WO2006029561A1

WO2006029561A1 - Negative electrode for lithium ion secondary battery, method of making the same, and lithium ion secondary battery including the same

Info

Publication number: WO2006029561A1
Application number: PCT/CN2005/001267
Authority: WO
Inventors: Junjie Zhou
Original assignee: Chen, Guanzong; Zhang, Cuiping
Priority date: 2004-09-16
Filing date: 2005-08-16
Publication date: 2006-03-23
Also published as: CN1750296A

Abstract

The present invention discloses a negative electrode for lithium ion secondary battery, a method of making the same, and a lithium ion secondary battery including the same. The negative electrode comprises: rhombic black phosphor having orthorhombic structure; inorganic solid electrolyte crystal film applied manually on the black phosphor, the said film having a thickness of 20-5000A and including lithium ionic conductive substance having an ionic conductivity of more than 1 X 10-10 S/cm. The negative electrode can be formed easily by depositing method. A lithium ion secondary battery including the said negative is able to be made by arranging the said negative electrode with the corresponding positive electrode and electrolyte solution. The negative electrode is easily made and ideal material for superseding graphite, and the battery made thereby have high capacity. The specific capacity of the negative material in the present invention is up to more than 700 mAh/g.

Description

Negative electrode of lithium ion secondary battery, preparation method thereof and lithium ion secondary battery including the same

The present invention relates to a negative electrode of a lithium ion secondary battery, a method of producing the same, and a lithium ion secondary battery including the same. More particularly, it relates to an artificially applied inorganic solid electrolyte crystal film which has good lithium ion conductivity and is effective in forming an existing lithium ion carbonate electrolyte.

A method for producing a negative electrode of a lithium ion secondary battery of an SEI film, and a lithium ion secondary battery including the negative electrode.

Background technique

Today's society is a society in which information is rapidly developing. The speed, accuracy, and mass storage and transmission of information are requirements of the information age. The development of portable electronic devices such as mobile phones, notebook computers, and palm-sized computers has placed higher demands on light-weight, large-capacity lithium-ion secondary batteries. At present, the commercial lithium ion secondary battery anode material is usually made of graphite-based carbon material, and its disadvantages are: 1), its theoretical specific capacity is only 372 mAh / g, thus limiting the further increase of the specific capacity of the lithium ion secondary battery; 2) the tap density is lower than the energy of a small volume causing its tap density is generally 0. 8g / ^{cm: i.}

Summary of the invention

The technical problem to be solved by the present invention is to provide a negative electrode of a lithium ion secondary battery, a preparation method thereof, and a lithium ion secondary battery including the same, the negative electrode comprising a layer having good lithium ion conductivity and reacting with carbonate An inorganic solid electrolyte crystal film with good liquid compatibility. The negative electrode of the lithium ion secondary battery can be prepared by a simple method.

The technical solutions of the present invention are as follows:

A negative electrode of a lithium ion secondary battery, comprising: orthorhombic black phosphorus having an orthogonal structure; artificially applying an inorganic solid electrolyte crystal film on black phosphorus, the crystal film having a thickness of 20 to 5000 A and including a Ionic conductivity of at least 1 X 10 - ^{1 (} 's/cm lithium ion conductive material. The lithium ion conductive substance is Li _x P0 _Y , wherein 2 < X < 4 and 3 < Y < 5.

The lithium ion conductive substance is Li ₃ P0 ₄ .

5。 The lithium ion-conducting material is Li _a P0, where a is 2 - 4, b is 3 - 5, c is 0. 1 - 0. The lithium ion conductive material is Li ₂ . ₉ P0 ₃ . . ₄ «.

A method for preparing a negative electrode of a lithium ion secondary battery, wherein black phosphorus is subjected to oxidation treatment in a strong oxidizing agent solution, and a solid electrolyte crystal film is deposited by reacting with a lithium-containing compound, the crystal film containing an ionic conductivity a lithium ion conductive material of at least 1 X l (T ⁿ _S / _C m; the strong oxidizing agent is selected from the group consisting of ammonium persulfate, nitric acid, hydrogen peroxide, and sulfuric acid; and the lithium-containing compound is selected from the group consisting of n-butyl lithium, t-butyl lithium Lithium hexafluorophosphate, lithium tetrafluoroborate, lithium citrate, lithium naphthalene and lithium hydroxide.

