Positive electrode active material and preparation method thereof, positive electrode slurry, positive electrode plate and battery

Abstract

The invention relates to the field of batteries, in particular to a positive active material and a preparation method thereof, positive slurry, a positive plate and a battery, and the positive active material comprises manganese-doped nickel sulfide; wherein the positive electrode active material has an aggregate morphology formed by aggregating nano-particles. When the positive electrode active material is used for a battery, the activation process of the battery can be shortened, and the retention rate of the capacity battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular, to a positive electrode active material, a preparation method thereof, a positive electrode slurry, a positive electrode sheet and a battery. BACKGROUND

[0002] Aluminum ion batteries have advantages of abundant reserves, high energy density, safety guarantee and the like. Aluminum is the third most abundant element and the most abundant metal element in the earth's crust. Since aluminum ions carry three charges, aluminum metal also has the second highest energy density among all metals, reaching 2980 mAh / g. However, the positive electrode material of the aluminum ion battery still has problems such as no stable discharge platform, low discharge voltage (<0.55 V), poor reversibility, low coulomb efficiency, unstable and low discharge capacity, limited cycle life and the like. Transition metal sulfides have low electronegativity and high polarizability, and nickel sulfide materials have high theoretical specific capacity and can be used as positive electrode materials of aluminum ion batteries. However, the activation time is long, the aluminum dissolution phenomenon is serious, the capacity retention rate is poor, and the discharge is unstable.

[0003] Therefore, it is a technical problem to be solved at present to provide an active material which can shorten the activation process in the positive electrode material of the aluminum ion battery and significantly reduce the dissolution of aluminum in the electrolyte and improve the capacity retention rate. SUMMARY

[0004] Therefore, the present application is devoted to providing a positive electrode active material, a preparation method thereof, a positive electrode slurry, a positive electrode sheet and a battery. The positive electrode active material can reduce the dissolution of aluminum in the electrolyte and improve the high capacity retention rate of the battery.

[0005] In order to solve the above technical problems, the present application is implemented as follows:

[0006] The first aspect of the present application provides a positive electrode active material, which comprises manganese-doped nickel sulfide; wherein the positive electrode active material has a morphology of agglomerates formed by agglomeration of nanoparticles.

[0007] In some specific embodiments, the average particle size of the nanoparticles is 100-200 nm.

[0008] In some specific embodiments, the nanoparticles are spherical.

[0009] In some specific embodiments, in the manganese-doped nickel sulfide, the mass content of manganese is 5%-30%.

[0010] The second aspect of the present application provides a preparation method of a positive electrode active material. A precursor solution containing a nickel source and a manganese source is mixed with a sulfur source solution containing a sulfur source, and then dried and calcined. In the calcination process, gaseous sulfur source is introduced.

[0011] In some embodiments, the preparation method at least satisfies at least one of the following conditions (1)-(7):

[0012] (1) a gaseous sulfur source is introduced in the middle or later stage of the calcination;

[0013] (2) the introduction time of the gaseous sulfur source is 1-10 min;

[0014] (3) the calcination conditions include: under the protection of inert atmosphere, the temperature is 400-600℃, the heating rate is 1-3℃ / min, and the heating time is 2h-5h;

[0015] (4) the mixing conditions include: room temperature, and the time is 0.5h-2h;

[0016] (5) the mixing manner includes: the precursor solution is dropped into the sulfur source solution for the mixing;

[0017] (6) the preparation method further includes: a grinding step between the drying and the calcination;

[0018] (7) the preparation method further includes: ball milling after the calcination.

[0019] In some embodiments, the preparation method at least satisfies at least one of the following conditions (1)-(9):

[0020] (1) the molar ratio of the nickel source (calculated as nickel element) to the manganese source (calculated as manganese element) is (3-7):1;

[0021] (2) the molar ratio of the nickel source (calculated as nickel element) to the sulfur source (calculated as sulfur element) is 1:(0.2-6);

[0022] (3) the molar ratio of the gaseous sulfur source (calculated as sulfur element) to the nickel source (calculated as nickel element) is 1:(2-15);

[0023] (4) the total concentration of the nickel source and the manganese source in the precursor solution is 5wt%-90wt%;

[0024] (5) the concentration of the sulfur source in the sulfur source solution is 5wt%-60wt%;

[0025] (6) the gaseous sulfur source includes H2S gas and / or sulfur vapor;

[0026] (7) the nickel source and the manganese source each independently include at least one of the sulfate, nitrate, acetate, hydrochloride and oxalate of the corresponding metal;

[0027] (8) the sulfur source comprises thiourea and / or thioacetamide;

[0028] (9) the solvent in the precursor solution and the solvent in the sulfur source solution each independently comprises water.

[0029] The third aspect of the present application provides a positive electrode slurry, comprising:

[0030] a binder;

[0031] The positive electrode active material of the first aspect of the present application, or the positive electrode active material prepared by the preparation method of the second aspect of the present application.

[0032] In some embodiments, the mass ratio of the binder to the positive electrode active material is (70-90):(5-15).

[0033] In some embodiments, the solid content of the positive electrode slurry is 40-70 wt%.

[0034] In some embodiments, the binder exists in the form of a blended polymer.

[0035] In some embodiments, the binder comprises a fluorine-containing binder and an amide-based binder.

[0036] In some embodiments, the binder further comprises a dispersant.

[0037] In some embodiments, the positive electrode slurry further comprises a conductive agent.

[0038] In some embodiments, the dispersant comprises at least one of carboxymethyl cellulose, polyacrylate, and polyethylene glycol.

[0039] In some embodiments, the content of the dispersant in the binder is 2%-15%.

[0040] In some embodiments, the fluorine-containing binder comprises at least one of polyvinylidene fluoride, a copolymer of polyhexafluoropropylene-polyvinylidene fluoride, and polytetrafluoroethylene.

