WO2019080237A1 - High safety coated high nickel ternary positive electrode material, positive electrode, and lithium ion battery - Google Patents

Abstract

A high safety coated high nickel ternary positive electrode material, comprising: a high nickel ternary positive electrode material and a coating layer coating the surface of the high nickel ternary positive electrode material, the coating layer being made of the following raw materials according to mass percentage: 1%-95% inorganic flame retardant; 1%-95% inorganic phase change material; and 1%-20% high thermal conductivity inorganic material.

Description

High-safety coated high-nickel ternary cathode material, positive electrode piece and lithium ion battery

This application is required to be submitted to the Chinese Patent Office on October 24, 2017, the application number is 201711000595.0, and the Chinese name of the invention is “a high-safe coated high-nickel ternary positive electrode material, positive electrode piece and lithium ion battery”. The priority of the application, the entire contents of which is incorporated herein by reference.

Technical field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-safe coated high-nickel ternary cathode material, a positive electrode pole piece and a lithium ion battery.

Background technique

Lithium-ion batteries have the advantages of high energy density and cycle efficiency, low self-discharge, and no memory effect, and have broad application prospects in power batteries. At present, many automobile manufacturers have chosen lithium-ion batteries as the power source for electric vehicles, and launched their own brand-type electric vehicles. As a kind of transportation vehicle, electric vehicle mileage, acceleration performance, safety performance, etc. are the focus of attention, and these aspects mainly depend on the performance of the power battery, focusing on energy density, power density, cycle life, safety, etc. aspect. Among them, the development of new electrode materials, especially cathode materials, is crucial for the energy density, cycle life and safety of power batteries.

From the perspective of battery energy density and electric vehicle cruising range, the ternary system containing nickel (Ni) has obvious advantages, especially the high nickel ternary nickel-cobalt lithium aluminate/nickel-cobalt-manganate material has a broad power battery. Application prospects. The high-nickel ternary cathode material combined with the silicon-carbon anode in Tesla battery technology has an energy density of 300Wh/kg, which represents the latest development of high-energy density batteries. Therefore, high-nickel ternary materials have good applications in the field of electric vehicles. prospect. High nickel ternary has the advantages of high specific capacity (half-cell capacity ≥190mAh/g), abundant raw material source and good low-temperature performance. It is considered to be one of the most promising cathode materials for power lithium-ion batteries. However, there are still some problems, including: 1) the amount of surface Li eluted during charging is larger, resulting in structural instability, resulting in a non-electrochemically active NiO phase with rock salt structure; 2) due to higher Ni content, thermal decomposition temperature is reduced, The heat release is increased, the thermal stability of the material is low; 3) the compatibility with the electrolyte is deteriorated, and it is easy to react with the electrolyte, causing the dissolution of Co and Ni ions, resulting in a decrease in cycle life and storage life. The above problems cause the cycle performance and safety performance of the lithium ion battery to deteriorate. In particular, safety performance is a key prerequisite for the high-nickel ternary cathode material to be widely used in the power supply field.

Therefore, the surface coating modification and the surface coating of the pole piece become one of the effective means to improve the safety performance of the high-nickel ternary positive electrode material and the pole piece.

At present, the NCA surface coating material generally includes oxides such as Al ₂ O ₃ , TiO ₂ , ZrO _{2 ,} etc., or Li ₃ PO ₄ , Mn ₃ (PO ₄ ) ₂ , LiCoO _{2 ,} etc., such as a high-performance ternary of the patent CN103151513B. A power battery and a preparation method thereof, which disclose a ternary material in which a positive electrode active material is lithium nickel cobalt manganese oxide coated with Al ₂ O ₃ , and the coating method contributes to improving safety performance of a ternary battery, but the effect is relatively limited.

