Chloride-coated modified positive electrode material, preparation method thereof and sulfide all-solid-state battery

Abstract

The invention belongs to the field of lithium ion battery materials, and discloses a chloride coated modified positive electrode material, which comprises a positive electrode material matrix and a chloride LiaMClb coated on the surface of the positive electrode material matrix, M is selected from at least one of Ti, Cr, Mn, Fe, Co and Cu, 1 < = a < = 4, 2 < = b < = 6. According to the preparation method, the chloride LiaMClb is deposited on the surface of the positive electrode material substrate in an atomic layer deposition mode. The invention also discloses a sulfide all-solid-state lithium ion battery which comprises the chloride coated modified positive electrode material. The LiaMClb is selected to coat the modified positive electrode material, the LiaMClb and the positive electrode material show good interface compatibility, and the good oxidation resistance of chloride ions can effectively inhibit the decomposition side reaction of the chloride ions and the positive electrode material in the lithium removal process.

Description

Technical Field

[0001] The present invention belongs to the field of sulfide solid-state batteries, and particularly relates to a chloride-coated modified cathode material, a preparation method thereof, and an application thereof in solid-state lithium batteries. Background Art

[0002] All-solid-state lithium-ion batteries are expected to fundamentally solve the problems of poor safety and low energy density of current liquid lithium-ion batteries, and are regarded as the next-generation ideal energy storage devices. Among them, sulfide solid electrolytes are considered the most promising liquid electrolyte substitutes due to their high ionic conductivity and good processing performance. However, when the cathode material comes into contact with the sulfide solid electrolyte, due to the difference in the electrochemical potential at the interface between the cathode active material and the sulfide solid electrolyte, a large number of side reactions will occur at the interface. Especially under high-voltage conditions, the interface will quickly fail, resulting in a sharp deterioration of the performance of all-solid-state batteries.

[0003] The patent application with the publication number CN114824247A discloses an inorganic solid electrolyte-coated high-voltage cathode material, which in-situ coats a layer of halide electrolyte on the surface of the cathode material active substance in a precursor solution. It has good electrochemical stability when mixed with the high-voltage cathode active substance, inhibits the formation of space charge, and thus successfully solves the severe side reactions between the sulfide solid electrolyte and the high-voltage cathode active substance and the problem of mismatched electrochemical windows when used in combination, and has better cycling performance. However, due to the poor compatibility of the halide electrolyte with the solvent, when forming the precursor solution, a part of the ionic conductor of the halide solid electrolyte will be sacrificed, and the residual solvent will cause a large amount of decomposition of the sulfide solid electrolyte, resulting in a rapid attenuation of the battery performance. In addition, during the subsequent heat treatment process, the halide material is extremely prone to the separation of metal elements and chlorine elements, affecting the uniformity of the coating.

[0004] The patent application with the publication number CN115275128A discloses a halide solid electrolyte-coated cathode material, a preparation method thereof, and an application thereof. It is coated on the surface of the ternary cathode material by means of manual grinding plus mechanical grinding; due to the 2 ZrCl 6 relatively high ionic conductivity (>1×10 -4 S / cm) and relatively low electronic conductivity (<1×10 -8 S / cm) of it, it can protect the cathode material from being reduced during high-voltage cycling, thereby reducing the occurrence of side reactions and improving the electrochemical performance of all-solid-state batteries. However, it is very difficult to ensure the uniformity of the coating only by mechanical grinding. And during the grinding process, it is extremely easy to cause distortion of the crystal lattice structure of the cathode material and even breakage of the cathode material particles, affecting the overall performance of all-solid-state batteries.

[0005] Therefore, the development of new coating materials and coating technologies to solve the problems of low conductivity, poor mechanical properties, and uneven coating in the prior art is crucial for improving the rate performance of sulfide all-solid-state batteries, enhancing the battery cycle stability, and further leveraging the advantages of high energy density and high safety performance of solid-state batteries. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background art, and provide a chloride-coated modified cathode material, its preparation method, and a sulfide all-solid-state battery.

[0007] To solve the above technical problems, the technical solution proposed by the present invention is as follows: A chloride-coated modified cathode material, comprising a cathode material matrix and chloride Li a MCl b coated on the surface of the cathode material matrix, where M is selected from at least one of Ti, Cr, Mn, Fe, Co, and Cu, 1 ≤ a ≤ 4, and 2 ≤ b ≤ 6.