[0041] In some embodiments, the amide-based binder comprises at least one of polyamide, polyacrylamide, acrylamide copolymer, and polyurethane-amide hybrid polymer.

[0042] In some embodiments, the mass ratio of the fluorine-containing binder to the amide-based binder is (1.5-10):1.

[0043] In some embodiments, the mass ratio of the conductive agent to the positive electrode active material is (5-15) : (70-90).

[0044] The fourth aspect of the present application provides a positive electrode sheet, comprising a positive electrode current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active layer comprises the positive electrode active material of the first aspect of the present application, or the positive electrode active material prepared by the preparation method of the second aspect of the present application, or the positive electrode slurry dried to form.

[0045] The fifth aspect of the present application provides a battery comprising the positive electrode sheet of the third aspect of the present application.

[0046] In some embodiments, the battery further comprises an aluminum battery electrolyte and a negative electrode sheet.

[0047] Through the above technical solutions, the present application has the following beneficial technical effects:

[0048] In the present application, by doping metal manganese with a large Gibbs free energy of variable valence, and by controlling the morphology of the positive electrode active material, when the positive electrode active material is used in a battery, especially an aluminum ion battery, the internal resistance of the battery is low, and the activation process can be shortened, the room temperature and high temperature cycle performance of the aluminum ion battery is improved, and the charge retention capacity and capacity recovery capacity are higher.

[0049] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0050] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and together with the following specific embodiments, serve to explain the present application, but do not constitute a limitation on the present application.

[0051] Figure 1 SEM images of the positive electrode active material prepared in Example 1 are shown. DETAILED DESCRIPTION

[0052] The present application discloses a positive electrode active material, a preparation method thereof, a positive electrode slurry, a positive electrode sheet and a battery. Those skilled in the art can refer to the content herein and appropriately improve the process parameters to realize. It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they are considered to be included in the present application. The method and application of the present application have been described by the preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0053] In the description of the present application, the list of items connected by the term "at least one of' or other similar terms means any combination of the listed items. For example, the phrase "at least one of A, B" means only A; only B; or A and B. In another example, the phrase "at least one of A, B, C" means only A; only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or A, B, and C. Item A can include a single element or multiple elements. Item B can include a single element or multiple elements. Item C can include a single element or multiple elements.

[0054] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be roughly about the ranges or values. For ranges, the endpoints are included; for values, the values are inclusive. The disclosure of a range or value includes each possible combination of the range or value. Unless specifically stated otherwise, the present application is not to be limited by any implied or explicit disclosure.

[0055] If there is no specific description, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0056] If there is no specific description, all the technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0057] If there is no specific description, the "includes" and "contains" mentioned in the present application means open, which can also be closed. For example, the "includes" and "contains" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0058] The sulfide nickel group nanomaterial has a high theoretical specific capacity and can be used as a positive electrode material of an aluminum ion battery. However, there are problems such as a long activation time, a serious aluminum dissolution phenomenon, a poor capacity retention rate, and unstable discharge. The inventors of the present application found that by doping manganese with a large variable valence Gibbs free energy, and controlling the micro-morphology of the positive electrode active material, the activation process in the aluminum ion battery can be shortened, and the internal resistance of the battery using the positive electrode active material is low. Therefore, the battery using the positive electrode active material of the present application can reduce the internal resistance of the battery while improving the room temperature and high temperature cycle performance of the aluminum ion battery, and has higher charge retention capacity and capacity recovery capacity.

[0059] Therefore, in a first aspect, the present application provides a positive electrode active material, the positive electrode active material comprising manganese-doped nickel sulfide; wherein the positive electrode active material has a morphology of agglomerates formed by agglomeration of nanoparticles.

[0060] The positive electrode active material in the application can reduce the internal resistance of the battery and shorten the activation process of the battery and improve the capacity retention rate of the battery when used in the battery. The reason is that manganese has a large Gibbs free energy of variable valence, which can form a conductive network in the first charge-discharge process, accelerate the activation process of subsequent nickel sulfide, and widen the Al ion diffusion channel by doping in the nickel sulfide, so that the phase change required for activation is easier to perform; and the unique agglomerate morphology of the agglomerate formed by the agglomeration of the nanoparticles can ensure the infiltration of the electrolyte and provide a fast transmission path for the Al ions, thereby shortening the activation time, and especially the agglomerate morphology can expose more active crystal surfaces, so that the activation reaction can quickly proceed from the surface to the bulk phase.

[0061] According to the application, the particle size of the nanoparticles can be selected within a wide range as long as the purpose of the application can be achieved. In some preferred embodiments, the average particle size of the nanoparticles is 100-200 nm, for example, 100 nm, 120 nm, 150 nm, 170 nm, 200 nm, or a range formed by any two of the above values.

[0062] In some embodiments of the application, the average particle size of the nanoparticles is controlled to be within the range of 100-200 nm, which can better shorten the activation process of the positive electrode active material as an aluminum ion battery positive electrode material.

[0063] According to the application, in some embodiments, the nanoparticles are spherical. The positive electrode active material in the foregoing embodiments can better achieve the effect of "fast activation and long cycle" of the aluminum ion battery positive electrode material.

[0064] In the application, the micro-morphology of the positive electrode active material and the average particle size of the nanoparticles can be obtained by SEM testing.

[0065] According to the application, in some embodiments, the mass content of manganese in the manganese-doped nickel sulfide is 5%-30%, for example, 5%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 20%, 25%, 28%, 30%, or a range formed by any two of the above values.

[0066] In the application, the mass content of manganese doped in the manganese-doped nickel sulfide can be obtained by ICP-MS testing.

[0067] In the second aspect, some embodiments of the application provide a preparation method of a positive electrode active material, which comprises: mixing a precursor solution containing a nickel source and a manganese source with a sulfur source solution containing a sulfur source, and then drying and calcining; wherein a gaseous sulfur source is introduced during the calcination process.

