TWI793893B - Material for anode of lithium-ion battery, method of making the same, and application of the same - Google Patents

Abstract

The present invention provides a material for anodes of lithium-ion batteries, a method of making the material, and an application thereof. The material uses a lithium-rich layered material as a core. By covering a layer of active spinel material (LiCo _aMn _2-aA _bO ₄) over the core to form a shell layer, the core and the shell layer together form a heterostructure of a lithium-rich material for anodes. Whereby, the present invention uses the active spinel material formed on a surface of the lithium-rich layered material in advance to provide three-dimensional channels of spinel phase for lithium ions to pass through, which increases the rate capability. Furthermore, the spinel phase has functions of suppressing structure collapses in materials and stabilizing the layered surface structure of the heterostructure of the lithium-rich material for anodes, whereby to lower the irreversible capacitance. In addition, LiCo _aMn _2-aA _bO ₄is a material of high voltage, of which the withstand voltage is 5.3V, and thereof can also increase the high voltage capacitance of the heterostructure of the lithium-rich material for anodes.

Description

Lithium ion battery positive electrode material and its preparation method and application

The invention relates to the technical field of lithium batteries, in particular to lithium-ion battery anode materials related to lithium-rich layered materials and their preparation methods and applications.

Lithium-ion batteries with high energy density have always been the top priority of researchers at this stage. At the same time, the continuous development of the automotive industry is driving the market demand for high energy density Li-ion batteries. The energy density of lithium-ion batteries is largely limited by the positive electrode material of the battery. Therefore, it is imminent to explore cathode materials for lithium-ion batteries with high energy density. Among them, lithium-rich layered cathode materials have attracted extensive attention due to their high energy density, low cost, environmental protection and good thermal stability, and are considered to be the best choice for the next generation of lithium-ion battery cathode materials. However, the shortcomings of lithium-rich layered cathode materials, including low initial Coulombic efficiency, poor rate performance, severe discharge voltage and capacity fading, hinder their further commercial application.

Specifically, when the voltage is charged to 4.5~4.8V, the Li ₂ MnO ₃ component in the lithium-rich layered material is activated, and lithium ions (Li ⁺ ) are released from Li ₂ MnO ₃ , accompanied by partial oxygen release; During the discharge process, the vacancies left in the bulk phase after the release of Li ₂ O are occupied by surface metal ions, forming an inactive spinel structure, resulting in the inability of lithium ions (Li ⁺ ) to be fully reintercalated into the lattice. Therefore, the activation process of Li ₂ MnO ₃ components in lithium-rich layered materials is the fundamental reason for providing high specific capacity, and it is this process that has caused a series of problems that restrict its further industrial development. In addition, under high voltage, the transition metal ions are easily soluble in the electrolyte, and the electrode surface is easily corroded by the HF generated by the electrolyte, forming an unstable solid electrolyte interface (SEI) film, resulting in an increase in interface impedance and accompanying capacity decay; During the first week of charging, the loss of oxygen causes the transition metal ions to migrate from the surface to the bulk phase to occupy lithium and oxygen vacancies, triggering the reorganization of the surface structure of the material, and an irreversible reaction in which the crystal structure changes from a layered structure to an inactive spinel structure. Lithium ions (Li ⁺ ) migration resistance increases, so that lithium ions (Li ⁺ ) cannot return to the original position, resulting in voltage decay and capacitance decay; in addition, due to the change of the inner and outer layer structure, the internal and external tension of the structure is different, which will eventually result in powder Cracks appear on the surface to break up the powder.

It can be seen from the above that the main problems faced by lithium-rich materials are poor crystal structure stability and many side reactions between the powder surface and the electrolyte, which lead to two major problems of capacitance decay and voltage decay. Therefore, in order to solve the aforementioned problems, it is known that the modification of lithium-rich layered materials through doping, surface coating, material microstructure design, crystal plane regulation and new activation technology can improve the electrochemical performance of lithium-rich layered materials. academic performance.