[0008] During the research on chloride coating, the present invention found that after traditional chloride coating, the metal element and chlorine are mainly bonded by ionic bonds, and lithium and chlorine are also bonded by ionic bonds. This bonding method endows the material with good ionic conductivity but does not participate in the redox reaction itself. Therefore, its electronic conductivity is poor, and the electronic conductivity of the composite cathode drops severely, resulting in a loss of discharge specific capacity of the modified material. To further construct a three-dimensional electron transport network, the applicant screened metal atoms with redox activity in the charge and discharge interval of sulfide all-solid-state batteries through literature research, theoretical calculation, and CV testing: Ti, Cr, Mn, Fe, Co, Cu, and found that these metal elements and halogens are mainly bonded by covalent bonds and ionic bonds, and lithium ions and halogens are mainly bonded by ionic bonds. This bonding method enables the material to have certain redox activity in the electrochemical reaction, can provide additional redox reaction sites, and helps to increase the proportion of active substances in the battery; and the chlorides of these elements, due to the existence of redox centers (such as Fe 4+ / Fe 3+ , Ti 3+ / T i4+ etc.), have relatively high ionic conductivity and electronic conductivity at the same time, which helps to construct a more perfect three-dimensional electron transport network and improve the electron mobility.

[0009] For the above chloride-coated modified cathode material, preferably, the cathode material matrix is LiCoO 2 , LiNi x Co y Mn 1-x-y O 2, LiNi x Co y Al 1-x-y O 2 , zLi 2 MnO 3 ·(1 - z)LiTMO 2 at least one of them, where TM is at least one of transition metals Ni, Co, Mn, 0 < x < 1, 0 < y < 1, x + y < 1, 0 ≤ z ≤ 1.

[0010] For the above chloride - coated modified cathode material, preferably, the chloride - coated modified cathode material is spherical particles with a particle size of 1 - 10 μm; the thickness of the chloride coating layer does not exceed 50 nm.

[0011] As a general inventive concept, the present invention also provides a preparation method of the above chloride - coated modified cathode material, comprising the following steps: (1) Place the cathode material substrate in the reaction chamber of an ALD (Atomic Layer Deposition) device. When the temperature of the reaction chamber reaches 240 - 300 °C, heat the lithium source and load the lithium source into the reaction chamber through an inert gas to deposit lithium atoms on the surface of the cathode material substrate; if the temperature of the reaction chamber is too low, the adsorption effect of the material source is poor, and if the temperature is too high, it will cause serious structural damage to the material surface. (2) After purging the excess lithium source with an inert gas, heat the M metal source and continue to load the M metal source into the reaction chamber through an inert gas to deposit M metal atoms on the surface of the cathode material substrate after step (1). (3) After purging the excess M metal source with an inert gas, heat the chlorine source and continue to load the chlorine source into the reaction chamber through an inert gas to deposit chlorine atoms on the surface of the cathode material substrate after step (2). (4) Repeat steps (1), (2) and (3) several times, and then cool to obtain the chloride - coated modified cathode material.

[0012] For the above preparation method, preferably, in step (1), the temperature of the reaction chamber is 260 - 280 °C, the chamber pressure is 0.5 - 1 MPa, and the temperature for heating the lithium source is 160 - 180 °C; the lithium source pulse time is 1 - 5 s, and the pulse number is 1 - 5 times.

[0013] For the above preparation method, preferably, in step (2), the reaction chamber pressure is 0.5 - 1 MPa, the temperature for heating the M metal source is 30 - 60 °C, preferably 40 - 50 °C; the metal source pulse time is 2 - 10 s, and the pulse number is 1 - 5 times.

[0014] In the above preparation method, preferably, in step (3), the pressure of the reaction chamber is 0.5 - 1 MPa, the temperature for heating the chlorine source is 50 - 80 °C, preferably 65 - 75 °C; the pulse time of the chlorine source is 2 - 10 s, and the number of pulses is 1 - 5 times.

[0015] In the above preparation method, preferably, the lithium source is at least one of lithium tert - butoxide and lithium 2,2,6,6 - tetramethyl - 3,5 - heptanedionate.

[0016] The M metal source is an organic M source, including titanium(IV) ethylmethylamine (Ti(NEtMe) 4 ), chromium tris(2,2,6,6 - tetramethyl - 3,5 - heptanedionate) (Cr(thd) 3 ), bis(ethylcyclopentadienyl)manganese (Mn(EtCp) 2 ), bis(tert - butylaminomethyl)iron (Fe( t BuAMD) 2 ), cobalt(II) chloride tetramethylethylenediamine (CoCl 2 (TMEDA)), copper acetylacetonato bis(trimethylsilyl)acetate (Cu(Ac(SiMe 3 ))(hfac)) and the like; the M metal source selects an organic M source, which has good volatility and reactivity, and at the same time, the by - products are usually inert and do not corrode the equipment. 2 The chlorine source is at least one of titanium tetrachloride, tin tetrachloride, and gallium trichloride. In the above preparation method, preferably, in step (4), the number of repetitions is 15 - 45 times, preferably 25 - 35 times. Correspondingly, the thickness of the chloride coating layer on the surface of the cathode material does not exceed 50 nm.

[0017] In the above preparation method, preferably, in steps (1) - (4), the inert gas is at least one of helium, argon, and nitrogen.