Patent CN103059613A is a lithium ion battery safety coating and a preparation method thereof. The material used for the lithium ion battery safety coating is aluminum hydroxide, calcium hydroxide, zirconium hydroxide, titanium hydroxide, aluminum hydroxide, magnesium hydroxide. a mixture of one or more of calcium carbonate, magnesium carbonate, calcium hydrogencarbonate and magnesium hydrogencarbonate. In addition to the heat-insulating insulation, the coating material has thermal decomposition endotherm, crystal structure change or powdering and release of water. Or the function of carbon dioxide. However, the decomposition temperature of these hydroxides and carbonates is relatively high, generally above 300 ° C, and for high nickel ternary materials, the critical temperature is around 230 ° C (closely related to nickel content), and heat is exceeded above this temperature. Loss of control occurs rapidly, so the heat absorption of the above materials is very limited, and the safety performance of materials and batteries cannot be effectively improved.

Patent CN106450435A is a ternary lithium ion battery and a preparation method thereof. The slurry is prepared by using an inorganic flame retardant material and coated on the surface of the positive electrode to form a coating. The inorganic flame retardant material is disclosed as red phosphorus, telluride and boride. One of aluminide, ammonium phosphate, and ammonium polyphosphate. The patent mainly considers the protective effect of the coating formed by the flame retardant material on the ternary material, and does not modify the material itself, and the coating formed by the flame retardant material alone has a good safety protection effect, and it is necessary to greatly Improve the DC internal resistance of the battery, without using the comprehensive performance improvement of the battery.

Therefore, there is still a need to find a means of modification that ensures a battery with higher safety performance while maintaining good electrical performance.

Summary of the invention

In view of this, the technical problem to be solved by the present invention is to provide a high-safety coated high-nickel ternary positive electrode material, a positive electrode pole piece and a lithium ion battery, and the lithium ion battery prepared by the positive electrode material provided by the invention has high Safety performance while maintaining good electrical performance.

The invention provides a high-safe coated high-nickel ternary cathode material, comprising: a high-nickel ternary cathode material and a coating layer coated on the surface of the high-nickel ternary cathode material, the coating layer Prepared from raw materials including the following mass percentages:

1% to 95% inorganic flame retardant;

1% to 95% inorganic phase change material;

1% to 20% of high thermal conductivity inorganic materials.

Preferably, the inorganic flame retardant is selected from one or more of the group consisting of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, cerium oxide, zinc borate, and an inorganic compound containing molybdenum.

Preferably, the inorganic phase change material is selected from one or more of a mixture or a composite of one or more of AlCl ₃ , LiNO ₃ , NaNO ₃ , KNO ₃ and NaNO ₂ and a molten salt compound. .

Preferably, the molten salt-based compound is selected from Na ₂ SO _4, LiNO ₃ -KCl one or more, and in LiNO ₃ -NaCl.

Preferably, the highly thermally conductive inorganic material is selected from one or more of graphite, graphene, carbon nanotubes, and aluminum nitride.

Preferably, the mass ratio of the high nickel ternary positive electrode material to the coating layer is (5 to 100):1.

Preferably, the high nickel ternary positive electrode material is selected from the group consisting of lithium nickel cobalt manganese oxide and/or lithium nickel cobalt aluminate.

The invention also provides a preparation method of the above high-safe coated high-nickel ternary positive electrode material, comprising the following steps:

The high-nickel ternary positive electrode material, the inorganic flame retardant, the inorganic phase change material and the high thermal conductive inorganic material are ball-milled under a dew point of less than -30 ° C to obtain a coated high-nickel ternary positive electrode material;

or,

The high-nickel ternary positive electrode material, the inorganic flame retardant, the inorganic phase change material and the high thermal conductive inorganic material are placed in a powder coating device under the condition of a dew point of less than -30 ° C for powder coating, and then subjected to demagnetization treatment. A coated high nickel ternary positive electrode material is obtained.

The invention also provides a high-safe coated high-nickel ternary positive electrode sheet, comprising a positive electrode layer formed of a high-nickel ternary positive electrode material, and a coating layer coated on the surface of the positive electrode layer, the package The coating is prepared from raw materials that include the following mass percentages:

1% to 95% inorganic flame retardant;

1% to 95% inorganic phase change material;

1% to 20% of high thermal conductivity inorganic materials.

