Coated modified solid-state electrolyte and preparation method and application thereof

Abstract

The application provides a coated modified solid electrolyte and a preparation method and application thereof. The preparation method provided by the application adopts an atomic layer deposition method for coating, so as to form a uniform and dense coating layer on the surface of a ternary positive electrode material, and the thickness of the obtained coating layer is controllable relative to traditional methods such as liquid phase coating. Moreover, the ionic conductivity of the coating layer provided by the application is higher than that of ordinary oxides, nitrides or phosphides, so that the coating layer not only can serve as an interface protection material, but also can isolate the side reaction between the ternary positive electrode material and the electrolyte. In addition, the coated modified solid electrolyte can accelerate the deintercalation process of lithium ions at the interface, so that the capacity density is ensured and the rate performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, specifically to a solid electrolyte, and more particularly to a coated modified solid electrolyte, its preparation method, and its application. Background Technology

[0002] In recent years, with the continuous demand for higher energy density, greater safety, and lower cost in lithium-ion batteries, improving the electrochemical performance of battery cathode materials has become a major challenge in addressing these needs. LiNi x Co y Mn z High-nickel layered ternary materials such as O2 (x≥0.8) have high energy density and are currently the most utilized cathode materials for lithium-ion batteries in electric vehicles. For ternary cathode materials, in order to reduce costs, the cobalt content must be reduced as much as possible, while in order to improve electrochemical capacity, the nickel content needs to be increased; however, with the increase of nickel content, the instability of the interface / structure increases, leading to voltage decay and affecting its capacity retention capability.

[0003] Currently, surface coating modification has attracted widespread attention among performance optimization methods for high-nickel ternary cathode materials due to its simple and feasible process and significant effects. Common coating materials such as oxides, nitrides, and phosphates can provide mechanical protection for the cathode material, effectively preventing side reactions caused by contact between the material and the electrolyte, maintaining the stability of the material's surface structure, and improving capacity retention during cycling. However, due to the low ionic conductivity of these protective materials, coating often results in difficulties in lithium-ion insertion / extraction, leading to a decrease in battery rate performance.

[0004] Lithium-ion conductor materials have high conductivity, good electrochemical stability, and a wide electrochemical window at room temperature. They can be used as coatings for cathode materials. This not only avoids side reactions between the electrode and the electrolyte, but also increases the lithium-ion insertion / extraction rate and improves rate performance, thereby obtaining high-nickel ternary cathode materials for lithium-ion batteries with high energy density, long cycle stability, and high rate performance.

[0005] Traditional coating methods are generally liquid phase coating methods, but the liquid phase coating process inevitably damages the structure of the cathode material, and because the coating process is uncontrollable, the quality of the final coating is poor, making it difficult to obtain a uniform and dense effective coating layer.

[0006] Therefore, there is a need to provide a coating modification method that has less impact on the cathode material, so that the solid electrolyte obtained by the coating modification method has excellent cycle capacity retention and rate performance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a coated modified solid electrolyte, its preparation method, and its application. The coating layer of the coated modified solid electrolyte has high ionic conductivity, which can not only isolate the side reactions between the ternary cathode material and the electrolyte, but also accelerate the lithium-ion intercalation / deintercalation process at the interface. When applied to batteries, it can not only ensure high capacity density, but also improve the rate performance of the battery.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a coated modified solid electrolyte, the method comprising the following steps:

[0010] (1) Atomic layer deposition of ternary cathode material is performed using aluminum source vapor, followed by a first purge;

[0011] (2) Continue atomic layer deposition using germanium source vapor, and then perform a second purging;

[0012] (3) Continue atomic layer deposition using lithium source vapor, and then perform a third purging;

[0013] (4) Continue atomic layer deposition using phosphorus source vapor, and then perform a fourth purging;

[0014] (5) Continue atomic layer deposition using water vapor, followed by a fifth purging;

[0015] Repeat steps (1) to (5) until the surface of the ternary cathode material is coated with the required thickness.