[0018] As a general inventive concept, the present invention also provides a sulfide all - solid - state lithium - ion battery, including the above chloride - coated modified cathode material or including the chloride - coated modified cathode material prepared by the above preparation method.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) By coating a layer of chloride on the surface of the cathode material, compared with the traditional coating materials, the present invention selects the chloride Li MCl a MCl bThe coating shows good interface compatibility with the positive electrode material, and the good oxidation resistance of chloride ions can effectively inhibit the decomposition side reaction of the positive electrode material during the delithiation process. In addition, the chloride coating material is an ion-electron mixed conductor, which makes the surface of the positive electrode material have good ion and electron transmission channels at the same time, which can effectively improve the overall electronic and ion conductivity of the pole piece and reduce the growth rate of the DC resistance of the battery during the cycle.

[0021] (2) The chloride metal atoms selected in the present invention have redox activity within the charge and discharge range of the sulfide all-solid-state battery, which helps to increase the proportion of active materials in the battery. In addition, the chlorides coated in the present invention can be used as halide positive electrode materials, with high ion conductivity and electronic conductivity, which helps to build a more complete three-dimensional electron transport network (such as Fe 4+ / Fe 3+ The redox center of the electrolyte can improve the electron mobility; it can solve the problem of traditional chloride-coated solid electrolytes (such as Li 2 ZrCl 6 ), a technical defect of high ion conductivity and extremely poor electron conductivity.

[0022] (3) The present invention utilizes ALD technology and adopts inert gas to gradually introduce the precursor source into the surface of the positive electrode material, and realizes the in-situ reaction of the precursor source at a certain temperature to form a uniform and highly consistent coating layer; the integrity and effect of the coating layer are better than those of traditional coating technology; at the same time, by adjusting the number of pulse cycles of the precursor source, the thickness of the coating layer can be precisely controlled, thereby optimizing the electrochemical performance of the positive electrode material.

[0023] (4) The preparation method of the present invention does not require a solvent, thus avoiding the occurrence of side reactions after the chloride-coated material contacts the solvent, which results in a decrease in ion conductivity. The preparation method of the present invention has a relatively low processing temperature, thus avoiding the separation and enrichment of metal elements and chlorine elements generated by the halide material during high-temperature heat treatment, thereby improving the uniformity of the coating. In addition, the process is automatically controlled, the flow is simple, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a rate performance diagram of the sulfide all-solid-state batteries prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention.

[0026] Figure 2 This is the chlorine element energy spectrum comparison diagram of the positive electrode materials in Example 1 and Comparative Example 2 of the present invention. Detailed implementation manners

[0027] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the accompanying drawings of the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0028] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0029] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0030] Example 1: The chloride-coated modified positive electrode material of this example includes a positive electrode material matrix LiNi 0.85 Co 0.10 Mn 0.05 O 2 and chloride Li 2 CoCl 4 coated on the surface of the positive electrode material matrix. The chloride-coated modified positive electrode material is spherical particles with a particle size of about 5 μm; the thickness of the chloride coating layer is about 5 nm.

[0031] The preparation method of the chloride-coated modified positive electrode material of this example includes the following steps: (1) Place 5 g of the positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 270 °C and the pressure reaches 0.7 MPa, heat lithium tert-butoxide to 170 °C, and load the precursor lithium tert-butoxide into the reaction chamber through nitrogen. Deposit lithium atoms on the surface of the positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O 2 wherein the pulse time of lithium tert-butoxide is 2 s and the number of pulses is 3 times.

[0032] (2) After purging the excess lithium tert-butoxide with nitrogen, heat the cobalt source CoCl 2 (TMEDA) to 45 °C, and continue to load the cobalt source CoCl 2 (TMEDA) into the reaction chamber through nitrogen to deposit cobalt atoms on the surface of the material after step (1), wherein CoCl2 The pulse time of (TMEDA) is 5 s, and the number of pulses is 2 times.

[0033] (3)Nitrogen N 2 Purge the excess CoCl 2 After (TMEDA), heat the chlorine source titanium tetrachloride to 70 °C, and continue to load titanium tetrachloride into the reaction chamber through nitrogen to deposit chlorine atoms on the surface of the material in step (2). Among them, the pulse time of titanium tetrachloride is 5 s, and the number of pulses is 3 times.

[0034] (4)Repeat steps (1), (2), and (3) 30 times, and then cool to obtain the chloride Li 2 CoCl 4 Coated LiNi 0.85 Co 0.10 Mn 0.05 O 2 positive electrode material.

[0035] Assemble the sulfide all-solid-state battery: Take 210 mg of the chloride Li 2 CoCl 4 Coated LiNi 0.85 Co 0.10 Mn 0.05 O 2 positive electrode material and 90 mg of Li 6 PS 5 Cl and put them into a mortar and grind for 10 min. Transfer the mixture to a 2 mL centrifuge tube and further mix for 6 minutes on a mixer at a rotation speed of 300 rpm to prepare a composite positive electrode material.

