CN105552322B - Composite modified anode material for lithium-ion batteries of quaternary ion and preparation method thereof - Google Patents

Abstract

The invention discloses a quaternary ion composite modified lithium ion battery positive electrode material, comprising: a positive electrode active material; and a conductive material coated on the surface of the positive electrode active material; the conductive material is Mn-Ni-Fe-Cu A quaternary composite _oxide nanopowder _, wherein the molecular formula of the Mn‑Ni‑Fe‑Cu quaternary composite oxide is _{MnzNiFexCuyO4 .} The present invention also relates to a preparation method of the above-mentioned quaternary ion composite modified lithium ion battery cathode material. The quaternary ion composite modified lithium ion battery positive electrode material provided by the present invention, because the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder has good conductivity, can be greatly improved by improving the electronic conductivity of the material Rate performance and cycle performance of cathode materials.

Description

Quaternary ion composite modified lithium ion battery cathode material and preparation method thereof

technical field

The invention relates to a quaternary ion composite modified lithium ion battery cathode material and a preparation method thereof, in particular to a Mn-Ni-Fe-Cu quaternary composite oxide nano powder modified cathode material and a preparation method thereof.

Background technique

As a new generation of green and environment-friendly power supply, lithium-ion batteries have the advantages of high energy density, high voltage, small self-discharge, and no memory effect. They are widely used in mobile phones, cameras, notebook computers, power tools, electric bicycles, and electric vehicles. . With the rapid development of electronic products, the energy and power requirements of lithium-ion batteries are getting higher and higher, and the positive electrode material of lithium-ion batteries is an important part of lithium-ion batteries and the main factor affecting the performance of lithium-ion batteries.

At present, the most widely used lithium-ion cathode materials are mainly lithium cobaltate, lithium nickelate, lithium manganate and nickel-cobalt lithium manganate ternary materials. These cathode materials have their own advantages, but they also have their own disadvantages, which can no longer meet the requirements of electronic products for lithium-ion batteries. Currently, commonly used modification methods include bulk doping and surface coating. Bulk phase doping can effectively stabilize the internal structure of the cathode material and inhibit the mixing of cations; while surface coating can effectively inhibit the surface of the cathode material from being corroded by hydrofluoric acid in the electrolyte. However, the doped phase and coating layer do not have good electrical conductivity and electrochemical activity, so the bulk phase doping and surface coating of the positive electrode material will affect the specific capacity and rate capability of the positive electrode material.

Contents of the invention

The invention provides a quaternary ion composite modified lithium ion battery cathode material and a preparation method thereof, which can effectively solve the above problems.

The invention provides a quaternary ion composite modified lithium ion battery positive electrode material, comprising: a positive electrode active material; and a conductive material coated on the surface of the positive electrode active material; the conductive material is Mn-Ni-Fe-Cu A quaternary composite oxide nanopowder, _{wherein the} molecular formula of the Mn-Ni-Fe-Cu quaternary composite oxide is _{MnzNiFexCuyO4 .}

Further, z is greater than or equal to 0.3 and less than or equal to 1, x is greater than or equal to 0.2 and less than or equal to 1, and y is greater than or equal to 0.17 and less than or equal to 1.

Further, z is greater than or equal to 0.4 and less than or equal to 0.9, x is greater than or equal to 0.5 and less than or equal to 0.7, and y is greater than or equal to 0.3 and less than or equal to 0.9.

Further, the mass ratio of the conductive material to the positive electrode active material is 0.001˜0.1:1.

Further, the mass ratio of the conductive material to the positive electrode active material is 0.01˜0.05:1.

Further, the positive electrode active material is at least one of lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium manganate, lithium cobaltate, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobaltate or lithium nickel manganate A sort of.

A preparation method of a quaternary ion composite modified lithium ion battery positive electrode material, comprising:

Add Mn-Ni-Fe-Cu quaternary composite oxide nanopowder into a volatile solvent for high-speed stirring and ultrasonic dispersion to form a mixed solution;

Adding the positive active material into the mixed solution under high-speed stirring, so that the mixed solution evenly coats the surface of the positive active material to obtain a mixture; and

The mixture is dried, calcined, cooled, pulverized and sieved to obtain the quaternary ion composite modified lithium ion battery cathode material.

