阅读说明：本技术 钠离子电池用正极添加剂、电池正极、钠离子电池及应用 (Positive electrode additive for sodium ion battery, battery positive electrode, sodium ion battery and application ) 是由 孟婧珂 戚兴国 鞠学成 任瑜 唐堃 于 2019-10-31 设计创作，主要内容包括：本发明实施例涉及一种钠离子电池用正极添加剂、电池正极、钠离子电池及应用,钠离子电池正极包括：正极活性材料和正极添加剂；所述正极添加剂为牺牲盐,化学式为Li<Sub>x</Sub>M<Sub>y</Sub>O<Sub>z</Sub>；其中,M为元素周期表中的第三、第四及第五周期中的一种或多种元素组合；x,y及z满足电荷平衡,并且满足x≥1,y≥1,z≥2；所述正极添加剂与所述正极活性材料的质量比小于等于1：5。(The embodiment of the invention relates to a positive electrode additive for a sodium ion battery, a battery positive electrode, the sodium ion battery and application, wherein the positive electrode of the sodium ion battery comprises: a positive electrode active material and a positive electrode additive; the positive electrode additive is sacrificial salt with a chemical formula of Li x M y O z (ii) a Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2; the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 1: 5.)

1. A positive electrode for a sodium-ion battery, comprising: a positive electrode active material and a positive electrode additive;

the positive electrode additive is sacrificial salt with a chemical formula of Li _xM _yO _z；

Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2;

the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 1: 5.

2. the sodium-ion battery positive electrode according to claim 1, further comprising: adhesives and conductive agents;

the positive active material, the positive additive, the adhesive and the conductive agent are mixed into slurry by a solvent, and the slurry is coated on the surface of a current collector and dried to form the positive electrode of the sodium-ion battery; or, mixing the positive active material, the positive additive, the adhesive and the conductive agent, and rolling to form a positive pole piece to form the positive electrode of the sodium-ion battery; or, the positive active material, the positive additive, the adhesive and the conductive agent are mixed and pressed on the surface of the current collector to form the positive electrode of the sodium-ion battery.

3. The positive electrode for sodium-ion batteries according to claim 2,

the positive electrode active material includes: a layered transition metal oxide or polyanion compound; the proportion of the positive electrode active substance in the positive electrode of the sodium ion battery is more than or equal to 70 wt%; wherein the layered transition metal oxide is sodium-deficient P2-Na _0.67MO ₂Or O3-NaMO ₂(ii) a The polyanion compound is Na _jM _pV _q(PO ₄) ₃F _n(ii) a j is more than or equal to 1, p is more than or equal to 0, q is more than or equal to 0, n is more than or equal to 0, and the charge balance is met;

the conductive agent is one or more of carbon nano tube, acetylene black, conductive carbon black, conductive graphite, carbon fiber and graphene; the conductive agent accounts for less than or equal to 20 wt% of the positive electrode of the sodium-ion battery;

the adhesive is one or more of polyolefin, fluorine-containing resin, polypropylene resin and rubber; the proportion of the adhesive in the positive electrode of the sodium-ion battery is less than or equal to 10 wt%.

4. The sodium ion battery positive electrode of claim 3, wherein the O3-NaMO is present in the electrolyte solution ₂Has a structural formula of Na _xCu _yFe _zMn _nM _1-x-y-nO ₂M is one or more of Ni, Mg, Al, Cr, Ti, Mo, Nb and V.

5. The positive electrode for sodium-ion battery according to claim 1, wherein the conductive agent is conductive carbon black; the binder is polyvinylidene fluoride (PVDF); the positive electrode additive includes Li ₂NiO ₂、Li ₂MnO ₂、Li ₂MnO ₃、Li ₅FeO ₄、Li ₆CoO ₄、Li ₆MnO ₄At least one of (1).

6. The positive electrode additive for the sodium-ion battery is characterized in that the positive electrode additive is sacrificial salt with a chemical formula of Li _xM _yO _z；

Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2; the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 20%.

7. The positive electrode additive for sodium-ion batteries according to claim 6, characterized in that the positive electrode additive comprises Li ₂NiO ₂、Li ₂MnO ₂、Li ₂MnO ₃、Li ₅FeO ₄、Li ₆CoO ₄、Li ₆MnO ₄At least one of (1).

