WO2018209762A1

WO2018209762A1 - Lithium battery anode and preparation method and application thereof

Info

Publication number: WO2018209762A1
Application number: PCT/CN2017/090252
Authority: WO
Inventors: 宋殿权; 张春涛; 王永鹤
Original assignee: 哈尔滨光宇电源股份有限公司
Priority date: 2017-05-15
Filing date: 2017-06-27
Publication date: 2018-11-22
Also published as: CN107093706A

Abstract

A preparation method of a lithium battery anode relates to the field of solid-state batteries and liquid-state batteries. The current problems of low gram specific capacity of a conventional graphite negative electrode, ready dendritic growth, low initial coulombic efficiency, and low battery energy density are solved accordingly. The method comprises: step 1, mixing 75%-90% by mass of a carbon material, 5%-20% by mass of a conductive agent, and 5%-10% by mass of a binding agent to form an adsorptive or porous intermediate layer (1), and coating the intermediate layer (1) at a thickness of 1-70 μm on a current collector (4); step 2, vapor depositing a lithium metal layer or a sodium metal layer (2) at a thickness of 1-30 μm uniformly on the intermediate layer (1); and step 3, connecting a battery tab (3) to the current collector (4) after carrying out step 1 and step 2 to complete the preparation of a lithium battery negative electrode. The lithium battery negative electrode can be applied in the solid-state battery field and the liquid-state battery field.

Description

Lithium battery anode and preparation method and application thereof

The present application claims priority to Chinese Patent Application No. JP-A No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No.

Technical field

The invention relates to a method for preparing a negative electrode of a lithium battery. It belongs to the field of solid-state batteries and liquid batteries.

Background technique

Lithium metal anodes can theoretically provide more capacity (3860mAh/g, graphite anode: 370mAh/g) compared to graphite anodes used in commercial lithium-ion batteries. Lithium metal anodes are expected to be in next-generation portable electronic devices. And large areas of applications such as electric vehicles. Lithium-sulfur batteries and lithium-ion batteries with lithium metal as the negative electrode have gradually attracted the attention of researchers, and have become a hot spot in academic and industrial research in recent years. However, there are still many problems in the research of lithium metal anodes, the most important of which is the growth of dendrites. The dendrites are dendritic lithium deposits which appear in the negative electrode during the multiple deposition/precipitation of the lithium ion negative electrode. Dendritic growth brings two problems: (1) the dendrite will pierce the diaphragm and cause short circuit of the battery. The short-circuit current inside the positive and negative electrodes generates heat inside the battery, causing the battery system to run out of control, which may cause the battery to catch fire or even explode. A series of safety issues; (2) dendrites will increase the side reaction of electrolyte and metal lithium, consume lithium active substances, and reduce battery utilization. The lithium dendrites that are out of the current collector are dead lithium, and the presence of dead lithium reduces the available active materials, reducing the efficiency and cycle life of the battery.

At present, lithium dendrites cannot be fundamentally avoided. Lithium batteries based on lithium metal anodes are still in the laboratory stage, and few industrial achievements have been made.

Summary of the invention

The invention is to solve the problem that the conventional graphite anode has a low specific capacity, a dendrite is easy to grow, a first coulombic efficiency is low, and a battery energy density is low, and a lithium battery anode preparation method is now provided.

The invention provides a method for preparing a negative electrode of a lithium battery, the method comprising the following steps:

Step 1: mixing a carbon material having a mass percentage of 75% to 90%, a conductive agent having a mass percentage of 5% to 20%, and a binder having a mass percentage of 5% to 10%. Adsorbing or porous intermediate substance layer (1), and then applying intermediate substance layer (1) to a thickness of 1 μm to 70 μm Current collector (4);

Step 2, uniformly depositing a metal lithium layer or a metal sodium layer (2) having a thickness of 1 μm to 30 μm on the intermediate material layer (1);

Step 3: After completing the operations of Step 1 and Step 2, the tab (3) is connected to the current collector (4) to complete the preparation of the anode of the lithium battery.

The invention provides a lithium battery negative electrode, which comprises:

a current collector connected to the ear;

Coating an intermediate substance layer formed on the current collector;

a metal lithium layer or a metallic sodium layer attached to the intermediate material layer;

The intermediate material layer is composed of the following mass percentage components: carbon-based material 75% to 90%, conductive agent 5-20%, and binder 5-10%; the intermediate material layer has a thickness of 1 μm~ 70 μm; the metal lithium layer or the metal sodium layer has a thickness of 1 μm to 30 μm.

