Lithium oxide-containing positive electrode material precursor, lithium oxide-containing positive electrode material, preparation method thereof and use thereof, positive electrode sheet and use thereof

Abstract

The present invention relates to the technical field of lithium ion batteries, and discloses a lithium oxide-containing positive electrode material precursor, a lithium oxide-containing positive electrode material and its preparation method and use, and a positive electrode sheet and its use. 100 ) is Δλ(P 100 )≧60%+(y / x)×5%, where y / x is the molar ratio of Mn / Ni in the positive electrode material. The lithium oxide-containing positive electrode material has high crushing strength and stability, and can withstand high pressure during the preparation of the electrode sheet with only slight fracture, and can continue the lithium ion release / absorption reaction without serious rupture.

Description

[Technical Field]

[0001] The present invention relates to the field of lithium ion battery technology, particularly to a lithium oxide-containing positive electrode material precursor, a lithium oxide-containing positive electrode material and its preparation method and use, and a positive electrode sheet and its use. [Background technology]

[0002] In recent years, new energy vehicles have shown favorable conditions for vigorous development as a national strategic emerging industry to address environmental pollution and the energy crisis, and lithium-ion batteries, as a new energy carrier with excellent comprehensive performance, have been widely applied in markets such as electric vehicles, energy storage power plants, communications and digital electronic products.

[0003] In lithium-ion batteries, the cathode is the core material of the lithium-ion battery, and it directly determines the technical performance level of the battery. Among the common lithium-ion battery cathode materials, LiNi 1-x-y Co x Mn y O2(NCM) and LiNi 1-x-y Co x Al y O2 (NCA) and lithium-rich manganese-based materials (LMR) have attracted attention and are being researched due to their high specific capacity and energy density. However, in order to obtain a higher volumetric energy density and comprehensive electrochemical performance, the cathode material must be roll-pressed with high strength during the battery electrode sheet fabrication process to obtain high electrode density. Low-strength cathode materials are easily crushed or crushed during this process, increasing the contact area with the electrolyte and side reactions, which deteriorates cycle performance and rate characteristics. In addition, during battery use, Li + Repeated desorption causes the volume expansion and contraction of the layered structure, causing the low-strength cathode material to become powdered. The continuous formation of new electrolyte layers due to insufficient contact between particles leads to increased side reactions, resulting in deterioration and failure of battery performance.

[0004] Therefore, developing new preparation methods, adjusting the microstructure of layered positive electrode materials, and increasing the crushing strength or particle strength of the positive electrode materials are of great significance in achieving long cycle life, high specific capacity, high rate capability, etc. of batteries. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a lithium oxide-containing positive electrode material precursor, a lithium oxide-containing positive electrode material, a preparation method and use thereof, and a positive electrode sheet and use thereof, in order to overcome the defects existing in the prior art, that is, the lithium-containing metal oxide material is prone to fracture during the preparation of an electrode sheet, or secondary particles are prone to rupture during charge and discharge cycles, resulting in poor rate characteristics, worsened cycle performance, and reduced safety performance. The lithium oxide-containing positive electrode material has high crushing strength and stability, and can withstand high pressure during the preparation of an electrode sheet with only slight fracture, and can continue the lithium ion absorption / release reaction without serious rupture. [Means for solving the problem]

[0006] To achieve the above object, a first aspect of the present invention provides a lithium oxide-containing positive electrode material, the positive electrode material having a crushing exponent Δλ(P 100 ) is Δλ(P 100 )≧60%+(y / x)×5% is satisfied, Here, y / x is the molar ratio of Mn / Ni in the positive electrode material.

[0007] A second aspect of the present invention provides a lithium oxide-containing cathode material precursor, wherein the precursor has a crushing exponent Δλ′(P 50 ) is Δλ´(P 50 ) ≥ 35% + (v / u) × 8% is satisfied, where v / u is the molar ratio of Mn / Ni in the precursor.

[0008] The third aspect of the present invention provides a method for preparing a lithium oxide-containing positive electrode material, where the preparation method includes: S1: uniformly mixing a precursor having a chemical formula represented by formula (1), a lithium source, and an optional element M2-containing additive, and performing primary sintering in an atmosphere furnace to obtain a primary sintered material having a chemical formula represented by formula (2); S2: uniformly mixing the primary sintered material and an element M'-containing additive, and performing secondary sintering on the mixed material in an atmosphere furnace to obtain a lithium-containing metal oxide having a chemical formula represented by formula (3). Ni u Mn v M 1γ (OH)2, formula (1) Here, u + v + γ = 1, 0.2 < u < 1, 0 < v ≤ 0.75, 0 ≤ γ ≤ 0.35, M1 is at least one element selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B. Li[Li a Ni x Mn y M j O2, formula (2) Li[Li a Ni x Mn y M j O2@M′, formula (3) Here, in formula (2) and formula (3): a + x + y + j = 1, 0 ≤ a ≤ 0.3, 0.2 < x < 1, 0 < y ≤ 0.75, 0 < j ≤ 0.35. M includes the M1 element in the precursor and the M2 element introduced during the primary sintering process. M1 and M2 may be the same or different, and each is at least one element selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B. In formula (3): M' is an oxide, phosphide, sulfide, fluoride or chloride containing at least one element selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B, and the molar content of cations in M' is w, and 0 <w / (a+x+y+j)≦0.1である。

[0009] A fourth aspect of the present invention provides a lithium oxide-containing positive electrode material prepared by the above-described method for preparing a lithium oxide-containing positive electrode material.

[0010] A fifth aspect of the present invention provides a cathode sheet, comprising at least 90 wt % of a lithium oxide-containing cathode material, based on the total weight of the cathode sheet; Here, the lithium oxide-containing positive electrode material is the lithium oxide-containing positive electrode material described above.

