preparing an oxyhalide solid electrolyte, comprising the following steps:

[0065] Step S11: mixing a first metal halide, a second metal halide, a third metal halide, and lithium oxide to obtain a mixture, wherein the chemical formula of the first metal halide is LiX', and the chemical formula of the second metal halide is MX' m , the chemical formula of the third metal halide is MX" n , X' and X" are each independently selected from halogen, and X' and X" are different, M is selected from Ta, In or Zr, and m and n are each independently selected from any integer from 1 to 5;

[0066] Step S12, ball milling the mixture to obtain an oxyhalide solid electrolyte precursor;

[0067] Step S13: annealing the oxyhalide solid electrolyte precursor to obtain an oxyhalide solid electrolyte.

[0068] In the step S11:

[0069] The molar ratio of the lithium oxide, the first metal halide, the second metal halide, and the third metal halide is (0.01-2):(0.01-2):(0.1-1.5):(0.1-1.5). Within the above mass ratio range, an oxyhalide solid electrolyte with good moisture resistance and high ionic conductivity is prepared.

[0070] The halogen includes, but is not limited to, F, Cl or Br.

[0071] In some embodiments, the mixing is performed under a protective atmosphere, and the gas in the protective atmosphere may be, but is not limited to, one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0072] In the step S12:

[0073] In some embodiments, the equipment used for ball milling is a planetary ball mill, which can effectively reduce the cost of ball milling.

[0074] In some embodiments, the ball milling beads are zirconia.

[0075] In some embodiments, the mass ratio of ball milling beads to the mixture is in the range of (8-20):1. When the ball milling bead to powder ratio is lower than this range, the impact energy is low, the mechanochemical reaction is insufficient, and an ordered crystal-amorphous phase cannot be formed. When the ball milling bead to powder ratio is higher than this range, the possibility of excessive crystal transformation increases, which may reduce the ionic conductivity of the product. In addition, an excessively high ball milling bead to powder ratio may lead to low equipment efficiency.

[0076] In some embodiments, the ball milling speed is 500-700 rpm, for example, 500 rpm, 530 rpm, 550, 580 rpm, 600 rpm, 620 rpm, 650 rpm, 670 rpm, 700 rpm, etc., and the effective ball milling time (i.e., the total time of the entire ball milling process minus the rest time) is 70-200 h, for example, 70 h, 100 h, 120 h, 130 h, 140 h, 150 h, 160 h, 180 h, 200 h, etc. Within the speed and time range, the efficiency of the mechanochemical reaction can be increased, which is conducive to obtaining an oxyhalide solid electrolyte with good moisture resistance.

[0077] In some embodiments, the ratio of the rest time to the ball milling time is (0.1-1):1, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, etc. Within the range, when the rest ratio is lower than this interval, more time is spent on ball milling, which in turn causes some particles to stick to the wall, i.e., reduces contact and collision, affecting the ball milling effect; and when the rest ratio is higher than this interval, the effective ball milling time is shorter and the ball milling efficiency is lower.

[0078] In step S13:

[0079] The annealing temperature is 100-300°C, for example, 100°C, 120°C, 130°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C, 260°C, 280°C, 300°C, etc., and the annealing time is 30-180min, for example, 30min, 60min, 80min, 100min, 120min, 150min, 160min, 180min, etc. Within the temperature and time range, the formation of the oxyhalide solid electrolyte crystal segment portion can be effectively promoted, and the ionic conductivity and moisture resistance of the oxyhalide solid electrolyte can be increased. Too high or too low will cause the ionic conductivity to drop rapidly in performance, or even fail to form the target product.

[0080] The preparation method of the oxyhalide solid electrolyte described in the present application can prepare an oxyhalide solid electrolyte with good moisture resistance by using a first metal halide, a second metal halide, a third metal halide, and lithium oxide in a specific ratio, through ball milling and annealing, so that the prepared oxyhalide solid electrolyte can still have good ionic conductivity in a humid environment.

[0081] In a third aspect, an embodiment of the present application further provides a battery comprising the oxyhalide solid electrolyte described above.

[0082] The present application will be described in detail below through specific examples. The following examples are only some examples of the present application and are not limitations of the present application.

