A chloride-coated modified cathode material, a preparation method thereof, and a sulfide all-solid-state battery

Abstract

The present invention belongs to the field of lithium ion battery materials and discloses a chloride-coated modified positive electrode material, comprising a positive electrode material matrix and a chloride Li coated on the surface of the positive electrode material matrix. a MCl b , the M is selected from at least one of Ti, Cr, Mn, Fe, Co, and Cu, 1≤a≤4, 2≤b≤6. The preparation method is to deposit chloride Li on the surface of the positive electrode material matrix by atomic layer deposition. a MCl b The present invention also discloses a sulfide all-solid-state lithium-ion battery, comprising the chloride-coated modified positive electrode material. a MCl b Coated modified cathode material, Li a MCl b It exhibits good interface compatibility with the positive electrode material, and the good oxidation resistance of chloride ions can effectively inhibit the decomposition side reactions with the positive electrode material during the delithiation process.

Description

Technical Field

[0001] The present invention belongs to the field of sulfide solid-state batteries, and in particular relates to a chloride-coated modified positive electrode 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 ideal next-generation energy storage device. Among them, sulfide solid electrolytes are considered to be the most promising liquid electrolyte alternatives due to their high ionic conductivity and good processing properties. However, when the positive electrode material comes into contact with the sulfide solid electrolyte, a large number of side reactions will occur at the interface due to the difference in electrochemical potential between the positive electrode active material and the sulfide solid electrolyte at the interface. Especially under high voltage conditions, the interface will fail rapidly, resulting in a sharp deterioration in the performance of the all-solid-state battery.

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

[0004] The patent application with publication number CN115275128A discloses a positive electrode material coated with a halide solid electrolyte, its preparation method and application, which is coated on the surface of a ternary positive electrode material by manual grinding and mechanical grinding; thanks to the high ionic conductivity (>1×10 -4 S / cm) and low electronic conductivity (<1×10 -8 S / cm), which protects the cathode material from reduction during high-voltage cycling, thereby reducing side reactions and improving the electrochemical performance of all-solid-state batteries. However, mechanical grinding alone is difficult to ensure uniform coating. Furthermore, the grinding process can easily distort the cathode material's lattice structure and even cause particle breakage, impacting the overall performance of all-solid-state batteries.

[0005] Therefore, developing new coating materials and coating technologies to solve the problems of low electrical conductivity, poor mechanical properties, and uneven coating in existing technologies is crucial to improving the rate performance of sulfide all-solid-state batteries, improving battery cycle stability, and further leveraging the high energy density and high safety performance advantages 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 technology and provide a chloride-coated modified positive electrode material and a preparation method thereof and a sulfide all-solid-state battery.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] A chloride-coated modified positive electrode material, comprising 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.

[0009] The present invention found in the process of studying chloride coating that after traditional chloride coating, the metal elements and chlorine are mainly bonded through ionic bonds, and lithium and chlorine are also bonded through ionic bonds. This bonding method makes the material have good ionic conductivity, but it does not participate in the redox reaction itself, which leads to poor electronic conductivity and a serious decrease in the electronic conductivity of the composite positive electrode, resulting in a loss of discharge capacity of the modified material. In order to further construct a three-dimensional electron transport network, the applicant screened metal atoms with redox activity in the charge and discharge range of sulfide all-solid-state batteries through literature research, theoretical calculations and CV tests: Ti, Cr, Mn, Fe, Co, Cu, and found that these metal elements and halogens are mainly bonded through covalent bonds and ionic bonds, and lithium ions and halogens are mainly bonded through ionic bonds. This bonding method makes the material 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 presence of redox centers (such as Fe 4+ / Fe 3+ 、Ti 3+ / T i4+ etc.), the high ion conductivity and electronic conductivity help to build a more complete three-dimensional electron transport network and improve electron mobility.

[0010] The above-mentioned chloride-coated modified positive electrode material, preferably, the positive electrode material matrix is ​​LiCoO2, LiNi x Co y Mn 1-x-y O2、LiNi x Coy 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。

[0011] The above-mentioned chloride-coated modified cathode material is preferably in the form of spherical particles with a particle size of 1-10 μm; and the thickness of the chloride coating layer does not exceed 50 nm.