[0011] A sixth aspect of the present invention provides use of the lithium oxide-containing positive electrode material described above, the lithium oxide-containing positive electrode material precursor described above, or the positive electrode sheet described above in a lithium ion battery.

[0012] With the above technical solutions, the present invention has the following advantages: (1) The lithium oxide-containing positive electrode material and precursor of the present invention achieve high crystallinity and densification of the precursor by controlling a specific microstructure, thereby improving the crushing index of the positive electrode material; (2) The present invention improves the crush index, cycle life and safety performance of the material through the use of suitable modifiers and doping elements; (3) The sintering precision in the preparation process of the lithium-containing metal oxide of the present invention affects the crushing index of the material. Therefore, when selecting the sintering precision, it is necessary to balance the cost, the crushing index of the material, the physical index of the material, and the electrochemical performance. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 5 and Comparative Example 1. [Figure 2]FIG. 10 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 1. [Figure 3] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 5 and Comparative Example 2. [Figure 4] FIG. 10 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 2. [Figure 5] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 5 and Comparative Example 3. [Figure 6] FIG. 10 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 3. [Figure 7] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 5 and Comparative Example 4. [Figure 8] FIG. 10 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 4. [Figure 9] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 9 and Comparative Example 5. [Figure 10] FIG. 10 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 5. [Figure 11] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 9 and Comparative Example 6. [Figure 12] FIG. 10 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 6. [Figure 13] FIG. 10 is a comparative schematic diagram of charge / discharge curves of Example 9 and Comparative Example 7. [Figure 14] FIG. 10 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0014] The endpoints of ranges and any value disclosed herein should be understood to be not limited to such exact ranges or values, but to include values ​​close to those ranges or values. In the case of ranges of numerical values, values ​​between the endpoints of each range, between the endpoints of each range and any single point value, and between any single point value can be combined with each other to create one or more new numerical ranges, and these numerical ranges are considered to be specifically disclosed in the specification.

[0015] Conventional lithium-containing metal oxide materials for lithium ion batteries must be subjected to high pressure during the preparation of electrode sheets. Furthermore, during sustained charge-discharge cycles, the materials lack crushing strength or have unstable structures, leading to rupture and increased side reactions with the electrolyte, accelerating the consumption of the electrolyte and the dissolution of transition metal cations in the positive electrode material, resulting in reduced cycle performance, safety performance, and capacity, and ultimately battery failure.

[0016] As described above, a first aspect of the present invention provides a lithium oxide-containing cathode material, wherein the crushing exponent Δλ(P 100 ) is Δλ(P 100 )≧60%+(y / x)×5% is satisfied, Here, y / x is the molar ratio of Mn / Ni in the positive electrode material.

[0017] JPEG0007733842000001.jpg53170

[0018] JPEG0007733842000002.jpg20170

[0019] According to the present invention, preferably, the crushing exponent Δλ(P 200 ) is Δλ(P 200 )≧45%+(y / x)×5%.

[0020] According to the present invention, it is more preferable that the crushing exponent Δλ(P 300 ) is Δλ(P 300 )≧35%+(y / x)×5%.

[0021] According to the present invention, it is still possible to 100 ) indicates the crushing index of the material when the material has a pressure strength P = 100 MPa, and Δλ(P 200 ) indicates the crushing index of the material when the material has a pressure strength P = 200 MPa, and is inferred from this.

[0022] The positive electrode material according to the present invention has excellent crushing strength, is difficult to rupture, has a stable structure, few side reactions, and excellent safety performance and capacity retention rate during the process of being used as a positive electrode.

[0023] According to the present invention, the lithium oxide-containing positive electrode material has a chemical formula represented by formula (3), Li[Li a Ni x Mn y M j O2@M′, formula (3) where a + x + y + j = 1, 0 ≤ a ≤ 0.3, 0.2 < x < 1, 0 < y ≤ 0.75, 0 < j ≤ 0.35, M is at least one selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B, M′ is an oxide, phosphide, sulfide, fluoride or chloride containing at least one element of Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B, the molar content of cations in M′ is w, and 0 < w / (a + x + y + j) ≤ 0.1.

[0024] According to the present invention, preferably, 0.02 ≤ a ≤ 0.3, 0.3 < x < 0.9, 0.05 < y ≤ 0.68, 0 < j ≤ 0.3, 0.001 < w / (a + x + y + j) ≤ 0.02.

[0025] According to the present invention, M is at least one selected from Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Ta and B, and M′ is an oxide, phosphide, sulfide or fluoride containing at least one element of Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Ta and B.

[0026] In the present invention, the inventor of the present invention has discovered that by adopting an appropriate modifier, the crushing strength and stability of the material particles can be enhanced, the DC internal resistance value and the gas generation amount of the material during the cycling process can be reduced, and the cycle life of the material can be improved.

[0027] Doping with elements such as Ti, Sc, Zr, W, Mg, Y, Co, Cr, and Ta stabilizes the crystalline structure of the material, improves the microzone structure of the material, and improves the crushing index, cycle life, and safety performance of the material. Doping with elements such as Ti, Zr, Nb, La, W, Co, and B can form lithium-containing compounds (e.g., LiNbO3, Li2ZrO3, or Li4Ti5O) on the surface of the material particles or at the interface between particles. 12 The positive electrode material according to the present invention further has the following characteristics:

[0028] According to the present invention, the tap density of the positive electrode material is ≧1.7 g / cm 3 and preferably ≥ 2 g / cm 3 and more preferably ≥ 2.4 g / cm 3 is.

[0029] According to the present invention, the compacted density of the positive electrode material is ≥ 2.8 g / cm 3 and preferably ≥ 3 g / cm 3 and more preferably ≥ 3.2 g / cm 3 is.

