CN115566162A - Lithium-containing oxide positive electrode material precursor, lithium-containing oxide positive electrode material, preparation method and application of lithium-containing oxide positive electrode material, positive plate and application of positive plate - Google Patents

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a lithium-containing oxide positive electrode material precursor, a lithium-containing oxide positive electrode material, a preparation method and application thereof, a positive electrode sheet and an application thereof. The compression index Δλ(P ₁₀₀ ) of the positive electrode material satisfies: Δλ(P ₁₀₀ )≥60%+(y/x)×5%; wherein, y/x is the molar ratio of Mn/Ni in the positive electrode material. The lithium-containing oxide positive electrode material has high compressive strength and stability, can only be broken to a small extent under high pressure during the production of the electrode sheet, and can continue to carry out lithium ion extraction/intercalation reactions. No severe rupture occurred.

Description

Lithium-containing oxide positive electrode material precursor, lithium-containing oxide positive electrode material and preparation thereof Method and application, positive electrode sheet and application thereof

technical field

The invention relates to the technical field of lithium-ion batteries, in particular to a lithium-containing oxide positive electrode material precursor, a lithium-containing oxide positive electrode material, a preparation method and application thereof, a positive electrode sheet and an application thereof.

Background technique

In recent years, new energy vehicles, as a national strategic emerging industry to deal with environmental pollution and energy crisis, have shown a good situation of vigorous development. As a new energy carrier with excellent comprehensive performance, lithium-ion batteries are widely used in electric vehicles, energy storage power stations, communications and digital electronic products and other markets.

In lithium-ion batteries, the positive electrode, as the core key material of lithium-ion batteries, directly determines the technical performance level of the battery. Among the commonly used cathode materials for lithium-ion batteries, LiNi _1-xy Co _x Mn _y O ₂ (NCM) and LiNi _1-xy Co _x Al _y O ₂ (NCA) with layered structures and lithium-rich manganese-based materials (LMR ) has attracted people's attention and research due to its high specific capacity and energy density. However, in order to obtain higher volumetric energy density and comprehensive electrochemical performance, during the production process of the battery pole piece, the positive electrode material must be rolled with greater strength to obtain a high electrode density. The low-strength positive electrode material will be fractured or crushed during this process, increasing the contact area with the electrolyte and side reactions, resulting in poor cycle performance and rate performance. In addition, during the use of the battery, the repeated Li ⁺ deintercalation will cause the volume expansion and contraction of the layered structure, which will cause the pulverization of the low-strength positive electrode material, resulting in insufficient contact between particles, and the continuous formation of new electrolyte layers and secondary layers. The reaction increases, causing battery performance to deteriorate and fail.

Therefore, it is of great significance to develop new preparation methods, regulate the microstructure of layered cathode materials, and enhance the compressive strength or particle strength of cathode materials to achieve long cycle life, high specific capacity, and high rate performance of batteries.

Contents of the invention

The purpose of the present invention is to overcome the lithium-containing metal oxide materials in the prior art that are broken during the production process of the electrode sheet or the secondary particles are broken during the charge-discharge cycle, resulting in poor rate performance, cycle performance deterioration, and safety performance. To reduce the problem of defects, provide lithium-containing oxide positive electrode material precursors, lithium-containing oxide positive electrode materials and their preparation methods and applications, positive electrode sheets and applications thereof, the lithium-containing oxide positive electrode materials have high compressive strength and stability In the process of electrode sheet production, only a small degree of fragmentation can occur under high pressure, and the lithium ion extraction/intercalation reaction can continue without serious rupture.

In order to achieve the above object, the first aspect of the present invention provides a lithium-containing oxide cathode material, wherein the compression index Δλ(P ₁₀₀ ) of the cathode material satisfies: Δλ(P ₁₀₀ )≥60%+(y/ x) × 5%;

Wherein, y/x is the molar ratio of Mn/Ni in the positive electrode material.

The second aspect of the present invention provides a lithium-containing oxide cathode material precursor, wherein the compressive index Δλ′(P ₅₀ ) of the precursor satisfies: Δλ′(P ₅₀ )≥35%+(v/u )×8%;

Among them, v/u is the molar ratio of Mn/Ni in the precursor.

The third aspect of the present invention provides a method for preparing a lithium-containing oxide positive electrode material, wherein the preparation method includes:

S1: Mix the precursor with the chemical formula shown in the formula (1), the lithium source, and the optional additive containing the element M ₂ evenly, and perform the first sintering in the atmosphere furnace to obtain the chemical formula shown in the formula (2) Primary sintered material of chemical formula;

S2: uniformly mix the primary sintered material with an additive containing the element M', and sinter the mixed material for a second time in an atmosphere furnace to obtain a lithium-containing metal oxide having a chemical formula shown in formula (3);

Ni _u Mn _v M _1γ (OH) ₂ , formula (1);

Wherein, u+v+γ=1, 0.2<u<1, 0<v≤0.75, 0≤γ≤0.35, M ₁ is selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, At least one element of 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);

Among them, 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 M ₁ element in the precursor and the M ₂ element introduced during the first sintering process;

M ₁ and M ₂ are the same or different, each selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B at least one element of

In formula (3):

M' is an oxide 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 , phosphide, sulfide, fluoride or chloride, the molar content of cations in M' is w, 0<w/(a+x+y+j)≤0.1.

The fourth aspect of the present invention provides a lithium-containing oxide cathode material prepared by the above-mentioned preparation method of the lithium-containing oxide cathode material.

The fifth aspect of the present invention provides a positive electrode sheet, wherein, based on the total weight of the positive electrode sheet, at least 90 wt% of a lithium-containing oxide positive electrode material is included;

Wherein, the lithium-containing oxide positive electrode material is the aforementioned lithium-containing oxide positive electrode material.

The sixth aspect of the present invention provides an application of the aforementioned lithium-containing oxide positive electrode material, the aforementioned lithium-containing oxide positive electrode material precursor, or the aforementioned positive electrode sheet in a lithium-ion battery.

