CN104733714B - Modification method of lithium ion battery cathode material - Google Patents

Abstract

The invention provides a method for surface modification of lithium manganese oxide, a cathode material of a lithium ion battery: a particle injection method is used to implant a coating material into the surface layer of a lithium manganate bulk material by bombarding with a high-speed particle beam. The coating uniformity of the surface modification method is good, and the coating thickness is controllable. The electrochemical performance test shows that the cycle stability, especially the high temperature performance, of the lithium manganate cathode material modified by the high-speed particle injection method is significantly improved.

Description

Modification method of lithium ion battery positive electrode material

technical field

The invention belongs to the technical field of preparation of positive electrode materials of lithium ion batteries, and in particular relates to a modification method of lithium manganate positive electrode materials.

Background technique

Lithium manganese oxide (LiMn ₂ O ₄ ), as the cathode material of lithium-ion batteries, has the advantages of simple synthesis, high platform voltage (3.9-4.1V), non-toxic, safe, and good overcharge resistance, and the raw material manganese resources Abundance and low price make it an ideal choice for power battery cathode materials. At present, lithium manganese oxide cathode materials mainly have problems such as storage under high temperature conditions, poor cycle performance, and severe capacity fading. The factors that cause capacity loss mainly include John-teller distortion, the dissolution and loss of manganese in the electrolyte, the decomposition of the electrolyte, and the existence of oxygen defects. These changes cause lattice instability, particle splitting, and electrolyte decomposition, making lithium manganate difficult to Form industrialization.

At present, the cycle performance of lithium manganate is mainly improved by doping and surface modification. Among them, a layer of anti-electrolyte erosion material (metal oxide, Li-containing compound, polymer, metal, fluoride, etc.) is coated on the surface of lithium manganate to form a layer that only allows Li ⁺ to pass freely, while H ⁺ and The impermeable membrane of the electrolyte can weaken the erosive effect of the electrolyte on its surface and inhibit the dissolution of Mn on the surface of lithium manganate, thereby improving its cycle stability.

US Patent No. 5,705,291 A discloses that boric acid H ₃ BO ₃ or boron oxide B ₂ O ₃ is used to coat lithium manganese oxide, which significantly improves the high-temperature storage performance.

Chinese patent 200410027362.6 discloses coating LiCoO ₂ on the surface of lithium manganate to improve the cycle stability and high temperature performance of the lithium manganate bulk material.

CN103746109A discloses a method for coating lithium manganate, the anode material of a lithium ion battery, in a liquid phase method. The acid salt of the metal oxide is made into a liquid, and stirred at a high speed to obtain a sol, and then the sol is mixed with lithium manganate and metal oxide. After the acid salt is mixed, add it to the high-speed stirring dispersant and chelating agent, mix the obtained mixture thoroughly, dry, crush and sieve, and sinter the sieved mixture in two stages in the air flow. After sintering, cool with the furnace and crush. Pass through a 400 mesh sieve. CN103456942A also adopts the liquid phase coating process.

CN104134793A discloses the preparation method of lithium manganese oxide, the cathode material of lithium ion battery, according to the following steps: 1. preparation of lithium manganate in the inner core, 2. preparation of doped modified lithium manganate, 3. mixing, 4. spray drying, 5. After sintering, the inner core of the particle obtained is lithium manganese oxide, and the surface layer is coated with doped modified lithium manganate, and the thickness of the coating layer is 200-400nm.

CN103172120A discloses a method for preparing a silicon-coated lithium-ion battery positive electrode material. The surface of the lithium manganate substrate is chemically precipitated and coated with SiO ₂ .H ₂ O, and the precipitation reaction is carried out. After the silicon precipitation is fully reacted, the discharged material After slurry washing, solid-liquid separation, and drying, a silicon dioxide-coated lithium manganate cathode material is obtained.

In summary, the surface modification of lithium manganate generally adopts liquid phase or wet chemical methods (such as sol-gel method, co-precipitation method, polymerization method, electroless plating method), and the coating material is dispersed in the lithium manganate body. The surface of the material is then subjected to subsequent heat treatment to achieve the coating of lithium manganese oxide. Among the many surface modification methods, how to control the consistency and uniformity of the coating, as well as the stability in the industrial production process, is the key technology to realize the industrial production of lithium manganate materials.

Contents of the invention

The purpose of the present invention is to solve the problems of unstable circulation and poor high-temperature performance existing in the existing lithium manganate positive electrode materials, and overcome the deficiencies of the prior art, and provide a surface modification method of lithium manganate and modified manganese Lithium Oxide Cathode Material.