[0030] According to the present invention, the content of the surface soluble alkali of the positive electrode material is: Li2CO3≦1wt%, LiOH≦0.5wt%, Preferably, Li2CO3≦0.5 wt%, LiOH≦0.4 wt%, More preferably, Li2CO3≦0.3 wt%, LiOH≦0.3 wt%, Even more preferably, Li2CO3≦0.2 wt% and LiOH≦0.2 wt% are satisfied.

[0031] According to the present invention, the positive electrode material has a full width at half maximum (FWHM) of the (003) crystal plane obtained by XRD.(003) and FWHM of the (104) crystal plane (104) teeth, 0.10≦FWHM (003) ≦0.25, preferably 0.13≦FWHM (003) ≦0.22, 0.20≦FWHM (104) ≦0.50, preferably 0.22≦FWHM (104) ≦0.42.

[0032] According to the present invention, the positive electrode material has a peak area S of the (003) crystal plane obtained by XRD. (003) and the peak area S of the (104) crystal plane (104) teeth, 1.1≦S (003) / S (104) ≦1.8, preferably 1.2≦S (003) / S (104) ≦1.6.

[0033] In the present invention, in addition to using appropriate additives, the precursor morphology and microstructure are controlled to achieve high crystallinity and densification of the precursor, thereby improving the crushing index of the positive electrode material.

[0034] A second aspect of the present invention provides a lithium oxide-containing cathode material precursor, wherein the precursor has a crushing exponent Δλ′(P 50 ) is Δλ´(P 50 ) ≥ 35% + (v / u) × 8% is satisfied, where v / u is the molar ratio of Mn / Ni in the precursor.

[0035] According to the invention, preferably, the crushing exponent Δλ′(P 100 ) is Δλ´(P 100 )≧25%+(v / u)×8%.

[0036] According to the present invention, it is still possible to 50 ) indicates the crushing index of the precursor material when the pressure strength of the precursor material is P = 50 MPa, and Δλ'(P 100() indicates the crushing index of the precursor material when the precursor material has a pressure strength P = 100 MPa, and the following can be inferred from this.

[0037] JPEG0007733842000003.jpg58170

[0038] JPEG0007733842000004.jpg24170

[0039] According to the present invention, the precursor has a chemical formula represented by formula (1), Ni u Mn v M γ (OH)2, formula (1), where u + v + γ = 1, 0.2 < u < 1, 0 < v ≤ 0.75, 0 ≤ γ ≤ 0.35, and M is at least one selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B, Preferably, 0.3 ≤ u ≤ 0.9, 0.05 ≤ v ≤ 0.68, 0 ≤ γ ≤ 0.3, and M is at least one selected from Ti, Al, Zr, W, Co, Nb, La, Na, and Mg. In the present invention, by doping elements such as Ti, Al, Zr, W, Co, Nb, La, Na, and Mg, the internal or surface structure of the microzone of the precursor can be stabilized. <​​​​​​​​​​​​​​​​​​​​​​ According to the present invention, the particle size distribution coefficient K 90 is 0.5≦K 90 ≦1.6, where K 90 =(D 90 -D 10 ) / D 50 And D 10 , D 50 and D 90 indicates the particle size values ​​when the particle cumulative volume distribution is 10%, 50%, and 90%, respectively.

[0044] According to the invention, the precursor has a full width at half maximum (FWHM) of the (001) crystal plane obtained by XRD. (001) , FWHM of (100) crystal plane (100) and FWHM of the (101) crystal plane (101) teeth, 0.3≦FWHM (001) ≦1, preferably 0.5≦FWHM (001) ≦0.8, that is, the precursor material according to the present invention satisfies FWHM measured by an X-ray diffraction device (001) 2θ is 0.3 or more and 1 or less, preferably 0.5 or more and 0.8 or less, 0.10≦FWHM (100) ≦0.5, preferably 0.25≦FWHM (100) ≦0.35, 0.30≦FWHM (101) ≦1.0, preferably 0.4≦FWHM (101) ≦0.8.

[0045] According to the present invention, the precursor has a peak area S of the (001) crystal plane obtained by XRD. (101) and the peak area S of the (101) crystal plane (104) is S (001) / S (101) ≧2.0.

[0046] According to the present invention, the precursor has an integrated area S of the (001) crystal plane obtained by XRD. (101) and the integral area S of the (101) crystal plane (104) is S (001) / S (101)≧2.0.

[0047] The present invention further provides a method for preparing a lithium oxide-containing cathode material precursor, wherein the method includes: (1) contacting and mixing a solution or suspension of a nickel salt, a manganese salt, and a compound containing M to obtain a mixed salt solution; (2) flowing the mixed salt solution, precipitant solution, and complexing agent solution into a reaction vessel to carry out a crystallization reaction, and then subjecting the resulting slurry to solid-liquid separation, washing, heat treatment, and sieving to obtain a lithium oxide-containing positive electrode material precursor.

[0048] The inventors of the present invention discovered that metal hydroxide precursors burst during compounding and sintering due to insufficient precursor crushing strength, resulting in reduced crushing strength, reduced tap density, and poor electrochemical performance of the resulting positive electrode material. The present invention achieves the synthesis of highly crystalline and dense precursors by controlling the precursor synthesis process, such as the concentration and type of complexing agent, precipitant concentration, stirring intensity, reaction temperature, additives, solid content, and feed rate. The crystallinity, tap density, and crushing index of the precursor material are improved by adjusting the particle size distribution and specific surface area of ​​the precursor. The crushing index of the precursor is also improved by adding appropriate additives to adjust the precursor microstructure and morphology.

[0049] According to the present invention, nickel salt, manganese salt or M element-containing additive is dissolved in a mixed salt solution with a molar ratio of u:v:γ and a concentration of 1-3 mol / L, an M-containing compound is added to water to prepare an M solution or suspension with a certain concentration, an alkali is dissolved in an alkali solution with a concentration of 2-10 mol / L, and a complexing agent is dissolved in a complexing agent solution with a concentration of 2-13 mol / L.