Through the above technical scheme, the present invention has the following advantages:

(1) The lithium-containing oxide positive electrode material and precursor provided by the present invention realize high crystallinity and densification of the precursor through the control of a specific microstructure, thereby improving the compression index of the positive electrode material;

(2) The present invention can improve the compression index, cycle life and safety performance of the material through suitable modifiers and doping elements;

(3) The sintering system in the preparation process of the lithium-containing metal oxide of the present invention affects the compressive index of the material. Therefore, when selecting the sintering system, consideration should be given to cost, material compressive index, material physical index and electrochemical performance.

Description of drawings

Fig. 1 is the comparative schematic diagram of the charge-discharge curve of embodiment 5 and comparative example 1;

Fig. 2 is the comparative schematic diagram of the cycle performance of embodiment 5 and comparative example 1;

Fig. 3 is the comparative schematic diagram of the charging and discharging curve of embodiment 5 and comparative example 2;

Fig. 4 is the comparative schematic diagram of the cycle performance of embodiment 5 and comparative example 2;

Fig. 5 is the comparative schematic diagram of the charging and discharging curve of embodiment 5 and comparative example 3;

Fig. 6 is a comparative schematic diagram of the cycle performance of Example 5 and Comparative Example 3;

Fig. 7 is a comparative schematic diagram of the charging and discharging curves of Example 5 and Comparative Example 4;

Fig. 8 is a comparative schematic diagram of the cycle performance of Example 5 and Comparative Example 4;

Fig. 9 is a comparative schematic diagram of the charging and discharging curves of Example 9 and Comparative Example 5;

Figure 10 is a comparative schematic diagram of the cycle performance of Example 9 and Comparative Example 5;

Fig. 11 is a comparative schematic diagram of the charging and discharging curves of Example 9 and Comparative Example 6;

Fig. 12 is a comparative schematic diagram of the cycle performance of Example 9 and Comparative Example 6;

Fig. 13 is a comparative schematic diagram of the charging and discharging curves of Example 9 and Comparative Example 7;

FIG. 14 is a schematic diagram of the cycle performance comparison between Example 9 and Comparative Example 7.

detailed description

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

For conventional lithium-ion battery materials containing lithium metal oxides, they must withstand high pressure during the preparation of electrode sheets and during continuous charge-discharge cycles, cracks occur due to insufficient compressive strength of the material or unstable structure. It increases the side reaction with the electrolyte, accelerates the consumption of the electrolyte and the dissolution of transition metal cations in the positive electrode material, resulting in a decrease in cycle performance, safety performance and capacity, and even battery failure.

As mentioned above, the first aspect of the present invention provides a lithium-containing oxide cathode material, wherein the compression index Δλ(P ₁₀₀ ) of the cathode material satisfies: Δλ(P ₁₀₀ )≥60%+(y/ x) × 5%;

Wherein, y/x is the molar ratio of Mn/Ni in the positive electrode material.

Additionally, in the present invention:

是指自然状态无外界机械压力(即P＝0Mpa)下材料的颗粒累积分布D₅值，

是指在P＝n Mpa下材料的颗粒累积分布D₅值，D₅指颗粒累积体积分布为5％的粒径值。in

It refers to the particle cumulative distribution D value of the material under the natural state without external mechanical pressure (ie P= _0Mpa ),

It refers to the particle cumulative distribution D ₅ value of the material under P=n Mpa, and D ₅ refers to the particle size value at which the particle cumulative volume distribution is 5%.

For example, the calculation method of the compression resistance index Δλ(P ₁₀₀ ) is:

According to the present invention, preferably, the compression index Δλ(P ₂₀₀ ) of the positive electrode material satisfies: Δλ(P ₂₀₀ )≥45%+(y/x)×5%.

According to the present invention, more preferably, the compression index Δλ(P ₃₀₀ ) of the positive electrode material satisfies: Δλ(P ₃₀₀ )≥35%+(y/x)×5%.

According to the present invention, it should be noted that Δλ(P ₁₀₀ ) represents the compressive index of the material when the pressure P=100Mpa; Δλ(P ₂₀₀ ) represents the compressive index of the material when the pressure P=200Mpa; And so on.

The positive electrode material provided by the invention has excellent compressive strength, is not easy to break, and has a stable structure, less side reactions, and excellent safety performance and capacity retention rate during application as the positive electrode.

According to the present invention, the lithium-containing oxide cathode material has a chemical formula shown in formula (3):

Li[Li _a Ni _x Mn _y M _j ]O ₂ @M′, formula (3);

Among them, a+x+y+j=1, 0≤a≤0.3, 0.2<x<1, 0<y≤0.75, 0<j≤0.35, M is selected from Al, Zr, Nb, Ti, Y, Sc , Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B at least one element, M' contains Al, Zr, Nb, Ti, Y, Sc, Cr , Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B at least one element oxide, phosphide, sulfide, fluoride or chloride, M' in the cation The molar content of is w, 0<w/(a+x+y+j)≤0.1.

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.

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

In the present invention, the inventors of the present invention have found that:

By using a suitable modifier, the compressive strength and stability of the material particles can be enhanced, the DC internal resistance and gas production of the material during the cycle can be reduced, and the cycle life of the material can be improved.

By doping Ti, Sc, Zr, W, Mg, Y, Co, Cr, Ta and other elements, the crystal structure of the material can be stabilized, the microstructure of the material can be improved, and the compression index, cycle life and safety performance of the material can be improved; doping Ti, Zr, Nb, La, W, Co, B and other elements will form lithium-containing compounds (such as LiNbO ₃ or Li ₂ ZrO ₃ or Li ₄ Ti ₅ O ₁₂ or Li ₃ BO ₃ or LaNiO ₃ , etc.), stabilize the surface structure of material particles or the interface strength between particles or the grain boundary structure between primary grains, improve the compression index and cycle life of materials, and can accelerate the lithium ion between particles and The transport between the interfaces improves the rate performance of the material. The positive electrode material provided by the invention is also characterized in that:

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

According to the present invention, the positive electrode material has a compacted density ≥ 2.8 g/cm ³ , preferably ≥ 3 g/cm ³ , more preferably ≥ 3.2 g/cm ³ .

According to the present invention, the content of the surface soluble alkali of the positive electrode material satisfies the following conditions:

_Li2CO3≤1wt %, _LiOH≤0.5wt %;

Preferably Li ₂ CO ₃ ≤0.5wt%, LiOH≤0.4wt%;

More preferably Li ₂ CO ₃ ≤0.3wt%, LiOH≤0.3wt%;

More preferably, Li ₂ CO ₃ ≤ 0.2 wt%, LiOH ≤ 0.2 wt%.

