CN106960955B - Vanadium sulfide-coated ternary cathode material for lithium ion battery and preparation method thereof - Google Patents

Abstract

The ternary cathode material of lithium ion battery and preparation method thereof of vanadium sulfide cladding, the material is made of following methods: (1) dispersing vanadium sulfide in organic solvent, ultrasonic disperse, obtain vanadium sulfide dispersion liquid；(2) ternary cathode material of lithium ion battery is added in vanadium sulfide dispersion liquid, stirring, reaction is heated in sealing reaction kettle, it is cooling, it washs, filters, it is dry, obtain mixing presoma；(3) it is heat-treated, grinds after cooling in a reducing atmosphere, obtain the ternary cathode material of lithium ion battery of vanadium sulfide cladding.For battery made of material of the present invention in 2.7~4.3V, first 10 times are 0.1C, are set as under 1C for the 11st~100 time, first discharge specific capacity is up to 195.6mAh/g, capacity has excellent multiplying power and cycle performance up to 77.27% up to 136mAh/g, capacity retention ratio after 100 circle of circulation；The method of the present invention is simple, low in cost, easy to spread.

Description

Vanadium sulfide-coated ternary cathode material for lithium ion battery and preparation method thereof

technical field

The invention relates to a ternary positive electrode material for a lithium ion battery and a preparation method thereof, in particular to a ternary positive electrode material for a lithium ion battery coated with vanadium sulfide and a preparation method thereof.

Background technique

At present, lithium ion battery cathode materials mainly include lithium iron phosphate, lithium cobaltate, lithium manganate and ternary materials. However, these four materials all have certain defects. Lithium iron phosphate has low conductivity, low tap density and low energy density; due to the limitation of lithium ion deintercalation ratio in lithium cobaltate, the capacity is relatively low, and cobalt resources are very expensive and toxic; although lithium manganate has high safety However, due to the unstable crystal structure during the charge and discharge process, the cycle performance is relatively poor; although the ternary material has the advantages of high energy density, long cycle life, environmental friendliness and good safety performance, it is currently the most promising lithium ion Battery cathode material, but its rate performance and cycle performance are poor. The above technical defects seriously restrict the wide application of the lithium-ion battery cathode material, especially, the defects of the ternary material make it difficult to use and popularize it in the field of electric vehicles and hybrid electric vehicles.

The poor rate performance and cycle performance of ternary materials are the key problems restricting the further development of lithium-ion ternary power batteries.

At present, the methods to improve the electrochemical performance of ternary materials mainly include: ion doping, surface coating and other measures. Material surface coating is one of the most commonly used, simple and low-cost methods at present. The materials coated on the surface of ternary materials are mainly metal oxides, metal fluorides and metal phosphates.

CN106384815A discloses a high-temperature stable nickel-cobalt lithium manganate composite electrode and its preparation method and application. The surface of nano-scale nickel-cobalt lithium manganate is pre-coated with a layer of two-dimensional layered material, and then the outer surface is coated with a layer of The lithium iron phosphate forms a nickel cobalt lithium manganate composite electrode with high temperature stability, which effectively inhibits the reaction between the electrode and the electrolyte and improves the structural stability of the material. However, due to the selection of nano-scale nickel-cobalt lithium manganate as the core material, the tap density becomes lower, which reduces the energy density of the nickel-cobalt lithium manganate material. At the same time, the preparation process is complicated and the cost is high, which restricts its commercial application.

CN103794753A discloses a lithium ion battery composite positive electrode material and a preparation method thereof. The surface of the lithium ion battery positive electrode material is coated with a layer of vanadium oxide, and the oxide layer reduces the contact area between the positive electrode material and the electrolyte, inhibiting the The side reactions caused by the direct contact between the two are eliminated, and the electrochemical performance of the cathode material is improved. The preparation method of the material is to add an organic solvent to deionized water under heating conditions, so that ammonium metavanadate is precipitated from the water and coated on the ternary material, but the uniformity of the surface coating cannot be guaranteed.

