A coated doped double-modified positive electrode material and a preparation method and application thereof

Abstract

The application discloses a coated and doped double-modified positive electrode material and a preparation method and application thereof. The coated and doped double-modified positive electrode material comprises a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer comprises conductive ceramics which are composite oxides containing at least two metal elements. The intrinsic properties of the positive electrode material can be regulated by doping the positive electrode material with phosphate anions, and the electronic and ionic transmission properties of the positive electrode material can be effectively improved by the synergistic effect of the coating of the conductive ceramics of multiple metals, so that the electrochemical performance of the material is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, and relates to a coated doped double-modified positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the wide application of lithium ion batteries, higher requirements are put forward for the performance of lithium ion batteries, and high-nickel ternary materials (such as Ni content > 80%) have the advantages of high energy density, but are faced with the problems of poor stability and poor conductivity.

[0003] CN113571692A discloses a high-safety conductive material modified high-nickel positive electrode material and a preparation method thereof, which comprises the following steps: an organic silicon monomer is subjected to a dehydration condensation reaction with a phosphorus-containing compound to prepare a modified polysiloxane; the modified polysiloxane, a polyol, a diisocyanate and a chain extender are subjected to a reaction to obtain a flame-retardant polymer; and the flame-retardant polymer is compounded with a conductive material and coated on the surface of the high-nickel positive electrode material to obtain the high-safety conductive material modified high-nickel positive electrode material. Through the synergistic effect of the flame-retardant polymer and aniline-p-phenylenediamine copolymer, the conductivity of the high-nickel positive electrode material is increased, the interface electrochemical reaction environment is effectively optimized, and the electrochemical performance of the material is improved.

[0004] CN118738357A discloses a high-nickel ternary positive electrode material with low residual alkali, high specific capacity and high cycle stability and a preparation method thereof, which comprises the following steps: preparation of a primary coating agent dispersion liquid, mixing of the high-nickel ternary positive electrode material and the primary coating agent dispersion liquid, vacuum drying of the primary mixture, solid-phase sintering of the primary coated high-nickel ternary positive electrode material, preparation of a secondary coating agent dispersion liquid, mixing of the primary coated high-nickel ternary positive electrode material matrix and the secondary coating agent dispersion liquid, and vacuum drying of the secondary mixture. x Co y Mn z O2(0.8≤x<1, 0<y<0.2, 0<z<0.2, and x+y+z=1) active substance, and a coating layer formed by primary co-coating of aluminum phosphate and lithium phosphate and secondary coating of a graphene, carbon nanotube and conductive carbon black composite coating agent, can effectively reduce the residual alkali content in the high-nickel ternary positive electrode material, and can improve the conductivity of the high-nickel ternary positive electrode material, thereby significantly improving the specific capacity and cycle stability of the high-nickel ternary positive electrode material.

[0005] CN118367145A discloses a multi-dimensional carbon network / polymer double-coated high-nickel ternary positive electrode material and a preparation method and application thereof, the preparation method comprising: uniformly dispersing graphene, carbon nanotubes and polymer A in an organic solvent in sequence to obtain a carbon-coated solution of multi-dimensional carbon network; adding high-nickel ternary material to the carbon-coated solution, uniformly dispersing, and then obtaining a mixed slurry; heating the mixed slurry to evaporate the solvent, sealing and standing, drying, grinding, and sintering to obtain a multi-dimensional carbon network-coated high-nickel ternary material; adding the multi-dimensional carbon network-coated high-nickel ternary material to a modified solution of electron-conducting / lithium ion-conducting polymer B, uniformly dispersing, and then heating to evaporate the solvent to obtain a multi-dimensional carbon network / polymer double-coated high-nickel ternary positive electrode material. The high-nickel ternary positive electrode material prepared by the method has a two-layer coating structure, which improves the structural stability and electrochemical performance of the high-nickel ternary material during charging and discharging.

[0006] The above method improves the conductivity and stability of the high-nickel ternary material by coating, which can improve the electrochemical performance of the material to a certain extent. However, on the one hand, the preparation of conductive materials such as graphene is complex and expensive, which increases the preparation cost. On the other hand, the method of coating the ternary positive electrode material with conductive substances cannot control the intrinsic properties of the ternary positive electrode material, and the effect of improving the electrochemical performance is limited.