[0036] Take 10 mg of the composite positive electrode material, 85 mg of the sulfide solid electrolyte Li 6 PS 5 Cl, and the lithium-indium alloy negative electrode are added to a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0037] Comparative Example 1: The positive electrode material of this comparative example is the unmodified positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O 2 .

[0038] The positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O 2 is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0039] Comparative Example 2: The positive electrode material coated with chloride prepared by the traditional liquid-phase coating method in this comparative example, and its preparation method includes: (1) Weigh LiCl and CoCl in a glove box according to a molar ratio of 2:1 2 , then add the reactant raw materials into a beaker, add the solvent ethylene glycol dimethyl ether (DME), and let the reactant raw materials fully contact and react in the solvent to obtain a chloride precursor slurry.

[0040] (2) Add LiNi 0.85 Co 0.10 Mn 0.05 O 2 to the chloride precursor slurry obtained in step (1), and stir for 6 h; then use vacuum drying to obtain the positive electrode material of chloride-coated LiNi 0.85 Co 0.10 Mn 0.05 O 2 .

[0041] Assemble the chloride-coated LiNi 0.85 Co 0.10 Mn 0.05 O 2 positive electrode material into a sulfide all-solid-state battery in the same manner as in Example 1.

[0042] Example 2: The chloride-coated modified positive electrode material in this example includes a positive electrode material matrix LiNiO 2 and chloride Li 2 MnCl 4 coated on the surface of the positive electrode material matrix. The chloride-coated modified positive electrode material is spherical particles with a particle size of about 5 μm and a chloride coating layer thickness of about 6 nm.

[0043] The preparation method of the chloride-coated modified positive electrode material in this example includes the following steps: (1) Place 5 g of the positive electrode material LiNiO 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 265 °C and the pressure reaches 0.6 MPa, heat lithium 2,2,6,6-tetramethyl-3,5-heptanedionate to 170 °C, and load the precursor lithium 2,2,6,6-tetramethyl-3,5-heptanedionate into the reaction chamber through nitrogen to deposit lithium atoms on the surface of the positive electrode material LiNiO 2 . Among them, the pulse time of lithium 2,2,6,6-tetramethyl-3,5-heptanedionate is 2 s, and the number of pulses is 4 times.

[0044] (2) After purging the excess lithium source 2,2,6,6 - tetramethyl - 3,5 - heptanedione lithium with nitrogen, heat the manganese source Mn(EtCp) 2 to 45 °C, and continue to load the manganese source Mn(EtCp) into the reaction chamber through nitrogen 2 to deposit manganese atoms on the surface of the material after step (1), where the pulse time of Mn(EtCp) 2 is 6 s and the number of pulses is 3 times.

[0045] (3) After purging the excess manganese source Mn(EtCp) with nitrogen 2 heat the chlorine source titanium tetrachloride to 70 °C, and continue to load titanium tetrachloride into the reaction chamber through nitrogen to deposit chlorine atoms on the surface after step (2). The pulse time of titanium tetrachloride is 5 s and the number of pulses is 3 times.

[0046] (4) Repeat steps (1), (2) and (3) 25 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, the chloride Li 2 MnCl 4 coated and modified LiNiO 2 cathode material is obtained.

[0047] The chloride Li 2 MnCl 4 coated and modified LiNiO 2 cathode material of this example is assembled into a sulfide all - solid - state battery in the same manner as in Example 1.

[0048] Comparative Example 3: The cathode material of this comparative example is the unmodified cathode material LiNiO 2 .

[0049] The cathode material LiNiO 2 of this comparative example is assembled into a sulfide all - solid - state battery in the same manner as in Example 1.

[0050] Comparative Example 4: The chloride - coated and modified cathode material of this comparative example is prepared by the traditional mechanical grinding method, and its preparation method includes: (1) Weigh LiCl and MnCl 2 in a glove box according to a molar ratio of 3:1, and then add the reactant raw materials into a ball - milling tank and ball - mill at a speed of 500 rpm for 5 h to obtain a chloride - coated material.

[0051] (2) Continue to add 5 g of LiNiO 2 into the ball - milling tank and ball - mill at a speed of 200 rpm for 5 h to obtain a chloride - coated and modified LiNiO 2 cathode material.

[0052] Li of this comparative example 2 MnCl 4 coated LiNiO 2 The cathode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0053] Example 3: The chloride-coated modified cathode material of this example includes a cathode material matrix LiNi 0.8 Co 0.15 Al 0.05 O 2 and chloride Li 2 FeCl 4 coated on the surface of the cathode material matrix. The chloride-coated modified cathode material is spherical particles with a particle size of about 4 μm and a chloride coating layer thickness of about 8 nm.

[0054] The preparation method of the chloride-coated modified cathode material of this example includes the following steps: (1) Place 5 g of the cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 275 °C and the pressure reaches 0.8 MPa, heat lithium 2,2,6,6-tetramethyl-3,5-heptanedionate to 176 °C, and load the precursor lithium 2,2,6,6-tetramethyl-3,5-heptanedionate into the reaction chamber through nitrogen. Deposit lithium atoms on the surface of the cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 where the pulse time of lithium 2,2,6,6-tetramethyl-3,5-heptanedionate is 4 s and the pulse number is 3 times.