The invention provides a method for preparing a modified lithium manganate positive electrode material for a lithium ion battery, which is characterized in that it comprises the following steps: adopting a particle injection method, implanting a coating material into a lithium manganate body material by bombarding with a high-speed particle beam In the surface layer, the cladding material is selected from metal oxides or nitrides. Correspondingly, a modified lithium manganate positive electrode material for lithium ion batteries is also provided, which is composed of lithium manganate and metal oxide or metal nitride, wherein the metal oxide or nitride is coated or embedded in lithium manganate in the surface layer of the material.

The invention adopts the particle injection method, and implants the cladding material into the surface layer of the lithium manganate body material through the bombardment of the high-speed particle beam.

In the modification method, the cladding material includes metal, metal compound, non-metal, and non-metal compound. The metal is selected from any one of aluminum, copper, zinc, nickel, platinum, gold, and silver. The metal compound is selected from one of metal oxides and metal nitrides. The metal oxide is selected from one of aluminum oxide, zinc oxide, magnesium oxide, titanium oxide, and copper oxide. The metal nitride is selected from one of titanium nitride and nickel nitride. The non-metal is selected from one of carbon and conductive polymers. The non-metallic compound is selected from silica.

The high-speed particle injection is carried out under any atmosphere or two atmospheres selected from argon, oxygen, nitrogen, and ammonia, preferably oxygen or ammonia, more preferably a mixture of oxygen and ammonia, and the gas flow rate is 5-60 sccm, The air pressure is 2×10 ^-4 ~ 5×10 ^-4 Pa. The temperature is 100-500°C, preferably 150-200°C.

The coating material has a thickness of 0.5-20 nm, preferably 2-10 nm.

Lithium manganate cathode material can be selected from lithium manganate LiMn ₂ O ₄ , cation-doped lithium manganate LiM _x Mn _2-x O ₄ (wherein, M is selected from Ge, Cr, Fe, Co, Ni, Zn, Al , Cu and Mg, 0<X≤0.5), anion-doped lithium manganate LiMn _2-x O _4-y M _y (where M is selected from one of O and F, 0<X≤ 0.25, 0<Y≤0.25), a variety of cation-doped LiM1 _x M2 _y Mn _2-xy O ₄ (where M1, M2 are selected from Ge, Cr, Fe, Co, Ni, Zn, Al, Cu, Mg Any one of them, 0<X≤0.25, 0<Y≤0.25), and anion-cation complex doped lithium manganate.

The invention also provides an electrode containing the positive electrode material of lithium manganate.

The present invention also provides an energy storage element containing the electrode, the energy storage element is preferably a lithium ion battery.

The present invention also provides a portable electronic device containing the energy storage element, and the portable electronic device is preferably a mobile phone, a camera, a video camera, MP3, MP4, and a notebook computer.

Compared with the prior art, the present invention has the following advantages: better coating uniformity and controllable coating thickness. The obtained lithium manganate cathode material has good consistency, and the electrochemical performance test shows that the cycle stability, especially the high temperature performance, of the lithium manganate cathode material modified by the high-speed particle injection method is significantly improved.

Description of drawings

Fig. 1 is the SEM scanning electron micrograph of the lithium manganate material bulk material that the present invention makes.

Fig. 2 is a SEM scanning electron micrograph of the modified lithium manganate material prepared in Example 1 of the present invention.

detailed description

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

In order to test the electrochemical performance of the lithium manganate cathode material prepared by the method of the present invention, the lithium manganate body material was first prepared: _LiNO3 and MnCl2 _were weighed according to the Li:Mn molar ratio of 0.55, dissolved in water Dubbed and stirred to obtain a clear solution, adding HNO ₃ to adjust the pH value at 2-2.5. Then spray drying to obtain lithium manganate precursor. The precursor was calcined in a muffle furnace at 750° C. for 10 h to obtain a lithium manganate bulk material (as shown in FIG. 1 ). Secondly, the high-speed particle injection method was used to modify the surface of the lithium manganate bulk material, and the specific preparation process was shown in Examples 1-4. Finally, the lithium manganate positive electrode material in the present invention is stirred and mixed with the binder polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) according to the ratio of 9:0.5:0.5 to form a uniform slurry, and coated on The surface of the aluminum foil is dried and sliced to obtain the positive electrode sheet; the metal lithium sheet is used as the counter electrode, and the electrolyte is ethylene carbonate (EC) and dimethyl carbonate (DMC) of 1M LiFP ₆ (volume ratio is 1:1) solution, assembled into a button cell. The assembled coin cells were tested for cycle performance using the Arbin battery test system at 25°C and 55°C, respectively. The charge and discharge current is 1C, and the charge and discharge voltage range is 3.0V to 4.3V. The battery test results of the lithium manganate cathode material prepared in this example are listed in Table 1.