The present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator, an electrolyte and a casing, the positive electrode being high in the above-mentioned high-safe coated high-nickel ternary positive electrode material or the above-mentioned high-safe coating type Nickel ternary positive electrode sheets are prepared.

Compared with the prior art, the present invention provides a high-safe coated high-nickel ternary positive electrode material, comprising: a high-nickel ternary positive electrode material and a coating coated on the surface of the high-nickel ternary positive electrode material. a layer, the coating layer is prepared from the following mass percentage of raw materials: 1% to 95% inorganic flame retardant; 1% to 95% inorganic phase change material; 1% to 20% high thermal conductivity inorganic material .

The invention uses a highly stable inorganic material having a flame retarding effect and an inorganic phase change material having an endothermic effect, and a mixture of a certain amount of a highly thermally conductive inorganic material is added as a coating layer of the high nickel ternary positive electrode material. The highly thermally conductive inorganic material can rapidly transfer the heat generated by the local thermal runaway to increase the cooling rate; at the same time, the part of the heat is absorbed by the inorganic phase change material, and a phase change occurs, which reduces or inhibits the temperature rise of the material; under extreme conditions, Local thermal runaway can cause Mars, etc. The inorganic flame retardant material in the surface coating of the positive electrode material particles or the surface coating of the positive electrode piece can suppress the flame spread and prevent the thermal runaway of the battery. The organic combination of the three materials can avoid thermal runaway caused by local abuse, but disperse heat transfer, rapidly cool the material, and absorb heat in the form of phase change. Further, the flame retardant material will inhibit the flame spread, thereby avoiding extremes. The occurrence of thermal runaway. Therefore, the lithium ion battery fabricated using the positive electrode material of the present invention has excellent safety performance. At the same time, the coating formed by the three materials does not adversely affect the electrical properties of the positive electrode material. The lithium ion battery prepared by using the positive electrode material has good safety performance and good electrical properties.

DRAWINGS

1 is a scanning electron micrograph of coated nickel cobalt cobalt manganate prepared in Example 1;

2 is a scanning electron micrograph of the coated nickel cobalt cobalt aluminate prepared in Example 2;

3 is a discharge curve of a battery prepared by preparing a positive electrode material prepared in Example 1.

Detailed ways

The invention provides a high-safe coated high-nickel ternary cathode material, comprising: a high-nickel ternary cathode material and a coating layer coated on the surface of the high-nickel ternary cathode material, the coating layer Prepared from raw materials including the following mass percentages:

1% to 95% inorganic flame retardant;

1% to 95% inorganic phase change material;

1% to 20% of high thermal conductivity inorganic materials.

The high-safe coated high-nickel ternary cathode material provided by the invention comprises a high-nickel ternary cathode material. Wherein, the high nickel ternary positive electrode material is selected from the group consisting of lithium nickel cobalt manganese oxide and/or lithium nickel cobalt aluminate. The high nickel ternary positive electrode material has a Ni content of ≥ 50%. In the present invention, the high nickel ternary positive electrode material is a nano- or micro-scale particle.

The high-safe coated high-nickel ternary positive electrode material provided by the present invention further comprises a coating layer coated on the surface of the high-nickel ternary positive electrode material.

The coating layer is prepared from a raw material comprising the following mass percentages:

1% to 95% inorganic flame retardant;

1% to 95% inorganic phase change material;

1% to 20% of high thermal conductivity inorganic materials.

The raw material for the preparation of the coating layer comprises from 1% to 95% of an inorganic flame retardant, preferably from 5% to 90%, more preferably from 20% to 60%, still more preferably from 30% to 50%. In the present invention, the inorganic flame retardant has an endothermic and flame retardant effect at 150 to 500 ° C, and is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, cerium oxide, zinc borate, and inorganic containing molybdenum. One or more of the compounds.