Among them, compared with the element doping method, surface coating is a more effective method to improve the performance of lithium-rich materials. Surface coating can effectively protect electrode materials, reduce side reactions between materials and electrolytes, and prevent manganese ion dissolution. At the same time, the surface coating can block the release of oxygen to a certain extent, retain lithium and oxygen vacancies, stabilize the layered structure of the material, increase the reversible capacity in the first week, improve cycle performance and suppress voltage decline. Coating materials are divided into electrochemical active substances and inactive substances. The common active substances are lithium-containing oxides or fluorides with redox properties (Li ₃ PO ₄ , Li ₂ O, LiF, AlF ₃ , LiVO ₄ ), Inactive material coating materials mainly include metal oxides. These materials can significantly improve the interface stability of lithium-rich layered materials and improve the cycle performance of materials. Common coating materials mainly include ZrO ₂ , TiO ₂ , and SiO ₂ , Al ₂ O ₃ and other materials.

It is worth noting that recent studies have shown that the surface coating of spinel phase heterostructure can significantly improve the electrochemical performance of lithium-rich materials.

In order to overcome the above-mentioned technical problems, the first object of the present invention is to provide a lithium-ion battery positive electrode material, which uses a lithium-rich layered material as a nucleus, through which the lithium-rich layered material (Li _1+x M _1+y O _2+z ) coated with a layer of active spinel material (LiCo _a Mn _2-a A _b O ₄ ) to form a shell, so that the core body and the shell together form a heterostructure lithium-rich cathode material to Improving the electrochemical performance of Li-rich materials.

In order to achieve the above-mentioned first purpose, the present invention provides a lithium-ion battery positive electrode material, including: a core body, which is a lithium-rich layered material, and its composition is as in formula (1): Li _1+x M _1+y O _2+z , wherein, M is selected from Ni, Co, Mn, Cr, Fe, Al, Mg or combinations thereof, 0.1≦x≦0.9, 0≦y≦0.5, 0≦z≦1; and, the shell layer is coated on The active spinel material on the surface of the core, the composition of the shell is as follows: LiCo _a Mn _2-a A _b O ₄ , wherein A is selected from Ni, Cr, Fe, Al, Mg or F, 0.01<a<1.2, 0.005<b<0.2; make the core and the shell together form a heterostructure lithium-rich cathode material.

The second object of the present invention is to provide a preparation method of the positive electrode material of the lithium ion battery.

In order to achieve the above-mentioned second purpose, the present invention further provides a method for preparing a lithium-ion battery positive electrode material, wherein the steps of the preparation method include: first synthesizing the precursor of the lithium-rich layered material, and then synthesizing the active The precursor of the spinel material is used to nucleate and grow on the surface of the precursor of the lithium-rich layered material, and then mixed with the lithium salt for calcination, so as to form the active spinel material on the surface of the lithium-rich layered material to produce The heterostructure lithium-rich cathode material was obtained.

The third object of the present invention is to provide the positive electrode material of the lithium ion battery in the lithium ion battery Positive application of the pool.

In order to achieve the above-mentioned third purpose, the present invention additionally provides a positive electrode of a lithium ion battery, which includes the positive electrode material of a lithium ion battery as described above, a conductive agent and a binder, wherein the positive electrode material of a lithium ion battery: conductive agent: binder The weight ratio is 5.9~9.9:4~0.1:4~0.1.

The fourth object of the present invention is to provide the application of the positive electrode material of the lithium ion battery in the lithium ion battery.

In order to achieve the above fourth objective, the present invention further provides a lithium ion battery, which comprises the aforementioned positive electrode of the lithium ion battery.

Thus, the present invention utilizes the active spinel structure pre-formed on the surface of the lithium-rich layered material to provide a 3D channel for the spinel phase to facilitate the migration of lithium ions, thereby improving the rate performance, and the spinel phase has an inhibitory material Structural collapse, the function of stabilizing the layered surface structure of heterostructure Li-rich cathode materials, thus reducing the irreversible capacity. In addition, LiCo _a Mn _2-a A _b O ₄ is a high-voltage material with a withstand voltage of 5.3V, so it can also improve the high-voltage capacitance characteristics of heterostructure lithium-rich cathode materials.

Regarding the technology, means and other effects adopted by the present invention to achieve the above-mentioned purpose, preferred feasible embodiments are given and described in detail in conjunction with the drawings as follows.