[0068] The preparation method in the application uses a manganese source as a doping metal source, and the positive electrode active material obtained by introducing a gaseous sulfur source during calcination can shorten the activation process and improve the capacity retention rate of the battery when used in an aluminum ion battery.

[0069] In the application, the gaseous sulfur source is introduced during calcination, that is, the gaseous sulfur source is introduced during any one time period or the whole process of calcination, preferably, in some embodiments, the gaseous sulfur source is introduced during the middle or later period of calcination.

[0070] In the application, the gaseous sulfur source is introduced during the middle period of calcination, that is, the gaseous sulfur source is introduced during the period from the beginning of reaching the calcination temperature to 33-67% (not including 67%) of the process of gradually reducing from the calcination temperature to room temperature; the gaseous sulfur source is introduced during the later period of calcination, that is, the gaseous sulfur source is introduced during the period from the beginning of reaching the calcination temperature to 67-100% (not including 100%) of the process of gradually reducing from the calcination temperature to room temperature.

[0071] In the application, the gaseous sulfur source is introduced during the middle or later period of calcination, which can further ensure the uniform incorporation of sulfur elements and promote the formation of the morphology of agglomerates formed by the agglomeration of nanoparticles of the positive electrode active material, thereby shortening the activation process of the positive electrode active material when used in an aluminum ion battery to improve the capacity retention rate of the battery.

[0072] According to the application, in some embodiments, the introduction time of the gaseous sulfur source is 1-10 min, for example, 1 min, 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, or a range formed by any two of the above values.

[0073] In the application, the introduction time of the gaseous sulfur source is controlled within the above range, which can better improve the room temperature and high temperature cycle performance of the aluminum ion battery while reducing the internal resistance of the battery, and has higher charge retention capacity and capacity recovery capacity.

[0074] According to the application, in some embodiments, the molar ratio of the gaseous sulfur source to the nickel source is 1:(2-15) in terms of nickel elements and sulfur elements, for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:9, 1:12, 1:15, or a range formed by any two of the above values.

[0075] According to the present application, the gaseous flow source can be introduced at a certain flow rate, and the gaseous sulfur source can be introduced for a certain time to achieve the usage amount of the corresponding gaseous sulfur source. For example, the flow rate of the gaseous flow source can be 300-1500 mL / min, such as 300 mL / min, 500 mL / min, 800 mL / min, 1000 mL / min, 1200 mL / min, or 1500 mL / min.

[0076] According to the present application, as long as the purpose of the present application can be achieved, the gaseous sulfur source can be any precursor in the art that provides sulfur element in the form of gas during the reaction. In some embodiments, the gaseous sulfur source includes H2S gas and / or sulfur vapor (by sublimation of sulfur powder).

[0077] According to the present application, in order to avoid the influence of the oxygen-containing atmosphere on the formation of nickel sulfide, in some embodiments, the calcination conditions include: being carried out under the protection of an inert atmosphere. The inert atmosphere includes but is not limited to nitrogen or zero group gases (such as helium, argon, etc.). In the embodiments of the present application, argon atmosphere is used as an example to illustrate the advantages of the present application, but it does not represent a limitation on the present application.

[0078] According to the present application, the calcination temperature in the present application can be selected within a wide range. In some embodiments, the calcination conditions include: the temperature is 400-600℃, such as 400℃, 450℃, 500℃, 550℃, 600℃, or a range formed by any two of the above values.

[0079] In the present application, within the above-mentioned calcination temperature range, the formation of manganese-doped nickel sulfide can be better promoted.

[0080] According to the present application, the calcination time in the present application can be adjusted according to the calcination temperature. In some embodiments, the calcination conditions include: the time is 2h-5h, such as 2h, 3h, 3h, 4h, or 5h, etc.

[0081] According to the present application, the reactor for calcination can be any reactor in the art, such as a tube furnace.

[0082] According to the present application, according to the present application, the temperature can be raised to the calcination temperature at a certain rate. In some embodiments, the calcination conditions include: the heating rate is 1-3℃ / min, such as 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min, etc. The aforementioned heating rate refers to the rate when the temperature is raised from room temperature to the calcination temperature. The calcination time refers to the time from reaching the calcination temperature to the end of calcination (i.e., from gradually reducing the calcination temperature to room temperature).

[0083] In the present application, controlling the heating rate within the above-mentioned range can better promote the formation of manganese-doped nickel sulfide.

[0084] In the present application, the method of mixing the precursor solution and the sulfur source solution is not particularly limited, as long as the precursor solution and the sulfur source solution can be uniformly mixed, for example, the mixing is performed under stirring, and in some embodiments, the mixing method comprises: dropping the precursor solution into the sulfur source solution for mixing.

[0085] According to the present application, in some embodiments, the mixing condition comprises: room temperature, and the time is 0.5h-2h, for example, 0.5h, 1h, 1.5h or 2h. When the precursor solution is dropped into the sulfur source solution for mixing, the mixing time refers to the time counted from the completion of dropping the precursor solution.

[0086] In the present application, "room temperature" refers to 15-30℃.

[0087] In the present application, by dropping the precursor solution into the sulfur source solution, the continuous supply of sulfur ions can be better maintained, and the rapid consumption of sulfur caused by one-time mixing can be prevented.

[0088] According to the present application, as long as the purpose of the present application can be achieved, when the precursor solution is dropped into the sulfur source solution for mixing, the speed of dropping is not particularly limited, and in some embodiments, the dropping of the precursor solution is completed within 0.5-1h.

[0089] According to the present application, in order to make the subsequent calcination more uniform, in some embodiments, the preparation method further comprises: a grinding step between drying and calcination. The aforementioned grinding can be any conventional grinding method in the art, as long as the dried material is ground into a powder, and the present application will not be described in more detail.