The above lithium ion conductive substance is Li _x P0 _Y , wherein 2 < X < 4 and 3 < Y < 5.

The above lithium ion conductive substance is Li ₃ P0 ₄ .

A lithium ion secondary battery having a negative electrode deposited on a black phosphorus substrate with a crystal having a thickness of 20 to 5000 A and containing a lithium ion conductive material having an ionic conductivity of at least 1 X 10" ⁿ s/cm. The positive electrode includes a combination of any one or a combination of two or more selected from the group consisting of lithium cobaltate, lithium nickelate, lithium manganate, lithium cobalt nickelate, lithium nickel manganese oxide, lithium iron phosphate, and lithium cobalt phosphate. The main salt of the electrolyte may be lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate or lithium perfluorodecyl sulfonate; the solvent component may be ethylene carbonate or dimethyl carbonate; And a combination of one or a mixture of two or more of diethyl carbonate, propylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, diethoxyethane, and 2-methyltetrahydrofuran.

The outstanding effect of the present invention is as follows: 1) Compared with the conventional carbon negative electrode, its specific capacity can be greatly increased to 700 mAh/g; 2), the tap density is large, and the density is generally 1.27 g/cm. Increase volumetric energy.

DRAWINGS 1 is a graph showing charge and discharge curves of a black phosphorus anode amorphous film of the present invention;

2 is a second charge and discharge curve of the black phosphorus anode deposited with the LLPOJ crystal film of the present invention; FIG. 3 is an XRD pattern of the black phosphorus anode amorphous film after charging and discharging according to the present invention;

4 is an XRD pattern of a black phosphorus anode amorphous film before charging and discharging according to the present invention;

Fig. 5 is a graph showing the second charge and discharge curve after the Li ^ crystal film is deposited on the black phosphorus anode of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION 5 g of black phosphorus powder sieved through 200 mesh was placed in 100 ml of a 10% strong nitric acid solution (10 ₃ ) to be oxidized at room temperature for 10 hours, and then washed with distilled water, and then It was placed in a dry box and dried at 120 ° C for 12 hours. Then use vinylidene fluoride as binder, N-methylpyrrolidone as organic solvent, acetylene black as conductive agent, and black phosphorus: acetylene black: vinylidene fluoride=90: 4: 6 ratio mixing and mixing slurry It was coated on a current collector copper foil and dried at 12 CTC for 16 hours. Then, it is immersed in a solution of lithium-containing compound n-butyllithium/ethane in any ratio for 12 hours, washed with monomethoxyethane, placed in a vacuum drying oven, and heated to 160 ° C for 48 hours. A lithium ion secondary battery negative electrode required for the present invention is obtained.

The lithium ion secondary battery negative electrode prepared above, the positive electrode material is lithium cobaltate, the electrolyte solution is lithium hexafluorophosphate, the solvent is ethylene carbonate and diethyl carbonate, and the volume ratio is 1:1, and the separator is CeLgrd 2300 microporous film. Into a 063048 battery, the capacity of the battery was determined to be 1385 mAh.

Example 2

The lithium ion secondary battery negative electrode prepared above, the positive electrode material is lithium manganate, the electrolyte solution is lithium hexafluoroborate, the solvent is ethylene carbonate and diethyl carbonate in a volume ratio of 1 ··3, and the separator is CeLgrd 2300 micropores. Membrane, made of 063048 battery. The capacity of the battery was determined to be 1345 mAh. The lithium ion secondary battery negative electrode prepared above, the positive electrode material is lithium nickelate, the electrolytic solution is lithium chlorate, the solvent is ethylene carbonate and diethyl carbonate, and the volume ratio is 1:1, and the separator is CeLgrd 2300 micropores. The film was made into a 063048 battery, and the capacity of the battery was measured to be 1425 mAh.

