CN210272536U

CN210272536U - Novel negative plate and lithium ion battery

Info

Publication number: CN210272536U
Application number: CN201920878922.0U
Authority: CN
Inventors: 何爱勤; 马华; 库志新; 李秋凤; 李文文; 从长杰
Original assignee: Tianjin EV Energies Co Ltd
Current assignee: Tianjin EV Energies Co Ltd
Priority date: 2019-06-12
Filing date: 2019-06-12
Publication date: 2020-04-07
Anticipated expiration: 2029-06-12

Abstract

The utility model provides a novel negative pole piece and lithium ion battery, the negative pole piece includes the mass flow body, the surface from interior to exterior of mass flow body has negative material layer and lithium titanate coating in proper order coated, contain negative pole active material in the negative material layer. Lithium titanate in the negative pole piece lithium titanate coating have better multiplying power charge-discharge performance, the cyclicity can promote the multiplying power performance of electric core, lithium titanate platform electric potential height can not form the lithium metal simultaneously, the short circuit that the lithium metal that the cover can avoid graphite negative pole charge-discharge in-process to produce leads to on graphite pole piece surface, the electric conductivity of lithium titanate is relatively poor, also can avoid the positive negative pole short circuit a little, reduces electric core self discharge rate.

Description

Novel negative plate and lithium ion battery

Technical Field

The utility model belongs to the technical field of lithium ion power battery, especially, relate to a novel negative pole piece and lithium ion battery.

Background

Lithium ion batteries have the advantages of light weight, large capacity, no memory effect, and the like, and are therefore widely used. The lithium ion battery has high energy density, capacity 1.5-2 times that of nickel-hydrogen battery in the same weight and low self-discharge rate. In addition, the advantages of almost no memory effect and no toxic substances of the lithium ion battery are also important reasons for the wide application of the lithium ion battery. For lithium ion battery electric vehicles, charging technology and safety performance are still important factors restricting the development of electric vehicles at present. On the aspect of a battery cell, the rate performance of the lithium ion battery is restricted by the intrinsic transmission characteristic of a positive electrode/electrolyte/negative electrode material matching system on one hand, and on the other hand, the pole piece process and the structural design of the battery cell also have great influence on the rate performance.

The lithium ion battery is commercialized to the present, the used negative electrode material is the most mature, the most widely used is carbon material, and the most important is still graphite. The graphite negative electrode material has high theoretical specific capacity and a low potential charge-discharge platform (0.01-0.2V), most of lithium intercalation capacity is generated in the voltage region, and the charge-discharge platform corresponds to the formation and decomposition of a graphite interlayer compound LiC6, so that high and stable working voltage can be provided for a lithium battery. However, the graphite cathode material also has certain defects, and lithium metal is easily generated in the process of high-rate charge and discharge, so that the short circuit of the anode and the cathode is caused, and safety accidents are caused; in addition, the graphite cathode has poor compatibility with the electrolyte, and is easy to co-embed with an organic solvent in the electrolyte, so that the graphite layer of the cathode expands and peels off, and the cycle stability of the lithium ion battery is reduced.

Disclosure of Invention

In view of this, the utility model aims at providing a novel negative pole piece and lithium ion battery, this negative pole piece has improved the multiplying power circulation and the security performance of battery, can prepare the high security lithium ion power battery of high multiplying power, has great production practice meaning.

In order to achieve the above purpose, the technical scheme of the utility model is realized like this:

the negative pole piece of the lithium battery comprises a current collector, wherein a negative pole material layer and a lithium titanate coating are sequentially coated on the surface of the current collector from inside to outside.

Furthermore, the thickness of the negative pole piece is 30-300 μm.

Further, the lithium titanate coating is 10 nm-50 um.

Further, the lithium titanate coating is 50 nm-20 um.

Further, the negative electrode material layer contains graphite, silicon or silicon carbon.

Furthermore, the negative electrode material layer and the lithium titanate coating both contain a binder, a conductive agent and a solvent.

A lithium ion battery comprises any one of the negative electrode sheets.

Compared with the prior art, novel negative pole piece and lithium ion battery have following advantage:

(1) compared with a graphite cathode material, lithium titanate has a higher lithium ion diffusion coefficient and can be charged and discharged at a high rate. And because the material is a zero strain material, the structural change can not occur in the charging and discharging process, and the material has very excellent cycle performance. Lithium titanate has high equilibrium potential, so that lithium dendrite cannot be formed on a negative electrode, and the lithium titanate has high safety.

(2) Lithium titanate in the lithium titanate coating has better multiplying power charge-discharge performance and cycle performance, can improve the multiplying power performance of the battery cell, can not form lithium metal due to high potential of a lithium titanate platform, can avoid short circuit caused by the lithium metal generated in the charge-discharge process of a graphite cathode by covering the surface of a graphite pole piece, has poor conductivity, can also avoid micro short circuit of the positive pole and the negative pole, and reduces the self-discharge rate of the battery cell.

Drawings

The accompanying drawings, which form a part hereof, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without undue limitation. In the drawings:

fig. 1 is a schematic structural diagram of a novel negative plate according to an embodiment of the present invention.

Description of reference numerals:

1. a current collector; 2. a negative electrode material layer; 3. a lithium titanate coating.

Detailed Description

It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

The utility model provides a lithium cell negative pole piece, negative pole piece includes the mass flow body 1, the surface from interior to exterior of mass flow body 1 has negative material layer 2 and lithium titanate coating 3 to coat in proper order.

The total thickness of the negative pole piece is 30-300 mu m. The lithium titanate coating is 10 nm-50 um. Preferably, the lithium titanate coating is 50 nm-20 um.

Further, the negative electrode material layer contains graphite, silicon or silicon carbon. The negative electrode material layer and the lithium titanate coating both contain a binder, a conductive agent and a solvent. Specifically, the binder, the conductive agent and the solvent are all materials commonly used in the field, and the binder is composed of one or more of Styrene Butadiene Rubber (SBR), polyacrylate, sodium carboxymethylcellulose (CMC-Na), lithium carboxymethylcellulose (CMC-Li) and polyvinylidene fluoride (PVDF); the solvent consists of one or more of N-methyl pyrrolidone (NMP), deionized water, methyl ethyl ketone and isopropanol; the conductive agent is one or a combination of acetylene black, SUPER P Li, carbon nano tubes, VGCF, graphene and the like.

The lithium battery negative plate is prepared by the following steps: homogenizing a negative main material (graphite, silicon-carbon composite material and the like), a binder, a conductive agent and a solvent according to the existing process requirements, then coating the slurry on a current collector to obtain a negative pole piece, and coating a lithium titanate coating on the surface of the obtained negative pole piece to obtain the novel negative pole piece.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium battery negative plate is characterized in that: the negative pole piece comprises a current collector, wherein a negative pole material layer and a lithium titanate coating are sequentially coated on the surface of the current collector from inside to outside, and the lithium titanate coating is 10-50 nm.

2. The negative electrode sheet for a lithium battery as claimed in claim 1, wherein: the thickness of the negative pole piece is 30-300 mu m.

3. The negative electrode sheet for a lithium battery as claimed in claim 1, wherein: the negative electrode material layer contains graphite, silicon or silicon carbon.

4. The negative electrode sheet for a lithium battery as claimed in claim 1, wherein: the negative electrode material layer and the lithium titanate coating both contain a binder, a conductive agent and a solvent.

5. A lithium ion battery, characterized by: the lithium ion battery comprises the negative electrode sheet of any one of claims 1 to 4.