Further, the preparation method of the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder comprises: wet mixing manganese oxide, nickel oxide, copper oxide and iron oxide according to the stoichiometric ratio to obtain a mixture ; The mixture is dried, sintered and ground to obtain Mn-Ni-Fe-Cu quaternary composite oxide nanopowder.

Further, the sintering temperature is 800-900° C., the sintering time is 2-6 hours, and the sintering atmosphere is air atmosphere.

Further, the calcination temperature is 400-700° C., the time is 3-8 hours, and the calcination atmosphere is air or oxygen atmosphere.

The quaternary ion composite modified lithium ion battery positive electrode material and preparation method thereof provided by the present invention have the following advantages:

⑴ Coating the electrochemically active Mn-Ni-Fe-Cu quaternary composite oxide nanopowder on the surface of the active material allows the coating layer to isolate the electrolyte and the positive electrode material while allowing lithium ions to pass through freely, thus completing charging The decomposition of the electrolyte is avoided while discharging, and the cycle performance and stability of the lithium-ion battery are improved without affecting the specific capacity.

(2) Mn-Ni-Fe-Cu quaternary composite oxide nanopowder has good electrical conductivity, which can greatly improve the rate performance of the positive electrode material by increasing the electronic conductivity of the material.

(3) Mn-Ni-Fe-Cu quaternary composite oxide nanopowder has a special layered structure, which can provide a channel for the migration of lithium ions, thereby improving the first-time efficiency of the material.

Description of drawings

Fig. 1 is a flow chart of the preparation method of the quaternary ion composite modified lithium ion battery positive electrode material provided by the embodiment of the present invention.

Fig. 2 is a cycle discharge curve diagram of the quaternary ion composite modified lithium ion battery positive electrode material provided by Example 1 of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings but not all structures.

The invention provides a quaternary ion composite modified lithium ion battery positive electrode material, comprising: a positive electrode active material; and a conductive material coated on the surface of the positive electrode active material; the conductive material is Mn-Ni-Fe-Cu A quaternary composite oxide nanopowder, _{wherein the} molecular formula of the Mn-Ni-Fe-Cu quaternary composite oxide is _{MnzNiFexCuyO4 .} Among them, Mn is positive tetravalent, positive trivalent and positive divalent mixed ions, Ni is positive divalent, Fe is positive trivalent and positive divalent mixed ions, and Cu is positive monovalent and positive divalent mixed ions. Since manganese has positive trivalent and positive tetravalent ion pairs, and there are positive divalent ions at the same time, it is these ion pairs of different valence states that constitute the core of electron hopping and conduction, which reduces the resistivity of the material. In the same way, for iron and copper, ion pairs of different valences constitute the core of electron hopping conduction, which further reduces the resistivity of the material, so that the core of electron hopping conduction from positive one to positive four valence can be formed.

It can be understood that when the content of the conductive material is high, although better conductivity can be obtained, it will affect the energy density of the positive electrode material of the lithium ion battery. When the content of the conductive material is small, the surface of the positive electrode active material cannot be completely covered. Since the conductive material is a nanopowder, a small amount of conductive material can completely cover the surface of the positive electrode active material. Therefore, the mass ratio of the conductive material to the positive electrode active material is 0.001˜0.1:1. Preferably, the mass ratio of the conductive material to the positive electrode active material is 0.01˜0.05:1. More preferably, the mass ratio of the conductive material to the positive electrode active material is 0.03˜0.05:1.

The positive electrode active material can be a commonly used positive electrode material, such as lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium manganate, lithium cobaltate, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobaltate, nickel manganese acid Lithium and its mixtures, etc.

Experiments have proved that by adjusting the content of each component in the quaternary structure, the conductivity of the nano-powder can be significantly improved. Preferably, z is greater than or equal to 0.3 and less than or equal to 1, x is greater than or equal to 0.2 and less than or equal to 1, and y is greater than or equal to 0.17 and less than or equal to 1. More preferably, z is greater than or equal to 0.4 and less than or equal to 0.9, x is greater than or equal to 0.5 and less than or equal to 0.7, and y is greater than or equal to 0.3 and less than or equal to 0.9. Most preferably, in the quaternary structure, the contents of positive monovalent, positive divalent, positive trivalent and positive tetravalent ions are the same. On the one hand, the mutual doping through the quaternary structure can improve the conductivity, and on the other hand, it can also form defects, which is conducive to the free passage of lithium ions. The particle size of the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder is 10 nm to 100 nm, preferably, the particle size is 30 nm to 40 nm.