[0007] Therefore, it is a technical problem to be solved at present to provide an improved strategy for high-nickel ternary materials to effectively improve the electrochemical performance and reduce the preparation cost. SUMMARY

[0008] To achieve the above-mentioned purpose, the purpose of the present application is to provide a coated and doped double-modified positive electrode material and a preparation method and application thereof.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a coated and doped double-modified positive electrode material, which comprises a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer comprises conductive ceramic, and the conductive ceramic is a composite oxide comprising at least two metal elements.

[0011] The present application can control the intrinsic properties of the positive electrode material by doping the positive electrode material with phosphate anions, and cooperate with the coating of multi-metal conductive ceramic. The synergistic effect can effectively improve the electronic and ionic transport properties of the positive electrode material and improve the electrochemical performance of the material.

[0012] The following is a preferred technical solution of the present application, but is not a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the technical purpose and beneficial effects of the present application can be better achieved and implemented.

[0013] Preferably, the particle size of the inner core is 10-15 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm, etc.

[0014] Preferably, the inner core is a ternary positive electrode material doped with phosphate, and the molar content of nickel in the inner core is ≥ 80%.

[0015] Preferably, the doping amount of phosphate is 0.2-2 wt%, for example, it can be 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt% or 2 wt%, etc., based on the total mass of the coated and doped double-modified positive electrode material.

[0016] Preferably, the conductive ceramic is CaO·ZrO2.

[0017] Preferably, the coating amount of the conductive ceramic is 0.1-0.8 wt%, for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt% or 0.8 wt%, etc., based on the total mass of the coated and doped double-modified positive electrode material.

[0018] In one embodiment, the chemical formula of the coated and doped double-modified positive electrode material is Li[Ni x Co y Mn z ]O2·A@B, x+y+z=1, 0.8≤x, 0<y, 0<z; A is a lithium salt of a doped anion (phosphate); B is a conductive ceramic coating layer.

[0019] In a second aspect, the present application provides a preparation method of the coated and doped double-modified positive electrode material according to the first aspect, and the preparation method comprises the following steps:

[0020] (1) preparing a first metal salt solution, an ammonium phosphate solution and a second metal salt solution respectively, wherein the first metal salt solution is used to form an inner core, and the second metal salt solution is used to form a conductive ceramic;

[0021] (2) under the protection of a protective gas, adding the first metal salt solution, the ammonium phosphate solution, a complexing agent solution and a precipitant solution into a bottom solution, and reacting;

[0022] (3) when the reaction reaches the preset particle size of the inner core, stop passing the first metal salt solution and the ammonium phosphate solution, and replace them with the second metal salt solution, and then react to obtain a precursor;

[0023] (4) mix the precursor with a lithium salt, and calcine to obtain the coated and doped double-modified positive electrode material.

[0024] The method of the present application can obtain a phosphate-doped and conductive ceramic-coated positive electrode material by using ammonium phosphate as a raw material of an anion phosphate group in the precursor preparation stage, carrying out a reaction, carrying out coating of a conductive ceramic precursor when the reaction reaches the preset particle size of the inner core, and carrying out lithium mixing and sintering of the precursor. Compared with directly doping and coating a ternary positive electrode material, the method of the present application can improve the doping and coating effect and is more conducive to improving the electrochemical performance of the material. As a preferred technical solution of the method of the present application, the first metal salt solution in step (1) is a nickel-cobalt-manganese ternary salt solution.

[0025] Preferably, the concentration of the first metal salt solution is 1 mol / L to 3 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.7 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.7 mol / L or 3 mol / L, etc.

[0026] Preferably, the concentration of the ammonium phosphate solution is 0.01 mol / L to 0.1 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, etc.

[0027] Preferably, the second metal salt solution is a calcium-zirconium metal salt solution.

[0028] Preferably, in the calcium-zirconium metal salt solution, the molar ratio of calcium to zirconium is (1-2):(1-2), wherein the selection range of calcium is "1-2", for example, it can be 1, 1.2, 1.5, 1.6, 1.8 or 2, etc.; the selection range of zirconium is "1-2", for example, it can be 1, 1.2, 1.5, 1.6, 1.8 or 2, etc.

[0029] Preferably, the concentration of the second metal salt solution is 0.01-0.1 mol / L, for example, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1 mol / L, etc.