The raw material for the preparation of the coating layer further comprises from 1% to 95% of the inorganic phase change material, preferably from 5% to 90%, more preferably from 20% to 60%, still more preferably from 30% to 50%. In the present invention, the inorganic phase change material has a phase transition temperature ranging from 80 to 400 ° C, and an endothermic reaction occurs, and the species is selected from the group consisting of AlCl ₃ , LiNO ₃ , NaNO ₃ , KNO _{3 ,} and NaNO ₂ . Or one or more of a plurality of formed mixtures or complexes and molten salt compounds. Wherein said compound is selected from molten salts Na ₂ SO _4, LiNO ₃ -KCl one or more, and in LiNO ₃ -NaCl.

The preparation material of the coating layer further comprises 1% to 20% of a highly thermally conductive inorganic material, preferably 5% to 15%, more preferably 8% to 12%. The high thermal conductivity inorganic material has a thermal conductivity of ≥ 20 W/(m·K) selected from one or more of graphite, graphene, carbon nanotubes, and aluminum nitride.

In the present invention, the thickness of the coating layer of the high-safe coated high-nickel ternary positive electrode material is preferably 10 nm to 1 μm, more preferably 100 nm to 800 nm, further preferably 300 nm to 500 nm; The mass ratio of the positive electrode material to the coating layer is (5 to 100):1; preferably (10 to 80):1, more preferably (30 to 60):1.

The invention also provides a preparation method of the above high-safe coated high-nickel ternary positive electrode material, comprising the following steps:

High nickel ternary cathode material, inorganic flame retardant, inorganic phase change material and high thermal conductivity inorganic material Ball milling is performed under a condition that the dew point is less than -30 ° C to obtain a coated high nickel ternary positive electrode material;

Wherein, the ball mill tank and the ball mill beads are preferably ceramics, and the rotation speed of the ball mill is preferably 100 to 400 r/min, more preferably 200 to 300 r/min, and the ball milling time is preferably 1 to 5 h, more preferably 2 to 4h.

or,

The high-nickel ternary positive electrode material, the inorganic flame retardant, the inorganic phase change material and the high thermal conductive inorganic material are placed in a powder coating device under the condition of a dew point of less than -30 ° C for powder coating, and then subjected to demagnetization treatment. A coated high nickel ternary positive electrode material is obtained.

The present invention also provides a high-safe coated high-nickel ternary positive electrode sheet comprising a positive electrode layer formed of a high-nickel ternary positive electrode material, and a coating layer coated on the surface of the positive electrode layer.

The high-safe coated high-nickel ternary positive electrode sheet provided by the invention comprises a positive electrode layer formed of a high-nickel ternary positive electrode material selected from lithium nickel cobalt manganese oxide and/or nickel cobalt Lithium aluminate. The high nickel ternary positive electrode material has a Ni content of ≥ 50%. In the present invention, the high nickel ternary positive electrode material is a nano- or micro-scale particle. The preparation method of the positive electrode layer of the present invention is not particularly limited, and a preparation method known to those skilled in the art may be used.

The high-safety coated high-nickel ternary positive electrode tab provided by the present invention comprises a coating layer coated on the surface of the positive electrode layer, and the coating layer is prepared from a raw material comprising the following mass percentages:

1% to 95% inorganic flame retardant;

1% to 95% inorganic phase change material;

1% to 20% of high thermal conductivity inorganic materials.

The amount and specific type of the raw material for preparing the coating layer are the same as those of the preparation material of the coating layer in the high-safe coated high-nickel ternary positive electrode material, and the specific types thereof are not described herein.

The preparation method of the coating layer of the present invention is not particularly limited, and a preparation method known to those skilled in the art may be used. Preferably, the "coated high-nickel ternary positive electrode material" prepared as described above is used as a raw material to directly prepare a positive electrode tab.

The present invention also provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator, an electrolyte and a casing, the positive electrode being high in the above-mentioned high-safe coated high-nickel ternary positive electrode material or the above-mentioned high-safe coating type Nickel ternary positive electrode sheets are prepared.