Example 4:

The crystal is deposited onto the black phosphorus electrode by a target under an inert gas atmosphere, and the crystal film comprises a lithium ion conductive material having a lithium ion conductivity of at least 1 x 10 s/cm.

The lithium ion conductive substance is Li _x P0 _Y , wherein 2 < X < 4 and 3 < Y < 5, and it is stable under a nitrogen atmosphere.

5。 The lithium ion-conducting material is Li _a P0 _h N, where a is 2 - 4, b is 3 - 5, c is 0. 1 - 0.

The inert gas is selected from the group consisting of helium, neon, and argon because none of the above gases chemically react with black phosphorus to produce by-products.

The target may be Li _:i P04 or a mixture of Li ₂ 0 and mixed in a suitable mixing ratio. A Li _:i P0 ₄ crystal film was formed by depositing a Li ₃ P0 ₄ target having a diameter of 4 inches at a black phosphorus electrode for 10 minutes at a pressure of 5 mTorr, an RF power of 300 W, and an argon atmosphere.

The deposition process is carried out by a suitable method such as plating, electron beam evaporation, vacuum thermal evaporation, laser ablation, chemical vapor deposition, thermal evaporation, plasma chemical vapor deposition, laser chemical vapor deposition or jet vapor phase. Deposition. Those skilled in the relevant art will appreciate that the deposition is not limited to the above methods and includes any conventional methods.

The untreated black phosphorus was used as the negative electrode, the lithium metal plate was used as the counter electrode, the separator was CeLgrd 2300 microporous film, and the electrolyte was 1.0 mol/L, LiPF6/EC: DEC, and the solvent volume ratio was 1: 1, in relative humidity. A simulated battery was fabricated in a small 1% glove box, and the results of black phosphorus charge and discharge were measured. In Fig. 1, since an effective SEI film is not formed at 0.8 volts, solvent molecules are co-embedded in the discharge capacity map. It is not zero.

The black phosphorus electrode prepared by the above method is a negative electrode, the lithium metal plate is a counter electrode, and the separator is

CeLgrd2300 microporous membrane, electrolyte is 1. Omol / LiPF6 / EC: DEC, solvent volume ratio of 1: 1, in a glove box with a relative humidity of 1% in a glove box, the determination of black phosphorus charge and discharge performance The results are shown in Figure 2 and Figure 5. It can be seen from Figs. 2 and 5 that the negative electrode of the present invention can perform an effective charge and discharge cycle, and the discharge capacity is 630 mAh/g in Fig. 2. In Fig. 5, V represents voltage and C represents specific capacity.

Test Conditions:

0 伏伏。 Charge and discharge current density, charging current lmA / cm ² , discharge current lmA / cm ² , cutoff voltage 0 - 1. 0 volts. The experimental results show that after the black phosphorus electrode is manually deposited, a voltage platform is formed at 0.8 volts for the first charge, which corresponds to a dense and effective SEI film attached to the crystal film. Since the formation of the SEI film prevents co-intercalation of organic molecules, the discharge capacity is greater than 650 mAh/g. The black phosphorus electrode without the deposited crystal film does not form an effective SEI film, and the solvent molecules are co-embedded, causing a fundamental destruction of the black phosphorus structure, and the discharge capacity is zero. Figure 3 is an XRD pattern after charging without deposition of a crystalline film.