The beneficial effects of the invention are:

The negative electrode of the lithium battery of the present invention is composed of a bottom layer current collector, an intermediate material layer and a metal lithium layer or a metal sodium layer attached to the intermediate material layer, wherein the intermediate material layer is composed of a component represented by the following mass percentage: carbon 75% to 90% of the material, 5% to 20% of the conductive agent and 5% to 10% of the binder, the thickness of the intermediate layer is 1 μm to 70 μm; the metal lithium layer or the metal sodium layer can be vapor deposited with lithium metal in the middle The material layer is obtained, wherein the metal lithium layer or the metal sodium layer has a thickness of 1 μm to 30 μm, which is a dense and uniform metal lithium layer or a metal sodium layer. The lithium battery negative electrode of the invention can adjust the distribution of lithium ions on the surface of the negative electrode by using the intermediate substance layer, avoid the aggregation of the lithium ion battery in time and space, realize the uniform distribution of lithium ions on the surface of the negative electrode, thereby inhibiting the occurrence of lithium dendrites. Improves the safety performance of lithium metal batteries. The negative electrode of the lithium battery is coupled with a positive electrode material having a high specific capacity such as sulfur, air, etc., and is important for constructing a lithium battery system with high energy density, high stability, and high safety.

The present invention provides the use of a lithium battery anode as described above in the preparation of a solid state battery or a liquid battery. Specifically, the present invention provides a lithium battery comprising a positive electrode and a negative electrode, wherein the negative electrode is the lithium battery negative electrode described above.

The lithium battery anode composed of the present application can be applied in the field of solid battery and liquid battery, and the evaporated lithium metal or metal sodium can inhibit the generation of lithium dendrites during charging and discharging of the battery, thereby improving the safety of the battery, and the new type The negative electrode of the lithium battery can reduce the irreversible capacity loss of the battery during the formation process. The first coulombic efficiency of the battery is improved, and the positive electrode material capacity is increased by 3%-20%.

The lithium battery anode of the present application and the nickel-cobalt-aluminum ternary cathode material are assembled into a button battery, and the first Coulomb efficiency of the battery is 97%, and the conventional graphite anode and the nickel-cobalt-aluminum ternary cathode material are assembled into a button battery, which is the first Coulomb battery. The efficiency is 92%.

The lithium battery negative electrode of the present application and the nickel cobalt aluminum ternary positive electrode material are assembled into a button battery, and the capacity is reduced by 1.8% in a cycle of 200 weeks, and the lithium metal plate is used as a negative electrode and the nickel cobalt aluminum ternary positive electrode material is assembled into a button battery. The cycle capacity decays by 3.4% for 200 cycles.

The negative electrode of the lithium battery of the present application is matched with the same nickel-cobalt-aluminum ternary positive electrode material as compared with the conventional graphite negative electrode. The quality of the negative electrode of the lithium battery of the present application is 10% to 80% lower than that of the conventional graphite negative electrode, and the thickness is thinner than that of the conventional negative electrode. %~90%.

Therefore, the quality of the negative electrode of the lithium battery constructed by the present application is 10% to 80% lower than that of the conventional graphite negative electrode, and the thickness is reduced by 10% to 90% compared with the conventional negative electrode, thereby greatly improving the gram capacity of the negative electrode material, and the battery can be The energy density is increased by 1 to 4 times, which improves the energy utilization rate of the battery.

DRAWINGS

1 is a schematic view showing the external structure of a negative electrode of a lithium battery, wherein reference numeral 1 denotes an intermediate substance layer, reference numeral 2 denotes a metallic lithium layer or a metallic sodium layer, and reference numeral 3 denotes a tab;

2 is a schematic view showing the internal structure of a negative electrode of a lithium battery, wherein reference numeral 1 denotes an intermediate substance layer, reference numeral 2 denotes a metallic lithium layer or a metallic sodium layer, and reference numeral 4 denotes a current collector (copper foil).

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for preparing a lithium battery negative electrode according to the present embodiment will be specifically described with reference to FIG. 1 and FIG. 2, and the method includes the following steps:

In the embodiment, the distribution of lithium ions on the surface of the negative electrode can be regulated by using the intermediate substance layer, the aggregation of the lithium ion battery in time and space is avoided, and the uniform distribution of lithium ions on the surface of the negative electrode is achieved, thereby suppressing the occurrence of lithium dendrites. The vapor-deposited metal lithium layer is realized by an intermediate substance layer which strongly adsorbs lithium ions. The structure of the negative electrode of the lithium battery can effectively inhibit the generation of lithium dendrites, improve the safety of the battery, and improve the energy utilization rate of the battery. For example, the use of a high specific capacity positive electrode material will help promote the new high energy density lithium battery. Practical process.

In the present embodiment, the carbon material having a mass percentage of 75% to 90% means that the ratio of the mass of the carbon material to the total mass of the intermediate material layer (1) is 75% to 90%; the mass percentage is 5 % to 20% of the conductive agent means that the ratio of the mass of the conductive agent to the total mass of the intermediate substance layer (1) is 5% to 20%; the binder having a mass percentage of 5% to 10% means the binder The ratio of the mass to the total mass of the intermediate substance layer (1) is 5% to 10%.

