CN105680025B - A kind of anode material of lithium battery and preparation method thereof and lithium battery - Google Patents

Abstract

The present application relates to a lithium battery positive electrode material, the lithium battery positive electrode material is spinel lithium nickel manganese oxide coated with a coating layer on the surface, and the coating layer contains Li _a B _b O _c and LiMnBO ₃ ; The structural formula of the spinel lithium nickel manganese oxide is LiM _x+y Ni _0.5-x Mn _1.5 - _y O ₄ , wherein M is selected from at least one of Co, Al, Cr, Fe, Mg, Zr or Ti , 0≤x<0.2, 0≤y<0.2; the Li _a B _b O _c is specifically LiBO ₂ , LiB ₃ O ₅ , LiB ₅ O ₈ , LiB ₇ O ₁₁ , Li ₂ B ₄ O ₇ , Li ₃ At least one of BO ₃ , Li ₃ B ₅ O ₉ , Li ₃ B ₇ O ₁₂ , Li ₄ B ₂ O ₅ or Li ₄ B ₆ O ₁₁ ; mixed sintering with spinel lithium nickel manganese oxide and boron compound , not only improves the cycle stability of spinel lithium nickel manganese oxide, but also inhibits the manganese dissolution of spinel lithium nickel manganese oxide in the electrolyte. The modification process is applicable to all spinel lithium nickel manganese oxide cathode materials, is simple and easy to implement, has low manufacturing cost, good reproducibility, and is convenient for large-scale industrial production.

Description

A lithium battery positive electrode material and preparation method thereof, and lithium battery

technical field

The present application relates to the technical field of lithium ion batteries, in particular to a lithium battery positive electrode material, a preparation method thereof, and a lithium battery.

Background technique

Compared with traditional lead-acid batteries, nickel-metal hydride batteries and other secondary batteries, lithium-ion batteries have the advantages of high energy density, high output voltage, low self-discharge, no memory effect and environmental friendliness, and have been widely used and developed. The performance of key materials for power and energy storage lithium-ion batteries is the ultimate decisive factor in battery performance, and the research on cathode materials has always been a hot spot for scientists. Cathode materials such as LiCoO ₂ , LiMnO ₄ , LiFePO ₄ , _LiNix Co _y Mn _1-xy O ₂ have been extensively studied. However, the lithium-ion battery system assembled with these positive electrode materials has defects such as low specific energy density, high cost, and poor safety, and it is difficult to meet the requirements of electric vehicles for energy storage batteries.

Spinel lithium nickel manganese oxide cathode material has always been a research hotspot in lithium-ion battery cathode materials due to its excellent rate performance, high operating voltage, and low cost. However, the instability of the surface structure of the spinel lithium nickel manganese oxide cathode material and the dissolution of metal manganese during the cycle have seriously inhibited the large-scale application of the spinel lithium nickel manganese oxide cathode material.

In order to develop spinel lithium nickel manganese oxide cathode materials with excellent performance and meet the battery rate performance requirements of electric vehicles, researchers have developed and disclosed a variety of technical means to modify spinel lithium nickel manganese oxide cathode materials. like,

One of the modification methods: Aluminum hydroxide-coated lithium nickel manganese oxide material is obtained by liquid phase coating, and then placed in a muffle furnace for heat treatment at 300-450°C to obtain alumina-coated modified lithium nickel manganese oxide cathode material , the modified lithium nickel manganese oxide positive electrode material is about 10% higher than that of the uncoated material.

Modification method 2: The combination of sol-gel method and solid-phase method is adopted, so that the Li ₂ TiO ₃ coated with LiNi _0.5 Mn _1.5 O4 material is evenly distributed, and the uniformity of the final positive electrode material is good, so that the obtained The cathode material has good cycle performance and rate capability.

Modification method 3: By adding microwave-sensitive material zirconia in the preparation process of the precursor, the reaction material can effectively absorb microwaves and rapidly heat up to a reaction temperature of 700-950°C, significantly shortening the microwave firing time of the product to 1-10 minutes; While the lithium nickel manganese oxide material is fired at high temperature, the zirconia reacts with the Li source to form a lithium ion conductor Li ₂ ZrO ₃ coating layer on the surface of the lithium nickel manganese oxide, which significantly improves the cycle performance and rate performance of the product.