The invention has a high-stability inorganic material with flame retardant effect and an inorganic phase change material with endothermic effect A mixture of a certain amount of a highly thermally conductive inorganic material is added as a coating for the high nickel ternary positive electrode material. The highly thermally conductive inorganic material can rapidly transfer the heat generated by the local thermal runaway to increase the cooling rate; at the same time, the part of the heat is absorbed by the inorganic phase change material, and a phase change occurs, which reduces or inhibits the temperature rise of the material; under extreme conditions, Local thermal runaway can cause Mars, etc. The inorganic flame retardant material in the surface coating of the positive electrode material particles or the surface coating of the positive electrode piece can suppress the flame spread and prevent the thermal runaway of the battery. The organic combination of the three materials can avoid thermal runaway caused by local abuse, but disperse heat transfer, rapidly cool the material, and absorb heat in the form of phase change. Further, the flame retardant material will inhibit the flame spread, thereby avoiding extremes. The occurrence of thermal runaway. Therefore, the lithium ion battery fabricated using the positive electrode material of the present invention has excellent safety performance. At the same time, the coating formed by the three materials does not adversely affect the electrical properties of the positive electrode material. The lithium ion battery prepared by using the positive electrode material has good safety performance and good electrical properties.

In order to further understand the present invention, the high-safe coated high-nickel ternary positive electrode material, positive electrode tab, and lithium ion battery provided by the present invention will be described below with reference to the embodiments, and the scope of the present invention is not limited by the following examples.

Example 1

Commercially available lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm), carbon nanotube powder (tube diameter about 10 nm, length 4-10 μm), LiNO ₃ -NaCl powder, Magnesium hydroxide nanopowder (D50 about 30 nm), mass ratio: 95:1:3:1.

9.5 Kg of nickel cobalt cobalt manganate powder, 100 g of carbon nanotube powder, 300 g of LiNO ₃ -NaCl powder, 100 g of magnesium hydroxide nanopowder, mixed in an environment having a dew point of less than -30 ° C, and then added to a dry ball mill The cans (ball mill jars and ball beads are ceramics), rotating at 200 r/min, ball milling for 2 h, and then coated lithium nickel cobalt manganate.

The coated nickel-cobalt-manganese oxide was subjected to electron microscopy, and the results are shown in FIG. 1. FIG. 1 is a scanning electron micrograph of the coated nickel-cobalt-manganate prepared in Example 1. As can be seen from Fig. 1, a lithium nickel cobalt manganate cathode material having a uniform surface coating was obtained.

Example 2

Commercially available nickel-cobalt lithium aluminate (Ni: Co: Al = 8.1: 1.5: 0.4, D50 about 6 μm), graphene (sheet thickness about 2 nm), LiNO _{3 -} KCl powder, yttrium oxide nano powder (D50 About 50 nm), the mass ratio is 96:0.5:2:1.5.

9.6Kg of nickel cobalt cobalt aluminate powder, 50g of graphene powder, 200g of LiNO ₃ -KCl powder, 150g of cerium oxide nanopowder, mixed in an environment with a dew point of less than -30 ° C, and then added to the powder coating equipment The powder coating is realized under the action of air flow and mechanical action, and then subjected to demagnetization treatment to obtain coated nickel cobalt cobalt aluminate.

The coated nickel cobalt cobalt aluminate was subjected to electron microscopy, and the results are shown in FIG. 2. FIG. 2 is a scanning electron micrograph of the coated nickel cobalt cobalt aluminate prepared in Example 2. As can be seen from Fig. 2, a lithium nickel cobalt aluminate cathode material having a uniform surface coating was obtained.

Example 3

Commercially available lithium nickel cobalt manganese oxide (Ni: Co: Mn = 7: 1.5: 1.5, D50 about 9 μm), carbon nanotube oil-based slurry (tube diameter about 10 nm, length 4-10 μm), LiNO ₃ /Na ₂ SO ₄ powder mixture (mass ratio 1:1), zinc borate powder (D50 about 100 nm), mass ratio: 95:1.5:2.5:1.