Working principle: Black phosphorus has a layered structure like graphite. The atoms in the layer are superimposed by σ covalent bonds, which are firmly bonded to each other. The two layers are only connected by weak van der Waals force. The crystal structure of this mixed bond type makes it The special chemical properties, that is, some atoms and molecules can be embedded between such crystal layers without destroying the covalent bonds of the stack, and only the interlayer spacing is changed to form inter-layer compounds. In graphite, one carbon atom is formed with a coordination number of three. Covalent bonds, only the remaining one electron participates in the formation of the delocalization bond, while in the black phosphorus, the phosphorus atom forms a σ covalent bond with a coordination number of 3, and a pair of orphan electrons participate in the formation of the delocalization bond. This shows that black phosphorus can provide more bonding electrons coordinated to lithium ions. Black phosphorus has a higher specific capacity than graphite. In the carbonate electrolyte system such as propylene carbonate or ethylene carbonate, the black phosphorus anode does not form an effective SEI film, resulting in co-intercalation of solvent molecules, which fundamentally destroys the black phosphorus crystal structure and makes black phosphorus. The electrode therefore loses its activity. But the orthorhombic black phosphorus of the orthogonal structure; Manually applying a film of an inorganic solid electrolyte crystal having a thickness of 20 to 5000 A and including a lithium ion conductive substance having an ionic conductivity of at least 1 X 10 s/cm, the experiment proves that the first charge is in the black phosphorus group. The negative electrode on which the crystal film is deposited on the surface of the material can form an effective SEI film, preventing the occurrence of black phosphorus structure collapse due to co-intercalation of solvent lithium ions. And it allows lithium ions to pass through it.

In the first embodiment of the present invention, the black phosphorus powder forms a phosphorus oxide and an acid under the action of a strong oxidizing agent, and after washing with distilled water, the oxide remaining on the surface of the black phosphorus is dried by heating under water and oxygen. A small amount of phosphoric acid is formed on the surface, and a crystal film of Li ₃ P0 ₄ is formed on the surface of the black phosphorus particles due to the action of phosphoric acid and a lithium-containing compound.

Claims

Rights request

A negative electrode for a lithium ion secondary battery, comprising: an orthorhombic structure having an orthogonal structure; and manually applying an inorganic solid electrolyte crystal film on the black phosphorus, the crystal film having 20 to 5000 A The thickness also includes an ion conductivity of at least 1 X 1 (T ⁽ ' _S / _C m lithium ion conductive material.

2. The anode according to claim 1, wherein the lithium ion conductive substance is Li _x P0 _Y , wherein 2 < X < 4 and 3 < Y < 5.

The negative electrode according to claim 2, wherein the lithium ion conductive substance is Li _:i P0 ₄ .

5。 The negative electrode of the present invention, wherein the lithium ion-conducting material is Li _a P0, where a is 2 - 4, b is 3 - 5, c is 0. 1 - 0.

The negative electrode according to claim 4, wherein the lithium ion conductive material is Li2.9PO3.3 No. 46.

6. A method for preparing a negative electrode of a lithium ion secondary battery, characterized in that: in a strong oxidizing agent solution, black phosphorus is subjected to an oxidation treatment, and a lithium electrolyte compound is deposited with a solid electrolyte crystal film, wherein the crystal film contains a lithium ion-conducting substance having an ionic conductivity of at least 1×10— ⁱⁿ s/cm; the strong oxidizing agent is selected from the group consisting of ammonium persulfate, nitric acid, hydrogen peroxide, and sulfuric acid; and the lithium-containing compound is selected from the group consisting of n-butyllithium, uncle Butyl lithium, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium citrate, lithium naphthalene and lithium hydroxide.

7. The method according to claim 6, wherein the lithium ion conductive substance is Li _x P0 _Y , wherein 2 < X < 4 and 3 < Y < 5.

8. The method according to claim 6, wherein: the lithium ion conductive substance is Li ₃ P (

9. A lithium ion secondary battery, characterized in that: the negative electrode is deposited on a black phosphorus substrate having a thickness of 20 to 5000 A and containing an ionic conductivity of at least 1 X 10" ^{1 (,} s/ a crystal film of a lithium ion conductive substance of cm; the positive electrode includes one selected from the group consisting of lithium cobaltate, lithium nickelate, lithium manganate, and cobalt nickel acid Lithium, lithium nickel manganese oxide, lithium iron phosphate, lithium cobalt silicate, any one or a combination of two or more of any ratio; the main salt of the electrolyte may be lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, high One of lithium chlorate or lithium perfluoroalkyl sulfonate; the solvent component may be ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, and One or a combination of two or more of ethoxyethane and 2-methyltetrahydrofuran in any ratio.