The above methods have relatively complex processes, making it difficult to carry out industrial production, and there is no corresponding solution to the dissolution of metal manganese. Therefore, it is urgent to find a simple and easy improvement of spinel lithium nickel manganese oxide cathode material at present. The positive method makes the spinel lithium nickel manganese oxide positive electrode material have high cycle stability, and can inhibit the dissolution of metal manganese in the electrolyte, so as to meet the requirements of the power battery.

Contents of the invention

The purpose of this application is to overcome the problems of the prior art, to provide a surface-modified spinel lithium nickel manganese oxide positive electrode material and its preparation method, and the surface structure of the material is stable, the cycle stability is good, and the metal manganese Not easy to dissolve.

The concrete technical scheme of this application is:

A lithium battery positive electrode material. The lithium battery positive electrode material is spinel lithium nickel manganese oxide coated with a coating layer on the surface, and the coating layer contains Li _a B _b O _c and LiMnBO ₃ .

Preferably, the structural formula of the spinel lithium nickel manganese oxide is LiM _x+y Ni _0.5-x Mn _1.5-y O ₄ , wherein M is selected from Co, Al, Cr, Fe, Mg, Zr or Ti At least one, 0≤x<0.2, 0≤y<0.2; preferably, 0<x+y<0.2.

Preferably, the Li _a B _b O _c is specifically LiBO ₂ , LiB ₃ O ₅ , LiB ₅ O ₈ , LiB ₇ O ₁₁ , Li ₂ B ₄ O ₇ , Li ₃ BO ₃ , Li ₃ B ₅ O ₉ , At least one of Li ₃ B ₇ O ₁₂ , Li ₄ B ₂ O ₅ or Li ₄ B ₆ O ₁₁ ; more preferably LiBO ₂ .

Preferably, the ratio of Li _a B _b O _c to LiMnBO ₃ is 1:0.5-4.

Preferably, the percentage of the cladding layer in the mass of the spinel lithium nickel manganese oxide is greater than zero and less than 3%.

Preferably, the thickness of the cladding layer is 1-10 nm.

The present application also relates to a method for preparing the positive electrode material of a lithium battery as described above, comprising the following steps:

(1) Evenly mix the spinel lithium nickel manganese oxide raw material with boron source and lithium source;

(2) Mixing and sintering in an oxygen-containing atmosphere to prepare the lithium battery cathode material.

Preferably, in the step (1), the boron source is at least one of diboron trioxide, boric acid, lithium borate; the lithium source is at least one of lithium hydroxide, lithium carbonate, lithium borate kind.

Preferably, the median particle diameter D50 of the spinel lithium nickel manganese oxide raw material is 3 μm to 15 μm, the median particle diameter D50 of the boron source is 10 nm to 500 nm, and the median particle diameter D50 of the lithium source is 0.1μm～5μm.

Preferably, the added amount of the boron source is 0.1-10% of the moles of the spinel lithium nickel manganese oxide raw material; the added amount of the lithium source is 0%-400% of the moles of the boron source .

Preferably, the oxygen-containing atmosphere is oxygen or air, and the gas flow rate is 100-5000ml/min; the heating rate of the mixed sintering is 1-10°C/min, and the mixed sintering is carried out at 400-800°C for 3-8h.

The present application also relates to a lithium battery, comprising a positive pole piece, a negative pole piece, a diaphragm and an electrolyte spaced between the positive pole piece and the negative pole piece, and the positive pole piece contains the aforementioned lithium battery cathode material.

The technical solution provided by the application can achieve the following beneficial effects:

Mixing sintering with spinel lithium nickel manganese oxide and boron compound not only improves the cycle stability of spinel lithium nickel manganese oxide, but also inhibits the manganese dissolution of spinel lithium nickel manganese oxide in the electrolyte. The modification process is applicable to all spinel lithium nickel manganese oxide cathode materials, is simple and easy to implement, has low manufacturing cost, good reproducibility, and is convenient for large-scale industrial production.

Description of drawings

Fig. ₁ is the XRD pattern of the spinel lithium nickel manganese oxide positive electrode material prepared in embodiment 1 and the lithium battery positive electrode material LiNi _0.5 Mn _1.5 O of comparative example 1;

Fig. 2 is the SEM picture of LiNi _0.5 Mn _1.5 O ₄ of lithium battery cathode material without sintering treatment;

Fig. 3 is the SEM picture of the lithium battery cathode material that embodiment 1 makes;

Fig. 4 is a cycle stability curve of the positive electrode material LiNi _0.5 Mn _1.5 O ₄ of Comparative Example 1 and the lithium battery positive electrode materials prepared in Examples 1-2.