CN104134796A discloses a modification method of ternary positive electrode material of lithium ion battery, which is to coat a layer of VOPO ₄ on the surface of ternary positive electrode material of lithium ion battery, so as to avoid direct contact between ternary positive electrode material and electrolyte, and suppress the concentration of ternary positive electrode material in the electrolyte. The corrosion of ternary cathode materials by HF to achieve the purpose of modification, and VOPO ₄ has excellent intercalation characteristics of lithium, allowing the transport of lithium ions between layers, which can improve the air storage performance, high temperature storage performance and cycling of the material. performance. However, the modification method of this material disperses the ternary cathode material in deionized water, and the moisture will seriously damage the structure of the ternary cathode material and reduce the electrochemical performance; and the use of spray drying technology is difficult and the process cost is high.

Therefore, conventional coating materials such as metal oxides and fluorides have poor electrical conductivity, inhibit the transport of lithium ions, and limit the capacity of ternary materials. There is an urgent need to develop a simple and feasible method for coating commercial lithium-ion battery ternary materials with vanadium sulfide.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art, and to provide a method that effectively reduces the residual content of lithium on the surface of the ternary material, and at the same time can prevent the erosion of the electrode surface by the electrolyte, and significantly improves the performance of the ternary positive electrode material. A vanadium sulfide-coated ternary positive electrode material for a lithium ion battery with a rate capability and cycle performance and a preparation method thereof.

The technical scheme adopted by the present invention to solve the technical problem is as follows: the lithium ion battery ternary positive electrode material covered by vanadium sulfide is made by the following methods:

(1) Dispersing vanadium sulfide in an organic solvent, and then ultrasonically dispersing to obtain a vanadium sulfide dispersion;

(2) Add the lithium-ion battery ternary positive electrode material into the vanadium sulfide dispersion obtained in step (1), stir evenly, and then conduct heating reaction in a sealed reactor, and then naturally cool, wash, filter, and dry to obtain a mixed precursor body;

(3) heat-treating the mixed precursor obtained in step (2) in a reducing atmosphere, and grinding after cooling to obtain a ternary positive electrode material for a lithium ion battery coated with vanadium sulfide.

Preferably, in step (1), after the vanadium sulfide is controlled to be dispersed in the organic solvent, the concentration of vanadium ions is 0.8-100 mmol/L (more preferably 0.9-50.0 mmol/L, still more preferably 1-15 mmol/L). The vanadium ion concentration in the organic solvent is relatively lower than that in the aqueous solution. If the vanadium ion concentration is too high, agglomeration is likely to occur, which affects the coating effect, but it cannot be too low, which will cause waste of organic solvent.

Preferably, in step (1), the vanadium sulfide is one or more of vanadium disulfide, vanadium tetrasulfide or pentavanadium octasulfide, etc. Vanadium sulfide is a typical transition metal sulfide with a two-dimensional layered structure similar to graphene. According to different ratios of sulfur and vanadium, there exist materials such as vanadium disulfide, vanadium tetrasulfide, and vanadium octasulfide. Among them, the vanadium disulfide layer is connected by S-V-S covalent bonds to form a sandwich structure, and the weak van der Waals between the layers forms a sandwich structure. The interlayer spacing is 5.76 Å; the vanadium octasulfide has a three-dimensional structure, and its structure is the insertion of vacant vanadium atoms between the vanadium disulfide layers, and the interlayer spacing can reach 11.32 Å. Due to the special structure of vanadium sulfide, smaller atoms, molecules and ions can be stored between the layers, which can effectively improve the electrochemical performance of the ternary cathode material.

Preferably, in step (1), the organic solvent is one or more of methanol, ethanol, n-propanol or isopropanol. Since ternary cathode materials, especially high-nickel ternary cathode materials, such as LiNi _0.8 Co _0.1 Mn _0.1 O ₂ or LiNi _0.8 Co _0.15 Al _0.05 O ₂ are relatively sensitive to moisture, the present invention uses an organic solvent instead of water as the dispersed phase, which can Avoid damage to the structure of the ternary cathode material.

Preferably, in step (1), the frequency of the ultrasonic dispersion is 40-60 kHz, the temperature of the ultrasonic dispersion is 20-40°C, and the time of the ultrasonic dispersion is 2-10 h (more preferably 5-8 h). Ultrasonic dispersion can make the vanadium sulfide dispersed evenly in the organic solvent, and the ultrasonic dispersion time should not be too short, which will lead to uneven dispersion and then agglomeration.