[0016] This invention employs atomic layer deposition to coat the surface of a ternary cathode material with a solid electrolyte, lithium aluminum germanium phosphate. Compared to the traditional liquid phase coating method, the thickness of the resulting solid electrolyte coating is controllable, and the coating is more uniform and dense.

[0017] The ternary cathode material mentioned in step (1) of this invention is preferably a high-nickel ternary cathode material, and the chemical formula of the "high-nickel ternary cathode material" is LiNi. x Co y Mn z O2, where x ≥ 0.8 and x + y + z = 1. The solid electrolyte layer deposited by atomic layer deposition in this invention has a composition of Li. 1.5 Al 0.5 Ge 1.5(PO4)3 has good chemical stability and a wide electrochemical window. It can not only avoid side reactions between ternary cathode materials and electrolytes, which affect the cycle performance of batteries, but also increase the lithium-ion insertion and extraction rate and improve the rate performance. Thus, a high-nickel ternary cathode material for lithium-ion batteries with high energy density, long cycle stability and high rate performance can be obtained.

[0018] The aluminum source vapor, germanium source vapor, lithium source vapor, and phosphorus source vapor described in this invention are generated independently under vacuum conditions, with the absolute vacuum degree during vapor generation ≤ 5 × 10⁻⁶. -3 This invention does not limit the specific conditions for generating a vacuum, as long as the absolute vacuum degree when generating steam meets the requirements.

[0019] Preferably, the aluminum source vapor in step (1) includes trimethylaluminum vapor and / or dimethylaluminum isopropoxide vapor.

[0020] Preferably, the temperature of the aluminum source vapor in step (1) is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] If the temperature of the aluminum source vapor is too high, it will cause the aluminum source vapor to decompose, and the solid electrolyte coating layer will easily deteriorate; if the temperature of the aluminum source vapor is too low, the amount of aluminum source vapor volatilization will be insufficient to meet the requirements of atomic layer deposition.

[0022] Preferably, the time for introducing aluminum source vapor in step (1) is 2-5s, for example, 2s, 3s, 4s, 4.5s or 5s, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the flow rate of the aluminum source vapor in step (1) is 35-45 mL / min, for example, it can be 35 mL / min, 36 mL / min, 38 mL / min, 40 mL / min, 42 mL / min or 45 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the first purging in step (1) is performed using a protective gas.

[0025] Preferably, in step (1), the first purging flow rate is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

[0026] The first purging flow rate of the present invention is 85-95 mL / min, for example, it can be 85 mL / min, 86 mL / min, 88 mL / min, 90 mL / min, 92 mL / min or 95 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] The temperature of the first purging in this invention is 95-105℃, for example, it can be 95℃, 96℃, 98℃, 100℃, 102℃ or 105℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] The first purging time of the present invention is 35-45s, for example, it can be 35s, 36s, 38s, 40s, 42s or 45s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, the germanium source vapor in step (2) includes tetraethylgermanium vapor and / or trimethylgermanium vapor.

[0030] Preferably, the temperature of the lithium source vapor in step (2) is 140-160°C, for example, it can be 140°C, 145°C, 150°C, 155°C or 160°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the lithium source vapor is introduced in step (2) for 5-10 seconds, for example, 5 seconds, 6 seconds, 7 seconds, 8.5 seconds, 9 seconds or 10 seconds, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the flow rate of the lithium source vapor in step (2) is 35-45 mL / min, for example, it can be 35 mL / min, 36 mL / min, 38 mL / min, 40 mL / min, 42 mL / min or 45 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, in step (2), the second purging is performed using a protective gas.