9.5Kg lithium nickel cobalt manganese oxide particles, 3Kg carbon nanotube oil slurry (CNT solid content 5wt%), 250g LiNO ₃ /Na ₂ SO ₄ powder mixture, 100g zinc borate powder, less than -30 ° C dew point Mix in the environment, add 2Kg ethanol to dilute, then add dry ball mill jar (ball mill jar and ball mill beads are ceramic), rotation speed 300r / min, ball milling 1.5h, 60 ° C drying for 12h, then get coated nickel cobalt manganese acid lithium.

Example 4

Commercially available nickel-cobalt lithium aluminate (Ni: Co: Al = 8.7: 1.2: 0.1, D50 about 12 μm), conductive carbon black (D50 about 40 nm), NaNO ₂ powder, aluminum hydroxide nano powder (D50 about 25 nm ), the mass ratio is: 90:2:5:3.

9Kg of nickel-cobalt-manganese oxide powder, 200g of conductive carbon black powder, 500g of NaNO ₂ powder, 300g of aluminum hydroxide nano-powder, mixed in an environment with a dew point of less than -30 ° C, and then added to a dry ball mill (ball mill) Both the can and the ball beads are ceramic), the rotation speed is 300r/min, and the ball is milled for 2.5 hours, and then the coated nickel-cobalt-manganese oxide is obtained.

Using the coated nickel-cobalt-manganese hydride prepared in Examples 1 to 4 as a positive electrode material, a conductive carbon black, a PVDF rubber, a slurry, and a coating were prepared at a ratio of 95:2:3 to prepare a positive electrode tab. Graphite is used as a negative electrode material, and is prepared by using a conventional electrolyte (containing solvent EC: EMC: DEC=3:5:2 (wt%), 1 mol/L LiPF ₆ , and 2% VC as an additive) and a conventional separator (PE). Lithium-ion soft pack battery with a capacity of 24Ah.

Comparative example 1

Using commercially available nickel-cobalt lithium aluminate (Ni: Co: Al = 8.1: 1.5: 0.4, D50 about 6 μm) as a positive electrode material, Other materials and preparation methods are the same as above, and a lithium ion soft pack battery is prepared with a capacity of 24 Ah.

Comparative example 2

A commercially available lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm) was used as a positive electrode material, and other materials and preparation methods were the same as above, and a lithium ion soft pack battery was prepared with a capacity of 24 Ah.

Comparative example 3

A nickel cobalt cobalt manganate (Ni: Co: Mn = 8:1:1, D50 of about 11 μm), a carbon nanotube powder (having a diameter of about 10 nm, a length of 4 to 10 μm), and a mass ratio of 95:1 were used.

9.5Kg of nickel-cobalt-manganese oxide powder and 100g of carbon nanotube powder are mixed in an environment with a dew point of less than -30 ° C, and then added to a dry ball mill tank (both ball mill and ball mill beads are ceramic) at a speed of 200 r/min. , ball milling for 2h, and then obtained coated lithium nickel cobalt manganese oxide;

Comparative example 4

Lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm) and LiNO ₃ -NaCl powder were used, and the mass ratio was 95:3.

9.5Kg of nickel-cobalt-manganese oxide powder and 300g of LiNO ₃ -NaCl powder are mixed in an environment with a dew point of less than -30 ° C, and then added to a dry ball mill tank (both ball mill and ball mill beads are ceramic) at a speed of 200 r / Min, ball milling for 2h, and then obtained coated lithium nickel cobalt manganese oxide;

Comparative example 5

Lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm) and magnesium hydroxide nanopowder (D50 about 30 nm) were used, and the mass ratio was 95:1.

9.5Kg of nickel-cobalt-manganese oxide powder and 100g of magnesium hydroxide nano-powder are mixed in an environment with a dew point of less than -30 ° C, and then added to a dry ball mill tank (both ball mill and ball mill beads are ceramic) at a speed of 200 r / Min, ball milling for 2h, and then obtained coated lithium nickel cobalt manganese oxide;

Comparative example 6

Using nickel cobalt cobalt manganate (Ni: Co: Mn = 8:1:1, D50 about 11 μm), carbon nanotube powder (tube diameter about 10 nm, length 4-10 μm), LiNO ₃ -NaCl powder, mass ratio For: 95:1:3.