10: Nucleosome

20: Shell

20a: Thin film shell

20b: Rough shell

Fig. 1 is the coating structure schematic diagram of lithium-ion battery cathode material of the present invention; Fig. 2 is the film-shaped coating structure schematic diagram of lithium-ion battery cathode material of the present invention; Fig. 3 is the rough coating structure of lithium-ion battery cathode material of the present invention Schematic diagram; Fig. 4, Fig. 5, Fig. 6, and Fig. 7 are sequentially shown in the positive electrode material embodiment of the present invention, the surface of the lithium-rich layered material is covered When covering 0wt%, 1wt%, 2.5wt%, 5wt% active spinel material, the voltage-capacity charge-discharge rate performance curve of the electrode to different charge-discharge current densities; Figure 8 is an embodiment of the positive electrode material of the present invention, in AC impedance curves when the surface of the lithium-rich layered material is coated with 0wt%, 1wt%, 2.5wt%, and 5wt% active spinel materials; Figure 9, Figure 10, Figure 11, and Figure 12 are the positive electrode materials of the present invention in sequence In the example, 5000 times magnification (left) and 30000 times magnification (right) of scanning electron microscope (SEM) images of 0wt%, 1wt%, 2.5wt%, 5wt% active spinel materials coated on the surface of lithium-rich layered materials ; Fig. 13, Fig. 14, Fig. 15, and Fig. 16 are sequentially in the positive electrode material embodiment of the present invention, the lithium-rich layered material surface is coated with 0wt%, 1wt%, 2.5wt%, 5wt% active spinel materials. Shot particle size distribution diagram; Figure 17 is an embodiment of the positive electrode material of the present invention, the charge-discharge cycle life curve when the surface of the lithium-rich layered material is coated with 0%, 1%, 2.5%, and 5% active spinel materials; Figure 18 and Figure 19 are sequentially the positive electrode material examples of the present invention, the surface of the lithium-rich layered material is coated with 0wt%, 2.5wt% active spinel material, and the electrode is charged and discharged under the condition of a voltage of 2-4.9V. Current density voltage-capacity charge-discharge rate performance curve; Figure 20 and Figure 21 are sequentially shown in the embodiment of the positive electrode material of the present invention, the surface of the lithium-rich layered material is coated with 0wt%, 2.5wt% active spinel material And under the condition of a voltage of 2-5V, the electrode has a graph of the charge-discharge rate performance curve of the voltage-capacitance of different charge-discharge current densities.

In order to facilitate the understanding of the present invention, the following will be described in conjunction with the examples.

The test methods described in the following examples, unless otherwise specified, are conventional methods; the test and materials, unless otherwise specified, can be obtained from commercial sources.

As shown in FIG. 1 , the lithium-ion battery cathode material of the present invention includes a core 10 made of lithium-rich layered material and a shell 20 coated on the surface of the core 10 and made of active spinel material. Wherein, the composition of the lithium-rich layered material is as the following formula (1), and the composition of the active spinel material is as the following formula (2): Formula (1): Li _1+x M _1+y O _2+z ; Wherein, M is selected from Ni, Co, Mn, Cr, Fe, Al, Mg or combinations thereof; wherein, 0.1≦x≦0.9, 0≦y≦0.5, 0≦z≦1. Preferably, x=0.4, y=0.02, z=0.4.

Specifically, M in formula (1) can be selected from the first single element or a combination of multiple elements. For example, M=the combination of Ni, Co, Mn and Cr, then formula (1) can be expressed as: Li _1.4 Ni _0.2 Co _0.2 Mn _0.6 Cr _0.02 O _2.4 .

Formula (2): LiCo _a Mn _2-a A _b O ₄ ; wherein, A is selected from Ni, Cr, Fe, Al, Mg or F; wherein, 0.01<a<1.2, 0.005<b<0.2. Preferably, a=1, b=0.01.

Specifically, A in formula (2) may be selected from the first single element or a combination of multiple elements. For example, if A=F, then formula (2) can be expressed as: LiCoMnF _0.1 O ₄ ; for another example, if A=Mg, then formula (2) can be expressed as LiCoMnMg _0.01 O ₄ .

In the embodiment of the lithium-ion battery cathode material of the present invention, based on the total weight of the lithium-ion battery cathode material, the lithium-ion battery cathode material includes 99.9 to 90 wt% of the core body 10 and 0.01 to 10 wt% of the shell layer 20. Preferably, the shell layer 20 accounts for 1wt%, 2.5wt%, 5wt% of the total amount of the positive electrode material of the lithium ion battery.