8. A sodium ion battery comprising a positive electrode for the sodium ion battery of any one of claims 1 to 5.

9. The sodium ion battery of claim 8, wherein the negative electrode material of the sodium ion battery is one or more of hard carbon, soft carbon, transition metal oxides, transition metal sulfides, transition metal phosphides, or alloy materials, and composites thereof.

10. Use of the sodium ion battery according to claim 8, wherein the sodium ion battery is used in power tools, electric vehicles, and energy storage devices for solar power generation, wind power generation, smart grid peak shaving, distributed power plants, backup power sources, or communication base stations.

Technical Field

The invention relates to the technical field of battery materials, in particular to a positive electrode additive for a sodium ion battery, a sodium ion battery positive electrode, a sodium ion battery and application.

Background

The sodium ion battery has a wide application prospect in the field of energy storage due to the cost advantage, the working principle of the sodium ion battery is similar to that of the lithium ion battery, and the reversible embedding and releasing of sodium ions between a positive electrode and a negative electrode are utilized to realize the storage and the release of energy. At present, common positive electrode materials of sodium ion batteries, such as layered transition metal oxides, tunnel structure oxides, polyanion compounds and the like, show higher energy density only when a metal sodium sheet is used as a counter electrode of the battery. However, when assembled into a full cell, the negative electrode sheet may form a solid electrolyte film (SEI film) during the first charge, consuming a portion of sodium ions, causing a loss of sodium of the positive electrode material, thereby reducing the energy density of the cell.

In view of the above problems, a concept of "compensation", that is, the consumption of ions when an SEI film is formed during the first charge and discharge, is supplemented by various methods, has been proposed. At present, sodium supplement methods mainly comprise a sodium cold pressing tablet method, an electrodeposition method, an additive method and the like. The use of sodium foil or electrochemical methods and other processes is cumbersome, the equipment cost is high, and the consistency of the battery is difficult to ensure. The additive method is adopted, the existing production process is not required to be changed, the additive is only required to be added into the slurry in the mixing process, and the operation is simple. At present, the commonly used compensation agent uses sacrificial sodium salt, and a large amount of sodium ions are removed in the process of charging a sodium ion full battery to supplement the consumption of the sodium ions when an SEI film is formed, so that the first efficiency of the battery is improved.

The invention aims to find a novel compensation agent which is separated from a sodium ion system, can also reduce the consumption of sodium ions and improve the energy density of a sodium ion battery.

Disclosure of Invention

The invention aims to provide a positive electrode additive for a sodium ion battery, a battery positive electrode, the sodium ion battery and application thereof.

To achieve the above object, in a first aspect, the present invention provides a positive electrode for a sodium-ion battery, comprising:

a positive electrode active material and a positive electrode additive;

the positive electrode additive is sacrificial salt with a chemical formula of Li _xM _yO _z；

Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2;

the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 1: 5.

preferably, the positive electrode for sodium-ion batteries further comprises: adhesives and conductive agents;

the positive active material, the positive additive, the adhesive and the conductive agent are mixed into slurry by a solvent, and the slurry is coated on the surface of a current collector and dried to form the positive electrode of the sodium-ion battery; or, mixing the positive active material, the positive additive, the adhesive and the conductive agent, and rolling to form a positive pole piece to form the positive electrode of the sodium-ion battery; or, the positive active material, the positive additive, the adhesive and the conductive agent are mixed and pressed on the surface of the current collector to form the positive electrode of the sodium-ion battery.

Preferably, the positive electrode active material includes: a layered transition metal oxide or polyanion compound; the proportion of the positive active material in the positive electrode of the sodium-ion battery is more than or equal to 70 wt%; wherein the layered transition metal oxide is sodium-deficient P2-Na _0.67MO ₂Or O3-NaMO ₂(ii) a The polyanion compound is Na _jM _pV _q(PO ₄) ₃F _n(ii) a j is more than or equal to 1, p is more than or equal to 0, q is more than or equal to 0, n is more than or equal to 0, and the charge balance is met;

the conductive agent is one or more of carbon nano tube, acetylene black, conductive carbon black, conductive graphite, carbon fiber and graphene; the conductive agent accounts for less than or equal to 20 wt% of the positive electrode of the sodium-ion battery;

the adhesive is one or more of polyolefin, fluorine-containing resin, polypropylene resin and rubber; the proportion of the adhesive in the positive electrode of the sodium-ion battery is less than or equal to 10 wt%.