[0090] According to the present application, during the calcination process, particle agglomerates may be formed, and in order to break the agglomerates to expose fresh surfaces, in some embodiments, the preparation method further comprises: ball milling after calcination.

[0091] According to the present application, the aforementioned ball milling method can be any ball milling method in the art, which can be dry ball milling or wet ball milling, and in some embodiments, the ball milling comprises wet ball milling.

[0092] According to the present application, wet ball milling generally refers to grinding the solid material in a solvent (for example, ethanol), which is generally performed in a planetary ball mill, for example, at a speed of 200rpm-500rpm for 2h-4h. After wet ball milling, the material may still contain solvent, and generally, drying is performed after wet ball milling. The drying method can be any conventional drying method in the art.

[0093] According to the present application, the purpose of drying is mainly to remove the solvent existing in the system, and the drying method can be a conventional drying method in the art, for example, drying at 80-120℃ for 8-36 hours. In order to make the drying efficiency higher, the material obtained after contacting can be transferred into a container with a larger cross section for drying.

[0094] According to the present application, in some embodiments, the molar ratio of the nickel source to the manganese source, in terms of nickel element and manganese element, is (3-7):1, for example, 3:1, 4:1, 5:1, 6:1, 7:1, or a range formed by any two of the above values.

[0095] According to the present application, in some embodiments, the molar ratio of the nickel source to the sulfur source, in terms of nickel element and sulfur element, is 1:(0.2-6), for example, 1:0.2, 1:1, 1:2, 1:2.5, 1:2.7, 1:3, 1:4, 1:5, 1:6, or a range formed by any two of the above values.

[0096] According to the present application, as long as the purpose of the present application can be achieved, the total content of the nickel source and the manganese source in the precursor solution is not particularly limited. In some embodiments, the total concentration of the nickel source and the manganese source in the precursor solution is 5wt%-90wt%, for example, 5wt%, 9wt%, 11wt%, 13wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, 70wt%, 80wt% or 90wt% and the like.

[0097] According to the present application, as long as the purpose of the present application can be achieved, the content of the sulfur source in the sulfur source solution is not particularly limited. In some embodiments, the concentration of the sulfur source in the sulfur source solution is 5wt%-60wt%, for example, 5wt%, 10wt%, 20wt%, 30wt%, 40wt% or 60wt% and the like.

[0098] According to the present application, the nickel source and the manganese source can be any precursor corresponding to the nickel element and the manganese element in the art. In some embodiments, the nickel source and the manganese source each independently comprises at least one of a sulfate, a nitrate, an acetate, a chloride and an oxalate of the corresponding metal, i.e. the nickel source comprises at least one of a sulfate, a nitrate, an acetate, a chloride and an oxalate of nickel. Specifically, it can be nickel sulfate, ammonium nickel sulfate, nickel nitrate, nickel acetate, nickel chloride, nickel oxalate, etc. The above compounds can be in the form of anhydrous compound or in the form of hydrated compound, for example, nickel sulfate hexahydrate, nickel sulfate heptahydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel chloride hexahydrate, nickel oxalate dihydrate, etc. In some embodiments of the present application, nickel nitrate is used as an exemplary illustration of the advantages of the present application, but it does not represent a limitation of the present application; the manganese source comprises at least one of a sulfate, a nitrate, an acetate, a chloride and an oxalate of manganese. Specifically, it can be manganese sulfate, manganese nitrate, manganese acetate, manganese chloride, manganese oxalate, etc. The above compounds can be in the form of anhydrous compound or in the form of hydrated compound, for example, manganese sulfate monohydrate, manganese sulfate tetrahydrate, manganese nitrate tetrahydrate, manganese nitrate hexahydrate, manganese acetate tetrahydrate, manganese acetate tetrahydrate, manganese oxalate dihydrate, etc. In some embodiments of the present application, manganese nitrate is used as an exemplary illustration of the advantages of the present application, but it does not represent a limitation of the present application.

[0099] According to the present application, the sulfur source can be any precursor capable of providing sulfur element in the art. In some embodiments, the sulfur source comprises thiourea and / or thioacetamide, and preferably the sulfur source comprises thiourea.

[0100] According to the present application, the precursor solution containing the nickel source and the manganese source refers to a solution formed by the nickel source, the manganese source and a solvent. The type of the solution is not particularly limited as long as it can dissolve the nickel source and the manganese source. The sulfur source solution containing the sulfur source refers to a solution formed by the sulfur source dissolved in a solvent. The type of the solution is not particularly limited as long as it can dissolve the sulfur source. In some embodiments, the solvent in the precursor solution and the solvent in the sulfur source solution each independently comprises water, i.e. the solvent in the sulfur source solution comprises water and the solvent in the precursor solution comprises water.

[0101] According to the present application, in some embodiments, the precursor solution containing the nickel source and the manganese source can be obtained by dissolving the nickel source and the manganese source in a solvent (e.g. water).

[0102] According to the present application, in some embodiments, the preparation method of the positive electrode active material comprises:

[0103] The nickel source and the manganese source are dissolved in water to obtain the precursor solution containing the nickel source and the manganese source. The precursor solution containing the nickel source and the manganese source is dropped into the sulfur source solution for mixing to form a homogeneous sol, and then dried to obtain a precursor gel.

[0104] The precursor gel is ground into powder and placed in a tube furnace for calcination. A gaseous sulfur source is introduced during the middle or later stage of the calcination.

[0105] The calcined powder is subjected to wet ball milling and drying to obtain the positive electrode active material.

[0106] According to the present application, the positive electrode active material of the first aspect of the present application can be prepared by the method for preparing the positive electrode active material of the second aspect of the present application.