[0030] As a preferred technical solution of the method of the present application, the pH of the bottom solution in step (2) is 10-12, for example, it can be 10, 10.2, 10.5, 10.7, 11, 11.3, 11.5, 11.6, 11.8 or 12, etc.; the ammonia concentration of the bottom solution is 0.5-2 mol / L, for example, it can be 0.5, 1, 1.2, 1.3, 1.4, 1.5, 1.7, 1.8 or 2 mol / L, etc.

[0031] Preferably, in step (2), the flow rate of the first metal salt solution is 2-5 L / h, for example, it can be 2, 2.2, 2.4, 2.5, 2.7, 3, 3.3, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5 L / h, etc.

[0032] Preferably, in step (2), the flow rate of the ammonium phosphate is 0.3-1 L / h, for example, it can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1 L / h, etc.

[0033] Preferably, the concentration of the complexing agent solution in step (2) is 5-10 mol / L, for example, it can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10 mol / L, etc.

[0034] Preferably, in step (2), the flow rate of the complexing agent solution is 0.2-0.5 L / h, for example, it can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5 L / h, etc.

[0035] Preferably, the concentration of the precipitant solution in step (2) is 3-6 mol / L, for example, it can be 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L or 6 mol / L, etc.

[0036] Preferably, in step (2), the flow rate of the precipitant solution is 2-5 L / h, for example, it can be 2 L / h, 2.5 L / h, 3 L / h, 3.5 L / h, 4 L / h, 4.5 L / h or 5 L / h, etc.

[0037] As a preferred technical solution of the method of the present application, in step (3), the concentration of the second metal salt solution is 7-13 L / h, for example, it can be 7 L / h, 7.5 L / h, 8 L / h, 8.5 L / h, 9 L / h, 9.5 L / h, 10 L / h, 10.5 L / h, 11 L / h, 11.5 L / h, 12 L / h, 12.5 L / h or 13 L / h, etc.

[0038] Preferably, in step (3), the flow rate of the complexing agent solution is 0.002-0.005 L / h, for example, it can be 0.002 L / h, 0.003 L / h, 0.004 L / h or 0.005 L / h, etc.

[0039] Preferably, in step (3), the flow rate of the precipitant solution is 0.1-0.5 L / h, for example, it can be 0.1 L / h, 0.2 L / h, 0.25 L / h, 0.3 L / h, 0.35 L / h, 0.4 L / h, 0.45 L / h or 0.5 L / h, etc.

[0040] Preferably, the reaction time in step (3) is 5-15 h, for example, it can be 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h, 12 h, 12.5 h, 13 h, 13.5 h, 14 h or 15 h, etc.

[0041] As a preferred technical solution of the method of the present application, the calcination in step (4) is a step-by-step calcination, which includes one-step calcination, two-step calcination and three-step calcination, the two-step calcination is followed by cooling, crushing, water washing and drying, and the drying is followed by three-step calcination; wherein the temperature of the two-step calcination is higher than that of the one-step calcination, and the temperature of the two-step calcination is higher than that of the three-step calcination.

[0042] The above method is used for calcination, the residual alkali on the surface of the positive electrode material is effectively removed, the side reaction between the material surface and the electrolyte is reduced, at the same time, the composite oxide coating layer on the surface further inhibits the erosion of HF to the positive electrode material, and the structure of the material is stabilized, thereby showing good comprehensive electrochemical performance.

[0043] Preferably, the temperature of the one-step calcination is 500-700℃, for example, it can be 500℃, 525℃, 550℃, 570℃, 600℃, 620℃, 640℃, 660℃, 680℃ or 700℃, etc.

[0044] Preferably, the time of the one-step calcination is 3-6h, for example, it can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, etc.

[0045] Preferably, the temperature of the two-step calcination is 750-950℃, for example, it can be 750℃, 770℃, 800℃, 825℃, 850℃, 860℃, 880℃, 900℃, 925℃ or 950℃, etc.

[0046] Preferably, the time of the two-step calcination is 10-18h, for example, it can be 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 16h, 17h or 18h, etc.

[0047] Preferably, the temperature of the three-step calcination is 650-750℃, for example, it can be 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 715℃, 730℃, 740℃ or 750℃, etc.

[0048] Preferably, the time of the three-step calcination is 0.5-3h, for example, it can be 0.5h, 0.7h, 0.8h, 1h, 1.2h, 1.3h, 1.5h, 1.7h, 2h, 2.3h, 2.6h, 2.8h or 3h, etc.

[0049] In a third aspect, the present application provides a positive electrode comprising the coated and doped double-modified positive electrode material of the first aspect.