Detailed ways

In order to make the purpose, technical solution and advantages of the application clearer, the technical solution of the application will be clearly and completely described below in conjunction with the embodiments of the application and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the application , but not all examples. All other embodiments obtained by those skilled in the art on the basis of the technical solutions and given embodiments provided in this application without creative efforts shall fall within the scope of protection of this application.

The anode material of a lithium battery involved in this application is a spinel lithium nickel manganese oxide coated with a coating layer on the surface, that is, a coating layer is coated on the surface of the spinel lithium nickel manganese oxide; coating The layer contains Li _a B _b O _c and LiMnBO ₃ .

Compared with Li _a B _b O _c alone and conventional oxides, Li _a B _b O _c and LiMnBO ₃ have the following advantages: 1) LiMnBO ₃ has a stable three-dimensional crystal structure, and can provide Li ⁺ intercalation/deintercalation Wider diffusion channel; 2) Manganese dissolution of spinel lithium nickel manganese oxide, mainly the Mn ³⁺ on the surface dissolves into the electrolyte, and migrates to the negative electrode to corrode the SEI film, passing through the surface Li _a B _b O _c and LiMnBO ₃ coating, LiMnBO ₃ stabilizes the manganese element on the surface of spinel lithium nickel manganese oxide, makes the Mn on the surface in a stable valence state, and reduces the dissolution of manganese in the electrolyte; 3) At the same time, the surface coating makes the positive electrode The material and the electrolyte are separated. When the voltage is as high as about 5V during the charging and discharging process, the electrolyte on the electrode surface will not be oxidized and decomposed and deposited on the electrode surface, which reduces the dissolution and erosion of the positive electrode material by the electrolyte during the charging and discharging process. influences.

Preferably, the structural formula of spinel lithium nickel manganese oxide is LiM _x+y Ni _0.5-x Mn _1.5-y O ₄ , wherein M is at least one of Co, Al, Cr, Fe, Mg, Zr or Ti 0≤x<0.2, 0≤y<0.2; preferably 0<x+y<0.2, more preferably 0<x+y<0.1.

As an improvement of the present application, a, b, and c are integers, and 1≤a≤4, 1≤b≤7, 2≤c≤12, a+3b=2c, that is, the Li _a B _b O _c Specifically LiBO ₂ , LiB ₃ O ₅ , LiB ₅ O ₈ , LiB ₇ O ₁₁ , Li ₂ B ₄ O ₇ , Li ₃ BO ₃ , Li ₃ B ₅ O ₉ , Li ₃ B ₇ O ₁₂ , Li ₄ B ₂ At least one of O ₅ or Li ₄ B ₆ O ₁₁ ; preferably LiBO ₂ .

As an improvement of the present application, the cladding layer accounts for the percentage of the core layer spinel lithium nickel manganese oxide mass to be greater than zero and less than ₃ %; the amount of Li _a B _b O _c and LiMnBO in the cladding layer The ratio is 1:0.5-4; the thickness of the cladding layer is 1-10nm.

As an improvement of the present application, the cladding layer is composed of Li _a B _b O _c and LiMnBO ₃ , and the cladding layer accounts for less than 3% of the mass ratio of the core layer spinel lithium nickel manganese oxide, wherein Li _a B _b O _c and The ratio of the amount of substances of LiMnBO ₃ is 1:0.5-4; the thickness of the cladding layer is 1-10nm.

For the cladding layer, too high a proportion of Li _a B _b O _c will increase the storage gas production of the positive electrode material, and too high a proportion of LiMnBO ₃ will increase the DC resistance (DCR) of the cell; at the same time, the cladding layer is too thin, the effect is not good Obviously; if the cladding layer is too thick, it will increase the polarization of the positive electrode material during charging and discharging.

The present application also relates to a preparation method of the above-mentioned lithium battery cathode material, comprising the following steps:

(1) Evenly mix the spinel lithium nickel manganese oxide raw material with boron source and lithium source;

(2) Mixing and sintering in an oxygen-containing atmosphere to prepare a cathode material for a lithium battery.