[0012] As a general inventive concept, the present invention also provides a method for preparing the chloride-coated modified positive electrode material as described above, comprising the following steps:

[0013] (1) Place the cathode material substrate in the reaction chamber of the ALD (atomic layer deposition) equipment. When the reaction chamber temperature reaches 240-300°C, heat the lithium source and load the lithium source into the reaction chamber through inert gas to deposit lithium atoms on the surface of the cathode material substrate. If the reaction chamber temperature 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.

[0014] (2) After the inert gas is used to purge the excess lithium source, the M metal source is heated and the M metal source is continuously 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);

[0015] (3) After the inert gas is used to purge the excess M metal source, the chlorine source is heated and the chlorine source is continuously loaded into the reaction chamber through the inert gas, and chlorine atoms are deposited on the surface of the cathode material substrate after step (2);

[0016] (4) Repeat steps (1), (2) and (3) several times and cool to obtain a chloride-coated modified positive electrode material.

[0017] In the above preparation method, preferably, 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.

[0018] In the above preparation method, preferably, in step (2), the reaction chamber pressure is 0.5-1 MPa, the temperature of heating the M metal source is 30-60°C, preferably 40-50°C; the metal source pulse time is 2-10s, and the number of pulses is 1-5 times.

[0019] In the above preparation method, preferably, 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, preferably 65-75°C; the pulse time of the chlorine source is 2-10s, and the number of pulses is 1-5 times.

[0020] 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-heptanedione.

[0021] The M metal source is an organic M source, including titanium (IV) ethylmethylamine (Ti(NEtMe)4), tris(2,2,6,6-tetramethyl-3,5-heptanedione) chromium (Cr(thd)3), di(ethylcyclopentadienyl) manganese (Mn(EtCp)2), di(tert-butylaminomethyl) iron (Fe( t At least one of: cobalt(II) chloride tetramethylethylenediamine (CoCl2(TMEDA)), and cupric acetylacetonate bis(trimethylsilyl)acetate (Cu(Ac(SiMe3)2)(hfac)); the M metal source is an organic M source with good volatility and reactivity, and the by-products are generally inert and do not corrode equipment.

[0022] The chlorine source is at least one of titanium tetrachloride, tin tetrachloride and gallium trichloride.

[0023] In the above preparation method, preferably, in step (4), the number of repetitions is 15-45 times, preferably 25-35 times, and correspondingly, the thickness of the chloride coating layer on the surface of the positive electrode material does not exceed 50 nm.

[0024] In the above preparation method, preferably, in steps (1) to (4), the inert gas is at least one of helium, argon, and nitrogen.

[0025] As a general inventive concept, the present invention also provides a sulfide all-solid-state lithium-ion battery, comprising the chloride-coated modified cathode material as described above or the chloride-coated modified cathode material prepared by the above preparation method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention coats a layer of chloride on the surface of the positive electrode material. Compared with traditional coating materials, the present invention selects chloride Li a MCl bThe coating exhibits good interfacial compatibility with the cathode material, and the excellent oxidation resistance of chloride ions can effectively inhibit the decomposition side reactions that occur with the cathode material during the delithiation process. In addition, the chloride coating material is a mixed ionic and electronic conductor, which provides good ion and electron transport channels on the surface of the cathode material, effectively improving the overall electronic and ion conductivity of the electrode and reducing the growth rate of DC resistance during battery cycling.

[0028] (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, which have high ion conductivity and electronic conductivity, and help to build a more complete three-dimensional electron transport network (such as Fe 4+ / Fe 3+ Redox centers) to improve electron mobility; it can solve the technical defects of traditional chloride-coated solid electrolytes (such as Li2ZrCl6), which have high ion conductivity and extremely poor electronic conductivity.

[0029] (3) The present invention utilizes ALD technology, uses 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 technologies; 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.

[0030] (4) The preparation method of the present invention does not require a solvent, thus avoiding the side reaction that occurs when the chloride-coated material contacts the solvent, which leads to a decrease in ion conductivity. In addition, the processing temperature during the preparation method of the present invention is relatively low, 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 it is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0032] 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.