[0050] In a fourth aspect, the present application provides a battery comprising the positive electrode of the third aspect.

[0051] The numerical range of the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and for the sake of brevity and simplicity, the present application does not exhaustively list the specific point values included in the range.

[0052] Compared with the prior art, the present application has the following beneficial effects:

[0053] (1) The present application can control the intrinsic properties of the positive electrode material by doping the positive electrode material with phosphate anions, and can effectively improve the electronic and ionic transport properties of the positive electrode material and improve the electrochemical performance of the material by the synergistic effect of the coating of the multi-metal conductive ceramic.

[0054] (2) The method of the present application can improve the doping and coating effect and be more conducive to improving the electrochemical performance of the material by using ammonium phosphate as the raw material of the anion phosphate in the precursor preparation stage, reacting, coating the conductive ceramic precursor after the preset particle size of the core, and obtaining the precursor, and by lithiumizing and sintering the precursor, the positive electrode material doped with phosphate and coated with conductive ceramic can be obtained. DETAILED DESCRIPTION

[0055] The technical solutions of the present application will be further described below through specific embodiments.

[0056] Example 1

[0057] The present embodiment provides a coated and doped double-modified positive electrode material, which comprises a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer comprises conductive ceramic, and the conductive ceramic is CaO·ZrO2.

[0058] The particle size of the core is 12 μm; the doping amount of the phosphate is 1 wt% based on the total mass of the coated and doped double-modified positive electrode material, and the coating amount of the conductive ceramic is 0.5 wt%.

[0059] The present embodiment also provides a preparation method of the coated and doped double-modified positive electrode material described above, comprising the following steps:

[0060] (1) Dissolve nickel chloride, cobalt chloride and manganese chloride in water to obtain a first solution, wherein the molar ratio of the metals is Ni:Co:Mn=90:5:5, and the total concentration of metal ions is 2 mol / L;

[0061] Dissolve ammonium phosphate in water to obtain a second solution, and the concentration is 0.02 mol / L;

[0062] Dissolve zirconium chloride and calcium chloride in water to obtain a third solution, wherein the molar ratio of the metals is Zr:Ca=1:1, and the concentration of metal ions is 0.01 mol / L;

[0063] Liquid alkali is a precipitating agent, and the concentration is 4 mol / L;

[0064] Ammonia water is a complexing agent, the concentration is 8mol / L;

[0065] (2) Under the protection of inert gas, 40L water, liquid alkali and ammonia water are added into the reaction kettle to form a bottom liquid with pH=11.2 and ammonia concentration of 0.6mol / L, the reaction temperature is controlled at 65℃, the stirring speed is 220rpm, the first solution flow rate is 2L / h, the second solution flow rate is 0.5L / h, the liquid alkali flow rate is 1L / h, and the ammonia water flow rate is 0.35L / h. When the particle size of the material in the reaction kettle reaches 10μm, the third solution, liquid alkali and ammonia water are used for feeding, the third solution flow rate is 10L / h, the liquid alkali flow rate is 0.1L / h, and the ammonia water flow rate is 0.003L / h. After 10h of reaction, the reaction is stopped, the material in the reaction kettle is washed with liquid alkali and water respectively, and the first product is obtained after drying;

[0066] (5) The first product is mixed with lithium hydroxide at a ratio of 1:1.05, and then is placed in a crucible and calcined at 550℃ for 5h, then calcined at 900℃ for 15h, and then cooled to room temperature, crushed, washed with water, dried, and then calcined at 700℃ for 1h. After cooling, the iron is removed by screening to obtain the second product, and the chemical formula of the second product is Li[Ni 0.9 Co 0.05 Mn 0.05 ]O2·Li3PO4@CaO·ZrO2.

[0067] Example 2

[0068] The present embodiment provides a coated and doped double modified positive electrode material, which comprises a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer comprises a conductive ceramic, and the conductive ceramic is CaO·ZrO2.

[0069] The particle size of the core is 10μm; the doping amount of the phosphate is 1.5wt%, and the coating amount of the conductive ceramic is 0.3wt% based on the total mass of the coated and doped double modified positive electrode material.