According to the present invention, the half-width FWHM ₍₀₀₃₎ of the (003) crystal plane and the half-maximum width FWHM ₍ 104) of the (104) crystal plane obtained by the positive electrode material through XRD satisfy the following conditions:

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.

According to the present invention, the peak area S ₍₀₀₃₎ of the (003) crystal plane and the peak area S ₍ 104) of the (104) crystal plane obtained by the positive electrode material through XRD satisfy the following conditions:

1.1≤S ₍₀₀₃₎ /S ₍₁₀₄₎ ≤1.8, preferably, 1.2≤S ₍₀₀₃₎ /S ₍₁₀₄₎ ≤1.6.

In addition to using appropriate additives, the present invention also achieves high crystallinity and densification of the precursor by controlling the morphology and microstructure of the precursor, thereby improving the compression index of the positive electrode material.

The second aspect of the present invention provides a lithium-containing oxide cathode material precursor, wherein the compressive index Δλ′(P ₅₀ ) of the precursor satisfies: Δλ′(P ₅₀ )≥35%+(v/u )×8%;

Among them, v/u is the molar ratio of Mn/Ni in the precursor.

According to the present invention, preferably, the compressive index Δλ′(P ₁₀₀ ) of the precursor satisfies: Δλ′(P ₁₀₀ )≥25%+(v/u)×8%.

According to the present invention, it should be noted that, Δλ'(P ₅₀ ) represents the compressive index of the precursor material when the pressure P=50MPa; Δλ'(P ₁₀₀ ) represents the pressure index of the precursor material when the pressure P=100MPa , the compressive index of the precursor material; and so on.

In the present invention,

是指自然状态无外界机械压力(即P＝0MPa)下前驱体材料的颗粒累积分布D₅值，

是指在P＝nMPa下前驱体材料的颗粒累积分布D₅值。in

It refers to the particle cumulative distribution D value of the precursor material under the natural state without external mechanical pressure (ie P= _0MPa ),

refers to the particle cumulative distribution D ₅ value of the precursor material under P=nMPa.

For example, the calculation method of the compressive index Δλ'(P ₅₀ ) of the precursor is as follows:

According to the present invention, the precursor has a chemical formula shown in formula (1):

Ni _u Mn _v M _γ (OH) ₂ , formula (1);

Among them, u+v+γ=1, 0.2<u<1, 0<v≤0.75, 0≤γ≤0.35, M is selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg , Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B at least one element;

Preferably, 0.3≤u≤0.9, 0.05≤v≤0.68, 0≤γ≤0.3, and M is at least one element selected from Ti, Al, Zr, W, Co, Nb, La, Na and Mg. In the present invention, doping Ti, Al, Zr, W, Co, Nb, La, Na, Mg and other elements can stabilize the internal or surface structure of the precursor micro-domain.

The precursor material provided by the present invention is also characterized in that:

According to the present invention, more preferably, the tap density of the precursor is ≥1.2 g/cm ³ , preferably ≥1.6 g/cm ³ , more preferably ≥2 g/cm ³ .

According to the present invention, the BET value of the specific surface area of the precursor satisfies: BET≤30m ² /g, preferably, BET≤25m ² /g.

According to the present invention, the particle size distribution coefficient K ₉₀ of the precursor satisfies: 0.5≤K ₉₀ ≤1.6; where K ₉₀ =(D ₉₀ -D ₁₀ )/D ₅₀ , D ₁₀ , D ₅₀ and D ₉₀ respectively refer to particle accumulation Particle size values at 10%, 50% and 90% volume distribution.

According to the present invention, the half width FWHM ₍₀₀₁₎ of the (001) crystal plane obtained by the precursor through XRD, the half width FWHM ₍ 100) of the (100) crystal plane and the half width FWHM of the (101) crystal plane ₍₁₀₁₎ Satisfy the following conditions:

0.3 ≤ FWHM ₍₀₀₁₎ ≤ 1, preferably, 0.5 ≤ FWHM ₍ 001) ≤ 0.8; that is, the 2θ of the FWHM ₍₀₀₁₎ of the precursor material provided by the present invention measured by an X-ray diffractometer is not less than 0.3 and not greater than 1, preferably not less than 0.5 and not more than 0.8;

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.

According to the present invention, the peak area S ₍₁₀₁₎ of the (001) crystal plane obtained by the precursor through XRD and the peak area S ₍₁₀₄ ) of the (101) crystal plane meet the following conditions: S ₍₀₀₁₎ / S ₍₁₀₁₎ ≥2.0.

According to the present invention, the integral area S ₍₁₀₁₎ of the (001) crystal plane obtained by the precursor through XRD and the integral area S ₍₁₀₄ ) of the (101) crystal plane meet the following conditions: S ₍₀₀₁₎ / S ₍₁₀₁₎ ≥2.0.

In the present invention, a method for preparing a lithium-containing oxide cathode material precursor is also provided, wherein the preparation method includes:

(1) Contact and mix nickel salt, manganese salt, and a solution or suspension of a compound containing M to obtain a mixed salt solution;

(2) Flow the mixed salt solution, precipitant solution, and complexing agent solution into the reaction kettle for crystallization reaction, and then subject the obtained slurry to solid-liquid separation, washing, heat treatment, and screening to obtain lithium-containing Oxide cathode material precursor.

In the present invention, the inventors of the present invention have found that: for metal hydroxide precursors, in the process of compounding and sintering, cracks will occur due to insufficient compressive strength of the precursors, resulting in the compressive strength of the prepared positive electrode material Decrease, tap density decrease, electrochemical performance decrease. In the present invention, high crystallinity and densified precursor synthesis can be achieved by controlling the precursor synthesis process, such as complexing agent concentration and type, precipitant concentration, stirring intensity, reaction temperature, additives, solid content and feed rate, etc. , adjust the particle size distribution and specific surface area of the precursor, thereby improving the crystallinity, tap density, and compressive index of the precursor material; it is also possible to improve the precursor by adding appropriate additives and adjusting the microstructure and morphology of the precursor. Body resistance index.