[0107] In a third aspect, some embodiments of the present application provide a slurry, comprising:

[0108] a binder;

[0109] the positive electrode active material of the first aspect of the present application; or the positive electrode active material prepared by the method for preparing the positive electrode active material of the second aspect of the present application.

[0110] The positive electrode slurry of the present application can shorten the activation process and improve the capacity retention rate of the battery when used in a battery.

[0111] According to the present application, the amount of the binder and the positive electrode active material in the slurry is not particularly limited as long as the purpose of the present application can be achieved. In some embodiments, the mass ratio of the binder to the positive electrode active material is (70-90):(5-15), for example, 80:10.

[0112] According to the present application, in some embodiments, the binder comprises a fluorine-containing binder and an amide-based binder.

[0113] The inventors of the present application have further found that when the binder comprises a fluorine-containing binder and an amide-based binder, the activation process of the positive electrode active material can be shortened and the capacity retention rate of the battery can be improved. The reason is that the amide polar group in the amide-based binder can complex with aluminum ions, and can make the small particle manganese-doped nickel sulfide nanomaterial uniformly dispersed and bonded to a certain extent during the aging process, preventing the subsequent positive electrode active material from dissolving in the electrolyte to cause capacity loss, and cooperating with the chemical stability and mechanical strength provided by the fluorine-containing binder, the amide group (-NH-CO-) in the amide-based binder is combined with the polar sites on the surface of nickel sulfide through hydrogen bond or coordination bond, enhancing the interfacial bonding force between the particles and the binder, and the chain segment movement of the polyamide adapts to the volume change of the electrode, reducing the expansion of microcracks, thereby inhibiting the capacity decay.

[0114] According to the present application, in some embodiments, the binder exists in the form of a blended polymer.

[0115] In the present application, the "blended polymer" refers to the existence of interaction (hydrogen bond, electrostatic interaction, entanglement, etc.) between at least two different polymer (for example, fluorine-containing binder and amide-based binder) components, rather than mechanical mixing.

[0116] According to the present application, the adhesive can be in the form of a blend polymer by any method in the art, for example, by physically blending the components of the adhesive, specifically, by solution blending, more specifically, by dissolving and mixing the components of the adhesive (for example, the fluorine-containing adhesive and the amide-based adhesive) in a solvent (for example, N-methyl pyrrolidone, NMP) and then drying.

[0117] According to the present application, in order to better form a blend polymer between the components in the blend polymer, in some embodiments, the adhesive further comprises a dispersant.

[0118] According to the present application, the dispersant is added during the process of physical blending, for example, solution blending.

[0119] According to the present application, the dispersant can be any one that can promote the interfacial adhesion between the fluorine-containing adhesive and the amide-based adhesive, and the type of the dispersant is not particularly limited as long as the purpose of the present application can be achieved, in some embodiments, the dispersant comprises at least one of carboxymethyl cellulose, polyacrylate, polyethylene glycol, and polyethylene glycol, and preferably carboxymethyl cellulose.

[0120] According to the present application, the content of the dispersant in the adhesive can be selected within a wide range, in some embodiments, the content of the dispersant in the adhesive is 2% to 15% by mass, for example, 1%, 2%, 2.5%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, or a range formed by any two of the above values.

[0121] According to the present application, as an example, the preparation method of the adhesive comprises: mixing the fluorine-containing adhesive and the amide-based adhesive, adding a solvent (for example, NMP) and magnetically stirring in a water bath at 60-80°C until completely dissolved to obtain a blend solution, adding a dispersant (for example, carboxymethyl cellulose) to the blend solution, high-speed dispersing (for example, 1500-3000 rpm for 1-5 h), removing the solvent to obtain a copolymer mixture, washing with acetonitrile for 3-5 times, and drying at 50-80°C for 8-24 h to obtain the adhesive; wherein the method of removing the solvent can be any method in the art, for example, by rotary evaporation.

[0122] According to the present application, the fluorine-containing adhesive refers to a type of high molecular polymer containing fluorine atoms in the molecular chain, in some embodiments, the fluorine-containing adhesive comprises at least one of polyvinylidene fluoride, a copolymer of polyhexafluoropropylene-polyvinylidene fluoride, and polytetrafluoroethylene.

[0123] According to the present application, in some embodiments, the fluorine-containing adhesive comprises polyvinylidene fluoride.

[0124] In the present application, the size of the high molecular polymer containing fluorine atoms in the molecular chain can be the size conventionally used in the art. For example, the average molecular weight of the high molecular polymer containing fluorine atoms in the molecular chain is 500,000-2,000,000.

[0125] According to the present application, the amide-based binder refers to a high molecular polymer containing amide groups (-CONH-) in the molecular chain. In some embodiments, the amide-based binder includes at least one of polyamide, polyacrylamide, acrylamide copolymer and polyurethane-amide hybrid polymer.

[0126] According to the present application, in some embodiments, the amide-based binder includes polyamide.

[0127] In the present application, the size of the high molecular polymer containing amide groups (-CONH-) in the molecular chain can be the size conventionally used in the art. For example, the average molecular weight of the high molecular polymer containing amide groups (-CONH-) in the molecular chain is 1,500,000-5,000,000.

[0128] According to the present application, in some embodiments, the mass ratio of the fluorine-containing binder to the polymer containing amide groups is (1.5-10):1, for example, 1.5:1, 1.8:1, 2.3:1, 2.5:1, 3:1, 5:1, 7:1, 10:1, or a range between any two of the above values.

[0129] In the present application, the amount of the fluorine-containing binder and the amide-based binder is controlled within the above range, which can better shorten the activation process of the positive active material and improve the capacity retention rate of the battery.

[0130] According to the present application, in order to better construct an efficient electron conduction network, in some embodiments, the positive slurry further includes a conductive agent.