[0033] Figure 2This is a comparison chart of the chlorine element energy spectra of the positive electrode materials of Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0034] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0037] Example 1:

[0038] The chloride-coated modified positive electrode material of this embodiment includes a positive electrode material matrix LiNi 0.85 Co 0.10 Mn 0.05 O2 and chloride Li2CoCl4 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 5μm; the thickness of the chloride coating layer is about 5nm.

[0039] The preparation method of the chloride-coated modified positive electrode material of this embodiment comprises the following steps:

[0040] (1) 5g of positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2 is placed in the reaction chamber of the ALD equipment. When the temperature of the reaction chamber reaches 270℃ and the pressure reaches 0.7MPa, lithium tert-butoxide is heated to 170℃ and the precursor lithium tert-butoxide is loaded into the reaction chamber by nitrogen. 0.85 Co 0.10 Mn 0.05 Lithium atoms are deposited on the O2 surface, where the pulse time of lithium tert-butoxide is 2s and the number of pulses is 3.

[0041] (2) After nitrogen is purged to remove excess lithium tert-butoxide, the cobalt source CoCl2(TMEDA) is heated to 45°C and the cobalt source CoCl2(TMEDA) is continuously loaded into the reaction chamber by nitrogen to deposit cobalt atoms on the surface of the material after step (1). The pulse time of CoCl2(TMEDA) is 5 s and the number of pulses is 2.

[0042] (3) After nitrogen gas N2 is purged to remove excess CoCl2(TMEDA), the chlorine source titanium tetrachloride is heated to 70°C and titanium tetrachloride is continuously loaded into the reaction chamber by nitrogen gas to deposit chlorine atoms on the surface of the material in step (2). The pulse time of titanium tetrachloride is 5 s and the number of pulses is 3.

[0043] (4) Repeat steps (1), (2) and (3) 30 times, and cool to obtain chloride Li2CoCl4 coated LiNi 0.85 Co 0.10 Mn 0.05 O2 positive electrode material.

[0044] Assembling sulfide all-solid-state batteries:

[0045] Take 210 mg of the chloride Li2CoCl4 prepared in this example to coat LiNi 0.85 Co 0.10 Mn 0.05 The O2 cathode material and 90 mg of Li6PS5Cl were placed in a mortar and ground for 10 min. The mixture was transferred to a 2 mL centrifuge tube and further mixed on a mixer for 6 min at a speed of 300 rpm to prepare a composite cathode material.

[0046] Take 10 mg of composite positive electrode material, 85 mg of sulfide solid electrolyte Li6PS5Cl, and lithium-indium alloy negative electrode and add them into a pressurized battery mold to assemble a sulfide all-solid-state battery.

[0047] Comparative Example 1:

[0048] The positive electrode material of this comparative example is unmodified positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2.

[0049] The positive electrode material LiNi 0.85 Co 0.10 Mn 0.05 O2 was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0050] Comparative Example 2:

[0051] The chloride-coated positive electrode material of this comparative example is prepared by a traditional liquid phase coating method, and its preparation method includes:

[0052] (1) LiCl and CoCl2 were weighed in a glove box at a molar ratio of 2:1, and then the reactant raw materials were added to a beaker, and the solvent ethylene glycol dimethyl ether (DME) was added to allow the reactant raw materials to fully contact and react in the solvent to obtain a chloride precursor slurry.

[0053] (2) Add LiNi to the chloride precursor slurry obtained in step (1) 0.85 Co 0.10 Mn 0.05 O2, stirred for 6h; then vacuum dried to obtain chloride-coated LiNi 0.85 Co 0.10 Mn 0.05 O2 positive electrode material.

[0054] The chloride of this comparative example is coated with LiNi 0.85 Co 0.10 Mn 0.05 The O2 positive electrode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0055] Example 2:

[0056] The chloride-coated modified positive electrode material of this embodiment includes a positive electrode material matrix LiNiO2 and chloride Li2MnCl4 coated on the surface of the positive electrode material matrix. The chloride-coated modified positive electrode material is a spherical particle with a particle size of about 5 μm and a chloride coating layer thickness of about 6 nm.