According to the present invention, nickel salts, manganese salts or additives containing M elements are dissolved in a molar ratio u:v:γ into a mixed salt solution with a concentration of 1-3mol/L, and the compound containing M is added into water to make a certain concentration M solution or suspension, the alkali is dissolved into an alkali solution with a concentration of 2-10mol/L, and the complexing agent is dissolved into a complexing agent solution with a concentration of 2-13mol/L.

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

According to the present invention, the mixed salt solution of Ni and Mn, lye, complexing agent solution, and M solution are respectively fed into the reaction kettle with overflow pipe through their respective liquid inlet pipes in parallel, the stirring speed is kept constant, and the mixed salt solution is controlled. solution, precipitant solution, complexing agent solution, M solution inflow rate.

According to the present invention, the reaction conditions include: the reaction temperature is 40-70°C, the reaction pH is 10.6-12.5, and the reaction time is 5-100h.

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

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

According to the present invention, the compound containing M is one of sulfate, chloride, nitrate, acetate, citrate, carbonate, phosphate, oxalate, fluoride containing M element or Several kinds.

According to the present invention, the precipitant is an alkali substance, and the alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

According to the present invention, the complexing agent is one or more of salicylic acid, ammonium sulfate, ammonium chloride, ammonia water, sulfosalicylic acid, and ethylenediaminetetraacetic acid.

According to the present invention, the sintering system (including sintering temperature, heating rate, sintering atmosphere, etc.) in the preparation process of the lithium-containing metal oxide is also very important, which will affect the compressive index of the material.

The third aspect of the present invention provides a method for preparing a lithium-containing oxide positive electrode material, wherein the preparation method includes:

S1: Mix the precursor with the chemical formula shown in the formula (1), the lithium source, and the optional additive containing the element M ₂ evenly, and carry out the first sintering of the mixed material in the atmosphere furnace to obtain the formula ( 2) The primary sintered material of the shown chemical formula;

S2: uniformly mix the primary sintered material with an additive containing the element M', and sinter the mixed material for a second time in an atmosphere furnace to obtain a lithium-containing metal oxide having a chemical formula shown in formula (3);

Ni _u Mn _v M _1γ (OH) ₂ , formula (1);

Wherein, u+v+γ=1, 0.2<u<1, 0<v≤0.75, 0≤γ≤0.35, M ₁ is selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, At least one element of 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);

Among them, in formula (2) and formula (3):

0≤a≤0.3, 0.2<x<1, 0<y≤0.75, 0<j≤0.35;

M includes the M ₁ element in the precursor and the M ₂ element introduced during the first sintering process;

M ₁ and M ₂ are the same or different, each selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B at least one element of

In formula (3):

M' is an oxide 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 , phosphide, sulfide, fluoride or chloride, the molar content of cations in M' is w, 0<w/(a+x+y+j)≤0.1.

According to the present invention, the source of the M element in the positive electrode material includes the M ₁ element in the precursor and the introduction of an additive containing the M ₂ element during the first sintering process.

According to the present invention, the lithium source is at least one of lithium hydroxide, lithium carbonate, and lithium nitrate;

According to the present invention, the additive containing the _M2 element is selected from at least one of oxides, hydroxides, oxyhydroxides, phosphates, fluorides, borides, and carbonates containing the element _M2 .

According to the present invention, the M1 element, the _M2 element and the _M element are the same or different, each selected from Al, Zr, Nb, Ti, Y, Sc, Cr, Co, W, Mg, La, Os , Pr, Re, Ru, Sr, Sm, Ta and B at least one element.

According to the present invention, the additive containing element M' is selected from oxides, hydroxides, oxyhydroxides, phosphates, fluorides, borides, nitrides, carbonates, oxalates containing elements M' at least one of the

According to the present invention, the molar ratio Li/(Ni+Mn+M ₁ +M ₂ ) of the amount of the lithium source to the sum of the amount of the precursor and the additive containing the element M ₂ is 1-1.85, preferably 1- 1.5.

According to the present invention, the additive containing element M ₂ is added in an amount of M ₂ /(Ni+Mn+M ₁ +M ₂ ) of 0.0005-0.3, preferably 0.001-0.2.

According to the present invention, the molar ratio M'/(Ni+Mn+M ₁ +M ₂ ) of the amount of the additive containing the element M' to the amount of the primary sintered material is 0-0.1, preferably 0.001-0.02.

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 first sintering temperature T ₁ and the Ni content satisfies: 550×(2-x)≤T ₁ ≤ 400×(3-x)°C, the sintering time is 6-20h, preferably 8-15h.

According to the present invention, when the molar ratio of Ni/Mn≤1, that is, y/x≥1, the relationship between the first sintering temperature T ₂ and the Mn content satisfies: 500×(1+y)≤T ₂ ≤ 650×(1+y)°C, the sintering time is 6-20h, preferably 8-15h.

According to the present invention, when x<0.5, the first and second sintering atmospheres are air; when 0.5≤x<0.6, the first and second sintering atmospheres are air or a mixture of air and oxygen gas; when x≥0.6, the first and second sintering atmospheres are oxygen or a mixed gas of oxygen and air.

The fourth aspect of the present invention provides a lithium-containing oxide cathode material prepared by the above-mentioned preparation method of the lithium-containing oxide cathode material.

The fifth aspect of the present invention provides a positive electrode sheet, wherein, based on the total weight of the positive electrode sheet, it contains at least 90 wt% of a lithium-containing oxide positive electrode material; the lithium-containing oxide positive electrode material is the aforementioned Lithium oxide cathode material.

According to the present invention, preferably, the mass proportion of the positive electrode material is not less than 95%.

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

The sixth aspect of the present invention provides an application of the aforementioned lithium-containing oxide positive electrode material, the aforementioned lithium-containing oxide positive electrode material precursor, or the aforementioned positive electrode sheet in a lithium-ion battery.

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples:

Unless otherwise specified, all raw materials are commercially available.