Preferably, the O3-NaMO ₂Has a structural general formula of Na _xCu _yFe _zMn _nM _1-x-y-nO ₂M is one or more of Ni, Mg, Al, Cr, Ti, Mo, Nb and V.

Preferably, the conductive agent is conductive carbon black; the binder is polyvinylidene fluoride (PVDF); the positive electrode additive includes Li ₂NiO ₂、Li ₂MnO ₂、Li ₂MnO ₃、Li ₅FeO ₄、Li ₆CoO ₄、Li ₆MnO ₄At least one of (1).

In a second aspect, embodiments of the present invention provide a positive electrode additive for a sodium ion battery, where the positive electrode additive is a sacrificial salt and has a chemical formula of Li _xM _yO _z；

Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2; the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 20%.

Preferably, the positive electrode additive includes Li ₂NiO ₂、Li ₂MnO ₂、Li ₂MnO ₃、Li ₅FeO ₄、Li ₆CoO ₄、Li ₆MnO ₄At least one of (1).

In a third aspect, an embodiment of the present invention provides a sodium-ion battery including the positive electrode of the sodium-ion battery described in the first aspect.

Preferably, the negative electrode material of the sodium ion battery is one or more of hard carbon, soft carbon, transition metal oxide, transition metal sulfide, transition metal phosphide or alloy material and composite material thereof.

In a fourth aspect, embodiments of the present invention provide a use of a sodium ion battery, where the sodium ion battery is used for an electric tool, an electric vehicle, and an energy storage device of solar power generation, wind power generation, smart grid peak shaving, a distributed power station, a backup power source, or a communication base station.

According to the sodium ion battery anode provided by the embodiment of the invention, the lithium-containing additive with stable chemical components is added to serve as sacrificial salt, and the additive has higher initial charge specific capacity and lower discharge capacity, so that the dosage of the additive is small. For a sodium ion battery, during the first charge, since a part of sodium ions extracted from a positive electrode material is used to participate in the formation of an SEI film, the number of effective sodium ions is reduced, thereby reducing the energy density of the battery. And by adding the lithium-containing additive into the positive electrode material, the energy density of sodium ions can be greatly improved: on one hand, the lithium-containing additive has higher specific capacity, and the integral first charging specific capacity of the battery can be improved by adding a small amount of the lithium-containing additive, so that the lithium-containing additive participates in the formation of an SEI film; on the other hand, the lithium-containing material has a high irreversible capacity loss, i.e., only a small amount of lithium is re-inserted into the positive electrode material after the first charge. In addition, the preparation method of the additive used in the invention has simple process and low requirement on the operating environment, does not change the existing production process of the sodium-ion battery, and greatly reduces the production cost.

Drawings

FIG. 1 shows Li as an additive for lithium-containing lithium in example 1 of the present invention ₅FeO ₄X-ray diffraction (XRD) pattern of (a);

FIG. 2 shows Li in example 1 of the present invention ₅FeO ₄The first charge-discharge curve of (1);

FIG. 3 shows that 1 wt% of Li is contained in example 1 of the present invention ₅FeO ₄The first charge-discharge curve of the NNM hybrid material of (a);

FIG. 4 shows that 5 wt% of Li was contained in example 2 of the present invention ₅FeO ₄The first charge-discharge curve of the NNM hybrid material of (a);

FIG. 5 shows that 10 wt% of Li was contained in example 3 of the present invention ₅FeO ₄Of NNM hybridThe first charge-discharge curve of the material;

FIG. 6 shows that 20 wt% of Li was contained in example 4 of the present invention ₅FeO ₄The first charge-discharge curve of the NNM hybrid material of (a);

FIG. 7 shows an example of the present invention in which 5 wt% of Li is contained ₅FeO ₄The first charge-discharge curve of the CFM hybrid material;

FIG. 8 shows an example of the present invention in which 5 wt% of Li is contained ₅FeO ₄The first charge-discharge curve of the NCFM hybrid material of (1);

FIG. 9 is a first charge-discharge curve of NNMs of comparative example 1 of the present invention;

FIG. 10 is a first charge and discharge curve of CFM of comparative example 2 of the present invention;

FIG. 11 is a first charge-discharge curve of NCFM in comparative example 3 of the present invention.