[0070] The present embodiment also provides a preparation method of the coated and doped double modified positive electrode material, comprising the following steps:

[0071] (1) Nickel chloride, cobalt chloride and manganese chloride are dissolved in water to obtain a first solution, wherein the molar ratio of the metals is Ni:Co:Mn=88:6:6, and the total concentration of metal ions is 1.5mol / L;

[0072] Ammonium phosphate is dissolved in water to obtain a second solution, and the concentration is 0.05mol / L;

[0073] Zirconium chloride and calcium chloride were dissolved in water to obtain a third solution, wherein the molar ratio of the metals was Zr:Ca=2:1, and the concentration of the metal ions was 0.03 mol / L;

[0074] Liquid alkali was used as the precipitant, and the concentration was 5 mol / L;

[0075] Ammonia was used as the complexing agent, and the concentration was 10 mol / L;

[0076] (2) Under the protection of inert gas, 40 L of water was added to the reaction kettle, liquid alkali and ammonia were added, and a bottom solution with pH=11.5 and ammonia concentration of 1 mol / L was prepared, the reaction temperature was controlled at 60℃, and the stirring speed was 300 rpm, the first solution was fed into the reaction kettle at a flow rate of 4 L / h, the second solution was fed at a flow rate of 0.8 L / h, the liquid alkali was fed at a flow rate of 1.3 L / h, and the ammonia was fed at a flow rate of 0.2 L / h. When the particle size of the material in the reaction kettle reached 13 μm, the third solution, liquid alkali and ammonia were used for feeding, the flow rate of the third solution was 8 L / h, the flow rate of the liquid alkali was 0.2 L / h, and the flow rate of the ammonia was 0.005 L / h. After 8 h of reaction, the reaction was stopped, the material in the reaction kettle was washed with liquid alkali and water respectively, and the first product was obtained after drying;

[0077] (5) The first product was mixed with lithium hydroxide at a ratio of 1:1.05, calcined at 600℃ for 5 h, then calcined at 850℃ for 15 h, then cooled to room temperature, crushed, washed with water, dried, and then calcined at 750℃ for 1 h. After cooling, the iron was removed by screening to obtain the second product, and the chemical formula of the second product was Li[Ni 0.88 Co 0.06 Mn 0.06 ]O2·Li3PO4@CaO·ZrO2.

[0078] Example 3

[0079] The coated and doped double-modified positive electrode material provided in the embodiment includes a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer includes a conductive ceramic, and the conductive ceramic is CaO·ZrO2.

[0080] The particle size of the core is 15 μm, the doping amount of the phosphate is 0.5 wt% based on the total mass of the coated and doped double-modified positive electrode material, and the coating amount of the conductive ceramic is 0.8 wt%.

[0081] The embodiment also provides a preparation method of the coated and doped double-modified positive electrode material, including the following steps:

[0082] (1) Dissolve nickel chloride, cobalt chloride and manganese chloride in water to obtain a first solution, wherein the molar ratio of the metals is Ni:Co:Mn=90:6:4, and the total concentration of metal ions is 3 mol / L;

[0083] Dissolve ammonium phosphate in water to obtain a second solution with a concentration of 0.1 mol / L;

[0084] Dissolve zirconium chloride and calcium chloride in water to obtain a third solution, wherein the molar ratio of the metals is Zr:Ca=1:2, and the concentration of metal ions is 0.05 mol / L;

[0085] Liquid alkali is a precipitant with a concentration of 6 mol / L;

[0086] Ammonia is a complexing agent with a concentration of 5 mol / L;

[0087] (2) Under the protection of inert gas, 40 L of water is added to a reaction kettle, and liquid alkali and ammonia are added to prepare a bottom solution with pH=11.8 and ammonia concentration of 1.5 mol / L. The reaction temperature is controlled at 68℃, and the stirring speed is 275 rpm. The first solution is fed into the reaction kettle at a flow rate of 5 L / h, the second solution at a flow rate of 0.3 L / h, the liquid alkali at a flow rate of 4.5 L / h, and the ammonia at a flow rate of 0.45 L / h. When the particle size of the material in the reaction kettle reaches 6 μm, the third solution, liquid alkali and ammonia are used for feeding, the third solution at a flow rate of 12 L / h, the liquid alkali at a flow rate of 0.5 L / h, and the ammonia at a flow rate of 0.004 L / h. The reaction is stopped after 15 h, and the material in the reaction kettle is washed with liquid alkali and water respectively, and dried to obtain a first product;

[0088] (5) The first product is mixed with lithium hydroxide at a ratio of 1:1.05, and then is placed in a crucible and calcined at 500℃ for 5 h, and then at 800℃ for 12 h. After cooling to room temperature, crushing, water washing, and drying, the mixture is calcined at 650℃ for 3 h. After cooling, iron is removed by sieving to obtain a second product. The chemical formula of the second product is Li[Ni 0.9 Co 0.06 Mn 0.04 ]O2·Li3PO4@CaO·ZrO2.