In the following examples, the performance involved is obtained by:

(1) Phase test: obtained through the X-ray diffractometer test of the SmartLab 9kW model of Rigaku Corporation;

(2) Morphology test: obtained through the S-4800 scanning electron microscope test of Hitachi HITACHI Corporation;

(3) Particle size test: obtained through the laser particle size analyzer test of the Hydro 2000mu model of Marvern;

(4) specific surface area: obtained by the specific surface tester test of the Tristar II3020 model of Micromertics Corporation of the United States;

(5) Tap density: obtained through the tap density tester test of Baxter's BT-30 model;

(6) Compaction density: obtained through the test of the MCP-PD51 powder impedance tester of Mitsubishi Chemical;

(7) Anti-compression index test: through the 4350 model manual tablet press of Carver Company in the United States, the material is compressed at a specific pressure, the particle size of the fractured material is tested, and it is calculated by substituting the anti-compression index formula;

(8) Surface residual alkali test: measured by titration with Metrohmm888 professional Tirando intelligent potentiometric titrator;

(9) thermal stability test: obtained by the thermogravimetric analysis tester of Mettler TGA-DSC3 model;

(10) Electrochemical performance test:

The electrochemical performance of the prepared lithium-containing oxide cathode material was obtained by testing the 2025-type button battery with the Xinwei battery test system, specifically:

1) The preparation process of the 2025 type button battery is as follows:

Preparation of pole piece: The positive electrode material containing lithium oxide, carbon black, and polyvinylidene fluoride are fully mixed with an appropriate amount of N-methylpyrrolidone according to a certain mass ratio to form a uniform slurry, which is coated on an aluminum foil at 120°C Drying, rolling, punching and shearing, made into a positive electrode sheet with a diameter of 11mm.

Assemble the battery: the negative electrode uses a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator uses a polyethylene porous film with a thickness of 25 μm; the electrolyte uses 1mol/L LiPF ₆ , ethylene carbonate (EC) and diethyl carbonate ( DEC) equal volume mixture.

The positive pole piece, separator, negative pole piece and electrolyte were assembled into a 2025-type button battery in an Ar gas glove box with water content and oxygen content less than 5ppm, and the battery at this time was regarded as an unactivated battery.

2), electrochemical performance test:

When the molar ratio of Ni/Mn is greater than 1, that is, x/y>1, the test condition of the button battery is as follows: after making the button battery, place it for 2 hours, and after the open circuit voltage is stable, charge it to 0.1C at the positive current density. The cut-off voltage is 4.3V, and then charged at a constant voltage for 30 minutes, and then discharged to the cut-off voltage of 3.0V at the same current density; carry out the same method once more, and the battery at this time is regarded as an activated battery. Use an activated battery, in the voltage range of 3.0-4.3V, at 25°C, in the charge-discharge range of 3.0-4.3V, and conduct a charge-discharge test at 0.1C to evaluate the charge-discharge capacity of the material; use an activated battery, at 0.1C, Charge and discharge tests were carried out at 0.2C, 0.33C, 0.5C, and 1C, and the ratio of 1C capacity to 0.1C capacity was used to evaluate the rate performance of the material; in the range of 3.0-4.4V, 1C cycled 80 times to evaluate the cycle performance of the material.

When the molar ratio of Ni/Mn is not greater than 1, that is, x/y≤1, the test conditions of the button battery are: after making the button battery, place it for 2 hours, and after the open circuit voltage is stable, charge it with a current density of 0.1C at the positive electrode To the cut-off voltage of 4.6V, charge at a constant voltage for 30 minutes, and then discharge at the same current density to the cut-off voltage of 2.0V; carry out the same method once more, and the battery at this time is regarded as an activated battery. Use an activated battery, in the voltage range of 2.0-4.6V, at 25°C, in the charge-discharge range of 2.0-4.6V, and conduct a charge-discharge test at 0.1C to evaluate the charge-discharge capacity of the material; use an activated battery, at 0.1C, Charge and discharge tests were carried out at 0.2C, 0.33C, 0.5C, and 1C, and the ratio of 1C capacity to 0.1C capacity was used to evaluate the rate performance of the material; in the range of 2.0-4.6V, 0.5C was cycled 80 times to evaluate the cycle performance of the material.

Example 1

This example is to illustrate the lithium-containing oxide positive electrode material prepared in the present invention.

Dissolve nickel sulfate and manganese sulfate according to the metal molar ratio of 5:3 to obtain a 2mol/L mixed salt solution, and dissolve cobalt sulfate and aluminum sulfate according to Co/(Ni+Mn+Co+Al)=0.18, Al/(Ni +Mn+Co+Al)=0.02 metal molar ratio is dissolved to obtain a mixed salt solution of 2mol/L, sodium hydroxide is dissolved into an alkali solution with a concentration of 6mol/L, and ammonia water is dissolved into a complex salt solution with a concentration of 5mol/L agent solution.

Then 20L of mixed salt solution, alkali solution and complexing agent solution were added to the reaction kettle in parallel and reacted. During the process, the stirring speed was kept constant at 600 rpm, and the flow rate of mixed salt solution was controlled to be 300mL/h at the same time. The reaction pH is controlled to be 11.6, the reaction temperature is 50°C, the concentration of ammonia in the reaction system is controlled to be 9g/L, the reaction is carried out in _N2 gas, the reaction stays for 60h, and the solid content is 500g/L. The material was subjected to solid-liquid separation and washing, then dried at 105°C for 10 h, and sieved to obtain a spherical Ni _0.5 Mn _0.3 Co _0.18 Al _0.02 (OH) ₂ precursor material, which was designated as P-1.

Precursor P-1, lithium carbonate, additives TiO ₂ and WO ₃ according to Li:(Ni+Mn+Co+Al+Ti+W)=1.03, Ti:(Ni+Mn+Co+Al+Ti+W) =0.003, W: (Ni+Mn+Co+Al+Ti+W)=0.002 Mix evenly in a high-mixer; in an air atmosphere, raise the temperature to 920°C, keep it for 10h, and cool down naturally to obtain the primary sintered positive electrode material Li [Li ₀ Ni _0.4975 Mn _0.2985 Co _0.1791 Al _0.0199 Ti _0.003 W _0.002 ]O ₂ , denoted as S-1.

The primary sintered material S-1, additives Nb ₂ O ₅ and La ₂ O ₃ according to Nb:(Ni+Mn+Co+Al+Ti+W)=0.002, La:(Ni+Mn+Co+Al+Ti+ W) = 0.002 and mix evenly; in air atmosphere, raise the temperature to 650°C, keep it for 6 hours, and cool down naturally to obtain the secondary sintered cathode material Li[Li ₀ Ni _0.4975 Mn _0.2985 Co _0.1791 Al _0.0199 Ti _0.003 W _0.002 ]O ₂ @Nb _0.002 La _0.002 , recorded as FS-1.