[0050] According to the present invention, the solid content of the slurry is 200-1000 g / L, preferably 300-800 g / L.

[0051] According to the present invention, the Ni-Mn mixed salt solution, the alkali solution, the complexing agent solution, and the M solution are fed into a reactor equipped with an overflow pipeline through their respective feed pipelines, and the stirring speed is kept constant while controlling the feed flow rates of the mixed salt solution, the precipitant solution, the complexing agent solution, and the M solution.

[0052] According to the present invention, the reaction conditions are: reaction temperature is 40-70°C, reaction pH is 10.6-12.5, and reaction time is 5-100 hours.

[0053] According to the present invention, the nickel salt is one or more of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate.

[0054] According to the present invention, the manganese salt is one or more of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate.

[0055] According to the present invention, the M-containing compound is one or more of sulfates, chlorides, nitrates, acetates, citrates, carbonates, phosphates, oxalates, and fluorides containing the M element.

[0056] According to the present invention, the precipitating agent is an alkaline substance, and the alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0057] According to the present invention, the complexing agent is one or more of salicylic acid, ammonium sulfate, ammonium chloride, aqueous ammonia, sulfosalicylic acid, ethylenediaminetetraacetic acid.

[0058] According to the present invention, the sintering quality (including sintering temperature, heating rate, sintering atmosphere, etc.) in the preparation process of the lithium-containing metal oxide is also very important and affects the crushing index of the material.

[0059] A third aspect of the present invention provides a method for preparing a lithium oxide-containing cathode material, said method comprising: S1: Mix the precursor having the chemical formula represented by formula (1), a lithium source, and an additive containing an optional element M2 uniformly, and subject the mixed material to primary sintering in an atmosphere furnace to obtain a primary sintered material having the chemical formula represented by formula (2). S2: Mix the primary sintered material and an additive containing element M' uniformly, and subject the mixed material to secondary sintering in an atmosphere furnace to obtain a lithium-containing metal oxide having the chemical formula represented by formula (3). Ni u Mn v M 1γ (OH)2, formula (1) Here, u + v + γ = 1, 0.2 < u < 1, 0 < v ≤ 0.75, 0 ≤ γ ≤ 0.35, and M1 is at least one selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B. Li[Li a Ni x Mn y M j O2, formula (2) Li[Li a Ni x Mn y M j O2@M′, formula (3) Here, in formula (2) and formula (3), 0 ≤ a ≤ 0.3, 0.2 < x < 1, 0 < y ≤ 0.75, 0 < j ≤ 0.35 are set. M includes the M1 element in the precursor and the M2 element introduced during the primary sintering process. M1 and M2 may be the same or different, and each is at least one selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B. In formula (3),[[ID=4,4]] M′ is an oxide, phosphide, sulfide, fluoride, or chloride containing at least one element of Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B. The molar content of the cation in M′ is w, and 0 < w / (a + x + y + j) ≤ 0.1 is set.

[0060] According to the present invention, the M element in the positive electrode material is derived from the M1 element in the precursor and the additive containing the M2 element introduced in the primary sintering process.

[0061] According to the present invention, the lithium source is at least one of lithium hydroxide, lithium carbonate, and lithium nitrate.

[0062] According to the present invention, the additive containing the element M2 is at least one selected from oxides, hydroxides, oxyhydroxides, phosphates, fluorides, borides, and carbonates containing the element M2.

[0063] According to the present invention, the M1 element, the M2 element, and the M element may be the same or different, and each is at least one selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B.

[0064] According to the present invention, the additive containing the element M' is at least one selected from oxides, hydroxides, oxyhydroxides, phosphates, fluorides, borides, nitrides, carbonates, and oxalates containing the element M'.

[0065] According to the present invention, the molar ratio Li / (Ni+Mn+M1+M2) of the sum of the amount of the lithium source used and the amount of the additive containing the precursor and element M2 used is 1-1.85, preferably 1-1.5.

[0066] According to the present invention, the additive containing the element M2 is added in such an amount that M2 / (Ni+Mn+M1+M2) is 0.0005-0.3, preferably 0.001-0.2.

[0067] According to the present invention, the molar ratio M' / (Ni+Mn+M1+M2) of the amount of additive containing the element M' to the amount of primary sintered material is 0-0.1, preferably 0.001-0.02.

[0068] According to the present invention, when the molar ratio of Ni / Mn is greater than 1, that is, x / y>1, the relationship between the primary sintering temperature T1 and the Ni content is 550×(2−x) ℃ ≦T1≦400×(3−x)°C is satisfied, and the sintering time is 6-20 hours, preferably 8-15 hours.

[0069] According to the present invention, when the molar ratio of Ni / Mn is ≦1, that is, y / x≧1, the relationship between the primary sintering temperature T2 and the Mn content is 500×(1+y) ℃ ≦T2≦650×(1+y)°C is satisfied, and the sintering time is 6-20 hours, preferably 8-15 hours.

[0070] According to the present invention, when x<0.5, the atmosphere for the primary sintering and secondary sintering is air; when 0.5≦x<0.6, the atmosphere for the primary sintering and secondary sintering is air or a mixed gas of air and oxygen; and when x≧0.6, the atmosphere for the primary sintering and secondary sintering is oxygen or a mixed gas of oxygen and air.

[0071] A fourth aspect of the present invention provides a lithium oxide-containing positive electrode material prepared by the above-mentioned method for preparing a lithium oxide-containing positive electrode material.