[0034] Preferably, in step (2), the flow rate of the second purging is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

[0035] The second purging flow rate of the present invention is 85-95 mL / min, for example, it can be 85 mL / min, 86 mL / min, 88 mL / min, 90 mL / min, 92 mL / min or 95 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] The second purging temperature of the present invention is 95-105℃, for example, it can be 95℃, 96℃, 98℃, 100℃, 102℃ or 105℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] The second purging time of the present invention is 35-45s, for example, it can be 35s, 36s, 38s, 40s, 42s or 45s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the lithium source vapor in step (3) includes any one or a combination of at least two of tert-butyllithium vapor, bis(trimethylsilyl)aminolithium vapor, or lithium acetoacetate vapor. Typical but non-limiting combinations include combinations of tert-butyllithium vapor and bis(trimethylsilyl)aminolithium vapor, combinations of bis(trimethylsilyl)aminolithium vapor and lithium acetoacetate vapor, combinations of tert-butyllithium vapor and lithium acetoacetate vapor, or combinations of tert-butyllithium vapor, bis(trimethylsilyl)aminolithium vapor, and lithium acetoacetate vapor.

[0039] Preferably, the temperature of the lithium source vapor in step (3) is 140-160°C, for example, it can be 140°C, 145°C, 150°C, 155°C or 160°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the lithium source vapor is introduced in step (3) for 5-10 seconds, for example, 5 seconds, 6 seconds, 7 seconds, 8.5 seconds, 9 seconds or 10 seconds, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the flow rate of the lithium source vapor in step (3) is 35-45 mL / min, for example, it can be 35 mL / min, 36 mL / min, 38 mL / min, 40 mL / min, 42 mL / min or 45 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the third purging in step (3) is performed using a protective gas.

[0043] Preferably, the flow rate of the third purging in step (3) is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

[0044] The flow rate of the third purging described in this invention is 85-95 mL / min, for example, it can be 85 mL / min, 86 mL / min, 88 mL / min, 90 mL / min, 92 mL / min or 95 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] The temperature of the third purging described in this invention is 95-105℃, for example, it can be 95℃, 96℃, 98℃, 100℃, 102℃ or 105℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] The third purging time described in this invention is 35-45s, for example, it can be 35s, 36s, 38s, 40s, 42s or 45s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the phosphorus source vapor in step (4) includes trimethyl phosphate vapor and / or tetramethylmethylene diphosphate vapor.

[0048] Preferably, the temperature of the phosphorus source vapor in step (4) is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] Preferably, the time for introducing phosphorus source steam in step (4) is 25-35s, for example, it can be 25s, 27s, 28s, 30s, 32s or 35s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] Preferably, the flow rate of the phosphorus source vapor in step (4) is 35-45 mL / min, for example, it can be 35 mL / min, 36 mL / min, 38 mL / min, 40 mL / min, 42 mL / min or 45 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] Preferably, the fourth purging in step (4) is performed using a protective gas.

[0052] Preferably, the flow rate of the fourth purging in step (4) is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

[0053] The flow rate of the fourth purging described in this invention is 85-95 mL / min, for example, it can be 85 mL / min, 86 mL / min, 88 mL / min, 90 mL / min, 92 mL / min or 95 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] The fourth purging temperature described in this invention is 95-105℃, for example, it can be 95℃, 96℃, 98℃, 100℃, 102℃ or 105℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] The fourth purging time described in this invention is 35-45s, for example, it can be 35s, 36s, 38s, 40s, 42s or 45s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] Preferably, the steam introduction time in step (5) is 90-110s, for example, it can be 90s, 95s, 100s, 105s or 110s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] Preferably, the flow rate of water vapor in step (5) is 120-130 mL / min, for example, it can be 120 mL / min, 121 mL / min, 122 mL / min, 124 mL / min, 125 mL / min, 127 mL / min, 128 mL / min or 130 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] Preferably, the fifth purging in step (4) is performed using a protective gas.

[0059] Preferably, the flow rate of the fifth purge in step (4) is 100-120 mL / min, the temperature is 95-105℃, and the time is 45-55 s.

[0060] The fifth purging flow rate described in this invention is 100-120 mL / min, for example, it can be 100 mL / min, 105 mL / min, 110 mL / min, 115 mL / min or 120 mL / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0061] The temperature of the fifth purging described in this invention is 95-105℃, for example, it can be 95℃, 96℃, 98℃, 100℃, 102℃ or 105℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] The fifth purging time described in this invention is 45-55s, for example, it can be 45s, 46s, 48s, 50s, 52s or 55s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] Preferably, the protective gas includes nitrogen and / or an inert gas.