[0083] Example 1

[0084] In an argon atmosphere, lithium oxide Li2O, a first metal halide LiCl, a second metal halide TaCl5, and a third metal chloride LiF are mixed in a molar ratio of 0.7:0.6:1.1:0.5 to obtain a mixture;

[0085] The mixture was added to a ball mill of a planetary ball mill, wherein the mass ratio of ball milling beads to the mixture was 15:1, and the ball milling beads were zirconium oxide. The ball mill was completely evacuated, and then the ball mill was placed in air and ball milled at a speed of 630 rpm, a rest time to ball milling ratio of 1:0.5, and an effective ball milling time of 150 h to obtain an oxyhalide solid electrolyte precursor.

[0086] The oxyhalide solid electrolyte precursor was taken out under the protection of an argon atmosphere, and transferred to a muffle furnace equipped in an argon atmosphere for high-temperature annealing. The annealing temperature was 250° C. and the annealing time was 60 min to obtain an oxyhalide solid electrolyte.

[0087] The oxyhalide solid electrolyte of this embodiment is Li 2.5 Ta 1.1 O 0.7 Cl 6.1 F 0.5 .

[0088] Example 2

[0089] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the molar ratio of Li2O, LiCl, TaCl5, and LiF is 0.5:0.6:1.0:0.4.

[0090] The oxyhalide solid electrolyte Li2TaO in this embodiment 0.5 Cl 5.6 F 0.4 .

[0091] Example 3

[0092] This embodiment is substantially the same as embodiment 1, except that in this embodiment, the second metal halide is ZrCl2, and the molar ratio of Li2O, LiCl, ZrCl4, and LiBr in this embodiment is 1.0:0.2:1.2:1.0.

[0093] The oxyhalide solid electrolyte in this embodiment is LiZrOCl4Br.

[0094] Example 4

[0095] This embodiment is basically the same as embodiment 1, except that, in this embodiment, the ball milling speed is 500 rpm.

[0096] Example 5

[0097] This embodiment is basically the same as embodiment 1, except that, in this embodiment, the ball milling speed is 700 rpm.

[0098] Example 6

[0099] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ball milling time is 70 hours.

[0100] Example 7

[0101] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ball milling time is 200 hours.

[0102] Example 8

[0103] This embodiment is basically the same as Example 1, except that, in this embodiment, the mass ratio of ball milling beads to the mixture is 8:1.

[0104] Example 9

[0105] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the mass ratio of the ball milling beads to the mixture is 20:1.

[0106] Example 10

[0107] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the annealing temperature is 300°C.

[0108] Example 11

[0109] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the annealing temperature is 100°C.

[0110] Example 12

[0111] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ratio of rest time to ball milling time is 1:1.

[0112] Example 13

[0113] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ratio of rest time to ball milling time is 1:0.1.

[0114] Example 14

[0115] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 0.5:0.5:1.0:0.5, and the oxyhalide solid electrolyte in this embodiment is Li2TaO 0.5 Cl 5.5 F 0.5 .

[0116] Example 15

[0117] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 1:0.5:1:0.5, and the oxyhalide solid electrolyte in this embodiment is Li3TaOCl 5.5 F 0.5 .

[0118] Comparative Example 1

[0119] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 0.4:0.1:0.5:0.4, and the oxyhalide solid electrolyte of this embodiment is Li 1.3 Ta 0.5 O 0.4 Cl 2.6 F 0.4 .

[0120] Comparative Example 2

[0121] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 2:1:1.6:0.6, and the oxyhalide solid electrolyte of this embodiment is Li 5.6 Ta 1.6 O2Cl9F 0.6 .

[0122] Comparative Example 3

[0123] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 0.3:0.1:0.7:0.6, and the oxyhalide solid electrolyte of this embodiment is Li 1.3 Ta 0.7 O 0.3 Cl 3.6 F 0.6 .

[0124] Comparative Example 4

[0125] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 1.7:1.0:1.6:0.6, and the oxyhalide solid electrolyte of this embodiment is Li5Ta 1.6 O 1.7 Cl9F 0.6 .

[0126] Comparative Example 5

[0127] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 0.2:0.2:0.6:0.4, and the oxyhalide solid electrolyte of this embodiment is LiTa 0.6 O 0.2 Cl 3.2 F 0.4 .