Please refer to Fig. 1, the present invention also provides a kind of preparation method of the positive electrode material of the lithium-ion battery of compound modification of quaternary ion, comprising:

S1, adding Mn-Ni-Fe-Cu quaternary composite oxide nanopowder into a volatile solvent for high-speed stirring and ultrasonic dispersion to form a mixed solution;

S2, adding the positive active material into the mixed solution under high-speed stirring, so that the mixed solution is uniformly coated on the surface of the positive active material to obtain a mixture; and

S3, the mixture is dried, calcined, cooled, pulverized and sieved to obtain the quaternary ion composite modified lithium ion battery positive electrode material.

In step S1, the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder can be obtained by the following method:

S11, wet mixing the manganese oxide, nickel oxide, copper oxide and iron oxide according to the stoichiometric ratio to obtain a mixture;

S12, drying, sintering and grinding the mixture to obtain Mn-Ni-Fe-Cu quaternary composite oxide nanopowder.

In step S11 , the sintering temperature is 800-900° C., the sintering time is 2-6 hours, and the sintering atmosphere is air atmosphere. Preferably, the sintering temperature is 840-850°C, so that better crystallization can be obtained.

In step S2, the time for the high-speed stirring is 20-40 minutes, and the time for the ultrasonic dispersion is 5-15 minutes. Preferably, high-speed stirring and ultrasonic dispersion are cycled 3 to 5 times in sequence. The frequency of the ultrasonic dispersion is 20kHz-40kHz. Preferably, it can be carried out by combining high-frequency (small-scale violent vibration) and low-frequency (large-scale general vibration) ultrasonic waves, such as 20kHz dispersion for 5 minutes and 40kHz dispersion for 5 dispersions, so that better dispersion can be obtained. The volatile solvent is deionized water, ethanol, methanol, acetone and mixtures thereof.

Further, in step S3, the mixture can be obtained by drying directly, or drying after filtering. The temperature of the calcination is 400-700° C., the time is 3-8 hours, and the calcination atmosphere is air or oxygen atmosphere. Experiments have proved that when the positive electrode active material is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , the calcination temperature is preferably 500-520°C; when the positive electrode active material is Li ₂ CoO ₂ , the calcination temperature is Preferably it is 600°C to 610°C.

Example 1:

Manganese dioxide, nickel oxide, copper oxide and iron oxide are mixed in a wet method according to the stoichiometric ratio of Mn _0.9 NiCu _0.3 Fe _0.6 O ₄ , mixed evenly and then dried, sintered and ground to obtain Mn-Ni-Fe-Cu Quaternary composite oxide nanopowder. Add the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder into the deionized water for high-speed stirring, and mix evenly to form a uniform solution. The active material LiNi _0.8 Co _0.15 Al _0.05 O ₂ was added to the above mixed solution under the condition of high-speed stirring, so that the coating material was evenly coated on the surface of the active material LiNi _0.8 Co _0.15 Al _0.05 O ₂ , and then the mixture was dried for 6 hours, The dried solid material was calcined at 500° C. for 8 hours, cooled, pulverized, and sieved to obtain the positive electrode material.

The electrochemical performance test of the material is tested at 25°C with the blue battery test system, and the test voltage range is 3V to 4.3V; the rate performance test conditions: 0.2C charge and discharge once, 0.2C charge 1C/5C/10C each discharge once ;;Cycle performance test conditions: charge and discharge at a rate of 1C, cycle 500 cycles, and investigate the capacity retention rate. The discharge specific capacity of the material at 0.2C rate is 196.1mAh/g, the discharge specific capacity at 1C rate is 185.8mAh/g, the discharge specific capacity at 5C rate is 176.2mAh/g, and the discharge specific capacity at 10C rate is 168.3mAh/g, 10C/0.2C discharge ratio is 85.8%, good rate performance. 1C charge-discharge cycle 500 cycle capacity retention rate is greater than 94%, good cycle performance.