In the embodiment of the positive electrode material for lithium ion battery of the present invention, the working voltage range of the positive electrode material for lithium ion battery is 2.0-5.3V. Preferably, the operating voltage range of the lithium-ion battery cathode material is 2.0-5.0V.

As shown in Fig. 2 and Fig. 3, the shell layer 20 of the positive electrode material of the lithium ion battery of the present invention can be formed in addition It is in the form of a thin film shell 20a as shown in FIG. 2 , or as a rough shell 20b in FIG. 3 . Specifically, in the present invention, depending on the synthesis method, concentration and calcination temperature of the shell, the morphology of the thick-film shell 20, the thin-film shell 20a, and the rough shell 20b can be obtained respectively. These three shell shapes can provide lithium ions with long continuous, short continuous and segmented 3D spinel structures, all of which can improve the performance of lithium ion battery cathode materials.

The preparation method of the lithium-ion battery positive electrode material of the present invention is to first synthesize the precursor of the lithium-rich layered material, and then synthesize the precursor of the active spinel material to nucleate and grow on the lithium-rich layer after drying The surface of the precursor of the layered material is then mixed with lithium salt and calcined to form the active spinel material on the surface of the lithium-rich layered material to obtain the heterostructure lithium-rich positive electrode material.

Wherein, the precursor of the lithium-rich layered material can be synthesized by a method selected from wet chemical method, sol-gel method, hydrothermal method, solid state method, spray granulation method and co-precipitation method.

Wherein, the precursor of the active spinel material is used as a surface coating material, which can be selected from wet chemical method, sol-gel method, hydrothermal method, solid state method, co-precipitation method, atomic layer deposition method, physical vacuum Coating, chemical formula vacuum plating and spray granulation methods are synthesized.

For example, in the embodiment of the lithium-ion battery cathode material manufacturing method of the present invention, the precursor of the lithium-rich layered material can be synthesized by a wet chemical method, and after drying, the active spinel can be synthesized by a wet chemical method again. The precursor of the material enables nucleation and growth on the surface of the precursor of the lithium-rich layered material, and then it is mixed with a lithium salt for calcination to form the active spinel material on the surface of the lithium-rich layered material to obtain the heterogeneous Structural lithium-rich cathode materials.

In the embodiment of the preparation method of the positive electrode material of the lithium ion battery of the present invention, the preparation steps also include, by adjusting the synthesis method, concentration and calcination temperature to control the forming thickness and shape of the active spinel material as shown in Figure 1, Figure 2 or image 3.

Lithium-rich heterostructure obtained by lithium-ion battery positive electrode material and preparation method thereof of the present invention The positive electrode material can also be used as a positive electrode material in the preparation of lithium-ion batteries or their positive electrodes.

In the embodiment in which the heterostructure lithium-rich positive electrode material of the present invention is applied to the positive electrode of a lithium ion battery, the positive electrode includes the positive electrode material of the lithium ion battery of the present invention, a conductive agent and a binder. Preferably, the weight ratio of lithium ion battery cathode material: conductive agent: binder is 5.9-9.9:4-0.1:4-0.1. More preferably, the weight ratio of positive electrode material: conductive agent: binder of the lithium ion battery is 9.0:0.5:0.5 or 9.2:0.4:0.4.

In the positive electrode embodiment of the lithium ion battery of the present invention, preferably, the binder used in the positive electrode of the lithium ion battery is selected from polyvinyl difluoride, styrene butadiene rubber, polyamide, or melamine resin.

In the positive electrode embodiment of the lithium ion battery of the present invention, preferably, the conductive agent used in the positive electrode of the lithium ion battery is selected from carbon powder, graphite, hard carbon, soft carbon, carbon fiber, carbon nanotubes, acetylene black, or the above-mentioned combination.

In the positive electrode embodiment of the lithium ion battery of the present invention, the preparation method steps of the positive electrode of the lithium ion battery include: dissolving the positive electrode material of the lithium ion battery of the present invention, an optional binder and an optional conductive agent in a solvent, mixing A slurry is formed, the slurry is coated on an aluminum foil, dried, and the pressed sheet is taken out to obtain the positive electrode of the lithium ion battery.