[0064] Preferably, the ternary cathode material in step (1) is placed in a constant temperature section at a temperature of 110-130°C; the temperature of the constant temperature section is 110°C, 115°C, 120°C, 125°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0065] As a preferred embodiment of the preparation method described in the first aspect of the present invention, the preparation method includes the following steps:

[0066] (1) Atomic layer deposition of ternary cathode material is performed using aluminum source vapor at a temperature of 40-60℃, followed by a first purging using a protective gas; the introduction time of aluminum source vapor is 2-5s, and the flow rate is 35-45mL / min; the flow rate of the first purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s.

[0067] (2) Continue atomic layer deposition using germanium source vapor at a temperature of 140-160℃, and then perform a second purging using a protective gas; the germanium source vapor is introduced for 5-10s and the flow rate is 35-45mL / min; the second purging flow rate is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s.

[0068] (3) Continue atomic layer deposition using lithium source vapor at a temperature of 140-160℃, and then perform a third purging using a protective gas; the lithium source vapor is introduced for 5-10s and the flow rate is 35-45mL / min; the flow rate of the third purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s.

[0069] (4) Continue atomic layer deposition using phosphorus source vapor at a temperature of 40-60℃, and then perform a fourth purging using a protective gas; the phosphorus source vapor is introduced for 25-35s and the flow rate is 35-45mL / min; the flow rate of the fourth purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s.

[0070] (5) Continue atomic layer deposition using saturated water vapor, and then perform a fifth purging using a protective gas; the water vapor introduction time is 90-110s, and the flow rate is 120-130mL / min; the flow rate of the fifth purging is 100-120mL / min, the temperature is 95-105℃, and the time is 45-55s.

[0071] Repeat steps (1) to (5) until the surface of the ternary cathode material is coated with the required thickness.

[0072] In a second aspect, the present invention provides a coated modified solid electrolyte, wherein the coated modified solid electrolyte is obtained by the preparation method described in the first aspect.

[0073] Thirdly, the present invention provides a battery comprising the coated modified solid electrolyte described in the second aspect.

[0074] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0075] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0076] This invention employs atomic layer deposition to deposit a solid electrolyte Li on the surface of a ternary cathode material. 1.5 Al 0.5 Ge 1.5 (PO4)3 has good chemical stability and a wide electrochemical window. It can not only avoid side reactions between ternary cathode materials and electrolytes, which affect the cycle performance of batteries, but also increase the lithium-ion insertion and extraction rate and improve the rate performance. Thus, a high-nickel ternary cathode material for lithium-ion batteries with high energy density, long cycle stability and high rate performance can be obtained. Detailed Implementation

[0077] The technical solution of the present invention will be further illustrated below through specific embodiments. The ternary cathode material used in the specific embodiments of the present invention is LiNi. 0.9 Co 0.05 Mn 0.05 O2 is used to clearly illustrate the technical solution of the present invention and should not be regarded as a limitation on the technical solution of the present invention.

[0078] Example 1

[0079] This embodiment provides a method for preparing a coated modified solid electrolyte, the method comprising the following steps:

[0080] (1)LiNi 0.9 Co0.05 Mn 0.05 O2 was placed on a constant temperature stage at 120°C, and then trimethylaluminum vapor at 50°C was used to treat LiNi. 0.9 Co 0.05 Mn 0.05 Atomic layer deposition was performed using O2, followed by a first purging with nitrogen; the introduction time of trimethylaluminum vapor was 3 s, and the flow rate was 40 mL / min; the first purging flow rate was 90 mL / min, the temperature was 100 °C, and the time was 40 s.