[0057] The preparation method of the chloride-coated modified positive electrode material of this embodiment comprises the following steps:

[0058] (1) 5g of the positive electrode material LiNiO2 was placed in the reaction chamber of the ALD equipment. When the temperature of the reaction chamber reached 265℃ and the pressure reached 0.6MPa, 2,2,6,6-tetramethyl-3,5-heptanedione lithium was heated to 170℃. The precursor 2,2,6,6-tetramethyl-3,5-heptanedione lithium was loaded into the reaction chamber by nitrogen gas, and lithium atoms were deposited on the surface of the positive electrode material LiNiO2. Among them, the pulse time of 2,2,6,6-tetramethyl-3,5-heptanedione lithium was 2s and the number of pulses was 4.

[0059] (2) After nitrogen is purged to remove excess lithium source 2,2,6,6-tetramethyl-3,5-heptanedione, the manganese source Mn(EtCp)2 is heated to 45°C and the manganese source Mn(EtCp)2 is continuously loaded into the reaction chamber by nitrogen gas to deposit manganese atoms on the surface of the material after step (1). The pulse time of Mn(EtCp)2 is 6 s and the number of pulses is 3.

[0060] (3) After nitrogen purging the excess manganese source Mn(EtCp)2, the chlorine source titanium tetrachloride was heated to 70°C and nitrogen was continued to be added to the reaction chamber to deposit chlorine atoms on the surface after step (2). The pulse time of titanium tetrachloride was 5 seconds and the number of pulses was 3.

[0061] (4) Repeat steps (1), (2) and (3) 25 times. The coated cathode material is naturally cooled directly in the ALD reaction chamber to obtain a chloride Li2MnCl4-coated modified LiNiO2 cathode material.

[0062] The chloride Li2MnCl4-coated modified LiNiO2 positive electrode material of this embodiment is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0063] Comparative Example 3:

[0064] The positive electrode material of this comparative example is unmodified positive electrode material LiNiO2.

[0065] The positive electrode material LiNiO2 of this comparative example was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0066] Comparative Example 4:

[0067] The chloride-coated modified positive electrode material of this comparative example was prepared by a traditional mechanical grinding method, and the preparation method thereof includes:

[0068] (1) LiCl and MnCl2 were weighed in a glove box at a molar ratio of 3:1. The reactants were then added to a ball mill and milled at 500 rpm for 5 h to obtain a chloride-coated material.

[0069] (2) Continue to add 5g LiNiO2 into the ball mill and ball mill at 200 rpm for 5h to obtain chloride-coated modified LiNiO2 positive electrode material.

[0070] The Li2MnCl4-coated LiNiO2 positive electrode material of this comparative example was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0071] Example 3:

[0072] The chloride-coated modified positive electrode material of this embodiment includes a positive electrode material matrix LiNi 0.8 Co 0.15 Al 0.05 O2 and chloride Li2FeCl4 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 4μm and a chloride coating layer thickness of about 8nm.

[0073] The preparation method of the chloride-coated modified positive electrode material of this embodiment comprises the following steps:

[0074] (1) 5g of positive electrode material LiNi 0.8 Co 0.15 Al 0.05O2 is placed in the reaction chamber of the ALD equipment. When the reaction chamber temperature reaches 275℃ and the pressure reaches 0.8MPa, 2,2,6,6-tetramethyl-3,5-heptanedione lithium is heated to 176℃. The precursor 2,2,6,6-tetramethyl-3,5-heptanedione lithium is loaded into the reaction chamber by nitrogen. 0.8 Co 0.15 Al 0.05 Lithium atoms were deposited on the O2 surface, where the pulse time of 2,2,6,6-tetramethyl-3,5-heptanedione lithium was 4 s and the number of pulses was 3.

[0075] (2) After nitrogen is purged of the excess lithium source 2,2,6,6-tetramethyl-3,5-heptanedione, the iron source Fe( t BuAMD)2 to 50 ° C, and then continue to load the iron source Fe( t BuAMD)2 into the reaction chamber, and iron atoms are deposited on the surface of the material after step (1), wherein Fe( t The pulse time of BuAMD)2 is 8s and the number of pulses is 2.