Wherein, the solvent is N-methylpyrrolidone (NMP).

Wherein, the preparation method of the positive electrode of the lithium ion battery is to dry in an oven, the operating condition is 120-180° C., and vacuum drying for 2-8 hours.

In the embodiment in which the heterostructure lithium-rich positive electrode material of the present invention is applied to a lithium ion battery, the lithium ion battery includes the positive electrode of the aforementioned lithium ion battery.

Wherein, the lithium-ion battery also includes a negative electrode, an electrolyte solution and a separator interposed between the positive and negative electrodes.

Wherein, the negative pole is graphite negative pole, lithium titania, silicon carbon negative pole or lithium sheet.

The above describes the lithium ion battery positive electrode material of the present invention and its preparation method and application. Please refer to Figures 4 to 21 and Tables 1 to 3 below to illustrate the electrochemical performance of the lithium ion battery positive electrode material of the present invention.

As shown in Fig. 4, Fig. 5, Fig. 6, Fig. 7 and Table 1, the charge and discharge rate performance (C-rate) of the lithium ion battery cathode material of the present invention is shown. In the embodiment shown in Figure 4 to Figure 7 and Table 1, the battery is first activated with a voltage range of 0.1C/0.1D of 2-4.8V, and then activated at a voltage range of 2~4.6V with 0.1C/0.1D, 0.2 C/0.2D, 0.2C/0.2D, 0.2C/0.5D, 0.2C/1D, 0.2C/2D, 0.2C/3D, 0.2C/4D, 0.2C/5D for charge and discharge test.

Among them, Fig. 4, Fig. 5, Fig. 6, and Fig. 7 sequentially provide the electrode pair when the surface of the lithium-rich layered material is coated with 0wt%, 1wt%, 2.5wt% and 5wt% of the active spinel material. Charge-discharge rate performance curves of voltage-capacity at different charge-discharge current densities.

Among them, Table 1 provides the voltage-capacitance of the electrode for different charge and discharge current densities when the surface of the lithium-rich layered material is coated with 0wt%, 1wt%, 2.5wt% and 5wt% of the active spinel material. Charge and discharge rate data.

From the results in Figure 4-Figure 7 and Table 1, it can be seen that the positive electrode material (lithium rich Layered material surface coated with 1wt%, 2.5wt%, 5wt% active spinel material heterostructure lithium-rich cathode material) and unmodified cathode material (lithium-rich layered material surface without coating (0wt%) active Compared with the positive electrode material of spinel material), when the discharge rate is from low rate to 2D, the charge-discharge rate (C-rate) of the surface modified positive electrode material of the present invention increases compared with the unmodified positive electrode material. When the rate is 5D, the positive electrode material (heterostructure lithium-rich positive electrode material) coated with 2.5wt% active spinel material has the best performance.

As shown in Figure 8, the AC impedance test (AC Impedance) of the positive electrode material of the lithium ion battery of the present invention is shown sequentially from bottom to top; Lithium-rich cathode materials with heterostructures of spar materials. After the battery is activated with 0.1C/0.1D voltage range 2-4.8V, then with 0.1C/0.1D, 0.2C/0.2D, 0.2C/0.2D, 0.2C/0.5D, 0.2C/1D, 0.2 C/2D, 0.2C/3D, 0.2C/4D, 0.2C/5D voltage range 2~4.6V charge and discharge, charge the voltage to 4.2V for testing. The test condition is that the amplitude is 0.001V, and the frequency range is 100000Hz~0.001Hz for scanning.

It can be seen from Figure 8 that all four groups of samples have similar patterns, including two semicircles in the high frequency area and a slanted line in the low frequency area. The first semicircle in the high frequency area includes the internal impedance R _s of the battery itself and the SEI film. The diffusion impedance R _f of Li ⁺ , the second semicircle is the charge transfer impedance R _ct , and the oblique line in the low frequency region is the Warburg impedance, which is related to the diffusion of Li + in the electrode. From Figure 8, it can be found that the material before modification (0wt%) has the largest charge transfer resistance R _ct , and the R _ct of the modified material is smaller than that before modification, and the value of 2.5wt% is the smallest. The corresponding 2.5wt% modified material has better electrochemical properties.