The boron source, lithium source and the unstable manganese in the spinel lithium nickel manganese oxide raw material form a coating layer containing Li _a B _b O _c and LiMnBO ₃ during the mixed sintering process, so that the spinel lithium nickel manganese oxide raw material Unstable manganese transfers and exists stably in the cladding layer, thereby inhibiting the dissolution of manganese in the electrolyte of spinel lithium nickel manganese oxide; during the sintering process, the spinel lithium nickel manganese oxide, boron source and lithium source are also in the The formation of boron-lithium composite oxide Li _a B _b O _c in the cladding layer can effectively improve the cycle stability of spinel lithium nickel manganese oxide. The solid-phase sintering modification process can be applied to all spinel lithium nickel manganese oxide cathode materials, is simple and easy to implement, has low manufacturing cost, good reproducibility, and is convenient for large-scale industrial production.

As an improvement of the present application, in step (1), the boron source is at least one of diboron trioxide, boric acid, and lithium borate; the lithium source is at least one of lithium hydroxide, lithium carbonate, and lithium borate.

Preferably, the added amount of the boron source is 0.1-10% of the moles of the spinel lithium nickel manganese oxide raw material; the added amount of the lithium source is 0%-400% of the moles of the boron source %. The case of 0% is when the boron source contains lithium at the same time, then the boron source can provide boron and lithium at the same time, so there is no need to add other lithium sources, such as when the boron source is lithium borate, lithium borate acts as boron at the same time source and lithium source.

As an improvement of the present application, the median particle size D50 of the spinel lithium nickel manganese oxide raw material is 3 μm to 15 μm, the median particle size D50 of the boron source is 10 nm to 500 nm, and the median particle size D50 of the lithium source is 0.1 μm～5μm.

As an improvement of the present application, the method of uniform mixing is ball milling, grinding or magnetic stirring, etc. The use of ball milling, grinding or magnetic stirring can effectively improve the uniformity of mixing, which is conducive to improving the conversion efficiency.

As an improvement of the present application, the oxygen-containing atmosphere is oxygen or air, the gas flow rate is 100-5000ml/min; the heating rate of mixed sintering is 1-10°C/min, and the mixed sintering time is 3-300°C at 400-800°C. 8h; using a certain oxygen-containing atmosphere can effectively replenish oxygen, and at the same time, the temperature is too high or too low will cause the thickness of the cladding layer to be too thick or too thin.

The present application also relates to a positive electrode active material for a lithium battery, which contains the aforementioned positive electrode material for a lithium battery. That is, the positive electrode active material of lithium ion battery involved in the present application, in addition to the positive electrode material of lithium battery provided above in the present application, does not exclude other components that can be used as the positive electrode active material of lithium ion battery.

The present application also relates to a positive electrode sheet of a lithium battery, including a current collector and a positive active material layer distributed on the current collector. The positive active material layer contains the aforementioned lithium battery positive active material, that is, the positive active material layer contains the aforementioned lithium battery. Cathode material. Generally, the positive electrode active material layer also contains a conductive agent and a binding agent, and the conductive agent and the binding agent in the positive electrode active material layer involved in the application can use existing conductive agents and binding agents; such as graphite, carbon nanotubes and other conductive agents; for example, PVDF and other binders.

The present application also relates to a lithium-ion battery, comprising a positive pole piece, a negative pole piece, a diaphragm and an electrolyte spaced between the positive pole piece and the negative pole piece, and the positive pole piece is the aforementioned lithium-ion battery positive pole piece, That is, the positive electrode sheet contains the aforementioned lithium battery positive electrode material.

Embodiments 1 to 6 and Comparative Examples 1 to 3: Take the spinel lithium nickel manganese oxide raw material, boron source, and lithium source according to a certain ratio of substance mass, mix them evenly, and then place them in an oxygen atmosphere, and set the gas flow rate as 1000ml/min, heating rate 5°C/min, and sintering at 450°C for 5h, the surface boron-modified spinel lithium nickel manganese oxide positive electrode material was prepared; Comparative Example 1 is the case of no sintering; the relevant parameters of the preparation process are specific As shown in Table 1.

Table 1 Examples 1 to 6 and comparative examples 1 to 3 prepare modified spinel lithium nickel manganese oxide positive electrode material related parameters

Examples 7-9 and Comparative Examples 4-7: Preparation of surface boron-modified spinel lithium nickel manganese oxide positive electrode material: the same raw materials and proportions as in Example 6, take spinel lithium nickel manganese oxide LiAl _0.1 Ni _0.5 Mn _1.4 O ₄ (D50 is 10 μm) and Li ₃ BO ₃ (D50 is 200nm) are ground and mixed evenly, and then solid phase sintering reaction is carried out under different sintering conditions. The specific conditions are shown in Table 2.