[0081] (2) Atomic layer deposition was continued using tetraethylgermanium vapor at a temperature of 150°C, followed by a second purging with nitrogen. The tetraethylgermanium vapor was introduced for 5 seconds at a flow rate of 40 mL / min. The second purging was carried out at a flow rate of 90 mL / min, a temperature of 100°C, and a time of 40 seconds.

[0082] (3) Atomic layer deposition was continued using tert-butyllithium vapor at a temperature of 150°C, followed by a third purging with nitrogen. The tert-butyllithium vapor was introduced for 5 seconds at a flow rate of 40 mL / min. The third purging was carried out at a flow rate of 90 mL / min, a temperature of 100°C, and a time of 40 seconds.

[0083] (4) Atomic layer deposition was continued using trimethyl phosphate vapor at 50°C, followed by a fourth purging with nitrogen. The trimethyl phosphate vapor was introduced for 30 seconds at a flow rate of 40 mL / min. The fourth purging was carried out at a flow rate of 90 mL / min, a temperature of 100°C, and a time of 40 seconds.

[0084] (5) Continue atomic layer deposition using saturated water vapor, and then perform a fifth purging using nitrogen; the water vapor introduction time is 100s and the flow rate is 125mL / min; the fifth purging flow rate is 110mL / min, the temperature is 100℃, and the time is 50s.

[0085] Repeat steps (1) to (5) until a coating layer with a thickness of 20 nm is obtained on the surface of the ternary cathode material.

[0086] Example 2

[0087] This embodiment provides a method for preparing a coated modified solid electrolyte, the method comprising the following steps:

[0088] (1)LiNi 0.9 Co 0.05 Mn 0.05 O2 was placed on a constant temperature stage at 110°C, and then trimethylaluminum vapor at 40°C was used to treat LiNi. 0.9 Co 0.05 Mn0.05 Atomic layer deposition was performed using O2, followed by a first purging with nitrogen; the introduction time of trimethylaluminum vapor was 4 s, and the flow rate was 45 mL / min; the first purging flow rate was 85 mL / min, the temperature was 95 °C, and the time was 45 s.

[0089] (2) Atomic layer deposition was continued using tetraethylgermanium vapor at a temperature of 140°C, followed by a second purging with nitrogen. The tetraethylgermanium vapor was introduced for 6 seconds at a flow rate of 45 mL / min. The second purging was carried out at a flow rate of 85 mL / min, a temperature of 95°C, and a time of 45 seconds.

[0090] (3) Atomic layer deposition was continued using tert-butyllithium vapor at a temperature of 140°C, followed by a third purging with nitrogen. The tert-butyllithium vapor was introduced for 6 seconds at a flow rate of 45 mL / min. The third purging was carried out at a flow rate of 85 mL / min, a temperature of 95°C, and a time of 45 seconds.

[0091] (4) Atomic layer deposition was continued using trimethyl phosphate vapor at a temperature of 40°C, followed by a fourth purging with nitrogen. The trimethyl phosphate vapor was introduced for 35 seconds at a flow rate of 45 mL / min. The fourth purging was carried out at a flow rate of 85 mL / min, a temperature of 95°C, and a time of 45 seconds.

[0092] (5) Continue atomic layer deposition using saturated water vapor, and then perform a fifth purging using nitrogen; the water vapor introduction time is 110s and the flow rate is 130mL / min; the fifth purging flow rate is 100mL / min, the temperature is 95℃, and the time is 55s.

[0093] Repeat steps (1) to (5) until a coating layer with a thickness of 20 nm is obtained on the surface of the ternary cathode material.

[0094] Example 3

[0095] This embodiment provides a method for preparing a coated modified solid electrolyte, the method comprising the following steps:

[0096] (1)LiNi 0.9 Co 0.05 Mn 0.05 O2 was placed on a constant temperature stage at 130°C, and then trimethylaluminum vapor at 60°C was used to treat LiNi. 0.9 Co 0.05 Mn 0.05 Atomic layer deposition was performed using O2, followed by a first purging with nitrogen; the introduction time of trimethylaluminum vapor was 5 s, and the flow rate was 35 mL / min; the first purging flow rate was 95 mL / min, the temperature was 105 °C, and the time was 35 s.