[0055] (2) After purging the excess lithium source lithium 2,2,6,6-tetramethyl-3,5-heptanedionate with nitrogen, heat the iron source Fe( t BuAMD) 2 to 50 °C, and continue to load the iron source Fe( t BuAMD) 2 into the reaction chamber through nitrogen to deposit iron atoms on the surface of the material after step (1), where the pulse time of Fe( t BuAMD) 2 is 8 s and the pulse number is 2 times.

[0056] (3) Purge the excess iron source Fe( t BuAMD) 2After that, heat the chlorine source gallium trichloride to 75 °C, and continue to load gallium trichloride into the reaction chamber through nitrogen to deposit chlorine atoms on the surface of the material after step (2). Among them, the pulse time of gallium trichloride is 4 s, and the number of pulses is 5 times.

[0057] (4) Repeat steps (1), (2), and (3) 40 times, and the coated positive electrode material is directly cooled naturally in the ALD reaction chamber to obtain the chloride Li 2 FeCl 4 coated and modified LiNi 0.8 Co 0.15 Al 0.05 O 2 positive electrode material.

[0058] The chloride-coated and modified LiNi 0.8 Co 0.15 Al 0.05 O 2 positive electrode material is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0059] Comparative Example 5: The chloride-coated and modified positive electrode material of this comparative example includes the positive electrode material matrix LiNi 0.8 Co 0.15 Al 0.05 O 2 and the chloride Li 2 ZrCl 4 .

[0060] The preparation method of the chloride-coated and modified positive electrode material of this comparative example includes the following steps: (1) Place 5 g of the positive electrode material LiNi 0.8 Co 0.15 Al 0.05 O 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 275 °C and the pressure reaches 0.8 MPa, heat lithium 2,2,6,6-tetramethyl-3,5-heptanedionate to 176 °C, and load the precursor lithium 2,2,6,6-tetramethyl-3,5-heptanedionate into the reaction chamber through nitrogen to deposit lithium atoms on the surface of the positive electrode material LiNi 0.8 Co 0.15 Al 0.05 O 2 . Among them, the pulse time of lithium 2,2,6,6-tetramethyl-3,5-heptanedionate is 4 s, and the number of pulses is 3 times.

[0061] (2) After purging the excess lithium source lithium 2,2,6,6-tetramethyl-3,5-heptanedionate with nitrogen, heat the zirconium source Zr(NEtMe)4 To 50 °C, continue to load the zirconium source Zr(NEtMe)4 through nitrogen 4 into the reaction chamber to deposit zirconium atoms on the surface of the material after step (1). Among them, the pulse time of Zr(NEtMe)4 is 8 s, and the number of pulses is 2 times.

[0062] (3) Nitrogen purge the excess zirconium source Zr(NEtMe)4 4 After that, heat the chlorine source gallium trichloride to 75 °C, and continue to load gallium trichloride into the reaction chamber through nitrogen N 2 to deposit chlorine atoms on the surface of the material after step (2). Among them, the pulse time of gallium trichloride is 4 s, and the number of pulses is 5 times.

[0063] (4) Repeat steps (1), (2), and (3) 40 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, the chloride Li 2 ZrCl 4 coated and modified LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode material is obtained.

[0064] The chloride-coated and modified LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode material of this comparative example is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0065] Comparative Example 6: The preparation method of the chloride-coated and modified cathode material of this comparative example includes the following steps: (1) Place 5 g of the cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 275 °C and the pressure reaches 0.8 MPa, heat lithium 2,2,6,6-tetramethyl-3,5-heptanedionate to 176 °C, and load the precursor lithium 2,2,6,6-tetramethyl-3,5-heptanedionate into the reaction chamber through nitrogen to deposit lithium atoms on the surface of the cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 Among them, the pulse time of lithium 2,2,6,6-tetramethyl-3,5-heptanedionate is 4 s, and the number of pulses is 3 times.

[0066] (2) After purging the excess lithium source lithium 2,2,6,6 - tetramethyl - 3,5 - heptanedionate with nitrogen, heat the iron source Fe( t BuAMD) 2 to 50 °C, and continue to load the iron source Fe( t BuAMD) 2 into the reaction chamber, and deposit iron atoms on the surface of the cathode material LiNi 0.8 Co 0.15 Al 0.05 O 2 . Among them, the pulse time of Fe( t BuAMD) 2 is 8 s, and the number of pulses is 2 times.

[0067] (3) After purging the excess iron source Fe( 2 BuAMD) t with nitrogen, heat the chlorine source gallium trichloride to 75 °C, and continue to load gallium trichloride into the reaction chamber through nitrogen N 2 . Deposit chlorine atoms on the surface of the cathode material LiNi 2 Co 0.8 Co 0.15 Al 0.05 O 2 . Among them, the pulse time of gallium trichloride is 4 s, and the number of pulses is 5 times.