Table 2 embodiment 7～9 and comparative example 4～7 reaction condition parameter list

Take the spinel lithium nickel manganese oxide positive electrode material prepared in Example 1 and LiNi _0.5 Mn _1.5 O ₄ respectively in X'Pert PRO X-ray diffractometer, step scanning, 0.02 degrees/second, each step residence time 1 second, 2θ The X-ray powder diffraction experiment was carried out under the scanning range of 10-80°, and the obtained XRD pattern is shown in Figure 1, and the scanning results of LiBO ₂ and LiMnBO ₃ under the same conditions are also summarized in Figure 1; it can be seen from the figure that the product The XRD pattern contains the same characteristic peaks as Li ₁ Ni _0.5 Mn _1.5 O ₄ , LiBO ₂ and LiMnBO ₃ , so it can be determined that LiBO ₂ and LiMnBO ₃ were formed by solid-state sintering in Example 1;

The scanning electron micrograph of the raw material LiNi _0.5 Mn _1.5 O ₄ is shown in Figure 2 (×50000); the scanning electron micrograph of the lithium battery cathode material prepared in Example 1 is shown in Figure 3 (×30000). Comparing Figure 2 and Figure 3, it can be seen that the spinel lithium nickel manganese oxide cathode material obtained by sintering is uniformly coated with a layer of material, and according to the above XRD pattern, the material of the coating layer is LiBO ₂ and LiMnBO ₃ , which further proves that a uniform coating layer of LiBO ₂ and LiMnBO ₃ can be formed on the surface of the spinel lithium nickel manganese oxide cathode material by the solid-state sintering method.

Using the same XRD diffraction conditions as above, X-ray diffraction analysis was carried out on the sintered products of Examples 1 to 9. As a result, the spinel lithium nickel manganese oxide cathode materials in Examples 1 to 9 all formed a layer of coating on the surface after sintering. Layer; The products obtained in Examples 1-9 and Comparative Examples 1-7 were subjected to X-ray diffraction, and qualitative and quantitative analysis were carried out according to the obtained XRD patterns, and the results were summarized in Table 3.

Among them, the quantitative analysis method is: the ratio of the XRD strongest peak integral area of the cladding layer Li _a B _b O _c and LiMnBO ₃ to the XRD strongest peak integral area of the core layer spinel lithium nickel manganese oxide, the cladding layer accounted for the molar ratio of the nuclear layer, thereby obtaining the mass percentage.

Table 3 The cathode material parameter list that embodiment 1～9 and comparative example 1～7 make

Cycle Stability Test:

The cathode materials for lithium batteries prepared in Examples 1-9 and Comparative Examples 1-7 were used to make full batteries, and the cycle stability test was carried out under the same conditions.

The test method is: at 25°C, charge to 4.9V at a rate of 0.5C (C is the battery capacity), discharge at a rate of 1.0C, and record the capacity retention rate of the battery cell after 200 cycles. The test results are shown in Table 4 shown.

The relationship curves between the number of cycles and the capacity retention rate of the materials in Examples 1-2 and Comparative Example 1 are shown in Figure 4. It can be seen from the figure that the capacity retention of the material decreases with the increase of the number of cycles; the surface-modified spinel lithium nickel manganese oxide positive electrode material prepared by the embodiment of the present application has no The spinel lithium nickel manganese oxide formed with LiBO ₂ /LiMnBO ₃ cladding layer has better cycle stability.

Mn Dissolution Test:

The cathode materials for lithium batteries prepared in Examples 1-9 and Comparative Examples 1-7 were taken to conduct a Mn dissolution test under the same conditions.

The test method is: place the material in the electrolyte (FEC:DMC=3:7), and at the same time make the mass ratio of the spinel lithium nickel manganese oxide to the electrolyte be 1:10, and isolate the air at 25°C Place it for 48 hours, take the supernatant in the electrolyte, use an inductively coupled plasma spectrometer to test the content of the Mn element in the electrolyte, and carry out the Mn dissolution test. The test results obtained are shown in 4. It can be seen that the conditions of this application are used to prepare Lithium battery cathode material, Mn dissolution content is extremely low.