[0131] The conductive agent can be any conductive agent in the art, including but not limited to conductive carbon black, carbon nanotube, conductive polymer, etc. In some embodiments of the present application, conductive carbon black is used as an exemplary illustration of the advantages of the present application, but it does not represent a limitation of the present application.

[0132] According to the present application, in some embodiments, the mass ratio of the conductive agent to the positive active material is (5-15):(70-90).

[0133] According to the present application, in some embodiments, the solid content of the positive slurry is 40-70 wt%, for example, 40 wt%, 50 wt%, 60 wt% or 70 wt%.

[0134] According to the present application, in some embodiments, the positive slurry further includes a solvent. For example, the solvent can be selected from but not limited to N-methyl pyrrolidone (NMP).

[0135] According to the present application, the components in the positive electrode slurry can be mixed uniformly, for example, the positive electrode active material, the binder and the conductive agent are fully hand ground in a mortar with N-methyl pyrrolidone to obtain the positive electrode slurry.

[0136] In the fourth aspect, some embodiments of the present application provide a positive electrode sheet, comprising a positive electrode current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector; the positive electrode active layer comprises: the positive electrode active material provided in the first aspect, or the positive electrode active material prepared by the preparation method of the positive electrode active material provided in the second aspect, or the positive electrode slurry provided in the third aspect.

[0137] The positive electrode sheet in the present application can shorten the activation process in the aluminum ion battery positive electrode material, and improve the capacity retention rate of the battery.

[0138] According to the present application, the positive electrode current collector is a key component in the battery positive electrode, which generally has the functions of electronic conduction and mechanical support, and the selection of the positive electrode current collector in the present application is not particularly limited, which can be any positive electrode current collector in the art, for example, metal-based positive electrode current collectors, including but not limited to titanium foil and molybdenum sheet, or carbon-based positive electrode current collectors, including but not limited to graphene film and carbon nanotube paper.

[0139] The positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode active material layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector, and is preferably arranged on both surfaces.

[0140] According to the present application, the thickness of the positive electrode active layer can be selected in a wide range, which can generally be 20-100 microns, and the present application does not have a special limitation on this, so it is not described one by one.

[0141] In the present application, the raw material components of the positive electrode active layer can be coated on the positive electrode current collector by a coating method, and in some embodiments, the preparation method of the positive electrode sheet comprises: coating the positive electrode active material, the binder, the conductive agent and the solvent on the positive electrode current collector after being fully hand ground in a mortar, and drying to obtain the positive electrode sheet.

[0142] In the fifth aspect, some embodiments of the present application provide a battery comprising the positive electrode sheet provided in the third aspect of the present application.

[0143] The battery in the present application has low internal resistance, excellent room temperature and high temperature cycle performance, and higher charge retention capacity and capacity recovery capacity.

[0144] According to the present application, in some embodiments, the battery further comprises an aluminum battery electrolyte and a negative electrode sheet. That is, the battery is an aluminum ion battery.

[0145] According to the present application, the negative electrode sheet can be any conventional negative electrode sheet in the art, including but not limited to metal aluminum material (such as commercially available high-purity aluminum, such as aluminum foil).

[0146] In the present application, the aluminum battery electrolyte can be any aluminum battery electrolyte in the art, including but not limited to aluminum triflate aqueous solution.

[0147] The components of the battery other than the positive electrode sheet (such as the negative electrode sheet, the separator, the electrolyte, etc.) and the assembly method of the present application can be performed in accordance with conventional methods in the art, which will not be described here.

[0148] The present application will be further described in detail by the following examples. The raw materials used in the examples can be obtained by commercial channels.

[0149] Example 1

[0150] Preparation of positive active material:

[0151] 100 g of nickel nitrate Ni(NO3)2 and 25 g of manganese nitrate (Mn(NO3)2) were dissolved in 1 L of deionized water to obtain a precursor solution, which was slowly added dropwise (added within 40 min) into 1200 g of aqueous thiourea solution (10% by mass concentration) under magnetic stirring for 1 hour to form a homogeneous sol, which was then placed in an 80℃ oven for drying for 12 hours to form a precursor gel;

[0152] The precursor gel was ground into powder and placed in a tube furnace, and argon (Ar) protective gas was introduced, and the temperature was raised to 500℃ at a rate of 3℃ / min, and calcined for 3 hours;

[0153] At 1.5h of calcination, H2S gas was introduced at a flow rate of 800 mL / min for 5 min;

[0154] The calcined powder and ethanol were mixed in a mass ratio of 10:1, and a planetary ball mill was used for ball milling for 3 hours (rotation speed 300 rpm), and the positive active material was dried.

[0155] The SEM image of the positive active material is shown in Figure 1 As shown in Figure 1 The positive active material has a morphology of spherical manganese-doped nickel sulfide nanoparticles with an average particle size of 150 nm.

[0156] Preparation of binder:

[0157] Mix 70 g of polyvinylidene fluoride PVDF (average molecular weight 1 million) and 30 g of polyamide PA (average molecular weight 200,000) powder, add 900 g of N-methyl pyrrolidone NMP, magnetically stir in a 70°C water bath for 24 hours to completely dissolve, form a transparent homogeneous blended solution, add 10 g of carboxymethyl cellulose to the blended solution, high-speed disperse at 2000 rpm for 3 hours, then rotary evaporate the N-methyl pyrrolidone NMP to obtain a blended polymer, wash with acetonitrile 3 times, and dry at 60°C for 12 hours to obtain the binder.

[0158] Preparation of the battery:

[0159] Take 40 g of the positive electrode active material in this embodiment, 5 g of the binder in this embodiment, and 5 g of conductive carbon black, and N-methyl pyrrolidone in a mortar to obtain a positive electrode slurry with a concentration of 65 wt%, then coat it on a high-purity molybdenum sheet to prepare a positive electrode sheet. Use dry aluminum foil as the negative electrode, and use aluminum triflate aqueous solution (concentration 25 wt%) as the electrolyte to assemble and prepare an aluminum ion battery.