Example 1

Titanium oxide-coated lithium manganate material: put the prepared lithium manganate body material into a vacuum chamber, evacuate to a vacuum degree of 3×10 ^-4 Pa, heat to 100°C, and bombard metallic titanium (purity 99.9 %), first feed argon into the vacuum chamber, the flow rate is 50 sccm, and then feed oxygen with a flow rate of 5 sccm, the whole process continues for 5 min, and the lithium manganate material (as shown in Figure 2) coated with nano-titanium oxide is obtained. The thickness of the cladding material is 1-3nm.

Example 2

The whole process of feeding oxygen lasts for 10 minutes, so as to control the thickness of the cladding material to be 8-10 nm, and the others are the same as in Example 1.

Example 3

Zinc oxide-coated lithium manganate material: put the prepared lithium manganate body material into a vacuum chamber, evacuate to a vacuum degree of 2×10 ^-4 Pa, heat to 150°C, and bombard metal zinc (purity 99.9 %), argon gas is first introduced into the vacuum chamber with a flow rate of 50 sccm, and then oxygen gas is introduced at a flow rate of 5 sccm. The whole process lasts for 3 minutes, and the thickness of the coating layer is controlled to be 3-5 nm, and lithium manganate coated with nano-zinc oxide is obtained. Material.

Example 4

Other conditions are the same as in Example 3, except that the vacuum is evacuated to a degree of 3×10 ^-4 Pa, and the temperature is heated to 180° C., so that the thickness of the cladding layer is 1-3 nm.

Example 5

Alumina-coated lithium manganate material: put the prepared lithium manganate body material into a vacuum chamber, evacuate to a vacuum degree of 3×10 ^-4 Pa, heat to 150°C, and bombard metal aluminum (purity 99.9 %), first feed argon into the vacuum chamber with a flow rate of 50 sccm, and then feed oxygen with a flow rate of 5 sccm. The whole process lasts for 5 minutes, and the thickness of the coating layer is controlled to be 1-3nm, and lithium manganate coated with nano-alumina is obtained. Material.

Example 6

Titanium nitride-coated lithium manganate material: put the prepared lithium manganate body material into a vacuum chamber, evacuate to a vacuum degree of 3×10 ^-4 Pa, heat to 200°C, and bombard metal titanium with high-speed particles (purity 99.9%), argon gas was introduced into the vacuum chamber at a flow rate of 50 sccm, and then nitrogen gas was introduced at a flow rate of 5 sccm. The whole process continued for 5 minutes, and a lithium manganate material coated with nano-titanium nitride was obtained. The thickness of the coating material was 1 -3nm.

Example 7

Preparation of magnesium doped lithium manganese oxide

Other conditions are the same as those for the preparation of the lithium manganate bulk material in the specific embodiment, except that when weighing LiNO _{3 and MnCl 2 according to the Li:Mn molar ratio of 0.55, while weighing LiNO 3 and MnCl 2 , weigh} Take 5% of MgNO ₃ by total weight of LiNO ₃ and MnCl ₂ .

Example 8

Titanium oxide coated magnesium doped lithium manganese oxide material

Other conditions are the same as in Example 1, except that the magnesium-doped lithium manganate prepared in Example 7 is used to obtain magnesium-doped lithium manganate coated with titanium oxide.

Comparative example 1

Immerse the lithium manganate body material in 100ml of 5% tetrabutyl titanate ethanol solution, stir for 1h, add 1ml of water, then heat the solution at 100°C for 6h, cool naturally and dry to obtain titanium oxide-coated manganese Lithium Oxide.

Table 1 Cycle performance comparison of lithium manganese oxide cathode materials

It can be seen from Table 1 that when the lithium manganese oxide cathode material is coated with nano-titanium oxide, zinc oxide, aluminum oxide, titanium nitride and other materials by high-speed particle injection method, the cycle performance is improved, and the high-temperature cycle performance is significantly improved. , among them, the effect of coating titanium nitride is the best.