[0076] (3) Nitrogen purges excess iron source Fe( t After BuAMD)2, the chlorine source gallium trichloride is heated to 75°C and the gallium trichloride is continuously loaded into the reaction chamber by nitrogen gas to deposit chlorine atoms on the surface of the material after step (2). The pulse time of gallium trichloride is 4s and the number of pulses is 5.

[0077] (4) Repeat steps (1), (2) and (3) 40 times, and the coated cathode material is naturally cooled directly in the ALD reaction chamber to obtain chloride Li2FeCl4 coated modified LiNi 0.8 Co 0.15 Al 0.05 O2 positive electrode material.

[0078] The chloride-coated modified LiNi 0.8 Co 0.15 Al 0.05 The O2 positive electrode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0079] Comparative Example 5:

[0080] The chloride-coated modified positive electrode material of this comparative example includes a positive electrode material matrix LiNi 0.8 Co 0.15 Al 0.05 O2 and chloride Li2ZrCl4 coated on the surface of the positive electrode material matrix.

[0081] The preparation method of the chloride-coated modified positive electrode material of this comparative example comprises the following steps:

[0082] (1) 5g of positive electrode material LiNi 0.8 Co 0.15 Al 0.05 O2 is placed in the reaction chamber of the ALD equipment. When the reaction chamber temperature reaches 275℃ and the pressure reaches 0.8MPa, 2,2,6,6-tetramethyl-3,5-heptanedione lithium is heated to 176℃. The precursor 2,2,6,6-tetramethyl-3,5-heptanedione lithium is loaded into the reaction chamber by nitrogen. 0.8 Co 0.15 Al 0.05 Lithium atoms were deposited on the O2 surface, where the pulse time of 2,2,6,6-tetramethyl-3,5-heptanedione lithium was 4 s and the number of pulses was 3.

[0083] (2) After nitrogen is purged to remove excess lithium source 2,2,6,6-tetramethyl-3,5-heptanedione, the zirconium source Zr(NEtMe)4 is heated to 50°C and then continuously loaded into the reaction chamber with nitrogen to deposit zirconium atoms on the surface of the material after step (1). The pulse time of Zr(NEtMe)4 is 8 seconds and the number of pulses is 2.

[0084] (3) After nitrogen purges excess zirconium source Zr(NEtMe)4, heat the chlorine source gallium trichloride to 75°C and continue to load gallium trichloride into the reaction chamber using nitrogen N2 to deposit chlorine atoms on the surface of the material after step (2). The pulse time of gallium trichloride is 4 seconds and the number of pulses is 5.

[0085] (4) Repeat steps (1), (2) and (3) 40 times. The coated cathode material is cooled naturally in the ALD reaction chamber to obtain chloride Li2ZrCl4 coated modified LiNi 0.8 Co 0.15 Al 0.05 O2 positive electrode material.

[0086] The chloride-coated modified LiNi 0.8 Co 0.15 Al 0.05 The O2 positive electrode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0087] Comparative Example 6:

[0088] The preparation method of the chloride-coated modified positive electrode material of this comparative example comprises the following steps:

[0089] (1) 5g of positive electrode material LiNi 0.8 Co0.15 Al 0.05 O2 is placed in the reaction chamber of the ALD equipment. When the reaction chamber temperature reaches 275℃ and the pressure reaches 0.8MPa, 2,2,6,6-tetramethyl-3,5-heptanedione lithium is heated to 176℃. The precursor 2,2,6,6-tetramethyl-3,5-heptanedione lithium is loaded into the reaction chamber by nitrogen. 0.8 Co 0.15 Al 0.05 Lithium atoms were deposited on the O2 surface, where the pulse time of 2,2,6,6-tetramethyl-3,5-heptanedione lithium was 4 s and the number of pulses was 3.

[0090] (2) After nitrogen is purged of the excess lithium source 2,2,6,6-tetramethyl-3,5-heptanedione, the iron source Fe( t BuAMD)2 to 50 ° C, and then continue to load the iron source Fe( t BuAMD)2 to the reaction chamber, in the positive electrode material LiNi 0.8 Co 0.15 Al 0.05 Iron atoms are deposited on the surface of O2. Among them, Fe( t The pulse time of BuAMD)2 is 8s and the number of pulses is 2.