[0089] Example 4

[0090] The difference between the coated and doped double modified positive electrode material of the present embodiment and that of Example 1 is that the doping amount of the phosphate is 0.1 wt% based on the total mass of the coated and doped double modified positive electrode material.

[0091] Example 5

[0092] The embodiment provides a coated and doped double-modified positive electrode material, which is different from the embodiment 1 in that the doping amount of the phosphate is 2.5 wt% based on 100% of the total mass of the coated and doped double-modified positive electrode material.

[0093] Embodiment 6

[0094] The embodiment provides a coated and doped double-modified positive electrode material, which is different from the embodiment 1 in that the coating amount of the conductive ceramic is 0.05 wt% based on 100% of the total mass of the coated and doped double-modified positive electrode material.

[0095] Embodiment 7

[0096] The embodiment provides a coated and doped double-modified positive electrode material, which is different from the embodiment 1 in that the coating amount of the conductive ceramic is 1.2 wt% based on 100% of the total mass of the coated and doped double-modified positive electrode material.

[0097] Comparative Example 1

[0098] A positive electrode material is provided, which is different from the embodiment 1 in that the phosphate doping is not performed.

[0099] Comparative Example 2

[0100] A positive electrode material is provided, which is different from the embodiment 1 in that the coating of the conductive ceramic is not performed.

[0101] The positive electrode materials in the embodiments 1-7 and the comparative examples 1-2 are used to prepare positive electrodes and assemble batteries, including the following steps:

[0102] 80 wt% of the positive electrode material, 10 wt% of Super P and 10 wt% of polyvinylidene fluoride (PVDF) are dispersed in an N-methyl pyrrolidone (NMP) solution to prepare a positive electrode slurry, which is coated on an aluminum foil and dried to obtain a positive electrode;

[0103] A lithium sheet is used as a negative electrode;

[0104] A separator is a PP microporous membrane (Celgard 2500);

[0105] The electrolyte is composed of 1M LiPF6 (a mixed solvent of EC, DMC and EMC as a solvent, wherein the volume ratio of EC:DMC:EMC is 1:1:1).

[0106] The above positive electrode, the separator, the negative electrode and the electrolyte are assembled to obtain a button cell.

[0107] Performance test: 200 cycles are performed at room temperature, in a voltage range of 2.7-4.3V and at a rate of 1C, and the initial discharge capacity and the capacity retention rate after 1000 cycles are recorded.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from Table 1, by doping anion phosphate and coating with conductive ceramic, the conductivity and stability of the positive electrode material can be effectively improved, and the initial discharge capacity and cycle performance are improved.

[0112] Meanwhile, as can be seen from the comparison of Example 1 and Examples 4-5 and Comparative Example 1, too little phosphate doping does not have a good effect and cannot significantly improve the conductivity of the material, and too much phosphate doping reduces the conductivity of the material, and at the same time, the initial discharge capacity and cycle performance are also reduced.

[0113] As can be seen from the comparison of Example 1 and Examples 6-7 and Comparative Example 2, coating the high-nickel positive electrode material with calcium-zirconium composite oxide ceramic can improve the cycle stability of the material, and too little coating can improve the cycle performance but also reduce the initial discharge capacity; too much coating greatly reduces the capacity of the material itself, and the improvement of the cycle performance is also reduced.

[0114] The applicant declares that the above examples are used to illustrate the detailed method of the present application, but the present application is not limited to the above detailed method, that is, it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A coated doped double modified positive electrode material, characterized in that, The coated and doped double-modified positive electrode material comprises a positive electrode core and a coating layer coated on the surface of the core, the core is doped with phosphate, and the coating layer comprises conductive ceramic which is a composite oxide comprising at least two metal elements; The core is a ternary positive electrode material doped with phosphate, and the molar content of nickel in the core is greater than or equal to 80%; The doping amount of the phosphate is 0.2wt%-2wt% based on the total mass of the coated and doped double-modified positive electrode material being 100wt%; The conductive ceramic is CaO·ZrO2; The coating amount of the conductive ceramic is 0.1wt%-0.8wt% based on the total mass of the coated and doped double-modified positive electrode material being 100wt%.