[0068] (4) Repeat steps (1), (2) and (3) 40 times. After the chloride coating process is completed, raise the temperature of the reaction chamber to 400 °C, anneal the coated cathode material directly in the ALD reaction chamber, and after natural cooling, the chloride - coated modified LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode material is obtained.

[0069] The chloride - coated modified LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode material of this comparative example is assembled into a sulfide all - solid - state battery in the same manner as in Example 1.

[0070] Example 4: The chloride - coated modified cathode material of this example includes a cathode material matrix LiCoO 2 and chloride Li 3 CrCl 6 coated on the surface of the cathode material matrix. The chloride - coated modified cathode material is spherical particles with a particle size of 8 μm and a chloride coating layer thickness of 7 nm.

[0071] The preparation method of the chloride-coated modified cathode material in this embodiment includes the following steps: (1) Place 5 g of the cathode material LiCoO 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 260 °C and the pressure reaches 1 MPa, heat lithium tert-butoxide to 160 °C, and load the precursor lithium tert-butoxide into the reaction chamber through argon, and deposit lithium atoms on the surface of the cathode material LiCoO 2 . Among them, the pulse time of lithium tert-butoxide is 1 s, and the number of pulses is 5 times.

[0072] After purging the excess lithium tert-butoxide with argon, heat the chromium source Cr(thd) 3 to 50 °C, and continue to load the chromium source Cr(thd) 3 into the reaction chamber through argon, and deposit chromium atoms on the surface of the material after step (1). Among them, the pulse time of Cr(thd) 3 is 10 s, and the number of pulses is 1 time.

[0073] After purging the excess Cr(thd) 3 with argon, heat the chlorine source tin tetrachloride to 75 °C, and continue to load tin tetrachloride into the reaction chamber through argon to deposit chlorine atoms on the surface of the material after step (2). Among them, the pulse time of tin tetrachloride is 5 s, and the number of pulses is 2 times.

[0074] (4) Repeat steps (1), (2), and (3) 25 times. After the coated cathode material is naturally cooled in the ALD reaction chamber, the chloride Li 3 CrCl 6 coated and modified LiCoO 2 cathode material is obtained.

[0075] The chloride-coated modified LiCoO 2 cathode material in this embodiment is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0076] Comparative Example 7: The preparation method of the chloride-coated modified cathode material in this comparative example includes the following steps: (1) Place 5 g of the cathode material LiCoO 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 260 °C and the pressure reaches 1 MPa, heat the chromium source Cr(thd) 3 to 50 °C, and load the chromium source Cr(thd) 3 into the reaction chamber through argon, and deposit chromium atoms on the surface of the cathode material LiCoO 2 . Among them, the pulse time of Cr(thd) 3The pulse time is 10 s and the number of pulses is 1 time.

[0077] (2) Purge the excess Cr(thd) with argon 3 After that, heat the chlorine source stannic chloride to 75 °C, and continue to load stannic chloride into the reaction chamber through argon to deposit chlorine atoms on the surface of the material after step (1). Among them, the pulse time of stannic chloride is 5 s and the number of pulses is 2 times.

[0078] (3) After purging the excess chlorine source stannic chloride with argon, heat lithium tert-butoxide to 160 °C, and continue to load the precursor lithium tert-butoxide into the reaction chamber through argon to deposit lithium atoms on the surface of the material after step (2). Among them, the pulse time of lithium tert-butoxide is 1 s and the number of pulses is 5 times.

[0079] (4) Repeat steps (1), (2) and (3) 25 times. After the coated cathode material is naturally cooled in the ALD reaction chamber, the chloride-coated modified LiCoO 2 cathode material is obtained.

[0080] The chloride-coated modified LiCoO 2 cathode material of this comparative example is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0081] Comparative Example 8: The preparation method of the chloride-coated modified cathode material of this comparative example includes the following steps: (1) Place 5 g of the cathode material LiCoO 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 400 °C and the pressure reaches 1 MPa, heat lithium tert-butoxide to 160 °C, and load the precursor lithium tert-butoxide into the reaction chamber through argon Ar to deposit lithium atoms on the surface of the cathode material LiCoO 2 . Among them, the pulse time of lithium tert-butoxide is 1 s and the number of pulses is 5 times.

[0082] (2) After purging the excess lithium tert-butoxide with argon, heat the chromium source Cr(thd) 3 to 50 °C, and continue to load the chromium source Cr(thd) 3 into the reaction chamber to deposit chromium atoms on the surface of the material after step (1). Among them, Cr(thd) 3 has a pulse time of 10 s and the number of pulses is 1 time.

[0083] (3) After purging the excess Cr(thd) with argon 3 heat the chlorine source stannic chloride to 75 °C, and continue to load stannic chloride into the reaction chamber through argon Ar to deposit chlorine atoms on the surface of the material after step (2). Among them, the pulse time of stannic chloride is 5 s and the number of pulses is 2 times.