Example 2:

Manganese dioxide, nickel oxide, copper oxide and iron oxide are mixed in a wet method according to the stoichiometric ratio of Mn _0.43 NiCu _0.9 Fe _0.67 O ₄ , mixed evenly and then dried, sintered and ground to obtain Mn-Ni-Fe-Cu Quaternary composite oxide nanopowder. Add the Mn-Ni-Fe-Cu quaternary composite oxide nanopowder into the deionized water for high-speed stirring, and mix evenly to form a uniform solution. The active material LiNi _0.5 Co _0.2 Mn _0.3 O ₂ was added to the above mixed solution under the condition of high-speed stirring, so that the coating material was evenly coated on the surface of the active material LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , and then the mixture was dried for 6 hours, Calcining the dried solid material at 600° C. for 6 hours, cooling, pulverizing, and sieving to obtain the positive electrode material.

Experiments have proved that the above material is the same as the material obtained in Example 1, and also has good rate performance and cycle performance.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (9)

1. a kind of composite modified anode material for lithium-ion batteries of quaternary ion, including：

Positive active material；And

Conductive material is coated on the positive active material surface；

It is characterized in that, the conductive material is Mn-Ni-Fe-Cu quaternary Composite Oxides Nanometric Powder bodies, wherein, the Mn- The molecular formula of Ni-Fe-Cu quaternary composite oxides is Mn_zNiFe_xCu_yO₄, Mn for positive tetravalence, positive trivalent and positive divalent mix from Son, Ni are positive divalent, and Fe is positive trivalent and positive divalent hybrid ionic, and Cu is more than or equal to for positive monovalence and positive divalent hybrid ionic, z 0.3 and it is more than or equal to 0.2 less than or equal to 1, x and is more than or equal to 0.17 and less than or equal to 1 less than or equal to 1, y.

2. the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 1, which is characterized in that z is big In being more than or equal to 0.5 equal to 0.4 and less than or equal to 0.9, x and be more than or equal to 0.3 and less than or equal to 0.9 less than or equal to 0.7, y.

3. the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 1, which is characterized in that described The mass ratio of conductive material and the positive active material is 0.001~0.1:1.

4. the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 3, which is characterized in that described The mass ratio of conductive material and the positive active material is 0.01~0.05:1.

5. the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 1, which is characterized in that described Positive active material is nickle cobalt lithium manganate, nickel cobalt lithium aluminate, LiMn2O4, cobalt acid lithium, LiFePO4, lithium ferric manganese phosphate, nickel cobalt acid At least one of lithium or nickel ion doped.

6. a kind of preparation method of the composite modified anode material for lithium-ion batteries of quaternary ion, which is characterized in that including：

Mn-Ni-Fe-Cu quaternary Composite Oxides Nanometric Powders body is added in, high-speed stirred and ultrasound point are carried out in easy volatile solvent It dissipates, forms a mixed solution；

Positive active material is added under conditions of high-speed stirred in the mixed solution, mixed solution is made to be evenly coated at just Pole active material surface obtains a mixture；And

By the mixture by drying, calcining is cooled down, is crushed and is sieved to obtain the composite modified lithium ion of the quaternary ion Cell positive material.

7. the preparation method of the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 6, special Sign is that the preparation method of the Mn-Ni-Fe-Cu quaternarys Composite Oxides Nanometric Powder body includes：

By manganese oxide, nickel oxide, copper oxide and iron oxide, stoichiometrically dispensing carries out wet-mixing, obtains a mixture；

Mn-Ni-Fe-Cu quaternary Composite Oxides Nanometric Powders will be obtained after mixture drying, sintering, grinding.

8. the preparation method of the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 7, special Sign is that the sintering temperature is 800~900 DEG C, and the time of sintering is 2~6h, and the atmosphere of sintering is air atmosphere.

9. the preparation method of the composite modified anode material for lithium-ion batteries of quaternary ion according to claim 6, special Sign is that 400~700 DEG C of calcination temperature, the time is 3~8h, and calcination atmosphere is air or oxygen atmosphere.