2. The coated doped double-modified cathode material of claim 1, wherein, The particle size of the core is 10μm-15μm.

3. A method for producing the coated doped double-modified positive electrode material according to claim 1 or 2, characterized in that The preparation method comprises the following steps: (1) preparing a first metal salt solution, an ammonium phosphate solution, and a second metal salt solution respectively, wherein the first metal salt solution is used to form the core, and the second metal salt solution is used to form the conductive ceramic; (2) under the protection of a protective gas, adding the first metal salt solution, the ammonium phosphate solution, a complexing agent solution, and a precipitant solution into a bottom liquid, and reacting; (3) when the core reaches a preset particle size, stopping the first metal salt solution and the ammonium phosphate solution, replacing them with the second metal salt solution, and reacting to obtain a precursor; (4) mixing the precursor with a lithium salt, and calcining to obtain the coated and doped double-modified positive electrode material.

4. The production method according to claim 3, characterized by, The first metal salt solution in step (1) is a nickel-cobalt-manganese ternary salt solution.

5. The preparation method according to claim 3, characterized in that, The concentration of the first metal salt solution is 1mol / L-3mol / L.

6. The preparation method according to claim 3, characterized in that, The concentration of the ammonium phosphate solution is 0.01mol / L-0.1mol / L.

7. The preparation method according to claim 3, characterized in that, The second metal salt solution is a calcium-zirconium metal salt solution.

8. The production method according to claim 7, characterized by, In the calcium-zirconium metal salt solution, the molar ratio of calcium to zirconium is (1-2):(1-2).

9. The preparation method according to claim 3, characterized in that, The concentration of the second metal salt solution is 0.01mol / L-0.1mol / L.

10. The preparation method according to claim 3, characterized in that, The pH of the bottom liquid in step (2) is 10-12, and the ammonia concentration of the bottom liquid is 0.5mol / L-2mol / L.

11. The preparation method according to claim 3, characterized in that, In step (2), the flow rate of the first metal salt solution is 2L / h-5L / h.

12. The method of claim 3, wherein, In step (2), the flow rate of the ammonium phosphate is 0.3L / h-1L / h.

13. The preparation method according to claim 3, characterized in that, The concentration of the complexing agent solution in step (2) is 5mol / L-10mol / L.

14. The method of claim 3, wherein, In step (2), the flow rate of the complexing agent solution is 0.2-0.5L / h.

15. The preparation method according to claim 3, characterized in that, The concentration of the precipitant solution in step (2) is 3mol / L-6mol / L.

16. The preparation method according to claim 3, characterized in that, In step (2), the flow rate of the precipitant solution is 1L / h-5L / h.

17. The preparation method according to claim 4, characterized in that, In step (3), the concentration of the second metal salt solution is 7L / h-13L / h.

18. The method of claim 3, wherein, In step (3), the flow rate of the complexing agent solution is 0.002L / h-0.005L / h.

19. The method of claim 3, wherein, In step (3), the flow rate of the precipitant solution is 0.1L / h-0.5L / h.

20. The method of claim 3, wherein, The reaction time in step (3) is 5h-15h.

21. The method of claim 4, wherein, The calcination in step (4) is a step-by-step calcination, which includes one-step calcination, two-step calcination, and three-step calcination, wherein the two-step calcination is followed by cooling, crushing, water washing, and drying, and the drying is followed by three-step calcination; wherein the temperature of the two-step calcination is higher than that of the one-step calcination, and the temperature of the two-step calcination is higher than that of the three-step calcination.

22. The method of claim 21, wherein, The temperature of the one-step calcination is 500-700 DEG C.

23. The preparation method according to claim 21, characterized in that, The time of the one-step calcination is 3-6 h.

24. The method of claim 21, wherein, The temperature of the two-step calcination is 750-950 DEG C.

25. The method of claim 21, wherein, The time of the two-step calcination is 10-18 h.

26. The method of claim 21, wherein, The temperature of the three-step calcination is 650-700 DEG C.

27. The method of claim 21, wherein, The time of the three-step calcination is 0.5-3 h.

28. A positive electrode, comprising: The positive electrode comprises the coated and doped double-modified positive electrode material in claim 1 or 2.

29. A battery, characterized by The battery comprises the positive electrode in claim 28.

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