Preferably, in step (2), the mass ratio of the lithium ion battery ternary positive electrode material to vanadium sulfide in the vanadium sulfide dispersion liquid is 1:8-100 (more preferably 1:9-30). If the amount of vanadium sulfide relative to the ternary cathode material is too low, the vanadium sulfide is not enough to coat the spherical secondary particles of the ternary cathode material, and it is difficult to achieve a good coating effect; If the amount of positive electrode material is too high, the coating layer will be too thick, which limits the rate of lithium ion insertion and extraction, which will lead to poor rate performance of the ternary positive electrode material.

Preferably, in step (2), the lithium ion battery ternary positive electrode material is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.4 Co _0.2 Mn _0.4 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O _2. One or more of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ or LiNi _0.8 Co _0.15 Al _0.05 O ₂ and the like.

Preferably, in step (2), the preparation method of the lithium ion battery ternary positive electrode material is as follows: grinding and mixing the lithium ion battery ternary positive electrode material precursor and lithium salt, after aerobic calcination, cooling, grinding, and finally . The ternary positive electrode material for the lithium ion battery is also commercially available.

Preferably, the molar ratio of the lithium element in the lithium salt to the total amount of metal elements in the precursor of the ternary positive electrode material for the lithium ion battery is 1.0-1.2:1 (more preferably 1.02-1.10:1).

Preferably, the calcination temperature is 700-1000°C, and the calcination time is 5-22h (more preferably 15-20h). During calcination, if the calcination temperature is too low, the lithium ions cannot well enter into the lattice of the ternary material; The longer the ion transport path, the worse the rate performance of the ternary cathode material, and the ternary cathode material with good crystallinity can be obtained by controlling the appropriate calcination conditions.

Preferably, the lithium ion battery ternary positive electrode material precursors are Ni _1/3 Co _1/3 Mn _1/3 (OH) ₂ , Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ , Ni _0.6 Co _0.2 Mn _0.2 ( One or more of OH) ₂ , Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ or Ni _0.8 Co _0.15 Al _0.05 (OH) ₂ and the like.

Preferably, the lithium salt is lithium carbonate, lithium nitrate or lithium hydroxide, etc., and one or more of the hydrates of the above lithium salts.

Preferably, when the precursors of the ternary cathode material for lithium ion batteries are Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ and Ni _0.8 Co _0.15 Al _0.05 (OH) ₂ with relatively high nickel content, calcining at 700-750° C.; When the precursors of ternary positive electrode materials for lithium ion batteries are Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ and Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ with moderate nickel content, they are calcined at 800-850 °C; When the precursors of the ternary cathode material are Ni _1/3 Co _1/3 Mn _1/3 (OH) ₂ and Ni _0.4 Co _0.2 Mn _0.4 (OH) ₂ with low nickel content, calcining at 900-950 °C.

Preferably, the atmosphere of the aerobic calcination is oxygen or air atmosphere. The oxygen is a high-purity gas with a purity of 99.99%.

Preferably, the grinding and mixing time is 0.5-1.5 h.

Preferably, the calcination is milled for 0.5-1.0 h to a particle size of 8-12 μm.

Preferably, in step (2), the stirring time is 1-4 hours.

Preferably, in step (2), the temperature of the heating reaction is 120-220°C (more preferably 150-180°C), and the time of the heating reaction is 3-24h (more preferably 10-20h). By heating and reacting in the sealed reaction kettle to create an atmosphere of high temperature and high pressure, the vanadium sulfide is evenly coated on the surface of the ternary positive electrode material.

Preferably, in step (2), the washing and filtering process uses the same organic solvent as step (1).

Preferably, in step (3), the temperature of the heat treatment is 200 to 600° C., and the time of the heat treatment is 4 to 8 hours. After the heating reaction in step (2), the vanadium sulfide is coated on the surface of the ternary positive electrode material in a relatively loose state, and by performing heat treatment at the temperature and time described in step (3), the vanadium sulfide can be coated The layer is more compact to obtain a vanadium sulfide-coated ternary cathode material with good crystalline properties and a tight coating layer, so the heat treatment temperature cannot be too high.

Preferably, in step (3), the reducing atmosphere is helium, nitrogen, argon or an argon/hydrogen mixture, wherein the volume fraction of hydrogen in the argon/hydrogen mixture is 1-10% (more preferably 4%). ~8%).