[0084] (4) Repeat steps (1), (2), and (3) 25 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, the chloride-coated modified LiCoO 2 cathode material is obtained.

[0085] The chloride-coated modified LiCoO 2 cathode material of this comparative example is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0086] Example 5: The chloride-coated modified cathode material of this example includes a cathode material matrix Li 1.2 Ni 0.2 Mn 0.6 O 2 and chloride Li 2 TiCl 6 coated on the surface of the cathode material matrix. The chloride-coated modified cathode material is spherical particles with a particle size of 7 μm and a chloride coating layer thickness of 10 nm.

[0087] The preparation method of the chloride-coated modified cathode material of this example includes the following steps: (1) Place 5 g of the cathode material Li 1.2 Ni 0.2 Mn 0.6 O 2 in the reaction chamber of the ALD device. When the temperature of the reaction chamber reaches 280 °C and the pressure reaches 0.6 MPa, heat lithium 2,2,6,6-tetramethyl-3,5-heptanedionate to 180 °C, and load the precursor lithium 2,2,6,6-tetramethyl-3,5-heptanedionate into the reaction chamber through helium. Deposit lithium atoms on the surface of the cathode material Li 1.2 Ni 0.2 Mn 0.6 O 2 . Among them, the pulse time of lithium 2,2,6,6-tetramethyl-3,5-heptanedionate is 5 s, and the number of pulses is 1 time.

[0088] (2) After purging the excess lithium source lithium 2,2,6,6-tetramethyl-3,5-heptanedionate with helium, heat the titanium source Ti(NEtMe) 4 to 40 °C, and continue to load the titanium source Ti(NEtMe) 4 into the reaction chamber through helium to deposit titanium atoms on the surface of the material after step (1). Among them, the pulse time of Ti(NEtMe) 4 is 6 s, and the number of pulses is 3 times.

[0089] (3) Purge the excess titanium source Ti(NEtMe) with helium4 After that, heat the chlorine source titanium tetrachloride to 75 °C, and continue to load titanium tetrachloride into the reaction chamber through helium to deposit chlorine atoms on the surface of the material after step (2). Among them, the pulse time of titanium tetrachloride is 3 s, and the number of pulses is 4 times.

[0090] (4) Repeat steps (1), (2) and (3) 45 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, the chloride Li 2 TiCl 6 coated and modified Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode material is obtained.

[0091] The chloride-coated and modified Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode material of this example is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0092] Comparative Example 9: The cathode material of this comparative example is the unmodified cathode material Li 1.2 Ni 0.2 Mn 0.6 O 2 .

[0093] The cathode material Li 1.2 Ni 0.2 Mn 0.6 O 2 of this comparative example is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0094] Solid-state battery performance test The sulfide all-solid-state batteries prepared in Examples 1-5 and Comparative Examples 1-9 were subjected to a 0.5C constant current charge-discharge test after activation at a current density of 0.1C. The test temperature was 25 °C. The voltage test ranges for Examples 1-3 and Comparative Examples 1-6 were 2.7V to 4.3V vs Li / Li + . The voltage test ranges for Example 4, Comparative Example 7, and Comparative Example 8 were 2.4V to 4.45V vs Li / Li + ; The voltage test ranges for Example 5 and Comparative Example 9 were 2.6V to 4.8V vs Li / Li + . The electrochemical performances of the sulfide all-solid-state batteries of each example and comparative example are shown in Table 1.

[0095] Table 1 Electrochemical performances of the sulfide all-solid-state batteries of each example and comparative example

[0096] As can be seen from Table 1, the electrochemical performances of the batteries assembled in Example 1, Example 2 and Example 5 are significantly better than those of the batteries assembled in Comparative Example 1, Comparative Example 3 and Comparative Example 9 respectively. After analysis, this is because the chloride coating material and coating method provided by the present invention can significantly improve the interfacial stability between the cathode material and the sulfide solid electrolyte. In addition, the coating material and preparation method proposed by the present invention not only facilitate the capacity performance of various electrode materials in different sulfide all-solid-state batteries, but also can stabilize the electrode materials during the cycling process, with excellent cycling retention rate. The electrochemical performances of the batteries assembled in Example 1 and Example 2 are significantly better than those of the batteries assembled in Comparative Example 2 and Comparative Example 4 respectively, which benefits from the integrity and effect of the coating layer prepared by the coating method proposed by the present invention being better than those of the traditional coating technology. The electrochemical performance of the battery assembled in Example 4 is significantly better than that of Comparative Example 7 and Comparative Example 8, which benefits from the particularly advantageous ALD process conditions selected in the preparation method of the present application. From the comparison of the test data of Example 3 and Comparative Example 5, it can be seen that compared with the traditional chloride coating material, the present invention selects chloride Li a MCl b exhibits good interfacial compatibility with the cathode material, and the good antioxidant property of chloride ions can effectively inhibit the decomposition side reaction that occurs between the cathode material and the sulfide solid electrolyte during the delithiation process, thus showing more excellent electrochemical performance.