[0097] (2) Atomic layer deposition was continued using tetraethylgermanium vapor at a temperature of 160°C, followed by a second purging with nitrogen. The tetraethylgermanium vapor was introduced for 7 seconds at a flow rate of 35 mL / min. The second purging was carried out at a flow rate of 95 mL / min, a temperature of 105°C, and a time of 35 seconds.

[0098] (3) Atomic layer deposition was continued using tert-butyllithium vapor at a temperature of 160°C, followed by a third purging with nitrogen. The tert-butyllithium vapor was introduced for 7 seconds at a flow rate of 35 mL / min. The third purging was carried out at a flow rate of 95 mL / min, a temperature of 105°C, and a time of 35 seconds.

[0099] (4) Atomic layer deposition was continued using trimethyl phosphate vapor at a temperature of 60°C, followed by a fourth purging with nitrogen. The trimethyl phosphate vapor was introduced for 25 seconds at a flow rate of 35 mL / min. The fourth purging was carried out at a flow rate of 95 mL / min, a temperature of 105°C, and a time of 35 seconds.

[0100] (5) Continue atomic layer deposition using saturated water vapor, and then perform a fifth purging using nitrogen; the water vapor introduction time is 90s and the flow rate is 120mL / min; the fifth purging flow rate is 120mL / min, the temperature is 105℃, and the time is 45s.

[0101] Repeat steps (1) to (5) until a coating layer with a thickness of 20 nm is obtained on the surface of the ternary cathode material.

[0102] Example 4

[0103] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the constant temperature stage is 100°C.

[0104] Example 5

[0105] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the constant temperature stage is 140°C.

[0106] Example 6

[0107] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the trimethylaluminum vapor is 30°C.

[0108] Example 7

[0109] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the trimethylaluminum vapor is 70°C.

[0110] Example 8

[0111] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of tetraethylgermanium vapor is 130°C.

[0112] Example 9

[0113] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of tetraethylgermanium vapor is 170°C.

[0114] Example 10

[0115] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the tert-butyl lithium vapor is 130°C.

[0116] Example 11

[0117] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the tert-butyl lithium vapor is 170°C.

[0118] Example 12

[0119] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the trimethyl phosphate vapor is 30°C.

[0120] Example 13

[0121] This embodiment provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the temperature of the trimethyl phosphate vapor is 70°C.

[0122] Comparative Example 1

[0123] This comparative example provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the first purging was not performed.

[0124] Comparative Example 2

[0125] This comparative example provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that a second purging was not performed.

[0126] Comparative Example 3

[0127] This comparative example provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that a third purging was not performed.

[0128] Comparative Example 4

[0129] This comparative example provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that a fourth purging was not performed.

[0130] Comparative Example 5

[0131] This comparative example provides a method for preparing a coated modified solid electrolyte, which is the same as in Example 1 except that the fifth purging was not performed.

[0132] Performance testing

[0133] The coated modified solid electrolytes provided in Examples 1-13 and Comparative Examples 1-5 were assembled into batteries. The assembly method was as follows: First, the active material, carbon black conductive agent, and PVDF binder were mixed in a ratio of 8:1:1. Specifically, the active material and conductive agent with a mass ratio of 8:1 were weighed into a mortar using an electronic balance and ground repeatedly for 30 minutes until uniformly mixed. The mixture was then removed and placed aside to stand. Next, a portion of PVDF was weighed and dissolved in NMP. After complete dissolution, the mixture was poured into the previously ground mixture and ground until uniform. The ground gel-like material was then coated into a 50-micron thick layer. The coating is evenly applied to the aluminum foil current collector, and then placed in a vacuum drying oven to dry at 80°C for 12 hours. Next, the battery is assembled. The separator and positive electrode are cut into circles. The electrolyte is a 1 mol / L LiPF6 solution with EC / DEC / DMC = 1:1:1. The assembly process is carried out in a glove box. The assembly sequence is negative electrode shell, spring plate, gasket, lithium metal sheet, separator, positive electrode, and positive electrode shell. After the assembled battery is pressed and sealed, it is left to stand for 10 hours. After aging, the first discharge specific capacity, cycle performance, and rate performance of the assembled battery are tested.