Example 2-14

This example is to illustrate the lithium-containing oxide positive electrode material prepared in the present invention.

The lithium-containing oxide cathode material was prepared according to the same method as in Example 1, except that the preparation process of the precursor, the preparation process of the primary sintered positive electrode material, and the preparation process of the secondary sintered positive electrode material were different, as shown in Table 1. Show.

Table 1

Table 1 (continued)

Table 1 (continued)

In Table 1, unless otherwise specified, the ratios and usage ratios are all molar ratios.

Comparative example 1

Using the same synthesis method and conditions as in Example 5, only adjusting the first sintering temperature to 600° C., the obtained positive electrode material is marked as D-1, as shown in Table 2.

Comparative example 2

Using the same synthesis method and conditions as in Example 5, only adjusting the first sintering temperature to 900° C., the obtained positive electrode material is marked as D-2, as shown in Table 2.

Comparative example 3

Using the same synthesis method and conditions as in Example 5, the additives rhenium oxide and thorium oxide were not added in the preparation process of the positive electrode material by sintering only once, and the obtained positive electrode material was recorded as D-3, as shown in Table 2.

Comparative example 4

Using the same synthesis method and conditions as in Example 5, only the additives tungsten nitride and aluminum fluoride were not added in the preparation process of the secondary sintered positive electrode material, and the obtained positive electrode material was recorded as D-4, as shown in Table 2.

Comparative example 5

Using the same synthesis method and conditions as in Example 9, only adjusting the solid content to 150 g/L in the precursor preparation process, the obtained positive electrode material is recorded as D-5, as shown in Table 2.

Comparative example 6

Using the same synthesis method and conditions as in Example 9, only the additives tungsten oxide and aluminum oxyhydroxide were not added in the preparation process of the positive electrode material for one-time sintering, and the obtained positive electrode material was recorded as D-6, as shown in Table 2.

Comparative example 7

Using the same synthesis method and conditions as in Example 9, except for the preparation process of secondary sintering of the positive electrode material, the obtained positive electrode material is marked as D-7, as shown in Table 2.

Table 2

Table 2 (continued)

test case 1

The performance of the lithium-containing oxide positive electrode material precursors prepared in Examples 1-14 and Comparative Examples 1-7 was tested, and the results are shown in Table 3; and the samples prepared in Examples 1-14 and Comparative Examples 1-7 The performance of the lithium-containing oxide cathode material was tested, and the results are shown in Table 4 and Table 5.

table 3

Table 4

Table 4 (continued)

Table 4 (continued)

table 5

test case 2

The lithium-containing oxide positive electrode material prepared in Examples 1-14 and Comparative Examples 1-7 was used as the positive electrode sheet of the lithium-ion battery to prepare a lithium-ion battery, and the performance of the lithium-ion battery was tested, and the results are shown in Table 6 .

Table 6

Lithium Ion Battery Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Electrode Density (g/cm³) 3.2 3.2 3.5 3.4 3.6 3.3 3.5 0.1C discharge capacity (mAh/g) 173.1 181.3 192.3 208.7 225.2 228.3 233.5 1C discharge capacity (mAh/g) 158.6 167.1 176.5 192.2 214.3 216.2 218.5 1C capacity/0.1C capacity (%) 91.6 92.2 91.8 92.1 95.1 94.7 93.6 Capacity retention (%) 99.1 95.2 94.8 99.0 94.6 96.3 93.3

Table 6 (continued)

Table 6 (continued)

Lithium Ion Battery Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Electrode Density (g/cm³) 3.2 3.6 3.5 3.3 2.8 2.8 2.9 0.1C discharge capacity (mAh/g) 216.9 208.3 221.7 214.3 240.9 241.9 233.0 1C discharge capacity (mAh/g) 190.9 188.5 200.2 194.4 203.3 198.8 190.3 1C capacity/0.1C capacity (%) 88.0 90.5 90.3 90.7 84.4 82.2 81.7 Capacity retention (%) 86.7 85.9 87.5 86.6 88.0 89.0 89.9

In addition, in the present invention, Fig. 1 is a schematic diagram of the comparison of the charge-discharge curves of Example 5 and Comparative Example 1; it can be seen from Fig. 1 that by comparing the charge-discharge curves of Example 5 and Comparative Example 1, it can be seen that the embodiment The 0.1C discharge capacity (225.2mAh/g) of the positive electrode material provided by 5 is higher than the 0.1C discharge capacity (216.9mAh/g) of the positive electrode material D-1 obtained when the first sintering temperature is too low (600°C).

Fig. 2 is a comparative schematic diagram of the cycle performance of Example 5 and Comparative Example 1; as can be seen from Fig. 2, by comparing the cycle performance of Example 5 and Comparative Example 1, it can be seen that the capacity retention rate (94.6%) of Example 5 It is obviously higher than the capacity retention rate (86.7%) of the cathode material provided by D-1. This is because when the sintering temperature is too low, the primary grain growth is incomplete, resulting in low compressive index and unstable structure, thus showing low capacity and cycle performance.

Fig. 3 is a comparative schematic diagram of the charge-discharge curves of Example 5 and Comparative Example 2; as can be seen from Fig. 3, by comparing the charge-discharge curves of Example 5 and Comparative Example 2, it can be seen that the positive electrode material provided by Example 5 is 0.1 The C discharge capacity (225.2mAh/g) is higher than the 0.1C discharge capacity (208.3mAh/g) of the positive electrode material D-2 obtained when the first sintering temperature is too high (900°C).

Fig. 4 is a comparative schematic diagram of the cycle performance of embodiment 5 and comparative example 2; as can be seen from Fig. 4, by comparing the cycle performance of embodiment 5 and comparative example 2, it can be seen that the capacity retention rate (94.6%) of embodiment 5 It is obviously higher than the capacity retention rate (85.9%) of the positive electrode material provided by D-2. This is because when the sintering temperature is too high, the excessive primary grain growth will also lead to low compressive index and unstable structure, thus showing low capacity and cycle performance.