[0091] (3) Nitrogen N2 purges excess iron source Fe( t After BuAMD)2, the chlorine source gallium trichloride is heated to 75 ° C, and the gallium trichloride is continuously loaded into the reaction chamber by nitrogen N2. 0.8 Co 0.15 Al 0.05 Chlorine atoms are deposited on the surface of O2. The pulse time of gallium trichloride is 4s and the number of pulses is 5.

[0092] (4) Repeat steps (1), (2) and (3) 40 times. After the chloride coating process is completed, the temperature of the reaction chamber is increased to 400°C, and the coated positive electrode material is directly annealed in the ALD reaction chamber. After natural cooling, the chloride-coated modified LiNi 0.8 Co 0.15 Al 0.05 O2 positive electrode material.

[0093] The chloride-coated modified LiNi 0.8 Co 0.15 Al 0.05 The O2 positive electrode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0094] Example 4:

[0095] The chloride-coated modified positive electrode material of this embodiment includes a positive electrode material matrix LiCoO2 and chloride Li3CrCl6 coated on the surface of the positive electrode material matrix. The chloride-coated modified positive electrode material is a spherical particle with a particle size of 8 μm and a chloride coating layer thickness of 7 nm.

[0096] The preparation method of the chloride-coated modified positive electrode material of this embodiment comprises the following steps:

[0097] (1) 5g of the cathode material LiCoO2 was placed in the reaction chamber of the ALD equipment. After the reaction chamber temperature reached 260°C and the pressure reached 1MPa, lithium tert-butoxide was heated to 160°C. The precursor lithium tert-butoxide was loaded into the reaction chamber using argon gas to deposit lithium atoms on the surface of the cathode material LiCoO2. The pulse time of lithium tert-butoxide was 1s and the number of pulses was 5.

[0098] (2) After purging 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 using argon to deposit chromium atoms on the surface of the material after step (1). The pulse time of Cr(thd)3 is 10 seconds and the number of pulses is 1.

[0099] (3) After purging 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 using argon to deposit chlorine atoms on the surface of the material after step (2). The pulse time of tin tetrachloride is 5 seconds and the number of pulses is 2.

[0100] (4) Repeat steps (1), (2) and (3) 25 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, a chloride Li3CrCl6-coated modified LiCoO2 cathode material is obtained.

[0101] The chloride-coated modified LiCoO2 positive electrode material of this embodiment is assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0102] Comparative Example 7:

[0103] The preparation method of the chloride-coated modified positive electrode material of this comparative example comprises the following steps:

[0104] (1) 5g of the cathode material LiCoO2 was placed in the reaction chamber of the ALD equipment. After the reaction chamber temperature reached 260°C and the pressure reached 1MPa, the chromium source Cr(thd)3 was heated to 50°C and loaded into the reaction chamber using argon gas to deposit chromium atoms on the surface of the cathode material LiCoO2. The pulse time of Cr(thd)3 was 10s and the number of pulses was 1.

[0105] (2) After purging 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 using argon to deposit chlorine atoms on the surface of the material after step (1). The pulse time of tin tetrachloride is 5 s and the number of pulses is 2.

[0106] (3) After purging the excess chlorine source tin tetrachloride with argon, heat lithium tert-butoxide to 160°C and continue to load the precursor lithium tert-butoxide into the reaction chamber using argon to deposit lithium atoms on the surface of the material after step (2). The pulse time of lithium tert-butoxide is 1 s and the number of pulses is 5.

[0107] (4) Repeat steps (1), (2) and (3) 25 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, a chloride-coated modified LiCoO2 cathode material is obtained.

[0108] The chloride-coated modified LiCoO2 positive electrode material of this comparative example was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0109] Comparative Example 8:

[0110] The preparation method of the chloride-coated modified positive electrode material of this comparative example comprises the following steps:

[0111] (1) 5g of the cathode material LiCoO2 was placed in the reaction chamber of the ALD equipment. After the reaction chamber temperature reached 400°C and the pressure reached 1MPa, lithium tert-butoxide was heated to 160°C. The precursor lithium tert-butoxide was loaded into the reaction chamber using argon gas Ar, and lithium atoms were deposited on the surface of the cathode material LiCoO2. The pulse time of lithium tert-butoxide was 1s and the number of pulses was 5.