Fig. 9, Fig. 10, Fig. 11 and Fig. 12 show the SEM images of the lithium ion battery cathode material of the present invention. From Figure 9 to Figure 12, it can be seen that the primary particle size of the unmodified positive electrode material (lithium-rich layered material with 0wt% active spinel material on the surface) is about 70nm, after modification, the surface is covered with active spinel The heterostructure lithium-rich cathode material coated with spar material has a surface primary particle size of about 100-200nm.

Fig. 13, Fig. 14, Fig. 15 and Fig. 16 show the laser particle size distribution diagram of the positive electrode material of the lithium ion battery of the present invention, which is measured by a laser particle size analyzer. From Figure 13 to Figure 16, it can be seen that the secondary particle size of the active spinel material coated on the surface of the positive electrode material with 0wt%, 1wt%, 2.5wt% and 5wt% increases with the increase of the coating concentration, respectively 7.26 μm, 8.38 μm, 8.68 μm, 8.97 μm.

As shown in FIG. 17 , it shows the charge-discharge cycle life test of the lithium-ion battery cathode material of the present invention. It can be seen from Figure 17 that the positive electrode materials coated with 0wt%, 1wt%, 2.5wt% and 5wt% active spinel materials were tested for cycle life at a charge rate of 0.2C and a discharge rate of 0.5C at a voltage range of 2-4.6V After 95 laps, the discharge capacity retention rates were 75.5%, 91.8%, 84.2%, and 85.8%, respectively. Coating the active spinel material can effectively improve the cycle life.

As shown in Fig. 18, Fig. 19 and Table 2, the high voltage range (2-4.9V) discharge capacity test of the positive electrode material of the lithium ion battery of the present invention is shown. In the embodiment shown in Figure 18 to Figure 19 and Table 2, the battery is set at 0.1C/0.1D, 0.2C/0.2D, 0.2C/0.5D, 0.2C/1D, 0.2C in the voltage range of 2~4.9V /2D, 0.2C/3D, 0.2C/4D, 0.2C/5D for charge and discharge test.

Figure 18 and Figure 19 sequentially provide the present invention when the surface of the lithium-rich layered material is coated with 0wt% and 2.5wt% active spinel materials, and the electrode is under the condition of a high voltage range of 2-4.9V. The discharge current density voltage-capacity charge-discharge rate performance curve.

Table 2 provides the present invention coating 0wt% and 2.5wt% activity on the surface of lithium-rich layered material When using a permanent spinel material, the electrode is charged and discharged at a high voltage range of 2-4.9V, and the voltage-capacity charge and discharge rate data of different charge and discharge current densities.

From the results in Figure 18, Figure 19 and Table 2, it can be seen that under the condition of charge and discharge voltage of 2-4.9V, the positive electrode material (lithium-rich layered material surface coated with 2.5wt % active spinel material heterogeneous structure lithium-rich positive electrode material) compared with unmodified positive electrode material (lithium-rich layered material surface without coating (0wt%) active spinel material positive electrode material), the present invention improves The charge and discharge performance of the positive electrode material coated with active spinel is higher than that of the unmodified positive electrode material.

As shown in Fig. 20, Fig. 21 and Table 3, it shows the high voltage range (2-5V) discharge capacity test of the positive electrode material of the lithium ion battery of the present invention. In the embodiment shown in Figure 20 to Figure 21 and Table 3, the battery is set at 0.1C/0.1D, 0.2C/0.2D, 0.2C/0.5D, 0.2C/1D, 0.2C/ 2D, 0.2C/3D, 0.2C/4D, 0.2C/5D for charge and discharge test.

Figure 20 and Figure 21 sequentially provide the present invention to coat 0wt% and When the active spinel material is 2.5wt%, the electrode is in the high voltage range of 2-5V, and the voltage-capacity charge-discharge rate performance curve for different charge-discharge current densities.

Table 3 provides the present invention when the surface of the lithium-rich layered material is coated with 0wt% and 2.5wt% active spinel materials, and the voltage of the electrode for different charge and discharge current densities under the condition of a high voltage range of 2-5V- Capacitance charge and discharge rate data.