[0160] Example 2

[0161] Preparation of the positive electrode active material:

[0162] Dissolve 75 g of nickel nitrate Ni(NO3)2 and 25 g of manganese nitrate Mn(NO3)2 in 1 L of deionized water to obtain a precursor solution. Slowly drop the precursor solution into 855 g of aqueous thiourea (mass concentration 10%) (addition completed within 30 min), magnetically stir for 1 hour to form a homogeneous sol, and then place it in an 80°C oven to dry for 12 hours to form a precursor gel.

[0163] Grind the precursor gel into powder and place it in a tube furnace. Introduce argon (Ar) protective gas, and increase the temperature to 450°C at a rate of 2°C / min, and calcine for 5 hours.

[0164] At 4h of calcination, introduce H2S gas at a rate of 500 mL / min for 4 min.

[0165] Mix the calcined powder with a mass ratio of 5:1 with ethanol, ball mill for 3 hours (rotation speed 300 rpm) using a planetary ball mill, and dry to obtain the positive electrode active material.

[0166] SEM image of the positive electrode active material and Figure 1 Similarly, the positive electrode active material has a morphology of agglomerates formed by spherical manganese-doped nickel sulfide nanoparticles.

[0167] Preparation of the binder:

[0168] 65 g of polyvinylidene fluoride PVDF (average molecular weight 1 million) and 35 g of polyacrylamide APAM (average molecular weight 400,000) powders were mixed, 900 g of N-methyl pyrrolidone NMP was added, and magnetic stirring was performed in a 70 °C water bath for 24 hours until complete dissolution to form a transparent and homogeneous blended solution. 15 g of carboxymethyl cellulose was added to the blended solution, and high-speed dispersion was performed at 2000 rpm for 3 hours. N-methyl pyrrolidone NMP was removed by rotary evaporation, and the blended polymer was obtained. The blended polymer was washed with acetonitrile three times and dried at 60 °C for 12 hours to obtain the binder.

[0169] Preparation of the battery:

[0170] An aluminum ion battery was prepared using the positive electrode active material and the binder in the present embodiment according to the method of Example 1.

[0171] Example 3

[0172] Preparation of the positive electrode active material:

[0173] 125 g of nickel nitrate Ni(NO3)2 and 25 g of manganese nitrate Mn(NO3)2 were dissolved in 1 L of deionized water to obtain a precursor solution. The precursor solution was slowly added dropwise (added dropwise within 60 min) into 1620 g of an aqueous thiourea solution (mass concentration of 10%) and magnetically stirred for 1 hour to form a homogeneous sol. The sol was then placed in an oven at 80 °C for drying for 12 hours to form a precursor gel.

[0174] The precursor gel was ground into powder and placed in a tube furnace. Argon (Ar) was introduced as a protective gas, and the temperature was increased to 450 °C at a rate of 2 °C / min. Calcination was performed for 5 hours.

[0175] At 4 h of calcination, 500 mL / min of H2S gas was introduced for 5 min.

[0176] The calcined powder and ethanol were mixed at a mass ratio of 15:1, and planetary ball milling was performed for 3 hours (rotation speed of 300 rpm). The positive electrode active material was obtained after drying.

[0177] The SEM image of the positive electrode active material and Figure 1 Similarly, the SEM image of the positive electrode active material and Figure 1 Similarly, the positive electrode active material has a morphology of agglomerates formed by agglomeration of spherical manganese-doped nickel sulfide nanoparticles.

[0178] Preparation of the binder:

[0179] 100 g of polyvinylidene fluoride PVDF and 50 g of polyacrylamide APAM (average molecular weight of 400,000) powder were mixed, 900 g of N-methyl pyrrolidone NMP was added, and the mixture was magnetically stirred in a 70 °C water bath for 24 hours until completely dissolved to form a transparent and homogeneous blended solution. 20 g of carboxymethyl cellulose was added to the blended solution, and high-speed dispersion was performed at 2000 rpm for 3 hours. After rotary evaporation, the blended polymer was obtained, washed with acetonitrile for 3 times, and dried at 60 °C for 12 hours to obtain the binder.

[0180] Preparation of the battery:

[0181] An aluminum-ion battery was prepared using the positive electrode active material and the binder in this example according to the method of Example 1.

[0182] Example 4

[0183] According to the method of Example 1, except that:

[0184] The binder was polyvinylidene fluoride PVDF.

[0185] Finally, an aluminum-ion battery was prepared.

[0186] Example 5

[0187] According to the method of Example 1, except that:

[0188] The binder was polyamide PA.

[0189] Finally, an aluminum-ion battery was prepared.

[0190] Comparative Example 1

[0191] According to the method of Example 1, except that:

[0192] Nickel nitrate Ni(NO3)2 was 100 g, and no manganese nitrate (Mn(NO3)2) was added (i.e., 100 g of nickel nitrate Ni(NO3)2 was dissolved in 1 L of deionized water to obtain a precursor solution);

[0193] The rest was the same as Example 1, and finally an aluminum-ion battery was prepared.

[0194] Comparative Example 2

[0195] According to the method of Example 1, except that:

[0196] The aqueous thiourea solution was 1336 g (concentration of 10%), and no H2S gas was introduced during calcination.

[0197] The rest was the same as Example 1, and finally an aluminum-ion battery was prepared.

[0198] Performance test

[0199] 1. Cycle performance test: the battery is respectively placed in a constant temperature box at 25℃ and 45℃, and the capacity retention rate of the battery under different temperature conditions is calculated by 1C / 1C charge-discharge for 50 cycles.

[0200] 2. Internal resistance test: test the internal resistance of the battery.

[0201] 3. Storage test: after the battery is placed in a constant temperature box at 55℃ for 60 days, the charge retention rate and capacity recovery rate are tested.