[0112] (2) After purging 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 using argon Ar to deposit chromium atoms on the surface of the material after step (1). The pulse time of Cr(thd)3 is 10 seconds and the number of pulses is 1.

[0113] (3) After purging 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 using argon Ar to deposit chlorine atoms on the surface of the material after step (2). The pulse time of tin tetrachloride is 5 s and the number of pulses is 2.

[0114] (4) Repeat steps (1), (2) and (3) 25 times. After the coated cathode material is naturally cooled directly in the ALD reaction chamber, a chloride-coated modified LiCoO2 cathode material is obtained.

[0115] The chloride-coated modified LiCoO2 positive electrode material of this comparative example was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0116] Example 5:

[0117] The chloride-coated modified positive electrode material of this embodiment includes a positive electrode material matrix Li 1.2 Ni 0.2 Mn 0.6 O2 and chloride Li2TiCl6 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 7μm and a chloride coating layer thickness of 10nm.

[0118] The preparation method of the chloride-coated modified positive electrode material of this embodiment comprises the following steps:

[0119] (1) 5g of positive electrode material Li 1.2 Ni 0.2 Mn 0.6 O2 is placed in the reaction chamber of the ALD equipment. When the temperature of the reaction chamber reaches 280℃ and the pressure reaches 0.6MPa, 2,2,6,6-tetramethyl-3,5-heptanedione lithium is heated to 180℃. The precursor 2,2,6,6-tetramethyl-3,5-heptanedione lithium is loaded into the reaction chamber by helium. 1.2 Ni 0.2 Mn 0.6 Lithium atoms are deposited on the O2 surface. The pulse time of 2,2,6,6-tetramethyl-3,5-heptanedione lithium is 5s and the number of pulses is 1.

[0120] (2) After helium gas is purged to remove excess lithium source 2,2,6,6-tetramethyl-3,5-heptanedione, the titanium source Ti(NEtMe)4 is heated to 40°C and then continuously loaded into the reaction chamber with helium gas to deposit titanium atoms on the surface of the material after step (1). The pulse time of Ti(NEtMe)4 is 6 seconds and the number of pulses is 3.

[0121] (3) After helium purging the excess titanium source Ti(NEtMe)4, the chlorine source titanium tetrachloride was heated to 75°C and then continuously loaded into the reaction chamber with helium to deposit chlorine atoms on the surface of the material after step (2). The pulse time of titanium tetrachloride was 3 seconds and the number of pulses was 4.

[0122] (4) Repeat steps (1), (2) and (3) 45 times. The coated cathode material is cooled naturally in the ALD reaction chamber to obtain chloride Li2TiCl6 coated modified Li 1.2 Ni 0.2 Mn0.6 O2 positive electrode material.

[0123] The chloride-coated modified Li 1.2 Ni 0.2 Mn 0.6 The O2 positive electrode material was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0124] Comparative Example 9:

[0125] The positive electrode material of this comparative example is the unmodified positive electrode material Li 1.2 Ni 0.2 Mn 0.6 O2.

[0126] The positive electrode material Li 1.2 Ni 0.2 Mn 0.6 O2 was assembled into a sulfide all-solid-state battery in the same manner as in Example 1.

[0127] Solid-state battery performance testing

[0128] The sulfide all-solid-state batteries prepared in Examples 1-5 and Comparative Examples 1-9 were activated at a current density of 0.1C and subjected to a 0.5C constant current charge and discharge test. The test temperature was 25°C. The voltage test range of Examples 1-3 and Comparative Examples 1-6 was 2.7V~4.3V vs Li / Li. + The voltage test range of Example 4, Comparative Example 7 and Comparative Example 8 is 2.4V~4.45V vs Li / Li + Example 5, Comparative Example 9 voltage test range is 2.6V~4.8V vs Li / Li + The electrochemical performance of the sulfide all-solid-state batteries of the embodiments and comparative examples are shown in Table 1.