From the results in Figure 20, Figure 21 and Table 3, it can be seen that under the condition of charge and discharge voltage of 2-5V, the positive electrode material with modified surface coated active spinel (lithium-rich layered material surface coated with 2.5wt% The heterogeneous structure lithium-rich positive electrode material of active spinel material) is compared with the unmodified positive electrode material (the positive electrode material of the lithium-rich layered material surface without coating (0wt%) active spinel material), the present invention modified The charge and discharge performance of the positive electrode material coated with active spinel is higher than that of the unmodified positive electrode material.

In summary, the present invention is formed by coating an active spinel material (LiCo _a Mn _2-a A _b O ₄ ) on the surface of a lithium-rich layered material (Li _1+x M _1+y O _2+z ). Lithium-ion battery cathode material (heterostructure lithium-rich cathode material), after charge and discharge, because the surface spinel phase can provide 3D channels to facilitate lithium ion migration, so the rate performance can be improved, and the spinel phase has an inhibitory material Structural collapse, the function of stabilizing the layered surface structure of heterostructure Li-rich cathode materials, thus reducing the irreversible capacity. In addition, the charge and discharge rate performance of the positive electrode material of the lithium ion battery of the present invention is the performance of charging and discharging at 2-4.6V after activation at the normal charging and discharging voltage condition of 2-4.8V, and when the charging and discharging voltage is increased to 4.9V and 5V Compared with the performance of the unmodified lithium-ion battery positive electrode material, the performance is more excellent; at the same time, the charge-discharge cycle life of the lithium-ion battery positive electrode material of the present invention is also better than that before the unmodified one.

10: Nucleosome

20: Shell

Claims (8)

A lithium-ion battery cathode material, comprising: a nucleus, which is a lithium-rich layered material, and its composition is as in formula (1): Li _1+x M _1+y O _2+z , wherein M is selected from Ni, Co, Mn , Cr, Fe, Al, Mg or a combination thereof, 0.1≦x≦0.9, 0≦y≦0.5, 0≦z≦1; and the shell layer is an active spinel material coated on the surface of the core body, the The composition of the shell is as formula (2): LiCo _a Mn _2a A _b O ₄ , wherein, A is selected from Cr, Fe, Al, Mg or F, 0.01<a<1.2, 0.005<b<0.2; make the core Together with the shell layer, a heterostructure lithium-rich positive electrode material is formed. The lithium ion battery positive electrode material according to claim 1, wherein, based on the total weight of the lithium ion battery positive electrode material, the lithium ion battery positive electrode material includes 99.99 to 90wt% of the core and 0.01 to 10wt% of the shell. The cathode material for lithium-ion batteries as described in Claim 1, wherein the operating voltage range of the cathode material for lithium-ion batteries is 2-5V. A method for preparing the positive electrode material of a lithium ion battery as described in any one of claims 1 to 3, wherein the steps of the method include: first synthesizing the precursor of the lithium-rich layered material, and then synthesizing the The precursor of the active spinel material enables nucleation and growth on the surface of the precursor of the lithium-rich layered material, followed by mixing with lithium salt and calcining to form the active spinel material on the surface of the lithium-rich layered material, The heterostructure lithium-rich positive electrode material is prepared. The preparation method of lithium-ion battery cathode material as described in claim 4, wherein, the precursor of this lithium-rich layered material is selected from wet chemical method, sol-gel method, hydrothermal method, solid state method, spray granulation method and co-precipitation method; the precursor of the active spinel material is selected from wet chemical method, sol-gel method, hydrothermal method, solid state method, co-precipitation method, atomic layer deposition method, physical vacuum coating , Chemical formula vacuum plating and spray granulation method synthesis. The manufacturing method of the lithium-ion battery cathode material according to claim 4, wherein the method step further includes controlling the forming thickness and shape of the active spinel material by adjusting the synthesis method, concentration and calcination temperature. A lithium-ion battery positive electrode, comprising the lithium-ion battery positive electrode material and a conductive agent and a binder as described in any one of claim items 1 to 3, wherein the lithium-ion battery positive electrode material: conductive agent: the weight ratio of the binder is 5.9~9.9: 4~0.1: 4~0.1; the binder is selected from polyvinyl difluoride, styrene butadiene rubber, polyamide, or melamine resin; the conductive agent is selected from carbon powder, graphite, hard carbon , soft carbon, carbon fiber, carbon nanotubes, acetylene black, or a combination of the above. A lithium ion battery, which comprises the positive electrode of the lithium ion battery as described in Claim 7.

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