9.5 Kg of lithium nickel cobalt manganese oxide powder, 100 g of carbon nanotube powder, 300 g of LiNO ₃ -NaCl powder, mixed under a dew point of less than -30 ° C, and then added to a dry ball mill tank (ball mill and ball mill beads are both For ceramics, the rotation speed is 200r/min, ball milling for 2h, and then the coated nickel-cobalt-manganese oxide is obtained;

Comparative example 7

Using nickel cobalt cobalt manganate (Ni: Co: Mn = 8:1:1, D50 about 11 μm), carbon nanotube powder (tube diameter about 10 nm, length 4-10 μm), magnesium hydroxide nano powder (D50 about 30nm), the mass ratio is: 95:1:1.

9.5 Kg of lithium nickel cobalt manganese oxide powder, 100 g of carbon nanotube powder, and 100 g of magnesium hydroxide nanopowder are mixed in an environment having a dew point of less than -30 ° C, and then added to a dry ball mill tank (ball mill and ball mill beads are both For ceramics, the rotation speed is 200r/min, ball milling for 2h, and then the coated nickel-cobalt-manganese oxide is obtained;

Comparative example 8

Lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm), LiNO ₃ -NaCl powder, magnesium hydroxide nano powder (D50 about 30 nm), mass ratio: 95:3 :1.

9.5 Kg of lithium nickel cobalt manganese oxide powder, 300 g of LiNO ₃ -NaCl powder, 100 g of magnesium hydroxide nanopowder, mixed under a dew point of less than -30 ° C, and then added to a dry ball mill tank (ball mill and ball beads) All are ceramics), the speed is 200r/min, ball milling for 2h, and then the coated nickel-cobalt-manganate is obtained;

Comparative example 9

Lithium nickel cobalt manganese oxide (Ni: Co: Mn = 8:1:1, D50 about 11 μm) and LiNO ₃ -NaCl powder were used, and the mass ratio was 95:5.

9.5Kg of nickel-cobalt-manganese oxide powder and 500g of magnesium hydroxide nano-powder are mixed in an environment with a dew point of less than -30 ° C, and then added to a dry ball mill tank (both ball mill and ball mill beads are ceramic) at a speed of 200 r / Min, ball milling for 2h, and then obtained coated lithium nickel cobalt manganese oxide;

Experimental example

Using lithium nickel cobalt manganese oxide prepared in Comparative Examples 1 to 9 as a positive electrode material, a positive electrode tab was prepared according to the method described above, and graphite was used as a negative electrode material, and the same type of separator and electrolyte used in the above examples were used. Made of lithium ion soft pack battery, capacity 24Ah.

Performance Testing:

1, safety performance

The batteries prepared in the above examples and comparative examples were tested for safety performance, and the results are shown in Table 1.

Table 1 Battery safety performance test

	acupuncture	extrusion
Example 1	by	by

Example 2	by	by
Example 3	by	by
Example 4	by	by
Comparative example 1	Fail	Fail
Comparative example 2	Fail	Fail
Comparative example 3	Fail	Fail
Comparative example 4	Fail	Fail
Comparative example 5	Fail	Fail
Comparative example 6	Fail	by
Comparative example 7	Fail	by
Comparative example 8	Fail	by
Comparative example 9	Fail	by

2, electrical performance

The batteries provided in the examples and the comparative examples were subjected to electrical property tests. The results are shown in Table 2 and Figure 3. Table 2 shows the results of the electrical properties test of the examples and comparative examples. 3 is a discharge curve of a battery prepared by preparing a positive electrode material prepared in Example 1.