Detailed Description

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

The positive electrode additive for the sodium-ion battery provided by the embodiment is used as a sacrificial salt in the positive electrode of the sodium-ion battery.

The chemical formula of the positive electrode additive is Li _xM _yO _z(ii) a Wherein M is one or more element combinations in the third, fourth and fifth periods of the periodic table; x, y and z satisfy charge balance, and satisfy x is more than or equal to 1, y is more than or equal to 1, and z is more than or equal to 2; the mass ratio of the positive electrode additive to the positive electrode active material is less than or equal to 20%.

In a preferred example, the positive electrode additive includes Li ₂NiO ₂、Li ₂MnO ₂、Li ₂MnO ₃、Li ₅FeO ₄、Li ₆CoO ₄、Li ₆MnO ₄At least one of (1).

The sodium ion battery positive electrode is used for the sodium ion battery positive electrode, and the sodium ion battery positive electrode further comprises: a positive electrode active material, a binder, and a conductive agent.

The positive electrode active material, the positive electrode additive, the adhesive and the conductive agent are mixed into slurry by a solvent, and the slurry is coated on the surface of a current collector and dried to form the positive electrode of the sodium-ion battery; or mixing the positive active material, the positive additive, the adhesive and the conductive agent, and rolling and pressing the mixture into a positive pole piece to form the positive pole of the sodium-ion battery; or, mixing the positive active material, the positive additive, the adhesive and the conductive agent, and pressing the mixture on the surface of the current collector to form the positive electrode of the sodium-ion battery.

The positive electrode active material includes: a layered transition metal oxide or polyanion compound; the proportion of the positive active material in the positive electrode of the sodium-ion battery is more than or equal to 70 wt%; wherein the layered transition metal oxide is sodium-deficient P2-Na _0.67MO ₂Or O3-NaMO ₂(ii) a The polyanionic compound is Na _jM _pV _q(PO ₄) ₃F _n(ii) a j is more than or equal to 1, p is more than or equal to 0, q is more than or equal to 0, n is more than or equal to 0, and the charge balance is met;

the conductive agent is one or more of carbon nano tube, acetylene black, conductive carbon black, conductive graphite, carbon fiber and graphene; the conductive agent accounts for less than or equal to 20 wt% of the positive electrode of the sodium-ion battery; in a preferred scheme, the conductive agent is conductive carbon black;

the adhesive is one or more of polyolefin, fluorine-containing resin, polypropylene resin and rubber; the proportion of the adhesive in the positive electrode of the sodium-ion battery is less than or equal to 10 wt%; in a preferred embodiment, the binder is polyvinylidene fluoride (PVDF).

The positive electrode material of the sodium ion battery and the negative electrode material of the sodium ion battery can jointly form the sodium ion battery, and the used negative electrode material is one or more of hard carbon, soft carbon, transition metal oxide, transition metal sulfide, transition metal phosphide or alloy material and composite material thereof. The alloy material may be an alloy of Sn, P, Se, Bi, or the like.

According to the sodium ion battery anode provided by the embodiment of the invention, the lithium-containing additive with stable chemical components is added to serve as sacrificial salt, and the additive has higher initial charge specific capacity and lower discharge capacity, so that the dosage of the additive is small. For a sodium ion battery, during the first charge, since a part of sodium ions extracted from a positive electrode material is used to participate in the formation of an SEI film, the number of effective sodium ions is reduced, thereby reducing the energy density of the battery. And by adding the lithium-containing additive into the positive electrode material, the energy density of sodium ions can be greatly improved: on one hand, the lithium-containing additive has higher specific capacity, and the integral first charging specific capacity of the battery can be improved by adding a small amount of the lithium-containing additive, so that the lithium-containing additive participates in the formation of an SEI film; on the other hand, the lithium-containing material has a high irreversible capacity loss, i.e., only a small amount of lithium is re-inserted into the positive electrode material after the first charge. In addition, the preparation method of the additive used in the invention has simple process and low requirement on the operating environment, does not change the existing production process of the sodium-ion battery, and greatly reduces the production cost.

The sodium ion battery obtained by the invention can be used for electric tools, electric vehicles, and energy storage equipment of solar power generation, wind power generation, smart grid peak regulation, distributed power stations, backup power supplies or communication base stations.

The preparation process and performance of the silicon-based negative electrode material for lithium batteries according to the present invention are illustrated in the following specific examples.