Fig. 5 is the comparative schematic diagram of the charge-discharge curve of embodiment 5 and comparative example 3; As can be seen from Fig. 5, by comparing the charge-discharge curve of embodiment 5 and comparative example 3, it can be seen that the 0.1C discharge capacity of embodiment 5 ( 225.2mAh/g) is higher than the 0.1C discharge capacity (221.7mAh/g) of the positive electrode material D-3 obtained in the first sintering without addition of rhenium oxide and thorium oxide additives.

Fig. 6 is a comparative schematic diagram of the cycle performance of embodiment 5 and comparative example 3; as can be seen from Fig. 6, by comparing the cycle performance of embodiment 5 and comparative example 3, it can be seen that the capacity retention rate (94.6%) of embodiment 5 It is obviously higher than the capacity retention rate (87.5%) of the positive electrode material provided by D-3. The above shows that the addition of rhenium oxide and oxide oxide additives in the first sintering can improve the capacity and cycle performance of the material, because appropriate doping modification can improve the microstructure of the material and form lithium-containing compounds on the particle surface or between particles, Both help to improve the compression index of the material, thus improving the electrochemical performance of the positive electrode material such as capacity and cycle performance.

Fig. 7 is the comparison schematic diagram of the charge-discharge curve of embodiment 5 and comparative example 4; As can be seen from Fig. 7, by comparing the charge-discharge curve of embodiment 5 and comparative example 4, it can be seen that the 0.1C discharge capacity of embodiment 5 ( 225.2mAh/g) is significantly higher than the 0.1C discharge capacity (214.3mAh/g) of the positive electrode material D-4 obtained in the second sintering without adding tungsten nitride and aluminum fluoride additives.

Figure 8 is a comparative schematic diagram of the cycle performance of Example 5 and Comparative Example 4; as can be seen from Figure 8, by comparing the cycle performance of Example 5 and Comparative Example 4, it can be seen that the capacity retention rate (94.6%) of Example 5 It is obviously higher than the capacity retention rate (86.6%) of the positive electrode material provided by D-4. The above shows that adding tungsten nitride and aluminum fluoride additives in the second sintering can improve the capacity and cycle performance of the material, because it can form a stable coating layer on the surface of the material, improve the surface microstructure of the material and reduce the surface area of the material. The side reaction also helps to improve the compression index of the material, thus improving the electrochemical performance of the positive electrode material such as capacity and cycle performance.

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

Figure 10 is a schematic diagram of the cycle performance comparison of Example 9 and Comparative Example 5; as can be seen from Figure 10, by comparing the cycle performance of Example 9 and Comparative Example 5, it can be seen that the capacity retention rate (93.9%) of Example 9 It is obviously higher than the capacity retention rate (88.0%) of the positive electrode material provided by D-5. This is because the low solid content will lead to poor crystallinity and compactness of the precursor, and the morphology and microstructure will also change, thus showing a low compressive index, resulting in deterioration of the electrochemical performance of the material such as capacity and cycle performance.

Fig. 11 is a comparative schematic diagram of the charge-discharge curves of embodiment 9 and comparative example 6; as can be seen from Fig. 11, by comparing the charge-discharge curves of embodiment 9 and comparative example 6, it can be seen that the 0.1C discharge capacity of embodiment 9 ( 250.7mAh/g) is significantly higher than the 0.1C discharge capacity (241.9mAh/g) of the positive electrode material D-6 obtained in the first sintering without adding tungsten oxide and aluminum oxyhydroxide additives.

Figure 12 is a comparative schematic diagram of the cycle performance of Example 9 and Comparative Example 6; as can be seen from Figure 12, by comparing the cycle performance of Example 9 and Comparative Example 6, it can be seen that the capacity retention rate (93.9%) of Example 9 It is obviously higher than the capacity retention rate (89.0%) of the positive electrode material provided by D-6. The above shows that the addition of tungsten oxide and aluminum oxyhydroxide additives in the first sintering can improve the capacity and cycle performance of the material, because proper doping modification can improve the microstructure of the material and form lithium-containing compounds on the particle surface or between particles , all help to improve the compression index of the material, thus improving the electrochemical performance of the positive electrode material such as capacity and cycle performance.

Fig. 13 is a comparative schematic diagram of the charge-discharge curves of embodiment 9 and comparative example 7; as can be seen from Fig. 13, by comparing the charge-discharge curves of embodiment 9 and comparative example 7, it can be seen that the 0.1C discharge capacity of embodiment 9 ( 250.7mAh/g) is significantly higher than the 0.1C discharge capacity (233.0mAh/g) of the positive electrode material D-7 obtained without the second sintering process.

Figure 14 is a schematic diagram of the cycle performance comparison of Example 9 and Comparative Example 7; as can be seen from Figure 14, by comparing the cycle performance of Example 9 and Comparative Example 7, it can be seen that the capacity retention rate (93.9%) of Example 9 It is obviously higher than the capacity retention rate (89.9%) of the positive electrode material provided by D-7. The above shows that the second sintering can effectively improve the capacity and cycle performance of the material, because the second sintering process can form a stable coating layer on the surface of the material and rearrange the atoms on the surface of the material, improve the surface microstructure of the material and reduce the The surface side reaction of the material, and the improvement of the compression index of the material, thus improving the electrochemical performance of the positive electrode material such as capacity and cycle performance.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (12)

1. A lithium oxide-containing positive electrode material characterized in that the positive electrode material has a compression resistance index [ Delta ]λ(P ₁₀₀ ) Satisfies the following conditions: delta lambda (P) ₁₀₀ )≥60％+(y/x)×5％；

Wherein y/x is the molar ratio of Mn/Ni in the positive electrode material.

2. The positive electrode material according to claim 1, wherein the positive electrode material has a compression resistance index Δ λ (P) ₂₀₀ ) Satisfies the following conditions: delta lambda (P) ₂₀₀ )≥45％+(y/x)×5％；

And/or the compression resistance index delta lambda (P) of the cathode material ₃₀₀ ) Satisfies the following conditions: delta lambda (P) ₃₀₀ )≥35％+(y/x)×5％。

3. The lithium-containing oxide positive electrode material according to claim 1 or 2, wherein the lithium-containing oxide positive electrode material has a chemical formula represented by formula (3):

Li[Li _a Ni _x Mn _y M _j ]O ₂ @ M', formula (3);

wherein a is not less than 0 and not more than 0.3, x is not more than 0.2 and not more than 1, Y is not more than 0 and not more than 0.75, j is not more than 0 and not more than 0.35, M 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, 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, the molar content of the cation in M' is W, 0<w/(a + x + Y + j) is not more than 0.1;

preferably, 0.02. Ltoreq. A.ltoreq.0.2, 0.3. Ltoreq. X.ltoreq.0.9, 0.05. Ltoreq. Y.ltoreq.0.68, 0. Ltoreq. J.ltoreq.0.3, 0.001. Ltoreq. W/(a + x + Y + j) 0.02, M is at least one element 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 selected from Zr, nb, ti, Y, sc, cr, co, W, mg, la, ta and B.