Claims (13)

1. a kind of preparation method of modified lithium ion battery mangaic acid lithium anode material, it is characterised in that comprise the steps：Adopt Particle injection method is used, covering material is implanted in the top layer of LiMn2O4 bulk material by high velocity beam bombardment, the bag Material selected from metal oxide or metal nitride are covered, the thus obtained manganate cathode material for lithium is by LiMn2O4 and metal oxygen Compound or metal nitride composition, wherein metal-oxide or metal nitride coat or are implanted in the top layer of lithium manganate material In.

2. the method described in claim 1, it is characterised in that：High-velocity particles is infused in selected from argon, oxygen, nitrogen, ammonia Carry out under any one atmosphere or two kinds of atmosphere；Gas flow is 5-60sccm, air pressure 2 × 10^-4～5 × 10^-4Pa。

3. the method described in claim 2, it is characterised in that：High-velocity particles is infused in any one gas selected from oxygen or ammonia Carry out under atmosphere or two kinds of atmosphere.

4. the method described in claim 1, it is characterised in that：High-velocity particles implantation temperature is at 100-500 DEG C；The cladding material of preparation Material thickness is 1-10nm.

5. the method described in claim 1, it is characterised in that：The metal-oxide of covering material is selected from aluminium oxide, Zinc Oxide, oxygen Change the one kind in magnesium, titanium oxide, copper oxide；The one kind of metal nitride in titanium nitride, nickel oxide.

6. the method described in claim 1, it is characterised in that：Manganate cathode material for lithium is selected from：

LiMn2O4 LiMn₂O₄；

The LiMn2O4 LiM of cation doping_xMn_2-xO₄, wherein, M be selected from Ge, Cr, Fe, Co, Ni, Zn, Al, Cu and Mg, 0 ＜ X≤ 0.5；

Anion doped LiMn2O4 LiMn_2-xO_4-yM_y, wherein, the one kind of M in two kinds of elements of O and F, 0 ＜ X≤0.25,0 ＜ Y≤0.25；

The LiM1 of various cation dopings_xM2_yMn_2-x-yO₄, wherein, M1, M2 are in Ge, Cr, Fe, Co, Ni, Zn, Al, Cu, Mg Any one, 0 ＜ X≤0.25,0 ＜ Y≤0.25；

And the LiMn2O4 of above-mentioned Anion-cation multiple dope.

7. a kind of method of modifying of lithium ion battery mangaic acid lithium anode material, it is characterised in that comprise the steps：Using particle Injection method, is implanted in covering material in the top layer of LiMn2O4 bulk material by high velocity beam bombardment.

8. the method for modifying described in claim 7, it is characterised in that：High-velocity particles is infused in selected from argon, oxygen, nitrogen, ammonia Carry out under any one atmosphere of gas or two kinds of atmosphere；Gas flow is preferably 5-60sccm, air pressure 2 × 10^-4～5 × 10^{- 4}Pa。

9. the method for modifying described in claim 7, it is characterised in that：High-velocity particles implantation temperature is at 100-500 DEG C；The bag of preparation Material thickness is covered for 1-10nm.

10. the method for modifying described in claim 7, it is characterised in that：The metal-oxide of covering material is selected from aluminium oxide, oxidation One kind in zinc, magnesium oxide, titanium oxide, copper oxide；The one kind of metal nitride in titanium nitride, nickel oxide.

Method of modifying described in 11. claim 7, it is characterised in that：

Manganate cathode material for lithium is selected from LiMn2O4 LiMn₂O₄；

The LiMn2O4 LiM of cation doping_xMn_2-xO₄, wherein, M be selected from Ge, Cr, Fe, Co, Ni, Zn, Al, Cu and Mg, 0 ＜ X≤ 0.5；

Anion doped LiMn2O4 LiMn_2-xO_4-yM_y, wherein, the one kind of M in two kinds of elements of O and F, 0 ＜ X≤0.25,0 ＜ Y≤0.25；

The LiM1 of various cation dopings_xM2_yMn_2-x-yO₄, wherein, M1, M2 are in Ge, Cr, Fe, Co, Ni, Zn, Al, Cu, Mg Any one, 0 ＜ X≤0.25,0 ＜ Y≤0.25；

And the LiMn2O4 of above-mentioned Anion-cation multiple dope.

12. a kind of manganate cathode material for lithium, it is characterised in that prepared by claim 1 methods described.

13. a kind of energy storage elements, it is characterised in that containing a kind of electrode, the electrode contains the manganese described in claim 12 Sour lithium anode material.