The vanadium sulfide layer coated on the surface of the ternary positive electrode material of the lithium ion battery of the invention has good cycle stability, and the vanadium sulfide material has a stable structure in the electrolyte, and can well isolate moisture, carbon dioxide and electrolyte in the air. It can prevent the occurrence of side reactions in the electrode, inhibit the phenomenon of mixed discharge of nickel and lithium in the electrode, stabilize the layered structure of the ternary cathode material, and the lithium ions can be inserted and extracted stably, which improves the cycle stability of the ternary cathode material. , and ensure the full play of its electrochemical performance. Vanadium sulfide has a two-dimensional layered structure and can also be used as an electrode material. Lithium ions can be stored between layers, which can improve the overall discharge capacity of the material. my country is rich in vanadium resources, and the use of vanadium sulfide as a coating material is low-cost. .

The beneficial effects of the present invention are as follows:

(1) The vanadium sulfide-coated lithium-ion battery ternary positive electrode material of the present invention has a uniform vanadium sulfide coating on the surface, which can prevent the corrosion of the electrode by the electrolyte and reduce the residual lithium content on the electrode surface; The battery was charged and discharged, and the results showed that at 2.7~4.3V, the charging current was 0.1C (1C=180mAh/g), the discharge current was set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. Under the circumstance, the first discharge specific capacity can reach up to 195.6mAh/g, after 100 cycles, the capacity can reach up to 136mAh/g, and the capacity retention rate can reach up to 77.27%, indicating that the material of the present invention has excellent rate performance and cycle performance;

(2) The preparation process of the present invention is simple, the cost of the vanadium sulfide raw material and the process is low, and it is easy to popularize.

Description of drawings

Fig. 1 is the SEM image of the ternary positive electrode material of lithium ion battery coated with vanadium sulfide obtained in Example 1 of the present invention;

Fig. 2 is the SEM image of the uncoated lithium-ion battery ternary positive electrode material obtained in Comparative Example 1;

3 is a discharge cycle specific capacity curve diagram of the lithium ion battery ternary positive electrode material obtained in Example 1 and Comparative Example 1 of the present invention;

4 is a discharge cycle specific capacity curve diagram of the lithium-ion battery ternary positive electrode material obtained in Example 2 of the present invention and Comparative Example 1;

Fig. 5 is the discharge cycle specific capacity curve diagram of the lithium ion battery ternary positive electrode material obtained in Example 3 and Comparative Example 1 of the present invention; Fig. 6 is the discharge cycle of the lithium ion battery ternary positive electrode material obtained in Example 4 and Comparative Example 1 of the present invention. Cyclic specific capacity curve.

Detailed ways

The present invention will be further described below with reference to the embodiments and accompanying drawings.

The purity of the high-purity oxygen used in the embodiment of the present invention is 99.99%; the raw materials or chemical reagents used in the embodiment of the present invention, unless otherwise specified, are obtained through conventional commercial channels.

In the embodiment of the present invention, Li:M represents the molar ratio of the lithium element in the lithium salt to the total amount of metal elements in the precursor of the ternary positive electrode material for the lithium ion battery.

Reference Example 1

Preparation method of ternary cathode material for lithium ion battery: accurately weigh 1g Ni _0.8 Co _0.15 Al _0.05 (OH) ₂ ternary cathode material precursor and 0.484g lithium hydroxide monohydrate (Li:M=1.05:1), grind Mix evenly for 1 hour, put it into a tubular resistance furnace, and calcinate it at 750°C for 15 hours in a high-purity oxygen atmosphere. After cooling, grind it for 1 hour until the particle size is 8-12 μm, to obtain LiNi, a ternary positive electrode material for lithium ion batteries. _0.8 Co _0.15 Al _0.05 O ₂ , put it in an oven for later use.

Reference example 2

Preparation method of ternary cathode material for lithium ion battery: Accurately weigh 1g Ni _0.8 Co _0.15 Al _0.05 (OH) ₂ ternary cathode material precursor and 0.426g lithium carbonate (Li:M=1.05:1), grind for 1h and mix well , put it into a tubular resistance furnace, in a high-purity oxygen atmosphere, calcined at 700 ° C for 20 hours, after cooling, ground for 0.5 hours to a particle size of 8-12 μm, to obtain LiNi _0.8 Co, a ternary positive electrode material for lithium ion batteries _0.15 Al _0.05 O ₂ ternary cathode material, put it in the oven for use.