[0072] A fifth aspect of the present invention provides a positive electrode sheet, comprising at least 90 wt % of a lithium oxide-containing positive electrode material, based on the total weight of the positive electrode sheet, wherein the lithium oxide-containing positive electrode material is the lithium oxide-containing positive electrode material described above.

[0073] According to the present invention, the mass occupancy of the positive electrode material is preferably 95% or more.

[0074] According to the present invention, the electrode sheet density of the positive electrode sheet is ≥ 2.8 g / cm 3 , preferably ≥ 3.2 g / cm 3 , more preferably ≥ 3.5 g / cm 3 is.

[0075] A sixth aspect of the present invention provides the use of the lithium oxide-containing positive electrode material described above, the lithium oxide-containing positive electrode material precursor described above, or the positive electrode sheet described above in a lithium ion battery.

[0076] The present invention will be described in detail below through examples.

[0077] In the following examples and comparative examples, Unless otherwise stated, all ingredients are commercially available.

[0078] In the following examples, the relevant performance is obtained in the following manner. (1) Material phase test: Tested by a SmartLab 9kW model X-ray diffractometer from Nippon Rigaku Co., Ltd. (2) Morphological test: Tested by S-4800 model scanning electron microscope of Hitachi, Japan. (3) Particle size test: Tested by Marvern Hydro 2000mu model laser particle sizer; (4) Specific surface area: Tested by a Tristar II3020 model specific surface tester from Micromertics, USA. (5) Tap density: Tested by Hyakutoku Co., Ltd.'s BT-30 model tap density tester. (6) Compaction density: Tested by Mitsubishi Chemical Japan's MCP-PD51 model powder impedance tester. (7) Crushing index test: The material was compressed at a specific pressure using a manual tablet press, model 4350, manufactured by Carver, USA, and the particle size test was conducted on the material after crushing. The results were then substituted into the crushing index formula to calculate the results. (8) Surface residual alkali test: measured by Metrohmm888 professional Tirando intelligent potential titrator; (9) Thermal stability test: Tested by Mettler TGA-DSC3 model thermogravimetric analyzer; (10) Electrochemical performance test: The electrochemical performance of the prepared lithium oxide-containing positive electrode material was tested on a 2025-type buckle battery using a Xinwei battery test system. Specifically, 1) 2025 type buckle battery manufacturing process: Electrode sheet production: The lithium oxide-containing cathode material, carbon black, and polyvinylidene fluoride were thoroughly mixed at a certain mass ratio with an appropriate amount of N-methylpyrrolidone to form a uniform slurry, which was then applied to aluminum foil, dried at 120°C, roll-pressed, and punched to produce a cathode sheet with a diameter of 11 mm.

[0079] Battery assembly: A Li metal piece with a diameter of 17 mm and a thickness of 1 mm is used as the negative electrode, a 25 μm thick polyethylene porous film is used as the separator, and a mixture of equal amounts of 1 mol / L LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC) is used as the electrolyte.

[0080] The positive electrode sheet, separator, negative electrode sheet and electrolyte are assembled into a 2025-type buckle battery in an Ar gas glove box in which the water content and oxygen content are both less than 5 ppm, and the battery at this stage is designated as an inactivated battery.

[0081] 2) Electrochemical performance test: When the Ni / Mn molar ratio is greater than 1, i.e., x / y > 1, the buckled battery test conditions are as follows: After the buckled battery is fabricated and left for 2 hours, after the open circuit voltage stabilizes, it is charged to a cutoff voltage of 4.3 V at a current density of 0.1 C, then charged at a constant voltage for 30 minutes, and then discharged to a cutoff voltage of 3.0 V at the same current density. This cycle is referred to as an activated battery. The activated battery is then subjected to a charge-discharge test at 0.1 C between 3.0 and 4.3 V at 25 °C and a charge-discharge interval of 3.0-4.3 V to evaluate the charge-discharge capacity of the material. The activated battery is then subjected to charge-discharge tests at 0.1 C, 0.2 C, 0.33 C, 0.5 C, and 1 C to evaluate the rate characteristics of the material based on the ratio of 1 C capacity to 0.1 C capacity. The material's cycle performance is evaluated by cycling 80 times at 1 C between 3.0 and 4.4 V.

[0082] When the Ni / Mn molar ratio is less than 1, i.e., x / y≦1, the buckled battery test conditions are as follows: After the buckled battery is fabricated and left for 2 hours, and after the open circuit voltage stabilizes, it is charged to a cutoff voltage of 4.6 V at a current density of 0.1 C, then charged at a constant voltage for 30 minutes, and then discharged to a cutoff voltage of 2.0 V at the same current density. This test is referred to as an activated battery. The activated battery is then subjected to a charge-discharge test at 0.1 C between 2.0 and 4.6 V at 25°C and a charge-discharge range of 2.0 to 4.6 V to evaluate the charge-discharge capacity of the material. The activated battery is then subjected to charge-discharge tests at 0.1 C, 0.2 C, 0.33 C, 0.5 C, and 1 C to evaluate the rate characteristics of the material based on the ratio of the 1 C capacity to the 0.1 C capacity. The material's cycle performance is evaluated by cycling 80 times at 0.5 C between 2.0 and 4.6 V.

[0083] Example 1 This example is intended to illustrate the lithium oxide-containing positive electrode material prepared in accordance with the present invention.

[0084] Nickel sulfate and manganese sulfate are dissolved in a metal molar ratio of 5:3 to obtain a 2 mol / L mixed salt solution, cobalt sulfate and aluminum sulfate are dissolved in metal molar ratios of Co / (Ni+Mn+Co+Al) = 0.18 and Al / (Ni+Mn+Co+Al) = 0.02 to obtain a 2 mol / L mixed salt solution, sodium hydroxide is dissolved to obtain an alkaline solution with a concentration of 6 mol / L, and ammonia water is dissolved to obtain a complexing agent solution with a concentration of 5 mol / L.