[0134] The method for testing the initial discharge specific capacity is as follows: At a temperature of 25°C, the battery is charged and discharged on a charge-discharge tester. First, it is charged at a constant current of 0.1C to a voltage of 4.2V, then charged at a constant voltage of 4.2V to a current of 0.05C, and then discharged at a constant current of 0.1C to a voltage of 2.8V to obtain the initial discharge specific capacity.

[0135] The test method for cycle performance is as follows: At a temperature of 25°C, the battery is first charged at a constant current of 0.1C to a voltage of 4.2V, then charged at a constant voltage of 4.2V to a current of 0.05C, and then discharged at a constant current of 0.1C to a voltage of 3.0V. This is one charge-discharge cycle. The battery is charged and discharged 100 times in the above manner, and the discharge capacity after 100 cycles is measured to obtain the capacity retention rate.

[0136] Test method for rate performance: At a temperature of 25°C, test the battery capacity density at a 5C rate, cycle 5 times and take the average value. The rate performance of the cathode material is evaluated by the capacity density value that the battery can achieve under high rate conditions.

[0137] The results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] In summary, this invention employs atomic layer deposition (ALD) to deposit a solid electrolyte Li on the surface of a ternary cathode material. 1.5 Al 0.5 Ge 1.5 (PO4)3 has good chemical stability and a wide electrochemical window. It can not only avoid side reactions between ternary cathode materials and electrolytes, which affect the cycle performance of batteries, but also increase the lithium-ion insertion and extraction rate and improve the rate performance. Thus, a high-nickel ternary cathode material for lithium-ion batteries with high energy density, long cycle stability and high rate performance can be obtained.

[0142] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a coated modified solid electrolyte, characterized in that, The preparation method includes the following steps: (1) Atomic layer deposition of ternary cathode material is performed using aluminum source vapor, followed by a first purge; The temperature of the aluminum source vapor is 40-60℃; (2) Continue atomic layer deposition using germanium source vapor, followed by a second purging; The temperature of the germanium source vapor is 140-160℃; (3) Continue atomic layer deposition using lithium source vapor, and then perform a third purging; The temperature of the lithium source vapor is 140-160℃; (4) Continue atomic layer deposition using phosphorus source vapor, and then perform a fourth purging; The temperature of the phosphorus source steam is 40-60℃; (5) Continue atomic layer deposition using water vapor, followed by a fifth purging; Repeat steps (1) to (5) until the surface of the ternary cathode material is coated with the required thickness.

2. The preparation method according to claim 1, characterized in that, The aluminum source vapor in step (1) includes trimethylaluminum vapor and / or dimethylaluminum isopropoxide vapor.

3. The preparation method according to claim 1, characterized in that, The aluminum source vapor is introduced in step (1) for 2-5 seconds.

4. The preparation method according to claim 1, characterized in that, The flow rate of the aluminum source vapor in step (1) is 35-45 mL / min.

5. The preparation method according to claim 1, characterized in that, Step (1) The first purging is performed using a protective gas.

6. The preparation method according to claim 1, characterized in that, Step (1) The first purging flow rate is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

7. The preparation method according to claim 1, characterized in that, The germanium source vapor in step (2) includes tetraethylgermanium vapor and / or trimethylgermanium vapor.

8. The preparation method according to claim 1, characterized in that, The time for introducing germanium source vapor in step (2) is 5-10s.

9. The preparation method according to claim 1, characterized in that, The flow rate of the germanium source vapor in step (2) is 35-45 mL / min.

10. The preparation method according to claim 1, characterized in that, Step (2) The second purging is performed using a protective gas.