4. The lithium-containing oxide positive electrode material according to any one of claims 1 to 3, wherein the lithium-containing oxide positive electrode material has a compacted density of not less than 2.8g/cm ³ Preferably ≥ 3g/cm ³ More preferably ≧3.2g/cm ³ ；

And/or the tap density of the lithium-containing oxide cathode material is more than or equal to 1.7g/cm ³ Preferably ≥ 2g/cm ³ More preferably not less than 2.4g/cm ³ ；

And/or the content of the surface soluble alkali of the lithium-containing oxide cathode material meets the following conditions:

Li ₂ CO ₃ ≤1wt％，LiOH≤0.5wt％；

preferably Li ₂ CO ₃ ≤0.5wt％，LiOH≤0.4wt％；

Further preferred is Li ₂ CO ₃ ≤0.3wt％，LiOH≤0.3wt％；

Even more preferred is Li ₂ CO ₃ ≤0.2wt％，LiOH≤0.2wt％；

And/or the presence of a gas in the gas,

the lithium-containing oxide cathode material has a full width at half maximum FWHM of a (003) crystal plane obtained by XRD ₍₀₀₃₎ And FWHM of full width at half maximum of (104) crystal plane ₍₁₀₄₎ The following conditions are satisfied:

0.10≤FWHM ₍₀₀₃₎ 0.25 or less, preferably 0.13 or less FWHM ₍₀₀₃₎ ≤0.22；

0.20≤FWHM ₍₁₀₄₎ 0.50 or less, preferably 0.22 or less FWHM ₍₁₀₄₎ ≤0.42；

And/or the presence of a gas in the gas,

the lithium-containing oxide cathode material has a peak area S of a (003) plane obtained by XRD ₍₀₀₃₎ Peak area S of (104) and (Z) plane ₍₁₀₄₎ The following conditions are satisfied:

1.1≤S ₍₀₀₃₎ /S ₍₁₀₄₎ 1.8, preferably 1.2S ₍₀₀₃₎ /S ₍₁₀₄₎ ≤1.6。

5. A lithium-containing oxide positive electrode material precursor is characterized in that the compression resistance index delta lambda' (P) of the precursor ₅₀ ) Satisfies the following conditions: Δ λ' (P) ₅₀ )≥35％+(v/u)×8％；

Wherein v/u is the molar ratio of Mn/Ni in the precursor.

6. According toThe precursor of claim 5, wherein the precursor has a crush resistance index Δ λ' (P) ₁₀₀ ) Satisfies the following conditions: Δ λ' (P) ₁₀₀ )≥25％+(v/u)×8％。

7. A method for preparing a lithium-containing oxide cathode material is characterized by comprising the following steps:

s1: a precursor having a chemical formula shown in formula (1), a lithium source, and optionally an element M ₂ The additive is uniformly mixed and is sintered for the first time in an atmosphere furnace to obtain a primary sintered material with a chemical formula shown in a formula (2);

s2: uniformly mixing the primary sintered material with an additive containing an element M', and carrying out secondary sintering on the mixed material in an atmosphere furnace to obtain a lithium-containing metal oxide with a chemical formula shown in a formula (3);

Ni _u Mn _v M _1γ (OH) ₂ formula (1);

wherein u + v + γ =1,0.2<u<1，0<v≤0.75，0≤γ≤0.35，M ₁ At least one element selected from the group consisting of 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 (ii) a Formula (2);

Li[Li _a Ni _x Mn _y M _j ]O ₂ @ M', formula (3);

wherein, 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 M in the precursor ₁ Element and M in the first sintering process ₂ An element;

M ₁ 、M ₂ at least one element, which is the same or different, each selected from the group consisting of 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 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 mole content of cation in M' is W, 0<w/(a + x + Y + j) is less than or equal to 0.1.

8. The production method according to claim 7, wherein when the molar ratio of Ni/Mn is more than 1, i.e., x/y>1, sintering temperature T of the first sintering ₁ The relationship with the Ni content satisfies: t is more than or equal to 550 x (2-x) ₁ Less than or equal to 400 x (3-x) DEG C, the sintering time is 6-20h, preferably 8-15h;

and/or when the molar ratio of Ni to Mn is less than or equal to 1, namely y/x is more than or equal to 1, the sintering temperature T of the first sintering ₂ The relation with the Mn content satisfies: t not more than 500 x (1+y) ₂ 650 x (1+y) DEG C or less, the sintering time is 6-20h, preferably 8-15h;

and/or, when x is less than 0.5, the atmosphere of the first and second sintering is air; when x is more than or equal to 0.5 and less than 0.6, the atmosphere of the first sintering and the second sintering is air or mixed gas of air and oxygen; when x is more than or equal to 0.6, the atmosphere of the first sintering and the second sintering is oxygen or mixed gas of oxygen and air.

9. A lithium-containing oxide positive electrode material produced by the method for producing a lithium-containing oxide positive electrode material according to claim 7 or 8.

10. A positive electrode sheet, comprising at least 90wt% of a lithium-containing oxide positive electrode material, based on the total weight of the positive electrode sheet;

wherein the lithium-containing oxide positive electrode material is the lithium-containing oxide positive electrode material according to any one of claims 1 to 4 and 9.

11. The positive plate according to claim 10, wherein the positive plate has a plate density of 2.8g/cm or more ³ Preferably ≥ 3.2g/cm ³ More preferably not less than 3.5g/cm ³ 。

12. Use of a lithium-containing oxide positive electrode material according to any one of claims 1 to 4 and 9, a lithium-containing oxide positive electrode material precursor according to claim 5 or 6, or a positive electrode sheet according to claim 10 or 11 in a lithium ion battery.

Images