[0085] Next, 20L of the mixed salt solution, alkali solution, and complexing agent solution were fed into the reactor together to react. During the process, the stirring speed was kept constant at 600 revolutions per minute. At the same time, the mixed salt solution flow rate was 300mL / h, the reaction pH was 11.6, the reaction temperature was 50°C, and the ammonia concentration in the reaction system was 9g / L. The reaction was carried out in N2 gas. The reaction was allowed to stand for 60 hours, and the solid content was 500g / L. The slurry obtained by the precipitation crystallization reaction was subjected to solid-liquid separation and washing. It was then dried at 105°C for 10 hours and sieved to obtain spherical Ni. 0.5 Mn 0.3 Co 0.18 Al0.02 The (OH)2 precursor material is obtained and recorded as P-1.

[0086] Precursor P-1, lithium carbonate, and additives TiO2 and WO3 were uniformly mixed in a high-mixer with Li:(Ni+Mn+Co+Al+Ti+W)=1.03, Ti:(Ni+Mn+Co+Al+Ti+W)=0.003, and W:(Ni+Mn+Co+Al+Ti+W)=0.002. The mixture was heated to 920°C in an air atmosphere, held for 10 hours, and then cooled naturally to obtain the primary sintered positive electrode material Li[Li0Ni 0.4975 Mn 0.2985 Co 0.1791 Al 0.0199 Ti 0.003 W 0.002 ]O2 is obtained and recorded as S-1.

[0087] The primary sintering material S-1, additives Nb2O5 and La2O3 were uniformly mixed in the ratio of Nb: (Ni + Mn + Co + Al + Ti + W) = 0.002, La: (Ni + Mn + Co + Al + Ti + W) = 0.002, and the mixture was heated to 650°C in an air atmosphere, held for 6 hours, and then cooled naturally to obtain the secondary sintering positive electrode material Li[Li0Ni 0.4975 Mn 0.2985 Co 0.1791 Al 0.0199 Ti 0.003 W 0.002 ]O2@Nb 0.002 La 0.002 is obtained and recorded as FS-1.

[0088] Example 2-14 This example is intended to illustrate the lithium oxide-containing positive electrode material prepared in accordance with the present invention.

[0089] The lithium oxide-containing positive electrode material was prepared in the same manner as in Example 1, except that the precursor preparation process, the primary sintered positive electrode material preparation process, and the secondary sintered positive electrode material preparation process were different, as shown in Table 1.

[0090] [Table 1-1]

[0091] [Table 1-2]

[0092] [Table 1-3]

[0093] [Table 1-4]

[0094] [Table 1-5]

[0095] [Table 1-6]

[0096] [Table 1-7]

[0097] [Table 1-8]

[0098] [Table 1-9]

[0099] In Table 1, unless otherwise specified, all ratios and amount ratios are molar ratios.

[0100] Comparative Example 1

[0101] The same synthesis method and conditions as in Example 5 were employed, except that the primary sintering temperature was adjusted to 600° C. The resulting positive electrode material was designated D-1 and is shown in Table 2.

[0102] Comparative Example 2 The same synthesis method and conditions as in Example 5 were employed, except that the primary sintering temperature was adjusted to 900° C. The resulting positive electrode material was designated D-2 and is shown in Table 2.

[0103] Comparative Example 3 The same synthesis method and conditions as in Example 5 were used, but the primary sintered cathode material was prepared without adding the additives rhenium oxide and samarium oxide. The resulting cathode material was designated D-3 and is shown in Table 2.

[0104] Comparative Example 4 The same synthesis method and conditions as in Example 5 were used, but the additives tungsten nitride and aluminum fluoride were not added in the secondary sintered positive electrode material preparation process. The resulting positive electrode material was designated D-4 and is shown in Table 2.

[0105] Comparative Example 5 The same synthesis method and conditions as in Example 9 were used, and the solid content was adjusted to 150 g / L only in the precursor preparation process. The resulting positive electrode material was designated D-5 and is shown in Table 2.

[0106] Comparative Example 6 The same synthesis method and conditions as in Example 9 were used, but the additives tungsten oxide and hydroxyl alumina were not added in the preparation process of the primary sintered positive electrode material. The obtained positive electrode material was designated D-6 and is shown in Table 2.

[0107] Comparative Example 7 The same synthesis method and conditions as in Example 9 were used, except for the preparation process of the secondary sintered positive electrode material. The resulting positive electrode material was designated D-7 and is shown in Table 2.

[0108] [Table 2-1]

[0109] [Table 2-2]

[0110] [Table 2-3]

[0111] [Table 2-4]

[0112] [Table 2-5]

[0113] Test example 1 The performance of the lithium oxide-containing positive electrode material precursors prepared in Examples 1-14 and Comparative Examples 1-7 was tested, and the results are shown in Table 3. The performance of the lithium oxide-containing positive electrode materials prepared in Examples 1-14 and Comparative Examples 1-7 was tested, and the results are shown in Tables 4 and 5.

[0114] [Table 3]

[0115] [Table 4-1]

[0116] [Table 4-2]

[0117] [Table 4-3]

[0118] [Table 5]

[0119] Test example 2 The lithium oxide-containing positive electrode materials prepared in Examples 1-14 and Comparative Examples 1-7 are used as the positive electrode sheets of lithium ion batteries to prepare lithium ion batteries, and the performance of the lithium ion batteries is tested. The results are shown in Table 6.

[0120] [Table 6-1]

[0121] [Table 6-2]

[0122] [Table 6-3]

[0123] Also, in the present invention, Figure 1 is a comparative schematic diagram of the charge-discharge curves of Example 5 and Comparative Example 1. Comparing the charge-discharge curves of Example 5 and Comparative Example 1 from Figure 1, it can be seen that the 0.1C discharge capacity (225.2 mAh / g) of the positive electrode material provided by Example 5 is higher than the 0.1C discharge capacity (216.9 mAh / g) of positive electrode material D-1 obtained when the primary sintering temperature was too low (600°C).