11. The preparation method according to claim 1, characterized in that, In step (2), the flow rate of the second purging is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

12. The preparation method according to claim 1, characterized in that, The lithium source vapor in step (3) includes any one or a combination of at least two of tert-butyllithium vapor, bis(trimethylsilyl)aminolithium vapor or lithium acetoacetate vapor.

13. The preparation method according to claim 1, characterized in that, The lithium source vapor is introduced in step (3) for 5-10 seconds.

14. The preparation method according to claim 1, characterized in that, The flow rate of the lithium source vapor in step (3) is 35-45 mL / min.

15. The preparation method according to claim 1, characterized in that, The third purging step (3) is performed using a protective gas.

16. The preparation method according to claim 1, characterized in that, The flow rate of the third purging in step (3) is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

17. The preparation method according to claim 1, characterized in that, The phosphorus source vapor in step (4) includes trimethyl phosphate vapor and / or tetramethylmethylene diphosphate vapor.

18. The preparation method according to claim 1, characterized in that, The phosphorus source steam introduced in step (4) is introduced for 25-35 seconds.

19. The preparation method according to claim 1, characterized in that, The flow rate of the phosphorus source vapor in step (4) is 35-45 mL / min.

20. The preparation method according to claim 1, characterized in that, The fourth purging step (4) is performed using a protective gas.

21. The preparation method according to claim 1, characterized in that, The flow rate of the fourth purge in step (4) is 85-95 mL / min, the temperature is 95-105℃, and the time is 35-45 s.

22. The preparation method according to claim 1, characterized in that, The steam introduction time in step (5) is 90-110s.

23. The preparation method according to claim 1, characterized in that, The flow rate of water vapor in step (5) is 120-130 mL / min.

24. The preparation method according to claim 1, characterized in that, The fifth purging step (5) is performed using a protective gas.

25. The preparation method according to claim 1, characterized in that, The fifth purge in step (5) has a flow rate of 100-120 mL / min, a temperature of 95-105℃, and a time of 45-55 s.

26. The preparation method according to any one of claims 5, 10, 15, 20 or 24, characterized in that, The protective gas includes nitrogen and / or an inert gas.

27. The preparation method according to claim 1, characterized in that, In step (1), the ternary cathode material is placed in a constant temperature chamber at a temperature of 110-130℃.

28. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Atomic layer deposition of ternary cathode material is performed using aluminum source vapor at a temperature of 40-60℃, followed by a first purge using a protective gas; the introduction time of aluminum source vapor is 2-5s, and the flow rate is 35-45mL / min; the flow rate of the first purge is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s. (2) Atomic layer deposition is continued using germanium source vapor at a temperature of 140-160℃, followed by a second purging using a protective gas; the introduction time of germanium source vapor is 5-10s, and the flow rate is 35-45mL / min; the flow rate of the second purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s. (3) Continue atomic layer deposition using lithium source vapor at a temperature of 140-160℃, and then perform a third purging using a protective gas; the lithium source vapor is introduced for 5-10s and the flow rate is 35-45mL / min; the flow rate of the third purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s. (4) Continue atomic layer deposition using phosphorus source vapor at a temperature of 40-60℃, and then perform a fourth purging using a protective gas; the phosphorus source vapor is introduced for 25-35s and the flow rate is 35-45mL / min; the flow rate of the fourth purging is 85-95mL / min, the temperature is 95-105℃, and the time is 35-45s. (5) Continue atomic layer deposition using saturated water vapor, and then perform a fifth purging using a protective gas; the water vapor introduction time is 90-110s, and the flow rate is 120-130mL / min; the flow rate of the fifth purging is 100-120mL / min, the temperature is 95-105℃, and the time is 45-55s. Repeat steps (1) to (5) until the surface of the ternary cathode material is coated with the required thickness.

29. A coated modified solid electrolyte, characterized in that, The coated modified solid electrolyte is obtained by the preparation method according to any one of claims 1-28.

30. A battery, characterized in that, The battery includes the coated modified solid electrolyte as described in claim 29.

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