[0097] The rate performances of Example 1, Comparative Example 1 and Comparative Example 2 were tested at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, and 0.1 C. The test temperature was 25 °C, and the voltage range was 2.1 - 3.7 V vs Li x In / Li + , which is equivalent to 2.7 - 4.3 V vsLi / Li + , and the charge-discharge current rate 1 C was set to 190 mA·g -1 , and the results are as Figure 1 shown. The cathode materials obtained from Example 1 and Comparative Example 2 were characterized by scanning electron microscopy and energy-dispersive spectroscopy, and the results are as Figure 2 shown. As can be seen from Figure 1 , compared with Comparative Example 1, the overall performance of the battery assembled in Example 1 is more excellent. After analysis, this benefits from the fact that a layer of chloride is coated on the surface of the cathode active material in Example 1, isolating the direct contact between the cathode material and the sulfide solid electrolyte, and effectively inhibiting the decomposition side reaction that occurs at the interface during charge and discharge. In addition, compared with Comparative Example 2, the high-rate performance of the battery assembled in Example 1 is more excellent, as shown in Figure 2 , which benefits from the better coating effect and more uniform coating using the method of Example 1.

[0098] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A chloride-coated modified positive electrode material, characterized in that: It includes a positive electrode material matrix and a chloride Li coated on the surface of the positive electrode material matrix. a MCl b , wherein M is selected from at least one of Ti, Cr, Mn, Fe, Co, and Cu, 1≤a≤4, 2≤b≤6.

2. The chloride-coated modified positive electrode material according to claim 1, characterized in that: The positive electrode material matrix is ​​LiCoO2, LiNi x Co y Mn 1-x-y O2、LiNi x Co y Al 1-x-y O2, zLi2MnO3·(1-z)LiTMO2, wherein TM is at least one of the transition metals Ni, Co, and Mn, 0 <x<1,0<y<1,x+y<1,0≤z≤1。 3. The chloride-coated modified positive electrode material according to claim 1, characterized in that: The chloride-coated modified positive electrode material is a spherical particle with a particle size of 1-10 μm; the thickness of the chloride coating layer does not exceed 50 nm.

4. A method for preparing a chloride-coated modified positive electrode material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Placing the cathode material substrate in the reaction chamber of the atomic layer deposition equipment, and when the temperature of the reaction chamber reaches 240-300°C, heating the lithium source and loading the lithium source into the reaction chamber through an inert gas, and depositing lithium atoms on the surface of the cathode material substrate; (2) After the inert gas is used to purge the excess lithium source, the M metal source is heated and loaded into the reaction chamber by the inert gas, and M metal atoms are deposited on the surface of the cathode material substrate after step (1); (3) After the inert gas is used to purge the excess M metal source, the chlorine source is heated and loaded into the reaction chamber by the inert gas, and chlorine atoms are deposited on the surface of the cathode material substrate after step (2); (4) Repeat steps (1), (2) and (3) several times and cool to obtain a chloride-coated modified positive electrode material.

5. The preparation method according to claim 4, characterized in that: In step (1), the reaction chamber temperature is 260-280°C, the chamber pressure is 0.5-1 MPa, the temperature of the heated lithium source is 160-180°C; the lithium source pulse time is 1-5s, and the number of pulses is 1-5 times.

6. The preparation method according to claim 4, characterized in that: In step (2), the pressure of the reaction chamber is 0.5-1 MPa, the temperature of the heated M metal source is 30-60°C; the pulse time of the M metal source is 2-10s, and the number of pulses is 1-5 times.

7. The preparation method according to claim 4, characterized in that: In step (3), the pressure of the reaction chamber is 0.5-1 MPa, the temperature of the heated chlorine source is 50-80°C; the pulse time of the chlorine source is 2-10s, and the number of pulses is 1-5 times.

8. The preparation method according to claim 4, characterized in that: The lithium source is at least one of lithium tert-butoxide and lithium 2,2,6,6-tetramethyl-3,5-heptanedione; The M metal source is an organic M source, including at least one of titanium (IV) ethylmethylamine, tris (2,2,6,6-tetramethyl-3,5-heptanedione) chromium, di (ethylcyclopentadienyl) manganese, di (tert-butylaminomethyl) iron, cobalt (II) chloride tetramethylethylenediamine, acetylacetonate di (trimethylsilyl) cupric acetate; The chlorine source is at least one of titanium tetrachloride, tin tetrachloride and gallium trichloride.

9. The preparation method according to claim 4, characterized in that: In step (4), the number of repetitions is 15-45 times.

10. A sulfide all-solid-state lithium-ion battery, characterized in that: The invention comprises the chloride-coated modified positive electrode material as claimed in any one of claims 1 to 3 or the chloride-coated modified positive electrode material prepared by the preparation method as claimed in any one of claims 4 to 9.

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