[0129] Table 1 Electrochemical performance of sulfide all-solid-state batteries of various embodiments and comparative examples

[0130] As can be seen from Table 1, the electrochemical performance of the batteries assembled in Example 1, Example 2 and Example 5 are significantly better than those 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 positive electrode material and the sulfide solid electrolyte. In addition, the coating material and preparation method proposed in the present invention are not only conducive to the capacity of various electrode materials in different sulfide all-solid-state batteries, but also can stabilize the electrode material during the cycle, and the cycle retention rate is excellent. The electrochemical performance of the batteries assembled in Example 1 and Example 2 is significantly better than that of the batteries assembled in Comparative Example 2 and Comparative Example 4, respectively. This is due to the fact that the integrity and effect of the coating layer prepared by the coating method proposed in the present invention are 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 is due to the special advantages of the ALD process conditions selected in the preparation method of the present invention. Comparison of the experimental data of Example 3 and Comparative Example 5 shows that compared with the traditional chloride coating material, the present invention selects chloride Li a MCl b It exhibits good interface compatibility with the positive electrode material, and the good oxidation resistance of chloride ions can effectively inhibit the decomposition side reactions with the positive electrode material during the delithiation process, thereby exhibiting better electrochemical performance.

[0131] The rate performance tests of Example 1, Comparative Example 1 and Comparative Example 2 were carried out at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C and 0.1 C, with the test temperature at 25°C and the voltage range of 2.1-3.7 V vs Li x In / Li + , equivalent to 2.7-4.3 V vsLi / Li + The charge and discharge current rate 1 C is set to 190 mA·g -1 , the results are as follows Figure 1 The cathode materials obtained in Example 1 and Comparative Example 2 were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results are shown in Figure 2 As shown. Figure 1 It can be seen that compared with Comparative Example 1, the overall performance of the battery assembled in Example 1 is better. After analysis, this is due to the fact that the embodiment coats a layer of chloride on the surface of the positive electrode active material, isolating the direct contact between the positive electrode material and the sulfide solid electrolyte, and effectively suppressing the decomposition side reaction of the interface during the charge and discharge process. In addition, compared with Comparative Example 2, the high rate performance of the battery assembled in Example 1 is better. Figure 2 As shown, this is due to the better coating effect and more uniform coating achieved by the method of Example 1.

[0132] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A chloride-coated modified cathode material, characterized in that: Including a cathode material matrix and a chloride Li coated on the surface of the cathode material matrix a MCl b , the M is selected from at least one of Ti, Cr, Mn, Fe, Co, and Cu, 1≤a≤4, 2≤b≤6, and the chloride-coated modified positive electrode material is prepared by the following preparation method, which comprises (1) placing a positive electrode material substrate in a reaction chamber of an atomic layer deposition device, waiting for the reaction chamber temperature to reach 240-300°C, heating a lithium source and loading the lithium source into the reaction chamber through an inert gas, and depositing lithium atoms on the surface of the positive electrode 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), wherein the temperature of the heated M metal source is 30-60°C; (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), wherein the temperature of the heated chlorine source is 50-80°C; (4) Repeat steps (1), (2) and (3) several times and cool to obtain a chloride-coated modified positive electrode material.

2. The chloride-coated modified cathode material according to claim 1, wherein 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 cathode material according to claim 1, wherein 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 cathode material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Place the cathode material substrate in the reaction chamber of the atomic layer deposition equipment. When the reaction chamber temperature reaches 240-300°C, heat the lithium source and load the lithium source into the reaction chamber through inert gas to deposit 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 through 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, wherein 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, wherein In step (2), the pressure of the reaction chamber is 0.5-1 MPa; the pulse time of the M metal source is 2-10 s, and the number of pulses is 1-5 times.

7. The preparation method according to claim 4, wherein In step (3), the pressure of the reaction chamber is 0.5-1 MPa; the pulse time of the chlorine source is 2-10 s, and the number of pulses is 1-5 times.

8. The preparation method according to claim 4, wherein 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, and acetylacetonate bis (trimethylsilyl) copper acetate; The chlorine source is at least one of titanium tetrachloride, tin tetrachloride and gallium trichloride.

9. The preparation method according to claim 4, wherein 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 according to any one of claims 1 to 3 or the chloride-coated modified positive electrode material prepared by the preparation method according to any one of claims 4 to 9.

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