Table 2 Example and Comparative Example Battery Electrical Performance Test Results

	Open circuit voltage /V after full charge	AC impedance / mΩ
Example 1	4.202	1.785
Example 2	4.200	1.895
Example 3	4.199	1.967
Example 4	4.189	2.085
Comparative example 1	4.198	1.685
Comparative example 2	4.203	1.649
Comparative example 3	4.201	1.564
Comparative example 4	4.196	2.153
Comparative example 5	4.187	2.042
Comparative example 6	4.195	1.852
Comparative example 7	4.192	1.936

Comparative example 8	4.185	2.451
Comparative example 9	4.186	2.978

As can be seen from Tables 1 and 2, the AC impedances of Examples 1 to 4 were not significantly increased as compared with Comparative Examples 1 and 2, and the safety was greatly improved; compared with Comparative Examples 1 to 2, Comparative Example 3 to 5 additions of one type of coating did not significantly improve the safety; compared with Comparative Examples 1 to 2, Comparative Examples 6 to 8 added two kinds of coatings, and the safety improvement was limited; compared with Comparative Examples 1 to 2, Comparative Example 9 increases the content of a coating, the safety improvement is limited, and the AC impedance is significantly increased. In summary, the embodiment has good safety performance while the AC impedance is not significantly increased.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims (10)

1. A high-safe coated high-nickel ternary positive electrode material, comprising: a high-nickel ternary positive electrode material and a coating layer coated on a surface of the high-nickel ternary positive electrode material, the coating layer Prepared from raw materials including the following mass percentages:

   1% to 95% inorganic flame retardant;

   1% to 95% inorganic phase change material;

   1% to 20% of high thermal conductivity inorganic materials.
2. The coated high-nickel ternary positive electrode material according to claim 1, wherein the inorganic flame retardant is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, cerium oxide, zinc borate, and molybdenum-containing material. One or more of the inorganic compounds.
3. The coated high nickel ternary positive electrode material according to claim 1, wherein the inorganic phase change material is one or more selected from the group consisting of AlCl ₃ , LiNO ₃ , NaNO ₃ , KNO ₃ and NaNO ₂ . One or more of the resulting mixture or composite and molten salt compound.
4. The coating type high-nickel ternary positive electrode material according to claim 3, wherein said compound is selected from molten salt Na ₂ SO _4, LiNO ₃ -KCl one kind and LiNO ₃ -NaCl or more .
5. The coated high nickel ternary positive electrode material according to claim 1, wherein the highly thermally conductive inorganic material is one or more selected from the group consisting of graphite, graphene, carbon nanotubes, and aluminum nitride.
6. The coated high-nickel ternary positive electrode material according to claim 1, wherein a mass ratio of the high-nickel ternary positive electrode material to the coating layer is (5 to 100):1.
7. The coated high nickel ternary positive electrode material according to claim 1, wherein the high nickel ternary positive electrode material is selected from the group consisting of lithium nickel cobalt manganese oxide and/or lithium nickel cobalt aluminate.
8. A method for preparing a high-safe coated high-nickel ternary positive electrode material according to any one of claims 1 to 7, which comprises the following steps:

   The high-nickel ternary positive electrode material, the inorganic flame retardant, the inorganic phase change material and the high thermal conductive inorganic material are ball-milled under a dew point of less than -30 ° C to obtain a coated high-nickel ternary positive electrode material;

   or,

   The high-nickel ternary positive electrode material, the inorganic flame retardant, the inorganic phase change material and the high thermal conductive inorganic material are placed in a powder coating device under the condition of a dew point of less than -30 ° C for powder coating, and then subjected to demagnetization treatment. , A coated high nickel ternary positive electrode material is obtained.
9. A high-safe coated high-nickel ternary positive electrode sheet characterized by comprising a positive electrode layer formed of a high-nickel ternary positive electrode material, and a coating layer coated on a surface of the positive electrode layer, the coating The layers are prepared from raw materials that include the following mass percentages:

   1% to 95% inorganic flame retardant;

   1% to 95% inorganic phase change material;

   1% to 20% of high thermal conductivity inorganic materials.
10. A lithium ion battery comprising a positive electrode, a negative electrode, a separator, an electrolyte, and a casing, wherein the positive electrode is a high-safe coated high-nickel ternary cathode material according to any one of claims 1 to 8. Or the high-safe coated high-nickel ternary positive electrode tab of claim 9.

Images