[0124] Figure 2 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 1. Comparing the cycle performance of Example 5 and Comparative Example 1 from Figure 2, it can be seen that the capacity retention rate of Example 5 (94.6%) is significantly higher than the capacity retention rate of the positive electrode material provided by D-1 (86.7%). This is because when the sintering temperature is too low, primary crystal grain growth and development are incomplete, resulting in a low crushing index and an unstable structure, resulting in low capacity and cycle performance.

[0125] Figure 3 is a schematic diagram comparing the charge-discharge curves of Example 5 and Comparative Example 2. Comparing the charge-discharge curves of Example 5 and Comparative Example 2 from Figure 3 reveals that the 0.1C discharge capacity (225.2 mAh / g) of the positive electrode material provided by Example 5 is higher than the 0.1C discharge capacity (208.3 mAh / g) of positive electrode material D-2 obtained when the primary sintering temperature was too high (900°C).

[0126] 4 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 2. Comparing the cycle performance of Example 5 and Comparative Example 2 from FIG. 4, it can be seen that the capacity retention rate of Example 5 (94.6%) is significantly higher than the capacity retention rate of the positive electrode material provided by D-2 (85.9%). This is because excessive growth and development of primary crystal grains when the sintering temperature is too high results in a low crushing index and an unstable structure, resulting in low capacity and cycle performance.

[0127] Fig. 5 is a schematic diagram comparing the charge-discharge curves of Example 5 and Comparative Example 3. Comparing the charge-discharge curves of Example 5 and Comparative Example 3 from Fig. 5 reveals that the 0.1C discharge capacity (225.2 mAh / g) of Example 5 is higher than the 0.1C discharge capacity (221.7 mAh / g) of positive electrode material D-3 obtained without adding rhenium oxide and samarium oxide additives to the primary sintering.

[0128] Figure 6 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 3. Comparing the cycle performance of Example 5 and Comparative Example 3, Figure 6 shows that the capacity retention of Example 5 (94.6%) is significantly higher than the capacity retention of the cathode material provided by D-3 (87.5%). The above indicates that adding rhenium oxide and samarium oxide additives to the primary sintering process can improve the capacity and cycle performance of the material. This is because proper doping modification improves the microzone structure of the material and forms lithium-containing compounds on the particle surface or between particles, which helps to improve the crushing index of the material and thereby improves the electrochemical performance of the cathode material, such as its capacity and cycle performance.

[0129] Fig. 7 is a schematic diagram comparing the charge-discharge curves of Example 5 and Comparative Example 4. Comparing the charge-discharge curves of Example 5 and Comparative Example 4 from Fig. 7 reveals that the 0.1C discharge capacity (225.2 mAh / g) of Example 5 is significantly higher than the 0.1C discharge capacity (214.3 mAh / g) of positive electrode material D-4 obtained without adding tungsten nitride or aluminum fluoride additives to the secondary sintering.

[0130] FIG. 8 is a schematic diagram comparing the cycle performance of Example 5 and Comparative Example 4. Comparing the cycle performance of Example 5 and Comparative Example 4 from FIG. 8, it can be seen that the capacity retention rate of Example 5 (94.6%) is significantly higher than the capacity retention rate of the cathode material provided by D-4 (86.6%). The above indicates that adding tungsten nitride and aluminum fluoride additives to the secondary sintering process can improve the capacity and cycle performance of the material. This is because a stable coating layer can be formed on the surface of the material, improving the surface microzone structure of the material, reducing side reactions on the surface of the material, and improving the crushing index of the material, thereby improving the electrochemical performance of the cathode material, such as the capacity and cycle performance.

[0131] 9 is a schematic diagram comparing the charge-discharge curves of Example 9 and Comparative Example 5. Comparing the charge-discharge curves of Example 9 and Comparative Example 5 from Fig. 9, it can be seen that the 0.1C discharge capacity (250.7 mAh / g) of Example 9 is significantly higher than the 0.1C discharge capacity (240.9 mAh / g) of positive electrode material D-5 obtained when the solid content was reduced to 150 g / L in the precursor preparation process.

[0132] 10 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 5. Comparing the cycle performance of Example 9 and Comparative Example 5 from FIG. 10, it can be seen that the capacity retention rate of Example 9 (93.9%) is significantly higher than the capacity retention rate of the positive electrode material provided by D-5 (88.0%). This is because the low solid content leads to poor crystallinity and compactness of the precursor, and changes in morphology and microstructure, resulting in a low crushing index and poor electrochemical performance, such as the capacity and cycle performance of the material.

[0133] Fig. 11 is a schematic diagram comparing the charge-discharge curves of Example 9 and Comparative Example 6. Comparing the charge-discharge curves of Example 9 and Comparative Example 6 from Fig. 11 reveals that the 0.1C discharge capacity (250.7 mAh / g) of Example 9 is significantly higher than the 0.1C discharge capacity (241.9 mAh / g) of positive electrode material D-6 obtained without adding tungsten oxide and hydroxyl alumina additives to the primary sintering.

[0134] FIG. 12 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 6. Comparing the cycle performance of Example 9 and Comparative Example 6 from FIG. 12, it can be seen that the capacity retention rate of Example 9 (93.9%) is significantly higher than the capacity retention rate of the cathode material provided by D-6 (89.0%). The above indicates that adding tungsten oxide and hydroxyl alumina additives to the primary sintering process can improve the capacity and cycle performance of the material. This is because proper doping modification improves the microzone structure of the material and forms lithium-containing compounds on the particle surface or between particles, which helps to improve the crushing index of the material and thereby improves the electrochemical performance of the cathode material, such as its capacity and cycle performance.