Embodiment 2 This embodiment further describes a method for preparing a negative electrode of a lithium battery according to the first embodiment. In the embodiment, an intermediate material layer formed by mixing carbon materials coated on the current collector (4) (1) For details, see Step 1 and metal lithium or metal sodium evaporated on the intermediate material layer (1). See step 2 for details.

The third embodiment of the present invention is to further describe the method for preparing a negative electrode of a lithium battery according to the first embodiment. In the embodiment, the carbon-based material in the first step includes soft carbon, hard carbon, silicon carbon, and graphite. One or several of all categories. In addition, the conductive agent and the binder in the first step may be those commonly used in the art, and the present invention is not particularly limited. In some embodiments of the invention, the conductive agent may be conductive carbon black (ie, super-P, SUPER-P). In some embodiments of the invention, the binder may be polyvinylidene fluoride (PVDF).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 4: This embodiment further describes a method for preparing a negative electrode of a lithium battery according to the first embodiment. In this embodiment, the intermediate material layer (1), the metal lithium layer, and the metal sodium layer are both lithium battery negative electrodes. Active substance.

The invention provides a lithium battery negative electrode, which comprises:

a current collector connected to the ear;

Coating an intermediate substance layer formed on the current collector;

The intermediate material layer is composed of the following mass percentage components: 75% to 90% of the carbon material, 5% to 20% of the conductive agent, and 5% to 10% of the binder; the thickness of the intermediate layer is 1 μm to 70 μm; the metal lithium layer or the metal sodium layer has a thickness of 1 μm to 30 μm.

Referring to FIG. 2, a negative electrode of a lithium battery provided by an embodiment of the present invention includes a current collector (4), which is usually located on the bottom layer; and a copper foil well known in the art can be used as a current collector. In an embodiment of the invention, the current collector is connected to a tab (3).

The lithium battery negative electrode provided by the embodiment of the present invention includes an intermediate substance layer (1) which is formed by coating an intermediate substance layer mixed component on the current collector (4). The intermediate substance layer is composed of 75% to 90% of a carbonaceous material, 5% to 20% of a conductive agent, and 5% to 10% of a binder according to a mass percentage. Wherein, the carbon-based material includes one or more of all kinds of soft carbon, hard carbon, silicon carbon, and graphite. The conductive agent and the binder are both generally used in the art, and the invention is not particularly limited.

In the present invention, the intermediate substance layer has a porous structure and has an adsorption effect. In the present invention, the intermediate substance layer has a thickness of from 1 μm to 70 μm. The invention utilizes the intermediate substance layer to regulate the distribution of lithium ions on the surface of the negative electrode, avoids the aggregation of the lithium ion battery in time and space, realizes the uniform distribution of lithium ions on the surface of the negative electrode, and thereby inhibits the occurrence of lithium dendrites.

The negative electrode of the lithium battery provided by the embodiment of the invention comprises a metal lithium layer or a metal sodium layer (2) attached to the intermediate material layer (1) and formed by evaporation. In the present invention, the metal lithium layer or the metal sodium layer has a thickness of from 1 μm to 30 μm; and its density is uniform. In some embodiments of the present invention, the evaporated lithium metal or sodium metal can inhibit the generation of lithium dendrites during charging and discharging of the battery, further improving the safety of the battery.

In summary, the structure of the negative electrode of the lithium battery of the invention can effectively inhibit the generation of lithium dendrites, improve the safety of the battery, and improve the energy utilization rate of the battery. Moreover, the quality of the negative electrode of the lithium battery of the invention is lighter than that of the conventional graphite negative electrode, and the thickness is thinner than that of the conventional negative electrode, which greatly increases the gram capacity of the negative electrode material.

In an embodiment of the invention, the method for preparing the lithium battery anode described above may include the following steps:

Step 1. Mix carbon materials with a mass percentage of 75% to 90%, a conductive agent with a mass percentage of 5% to 20%, and a binder with a mass percentage of 5% to 10%, according to 1 μm. a thickness of ~ 70 μm is coated on the current collector (4) to form a porous intermediate material layer (1);

The invention also provides the use of a lithium battery anode as described above in the preparation of a solid state battery or a liquid battery. Specifically, the present invention provides a lithium battery comprising a positive electrode and a negative electrode, wherein the negative electrode is the lithium battery negative electrode described above.

In some embodiments of the present invention, the active material in the positive electrode is selected from sulfur or air; the negative electrode of the lithium battery is coupled with a high specific capacity positive electrode material such as sulfur and air for constructing high energy density, high stability, and high safety. The lithium battery system is of great significance. In still another embodiment of the present invention, the active material in the positive electrode is a nickel-cobalt-aluminum ternary positive electrode material; the button battery or the like can be assembled according to a conventional method, and the lithium battery has a high first coulombic efficiency and a high Battery energy density and excellent cycle performance.