Reference Example 3

Preparation method of ternary cathode material for lithium ion battery: accurately weigh 1g Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ ternary cathode material precursor and 0.469 g lithium hydroxide monohydrate (Li:M=1.03:1), grind Mix evenly for 1 hour, put it into a tubular resistance furnace, calcined at 800°C for 15 hours in a high-purity oxygen atmosphere, and after cooling, grind it for 0.5 hours to a particle size of 8-12 μm to obtain a ternary cathode material for lithium ion batteries LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , put it in an oven for later use.

Example 1

(1) Accurately weigh 0.05 g of vanadium disulfide, disperse it in 80 mL of anhydrous ethanol, and ultrasonically disperse it for 6 hours at 40 kHz and 20 °C to obtain a vanadium disulfide dispersion;

(2) Take 0.95 g of LiNi _0.8 Co _0.15 Al _0.05 O ₂ positive electrode ternary positive electrode material obtained in Reference Example 1 and add it to the vanadium disulfide dispersion obtained in step (1). After magnetic stirring for 4 hours, the mixed solution is added to the polytetrafluoroethylene In the reaction kettle, after sealing, it was placed in an oven at 180°C, reacted for 12 hours, taken out for natural cooling, washed with absolute ethanol, filtered for 3 times, and dried to obtain a mixed precursor;

(3) The mixed precursor obtained in step (2) is placed in a tubular resistance furnace, and in a reducing atmosphere of argon/hydrogen mixed gas (the volume fraction of hydrogen is 5%), calcined at 400 ° C for 6 hours, and then cooled After grinding, a LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material coated with vanadium disulfide is obtained.

As shown in FIG. 1 , the surface of the vanadium disulfide-coated LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material is uniformly coated with a layer of vanadium disulfide coating with a rough surface.

The vanadium disulfide-coated LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material obtained in this example was made into a CR2025 type button battery. The charging and discharging procedures are set as follows: the charging and discharging voltage range is 2.7~4.3V, the charging current is 0.1C (1C=180mAh/g), the discharge current is set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. The first discharge specific capacity was 183.1mAh/g, the capacity after 100 cycles was 132.1mAh/g, and the capacity retention rate was 72.15%. It can be seen that the lithium-ion battery prepared by adding vanadium sulfide material has good cycle stability and high capacity retention rate.

Example 2

(1) Accurately weigh 0.01g of vanadium disulfide, disperse it in 80mL of anhydrous isopropanol, and ultrasonically disperse it at 60kHz and 40°C for 8h to obtain a vanadium disulfide dispersion;

(2) Take 0.99 g of LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary cathode material obtained in Reference Example 2 and add it to the vanadium disulfide dispersion obtained in step (1). After magnetic stirring for 2 hours, the mixed solution is added to PTFE for reaction In the kettle, after sealing, it was placed in an oven at 150 °C, reacted for 20 hours, taken out and cooled naturally, washed with anhydrous isopropanol, filtered 3 times, and dried to obtain a mixed precursor;

(3) The mixed precursor obtained in step (2) was placed in a tubular resistance furnace, and in a reducing atmosphere of argon/hydrogen mixed gas (the volume fraction of hydrogen was 8%), calcined at 200 ° C for 6 hours, and then cooled After grinding, a LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material coated with vanadium disulfide is obtained.

The vanadium disulfide-coated LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material obtained in this example was made into a CR2025 type button battery. The charging and discharging procedures are set as follows: the charging and discharging voltage range is 2.7~4.3V, the charging current is 0.1C (1C=180mAh/g), the discharge current is set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. The first discharge specific capacity was 184.9mAh/g, the capacity after 100 cycles was 111mAh/g, and the capacity retention rate was 60%. It can be seen that the lithium-ion battery prepared by adding vanadium sulfide material has good cycle stability and high capacity retention rate.

Example 3

(1) Accurately weigh 0.10 g of vanadium disulfide, disperse it in 80 mL of absolute ethanol, and ultrasonically disperse it at 40 kHz and 20 °C for 8 hours to obtain a vanadium disulfide dispersion;

(2) Take 0.90 g of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ternary positive electrode material obtained in Reference Example 3 and add it to the vanadium disulfide dispersion obtained in step (1), stir magnetically for 4 hours, and then add the mixed solution to PTFE for reaction In the kettle, after sealing, it was placed in an oven at 160°C, reacted for 12 hours, taken out to be cooled naturally, washed with absolute ethanol, filtered 3 times, and dried to obtain a mixed precursor;

(3) Place the mixed precursor obtained in step (2) in a tubular resistance furnace, in a reducing atmosphere of argon/hydrogen mixed gas (the volume fraction of hydrogen is 5%), calcined at 400 ° C for 8 hours, and then cooled After grinding, a LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ternary positive electrode material coated with vanadium disulfide is obtained.