[0135] Fig. 13 is a schematic diagram comparing the charge-discharge curves of Example 9 and Comparative Example 7. Comparing the charge-discharge curves of Example 9 and Comparative Example 7 from Fig. 13 reveals that the 0.1C discharge capacity (250.7 mAh / g) of Example 9 is significantly higher than the 0.1C discharge capacity (233.0 mAh / g) of positive electrode material D-7 obtained without the secondary sintering process.

[0136] FIG. 14 is a schematic diagram comparing the cycle performance of Example 9 and Comparative Example 7. Comparing the cycle performance of Example 9 and Comparative Example 7 from FIG. 14, it can be seen that the capacity retention rate of Example 9 (93.9%) is significantly higher than the capacity retention rate of the cathode material provided by D-7 (89.9%). The above indicates that secondary sintering effectively improves the capacity and cycle performance of the material. This is because the secondary sintering process forms a stable coating layer on the surface of the material, rearranges the atoms on the surface of the material, improves the surface microzone structure of the material, reduces side reactions on the surface of the material, and also helps improve the crushing index of the material, thereby improving the electrochemical performance of the cathode material, such as the capacity and cycle performance.

[0137] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited thereto. Within the technical conception of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining each technical feature in any other suitable manner, and these simple modifications and combinations are also considered to be the contents disclosed in the present invention, and all belong to the protection scope of the present invention.

Claims

[Request 1]

2. The crushing index Δλ(P ２００ ) is Δλ(P ２００ 2. The lithium oxide-containing positive electrode material according to claim 1, wherein y / x satisfies the following: y / x≧45%+(y / x)×5%.

3. The compacted density of the lithium oxide-containing positive electrode material is ≧2.8 g / cm ３ and And / or, the tap density of the lithium oxide-containing positive electrode material is ≧1.7 g / cm ３ and And / or, the content of the surface soluble alkali of the lithium oxide-containing positive electrode material is Li ２ CO ３ ≦1 wt%, LiOH≦0.5 wt%, and / or The lithium oxide-containing positive electrode material has a half-width FWHM of the (003) crystal plane obtained by XRD. （００３） and FWHM of the (104) crystal plane （１０４） teeth, 0.10≦FWHM （００３） ≦0.25、 0.20≦FWHM （１０４） ≦0.50, and / or The lithium oxide-containing positive electrode material has a peak area S of the (003) crystal plane obtained by XRD. （００３） and the peak area S of the (104) crystal plane （１０４） teeth, 1.1≦S （００３） / S （１０４） The lithium oxide-containing positive electrode material according to claim 1, wherein the lithium oxide-containing positive electrode material satisfies the following:

4.

5. The crushing index Δλ′(P １００ ) is Δλ'(P １００ 5. The lithium oxide-containing positive electrode material according to claim 4, wherein the lithium oxide-containing positive electrode material satisfies the following:

6. A method for preparing the lithium oxide-containing positive electrode material of claim 1, comprising: S1: A precursor having the chemical formula shown in formula (1), a lithium source, and an optional element M ２ A step of uniformly mixing the contained additives and performing primary sintering in an atmospheric furnace to obtain a primary sintered material having a chemical formula represented by formula (2); S2: uniformly mixing the primary sintering material and the element M′-containing additive, and subjecting the mixed material to secondary sintering in an atmospheric furnace to obtain a lithium-containing metal oxide having a chemical formula represented by formula (3), Ni ｕ Mn ｖ M １γ (OH) ２ , formula (1) Here, u+v+γ=1, 0.2<u<1, 0<v≦0.75, 0≦γ≦0.35, and M １ is at least one element selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B; Li[Li ａ Ni ｘ Mn ｙ M ｊ O ２ 、Formula (2) Li[Li ａ Ni ｘ Mn ｙ M ｊ O ２ @M′, formula (3) Here, in equations (2) and (3), a+x+y+j=1, 0≦a≦0.3, 0.2<x<1, 0<y≦0.75, 0<j≦0.35, M is M in the precursor １ Elements and M introduced during the primary sintering process ２ Contains elements, M １ , M ２ may be the same or different and each is at least one element selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B.

7. When the molar ratio of Ni / Mn is greater than 1, i.e., x / y>1, the sintering temperature T １ The relationship between the temperature and the Ni content is 550×(2−x)°C≦T １ ≦400×(3−x)°C, and the sintering time is 6 to 20 hours, And / or, when the molar ratio of Ni / Mn is ≦1, that is, when y / x≧1, the sintering temperature T ２ The relationship between the temperature and the Mn content is 500 × (1 + y) ° C. ≦ T ２ ≦650×(1+y)°C, and the sintering time is 6 to 20 hours, and / or, when x<0.5, the atmosphere for the primary sintering and the secondary sintering is air; when 0.5≦x<0.6, the atmosphere for the primary sintering and the secondary sintering is air or a mixed gas of air and oxygen; and when x≧0.6, the atmosphere for the primary sintering and the secondary sintering is oxygen or a mixed gas of oxygen and air.

8. a positive electrode sheet comprising at least 90 wt % of a lithium oxide-containing positive electrode material based on the total weight of the positive electrode sheet; A positive electrode sheet, characterized in that the lithium oxide-containing positive electrode material is the lithium oxide-containing positive electrode material according to claim 1.

9. The electrode sheet density of the positive electrode sheet is ≧2.8 g / cm ３ The positive electrode sheet according to claim 8 ,

10. Use of the lithium oxide-containing positive electrode material according to any one of claims 1 to 3, the lithium oxide-containing positive electrode material precursor according to claim 4 or 5, or the positive electrode sheet according to claim 8 or 9 in a lithium ion battery.

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