The test result of table 4 embodiment 1～9 and comparative example 1～7 cathode material

It can also be seen from the above table that, compared with the uncoated material, the cycle stability of the material after the coating layer is formed by the surface modification of the present application is improved; the material lithium nickel manganese oxide doped with Al and Mg can effectively improve the cycle stability of the material properties; LiBO ₂ exhibits more excellent performance than LiB ₃ O ₅ ; moreover, too high temperature and too long sintering time will cause the thickness of the cladding layer to be too thick, which will reduce the cycle stability of the material.

At the same time, it was also found during the experiment that too high a ratio of Li _a B _b O _c in the cladding layer would increase the storage and gas production of the positive electrode material, and too high a ratio of LiMnBO ₃ would increase the DC resistance (DCR) of the cell; If the coating is too thin, the effect of improving the material is not obvious; if the coating is too thick, it will increase the polarization of the positive electrode material during charging and discharging.

Although the present application is disclosed as above with preferred embodiments, it is not used to limit the claims. Any person skilled in the art can make some possible changes and modifications without departing from the concept of the present application. Therefore, the present application The scope of protection shall be based on the scope defined by the claims of the present application.

Claims (11)

1. A lithium battery positive electrode material, characterized in that, the lithium battery positive electrode material is a spinel lithium nickel manganese oxide whose surface is coated with a cladding layer, and the cladding layer comprises Li _a B _b O _c and LiMnBO ₃ , wherein a, b, and c are integers, and 1≤a≤4, 1≤b≤7, 2≤c≤12, a+3b=2c; the substance of Li _a B _b O _c and LiMnBO ₃ The amount ratio is 1:0.5~4; The percentage of the cladding layer in the mass of the spinel lithium nickel manganese oxide is greater than zero and less than 3%; The thickness of the cladding layer is 1-10 nm. 2. The lithium battery positive electrode material according to claim 1, wherein the structural formula of the spinel lithium nickel manganese oxide is LiM _x+y Ni _0.5-x Mn _1.5-y O ₄ , wherein M is selected from At least one of Co, Al, Cr, Fe, Mg, Zr or Ti, 0≤x<0.2, 0≤y<0.2. 3. The lithium battery cathode material according to claim 2, wherein 0<x+y<0.2. 4. The lithium battery positive electrode material according to claim 1, wherein the Li _a B _b O _c is specifically LiBO ₂ , LiB ₃ O ₅ , LiB ₅ O ₈ , LiB ₇ O ₁₁ , Li ₂ B ₄ At least one of O ₇ , Li ₃ BO ₃ , Li ₃ B ₅ O ₉ , Li ₃ B ₇ O ₁₂ , Li ₄ B ₂ O ₅ or Li ₄ B ₆ O ₁₁ . 5 . The lithium battery cathode material according to claim 4 , wherein the Li _a B _b O _c is LiBO ₂ . 6. A method for preparing the lithium battery positive electrode material according to any one of claims 1 to 5, comprising the following steps: (1) Evenly mix the spinel lithium nickel manganese oxide raw material with boron source and lithium source; (2) Mixing and sintering in an oxygen-containing atmosphere to obtain the lithium battery cathode material. 7. preparation method according to claim 6, is characterized in that, in described step (1), described boron source is at least one in diboron trioxide, boric acid, lithium borate; Described lithium source is At least one of lithium hydroxide, lithium carbonate, and lithium borate. 8. The preparation method according to claim 7, characterized in that, in the step (1), the median particle diameter D50 of the spinel lithium nickel manganese oxide raw material is 3 μm to 15 μm, and the boron source The median particle diameter D50 of the lithium source is 10 nm to 500 nm, and the median particle diameter D50 of the lithium source is 0.1 μm to 5 μm. 9. preparation method according to claim 7, is characterized in that, the add-on of described boron source is 0.1～10% of the mol number of described spinel lithium nickel manganese oxide raw material; The add-on of described lithium source is 0%-400% of moles of the boron source. 10. The preparation method according to claim 6, wherein the oxygen-containing atmosphere is oxygen or air, and the gas flow rate is 100-5000ml/min; the heating rate of the mixed sintering is 1-10°C/min, Mix and sinter at 400-800°C for 3-8 hours. 11. A lithium battery, comprising a positive pole piece, a negative pole piece, a diaphragm and an electrolyte disposed between the positive pole piece and the negative pole piece at intervals, wherein the positive pole piece contains the 5. Any one of the lithium battery cathode materials.