[0202] Table 1

[0203]

[0204]

[0205] From the relevant data in Table 1, it can be seen that:

[0206] As can be seen from the comparison of Examples 1-5 and Comparative Example 1, compared with the positive electrode active material without manganese doping in Comparative Example 1, the positive electrode active material in the present application can reduce the internal resistance of the battery while the battery also has excellent normal temperature and high temperature cycle performance, higher charge retention capacity and capacity recovery capacity; as can be seen from the comparison of Examples 1-5 and Comparative Example 2, compared with Comparative Example 1, when preparing the positive electrode active material, not passing H2S gas during calcination, the positive electrode active material containing the present application can reduce the internal resistance of the battery while the battery also has excellent normal temperature and high temperature cycle performance, higher charge retention capacity and capacity recovery capacity. The reason is that not passing H2S gas during calcination can make the positive electrode active material have a unique micro-morphology, while ensuring the uniform doping of sulfur elements. That is, the positive electrode active material in the present application dopes metal manganese with a large variable valence Gibbs free energy, and cooperates with the control of the morphology of the positive electrode active material. When the positive electrode active material is used in the battery, especially in the aluminum ion battery, the internal resistance of the battery is low, and the activation process can be shortened.

[0207] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A positive electrode active material, characterized in that, The positive electrode active material includes manganese-doped nickel sulfide; The positive electrode active material has an aggregate morphology formed by the aggregation of nanoparticles.

2. The positive electrode active material according to claim 1, characterized in that, The average particle size of the nanoparticles is 100nm-200nm; And / or, the nanoparticles are spherical; And / or, in the manganese-doped nickel sulfide, the manganese content is 5%-30% by mass.

3. A method for preparing a positive electrode active material, characterized in that, The preparation method includes: The precursor solution containing nickel and manganese sources was mixed with the sulfur source solution containing sulfur source, and then dried and calcined. In this process, a gaseous sulfur source is introduced.

4. The method for preparing the positive electrode active material according to claim 3, characterized in that, The preparation method shall satisfy at least one of the following conditions (1)-(7): (1) A gaseous sulfur source is introduced during the middle or later stages of the calcination; (2) The gaseous sulfur source is introduced for 1-10 min; (3) The calcination conditions include: being carried out under an inert atmosphere, at a temperature of 400-600℃, at a heating rate of 2-5℃ / min, and for a time of 2-5h. (4) The mixing conditions include: room temperature, and a time of 0.5h-2h; (5) The mixing method includes: adding the precursor solution dropwise into the sulfur source solution to carry out the mixing; (6) The preparation method further includes a grinding step between the drying and the calcination; (7) The preparation method further includes: ball milling after calcination.

5. The method for preparing the positive electrode active material according to claim 3 or 4, characterized in that, The preparation method shall satisfy at least one of the following conditions (1)-(9): (1) The nickel source is calculated as nickel element and the manganese source is calculated as manganese element, and the molar ratio of the nickel source to the manganese source is (3-7):1; (2) The nickel source is calculated as nickel element and the sulfur source is calculated as sulfur element, and the molar ratio of the nickel source to the sulfur source is 1:(0.2-6); (3) The nickel source is calculated as nickel element and the gaseous sulfur source is calculated as sulfur element, and the molar ratio of the gaseous sulfur source to the nickel source is 1:(2-15); (4) In the precursor solution, the total concentration of the nickel source and the manganese source is 5wt%-90wt%; (5) In the sulfur source solution, the concentration of the sulfur source is 5wt%-60wt%; (6) The gaseous sulfur source includes H2S gas and / or sulfur vapor; (7) The nickel source and the manganese source each independently include at least one of the sulfate, nitrate, acetate, hydrochloride and oxalate of the corresponding metal; (8) The sulfur source includes thiourea and / or thioacetamide; (9) The solvent in the precursor solution and the solvent in the sulfur source solution each independently include water.

6. A positive electrode slurry, characterized in that, include: Adhesive; The positive electrode active material according to claim 1 or 2, or the positive electrode active material prepared by the preparation method of any one of claims 3-5.

7. The positive electrode slurry according to claim 6, characterized in that, The mass ratio of the binder to the positive electrode active material is (70-90):(5-15); And / or, the solid content of the positive electrode slurry is 40-70 wt%; And / or, the binder is present in the form of a blended polymer; And / or, the adhesive includes fluorinated adhesives and amide-based adhesives; And / or, the adhesive further includes a dispersant; And / or, the positive electrode slurry also includes a conductive agent.

8. The positive electrode slurry according to claim 7, characterized in that, And / or, the dispersant includes at least one of carboxymethyl cellulose, polyacrylate, and polyethylene glycol; And / or, in the adhesive, the dispersant content is 2%-15% by mass; And / or, the fluorinated adhesive includes at least one of polyvinylidene fluoride, a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, and polytetrafluoroethylene; And / or, the amide-based binder comprises at least one of polyamide, polyacrylamide, acrylamide copolymer, and polyurethane-amide hybrid polymer; And / or, the mass ratio of the fluorinated adhesive to the amide-based adhesive is (1.5-10):1; And / or, the mass ratio of the conductive agent to the positive electrode active material is (5-15):(70-90).

9. A positive electrode plate, characterized in that, It includes a positive current collector and a positive active layer disposed on at least one surface of the positive current collector; The positive electrode active layer comprises: the positive electrode active material according to claim 1 or 2, or the positive electrode active material prepared by the preparation method of the positive electrode active material according to any one of claims 3-5, or the positive electrode slurry according to any one of claims 6-8, which is dried to form the positive electrode active layer.

10. A battery, characterized in that, Including the positive electrode sheet as described in claim 9; The battery also includes aluminum battery electrolyte and negative electrode sheet.

Images