[0128] Comparative Example 6

[0129] This embodiment is basically the same as embodiment 1, except that in this embodiment, the molar ratio of Li2O, LiCl, TaCl5 and LiF is 2:1:2:1, and the oxyhalide solid electrolyte in this embodiment is Li6Ta2O2Cl 11 F.

[0130] Comparative Example 7

[0131] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the second metal halide TaCl 5 and the third metal chloride LiF are not included.

[0132] Comparative Example 8

[0133] This embodiment is substantially the same as embodiment 1, except that the third metal chloride LiF is not included in this embodiment.

[0134] Comparative Example 9

[0135] This embodiment is substantially the same as embodiment 1, except that annealing is not included in this embodiment.

[0136] Comparative Example 10

[0137] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ratio of rest time to ball milling time is 1:0.01.

[0138] Comparative Example 11

[0139] This embodiment is substantially the same as embodiment 1, except that, in this embodiment, the ratio of rest time to ball milling time is 1:0.15.

[0140] The ionic conductivities of the oxyhalide solid electrolytes of Examples 1 to 15 and Comparative Examples 1 to 11 were tested at relative humidity of 0%, 5%, 10%, 15%, 20%, and 30%, respectively. The test results are shown in Table 1.

[0141] The test method is as follows: the powdered electrolyte is placed in an airtight chamber with controlled humidity and gas, the powdered electrolyte is pressed into a sheet electrolyte to be tested at a pressure of 300 MPa, and then exposed to argon gas in a closed chamber with different humidity atmospheres for 12 hours, and the electrochemical impedance spectroscopy (EIS) test is performed after loading the mold battery.

[0142] Table 1:

[0143] From Table 1 we can see that:

[0144] Compared with the oxyhalide solid electrolytes of Comparative Examples 1 to 8, the oxyhalide solid electrolytes of Examples 1 to 15 have higher ionic conductivity at the same humidity, which shows that the oxyhalide solid electrolytes of the present application have good moisture resistance;

[0145] Compared with the oxyhalide solid electrolyte of Comparative Example 9, the oxyhalide solid electrolytes of Examples 1 to 15 have higher ionic conductivity at the same humidity. It can be seen that the annealing process can make the prepared oxyhalide solid electrolyte have better moisture resistance;

[0146] Compared with the oxyhalide solid electrolytes of Comparative Examples 10 to 11, the oxyhalide solid electrolytes of Examples 1 to 15 have higher ionic conductivity at the same humidity. It can be seen that within the rest and ball milling time ratio of the present application, the prepared oxyhalide solid electrolyte can have better moisture resistance.

[0147] Battery performance test

[0148] Battery composition: The positive electrode is LiNi8Co1Mn1O2, the electrolyte is the oxyhalide solid electrolyte of Example 1, and the positive electrode is Li 5.4 PS 4.4 Cl 1.6 Modified LiIn anode.

[0149] Testing method: The modified negative electrode, 20 mg of the oxyhalide solid electrolyte powders from Examples 1, 8, and 10, and Comparative Examples 1, 2, and 8, and the positive electrode material were placed in a 10 mm mold. The cold pressing and material addition process was repeated until the positive electrode was placed and compacted. Finally, electrochemical impedance spectroscopy (EIS) was performed at a given pressure of 50 MPa, resulting in the electrochemical impedance spectra (EIS graphs) shown in Figures 2 to 7.

[0150] It can be seen from Figures 2, 5 and 6 that when the values ​​of a and b are lower than the specified range, the ionic conductivity of the product powder decreases significantly, while when a and b are higher than the range, the decrease in ionic conductivity is relatively low.

[0151] As shown in Figures 3 and 4, the ball-to-powder ratio and annealing temperature have a significant effect on the ionic conductivity of the product powder.

[0152] As shown in FIG7 , when the additive does not contain the third metal halide, the ionic conductivity decreases significantly, indicating the necessity of adding the third metal halide.

[0153] The oxyhalide solid electrolyte in Example 1 was characterized by X-ray powder diffraction, and the XRD pattern shown in FIG8 was obtained.

[0154] Figure 8 shows that the phase structure of the oxyhalide solid electrolyte in Example 1 is a relatively pure single phase, with both crystalline and amorphous phases coexisting. The crystalline phase is primarily formed by mechanochemical reactions and annealing. Previous research suggests that a mixed crystalline-amorphous phase system can provide improved Li-ion conductivity, and an appropriate crystalline phase ratio can also improve moisture resistance.