The vanadium disulfide-coated LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ternary positive electrode material obtained in this example was made into a CR2025 type button battery. The charging and discharging procedures are set as follows: the charging and discharging voltage range is 2.7~4.3V, the charging current is 0.1C (1C=175mAh/g), the discharge current is set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. The first discharge specific capacity was 176mAh/g, the capacity after 100 cycles was 136mAh/g, and the capacity retention rate was 77.27%. It can be seen that the lithium-ion battery prepared by adding vanadium sulfide material has good cycle stability and high capacity retention rate.

Example 4

(1) Accurately weigh 0.05g of vanadium octasulfide, disperse it in 80mL of anhydrous ethanol, and ultrasonically disperse it for 6 hours at 40kHz and 20°C to obtain a dispersion of vanadium octasulfide;

(2) Take 0.95g Li Ni _0.8 Co _0.15 Al _0.05 O ₂ ternary cathode material (purchased from Changyuan Lithium Branch, product model LY308) and add it to the dispersion liquid of vanadium octasulfide obtained in step (1). After magnetic stirring for 1 hour, The mixed solution was added to the polytetrafluoroethylene reactor, sealed, placed in an oven at 180°C, reacted for 12 hours, taken out and cooled naturally, washed with absolute ethanol, filtered for 3 times, and dried to obtain a mixed precursor;

(3) Place the mixed precursor obtained in step (2) in a tubular resistance furnace, in a reducing atmosphere of argon/hydrogen mixed gas (the volume fraction of hydrogen is 5%), calcined at 400 ° C for 8 hours, and then cooled After grinding, a LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material coated with pentavanadium octasulfide is obtained.

The LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material obtained in this example and coated with pentasulfide pentasulfide was used to make a CR2025 type button battery. The charging and discharging procedures are set as follows: the charging and discharging voltage range is 2.7~4.3V, the charging current is 0.1C (1C=180mAh/g), the discharge current is set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. The first discharge specific capacity was 195.6mAh/g, the capacity after 100 cycles was 130.2mAh/g, and the capacity retention rate was 66.56%. It can be seen that the lithium-ion battery prepared by adding vanadium sulfide material has good cycle stability and high capacity retention rate.

Comparative Example 1

Accurately weigh 1g of Ni _0.8 Co _0.15 Al _0.05 (OH) ₂ ternary cathode material precursor and 0.484g of lithium hydroxide monohydrate (Li:M=1.05:1), gently grind for 1h, mix well, and put in the tube resistor In a furnace, in an oxygen atmosphere, calcined at 750° C. for 15 hours, and after cooling, crushed to obtain LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material.

As shown in Figure 2, it is a LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary cathode material with uncoated surface, and the surface is smooth and complete.

The LiNi _0.8 Co _0.15 Al _0.05 O ₂ ternary positive electrode material obtained in this comparative example was made into a CR2025 type button battery. The charging and discharging procedures are set as follows: the charging and discharging voltage range is 2.7~4.3V, the charging current is 0.1C (1C=180mAh/g), the discharge current is set to 0.1C for the first 10 times, and 1C for the 11th to 100th times. The specific capacity of the first discharge was 193.7mAh/g, the capacity after 100 cycles was 79.8mAh/g, and the capacity retention rate was only 41.20%.

Claims (32)

1. a kind of ternary cathode material of lithium ion battery of vanadium sulfide cladding, which is characterized in that be made of following methods:

(1) it disperses vanadium sulfide in organic solvent, then carries out ultrasonic disperse, obtain vanadium sulfide dispersion liquid；The vanadium vulcanization Object is one or more of vanadium disulfide, four vanadic sulfides or eight five vanadium of vulcanization；

(2) ternary cathode material of lithium ion battery is added in vanadium sulfide dispersion liquid obtained by step (1), is stirred evenly, then Heating reaction is carried out in sealing reaction kettle, then natural cooling, washed, filtered, it is dry, obtain mixing presoma；The lithium ion The mass ratio of vanadium sulfide is 1:8~100 in battery tertiary cathode material and vanadium sulfide dispersion liquid；

(3) mixing presoma obtained by step (2) is heat-treated in a reducing atmosphere, is ground after cooling, obtain vanadium sulfide cladding Ternary cathode material of lithium ion battery.

2. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1, which is characterized in that step (1) in, after control vanadium sulfide is scattered in organic solvent, the concentration of vanadium ion is 0.8~100 mmol/L；The organic solvent For one or more of methanol, ethyl alcohol, normal propyl alcohol or isopropanol.

3. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1 or claim 2, which is characterized in that step Suddenly in (1), the frequency of the ultrasonic disperse is 40~60kHz, and the temperature of ultrasonic disperse is 20~40 DEG C, the time of ultrasonic disperse For 2~10h.

4. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1 or claim 2, which is characterized in that step Suddenly in (2), the ternary cathode material of lithium ion battery is LiNi_1/3Co_1/3Mn_1/3O₂、LiNi_0.4Co_0.2Mn_0.4O₂、 LiNi_0.5Co_0.2Mn_0.3O₂、LiNi_0.6Co_0.2Mn_0.2O₂、LiNi_0.8Co_0.1Mn_0.1O₂Or LiNi_0.8Co_0.15Al_0.05O₂One of Or it is several.

5. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 3, which is characterized in that step (2) in, the ternary cathode material of lithium ion battery is LiNi_1/3Co_1/3Mn_1/3O₂、LiNi_0.4Co_0.2Mn_0.4O₂、 LiNi_0.5Co_0.2Mn_0.3O₂、LiNi_0.6Co_0.2Mn_0.2O₂、LiNi_0.8Co_0.1Mn_0.1O₂Or LiNi_0.8Co_0.15Al_0.05O₂One of Or it is several.

6. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1 or claim 2, which is characterized in that step Suddenly in (2), the preparation method of the ternary cathode material of lithium ion battery is: by ternary cathode material of lithium ion battery presoma It is cooling after aerobic calcining with lithium salts ground and mixed, grinding,；Elemental lithium and lithium ion battery ternary in the lithium salts are just The molar ratio of metallic element total amount is 1.0~1.2:1 in the material precursor of pole；The temperature of the calcining is 700~1000 DEG C, is forged The time of burning is 5~22h.

7. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 3, which is characterized in that step (2) in, the preparation method of the ternary cathode material of lithium ion battery is: by ternary cathode material of lithium ion battery presoma and Lithium salts ground and mixed, cooling after aerobic calcining, grinding,；Elemental lithium and lithium ion battery tertiary cathode in the lithium salts The molar ratio of metallic element total amount is 1.0~1.2:1 in material precursor；The temperature of the calcining is 700~1000 DEG C, calcining Time be 5~22h.

8. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 4, which is characterized in that step (2) in, the preparation method of the ternary cathode material of lithium ion battery is: by ternary cathode material of lithium ion battery presoma and Lithium salts ground and mixed, cooling after aerobic calcining, grinding,；Elemental lithium and lithium ion battery tertiary cathode in the lithium salts The molar ratio of metallic element total amount is 1.0~1.2:1 in material precursor；The temperature of the calcining is 700~1000 DEG C, calcining Time be 5~22h.

9. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 6, it is characterised in that: the lithium Ion battery ternary anode material precursor is Ni_1/3Co_1/3Mn_1/3(OH)₂、Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2 (OH)₂、Ni_0.8Co_0.1Mn_0.1(OH)₂Or Ni_0.8Co_0.15Al_0.05(OH)₂One or more of；The lithium salts is lithium carbonate, nitre One or more of sour lithium or lithium hydroxide and the hydrate of above-mentioned lithium salts.

10. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 7, it is characterised in that: described Ternary cathode material of lithium ion battery presoma is Ni_1/3Co_1/3Mn_1/3(OH)₂、Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2 (OH)₂、Ni_0.8Co_0.1Mn_0.1(OH)₂Or Ni_0.8Co_0.15Al_0.05(OH)₂One or more of；The lithium salts is lithium carbonate, nitre One or more of sour lithium or lithium hydroxide and the hydrate of above-mentioned lithium salts.

11. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 8, it is characterised in that: described Ternary cathode material of lithium ion battery presoma is Ni_1/3Co_1/3Mn_1/3(OH)₂、Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2 (OH)₂、Ni_0.8Co_0.1Mn_0.1(OH)₂Or Ni_0.8Co_0.15Al_0.05(OH)₂One or more of；The lithium salts is lithium carbonate, nitre One or more of sour lithium or lithium hydroxide and the hydrate of above-mentioned lithium salts.

12. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 9, it is characterised in that: work as lithium Ion battery ternary anode material precursor is the higher Ni of nickel content_0.8Co_0.1Mn_0.1(OH)₂And Ni_0.8Co_0.15Al_0.05(OH)₂ When, it is calcined at 700~750 DEG C；When ternary cathode material of lithium ion battery presoma is that nickel content is medium Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2(OH)₂When, it is calcined at 800~850 DEG C；When lithium ion battery tertiary cathode Material precursor is the lower Ni of nickel content_1/3Co_1/3Mn_1/3(OH)₂And Ni_0.4Co_0.2Mn_0.4(OH)₂When, at 900~950 DEG C Calcining.

13. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 10, it is characterised in that: work as lithium Ion battery ternary anode material precursor is the higher Ni of nickel content_0.8Co_0.1Mn_0.1(OH)₂And Ni_0.8Co_0.15Al_0.05(OH)₂ When, it is calcined at 700~750 DEG C；When ternary cathode material of lithium ion battery presoma is that nickel content is medium Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2(OH)₂When, it is calcined at 800~850 DEG C；When lithium ion battery tertiary cathode Material precursor is the lower Ni of nickel content_1/3Co_1/3Mn_1/3(OH)₂And Ni_0.4Co_0.2Mn_0.4(OH)₂When, at 900~950 DEG C Calcining.

14. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 11, it is characterised in that: work as lithium Ion battery ternary anode material precursor is the higher Ni of nickel content_0.8Co_0.1Mn_0.1(OH)₂And Ni_0.8Co_0.15Al_0.05(OH)₂ When, it is calcined at 700~750 DEG C；When ternary cathode material of lithium ion battery presoma is that nickel content is medium Ni_0.5Co_0.2Mn_0.3(OH)₂、Ni_0.6Co_0.2Mn_0.2(OH)₂When, it is calcined at 800~850 DEG C；When lithium ion battery tertiary cathode Material precursor is the lower Ni of nickel content_1/3Co_1/3Mn_1/3(OH)₂And Ni_0.4Co_0.2Mn_0.4(OH)₂When, at 900~950 DEG C Calcining.

15. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 6, it is characterised in that: described The atmosphere of aerobic calcining is oxygen or air atmosphere；The time of the ground and mixed is 0.5~1.5h；It is ground after the calcining 0.5~1.0h to partial size be 8~12 μm.

16. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 9, it is characterised in that: described The atmosphere of aerobic calcining is oxygen or air atmosphere；The time of the ground and mixed is 0.5~1.5h；It is ground after the calcining 0.5~1.0h to partial size be 8~12 μm.

17. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 12, it is characterised in that: described The atmosphere of aerobic calcining is oxygen or air atmosphere；The time of the ground and mixed is 0.5~1.5h；It is ground after the calcining 0.5~1.0h to partial size be 8~12 μm.

18. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1 or claim 2, which is characterized in that step Suddenly in (2), the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3~for 24 hours.

19. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 3, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

20. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 4, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

21. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 6, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

22. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 9, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

23. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 12, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

24. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 15, which is characterized in that step (2) in, the time of the stirring is 1~4h；The temperature of the heating reaction is 120~220 DEG C, and the time for heating reaction is 3 ~for 24 hours.

25. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 1 or claim 2, which is characterized in that step Suddenly in (3), the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere be helium, Nitrogen, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

26. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 3, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

27. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 4, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

28. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 6, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

29. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 9, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

30. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 12, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

31. the ternary cathode material of lithium ion battery of vanadium sulfide cladding according to claim 15, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.

32. the ternary cathode material of lithium ion battery of the 8 vanadium sulfide claddings according to claim 1, which is characterized in that step (3) in, the temperature of the heat treatment is 200~600 DEG C, and the time of heat treatment is 4~8h；The reducing atmosphere is helium, nitrogen Gas, argon gas or argon/hydrogen gaseous mixture, wherein the volume fraction of hydrogen is 1~10% in argon/hydrogen gaseous mixture.