In order to further understand the present application, the lithium battery negative electrode provided by the present invention and a preparation method and application thereof will be specifically described below in conjunction with the embodiments.

Example 1

Step 1: Mixing 90% by mass of graphite, 5% by weight of SUPER-P and 5% by mass of PVDF, and coating the current collector copper foil with a thickness of 70 μm (4) a porous intermediate material layer (1);

Step 2, uniformly depositing a metal lithium layer (2) having a thickness of 3 μm on the intermediate material layer (1);

The lithium battery negative electrode of the present application and the nickel cobalt aluminum ternary positive electrode material are assembled into a button battery for circulation The 200-week capacity is attenuated by 1.8%, and a pure metal lithium plate is used as a negative electrode and a nickel-cobalt-aluminum ternary positive electrode material is assembled into a button battery, and the cycle capacity is reduced by 3.4% in 200 cycles.

The quality of the negative electrode of the lithium battery formed by the present application is 40% lower than that of the conventional graphite negative electrode, and the thickness is reduced by 35% compared with the conventional negative electrode, which greatly increases the gram capacity of the negative electrode material, and can increase the energy density of the battery by 1.5 times, thereby improving the energy density of the battery. Battery energy utilization.

Example 2

Step 1: Mixing 90% by mass of graphite, 5% by weight of SUPER-P and 5% by mass of PVDF, and coating the current collector copper foil according to a thickness of 40 μm (4) a porous intermediate material layer (1);

Step 2, uniformly depositing a metal sodium layer (2) having a thickness of 10 μm on the intermediate material layer (1);

The lithium battery negative electrode of the present application and the nickel cobalt aluminum ternary positive electrode material are assembled into a button battery, and the first coulombic efficiency of the battery is 98%.

The lithium battery negative electrode of the present application and the nickel-cobalt-aluminum ternary positive electrode material were assembled into a coin cell battery, and the capacity was reduced by 1.6% in a cycle of 200 weeks.

The quality of the negative electrode of the lithium battery formed by the present application is 60% lower than that of the conventional graphite negative electrode, and the thickness is reduced by 50% compared with the conventional negative electrode, which greatly increases the gram capacity of the negative electrode material, and can increase the energy density of the battery by 2 times, thereby improving the energy density of the battery. Battery energy utilization.

The above is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can implement various modifications to these embodiments without departing from the technical principles of the present invention. These modifications are also considered to be within the scope of the invention.

Claims

A method for preparing a negative electrode of a lithium battery, characterized in that the method comprises the following steps:

Step 1. Mix carbon materials with a mass percentage of 75% to 90%, a conductive agent with a mass percentage of 5% to 20%, and a binder with a mass percentage of 5% to 10%, according to 1 μm. a thickness of ~ 70 μm is coated on the current collector (4) to form a porous intermediate material layer (1);

Step 2, uniformly depositing a metal lithium layer or a metal sodium layer (2) having a thickness of 1 μm to 30 μm on the intermediate material layer (1);

Step 3: After completing the operations of Step 1 and Step 2, the tab (3) is connected to the current collector (4) to complete the preparation of the anode of the lithium battery.
The method for preparing a negative electrode for a lithium battery according to claim 1, wherein the intermediate material layer (1) formed by mixing the carbon-based materials coated on the current collector (4) is as described in Step 1 and in the intermediate material layer ( 1) Evaporated metal lithium or sodium metal, see step 2 for details.
The method for preparing a negative electrode for a lithium battery according to claim 1, wherein the carbon-based material in the first step comprises one or more of all kinds of soft carbon, hard carbon, silicon carbon and graphite.
The method for preparing a negative electrode for a lithium battery according to claim 1, wherein the intermediate substance layer (1), the metallic lithium layer and the metallic sodium layer are active materials of a lithium battery negative electrode.
A lithium battery negative electrode, comprising:

a current collector connected to the ear;

Coating an intermediate substance layer formed on the current collector;

a metal lithium layer or a metallic sodium layer attached to the intermediate material layer;

The intermediate material layer is composed of the following mass percentage components: carbon-based material 75% to 90%, conductive agent 5-20%, and binder 5-10%; the intermediate material layer has a thickness of 1 μm~ 70 μm; the metal lithium layer or the metal sodium layer has a thickness of 1 μm to 30 μm.
The use of the lithium battery negative electrode according to claim 5 in the preparation of a solid battery or a liquid battery.
A lithium battery comprising a positive electrode and a negative electrode, wherein the negative electrode is the lithium battery negative electrode according to claim 5.
The lithium battery according to claim 7, wherein the active material in the positive electrode is selected from the group consisting of sulfur, air or a nickel-cobalt-aluminum ternary positive electrode material.