[0155] The above is a detailed introduction to the technical solutions provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A kind of oxyhalide solid electrolyte, wherein, The general formula of the oxohalide solid electrolyte is Li 2a+b M b O a X’ c X” d , where M is selected from Ta, In or Zr, X is selected from halogens, 0.5 ≤ a ≤ 1.6, 1 ≤ b ≤ 1.5, 5 ≤ c + d ≤ 7.5, and both c and d are numbers greater than 0.

2. The oxohalide solid electrolyte according to claim 1, wherein The halogen includes one or more of F, Cl, and Br.

3. The oxohalide solid electrolyte according to claim 1, wherein the range of a is 0.5 ≤ a ≤ 0.8; and / or the range of b is 1 ≤ b ≤ 1.2; and / or the range of c + d is 5 ≤ c + d ≤ 6.

8.

4. The oxohalide solid electrolyte according to claim 1, wherein, The general formula of the oxohalide solid electrolyte is Li 2.5 Ta 1.1 O 0.7 Cl 6.1 F 0.5 , Li2TaO 0.5 Cl 5.6 F 0.4 , Li 3.2 Zr 1.2 OCl5Br, Li4Zr2OCl8F2, or one or more of them.

5. The oxohalide solid electrolyte according to claim 1, wherein The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 0% ranges from 10.7 to 11.8 mS / cm.

6. The oxohalide solid electrolyte according to claim 1, wherein The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 5% ranges from 9.1 to 10.9 mS / cm.

7. The oxohalide solid electrolyte according to claim 1, wherein The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 10% ranges from 10.5 to 10.7 mS / cm.

8. The oxohalide solid electrolyte according to claim 1, wherein, The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 15% ranges from 8.0 to 10.1 mS / cm.

9. The oxohalide solid electrolyte according to claim 1, wherein The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 20% ranges from 7.1 to 10.0 mS / cm.

10. The oxohalide solid electrolyte according to claim 1, wherein, The ionic conductivity of the oxohalide solid electrolyte at a relative humidity of 30% ranges from 5.9 to 7.5 mS / cm.

11. A method for preparing an oxygen halide solid electrolyte, wherein, comprising the following steps: Mix a first metal halide, a second metal halide, a third metal halide, and lithium oxide to obtain a mixture, where the chemical formula of the first metal halide is LiX', and the chemical formula of the second metal halide is MX' m , and the chemical formula of the third metal halide is MX'' n , and X' and X'' are each independent selected from halogens, and X' and X" are different, M is selected from Ta, In, or Zr, and m and n are each independently any integer selected from 1 to 5; ball milling the mixture to obtain a precursor of the oxohalide solid electrolyte; annealing the precursor of the oxohalide solid electrolyte to obtain the oxohalide solid electrolyte.

12. The preparation method according to claim 11, wherein, The molar ratio of the lithium oxide, the first metal halide, the second metal halide, and the third metal halide is (0.01 - 2):(0.01 - 2):(0.1 - 1.5):(0.1 - 1.5).

13. The preparation method according to claim 11, wherein, The range of the mass ratio of the ball milling beads to the mixture is (8 - 20):

1.

14. The preparation method according to claim 11, wherein, The halogen includes F, Cl, or Br.

15. The preparation method according to claim 11, wherein, The equipment used for the ball milling is a planetary ball mill.

16. The preparation method according to claim 11, wherein the rotation speed of the ball milling is 500 - 700 rpm; and / or the effective ball milling time is 70 - 200 h.

17. The preparation method according to claim 11, wherein, The ratio of the rest time to the ball milling time of the ball milling is (0.1 - 1):

1.

18. The preparation method according to claim 11, wherein, The annealing temperature is 100 - 300 °C, and the annealing time is 30 - 180 min.

19. The preparation method according to claim 11, wherein, The mixing is carried out under a protective atmosphere, and the gas in the protective atmosphere includes one or more of nitrogen, helium, neon, argon, krypton, and xenon.

20. A battery, wherein, comprising the oxohalide solid electrolyte according to any one of claims 1 - 10.

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