CN210778811U

CN210778811U - Lithium composite electrode and lithium ion battery

Info

Publication number: CN210778811U
Application number: CN201921786437.7U
Authority: CN
Inventors: 王亚龙; 刘承浩; 陈强; 牟瀚波; 郇庆娜
Original assignee: China Energy Lithium Co ltd
Current assignee: China Energy Lithium Co ltd
Priority date: 2019-10-23
Filing date: 2019-10-23
Publication date: 2020-06-16
Anticipated expiration: 2029-10-23

Abstract

The utility model provides a lithium combined electrode and lithium ion battery, this lithium combined electrode have the stromatolite composite construction who contains lithium layer/embedding part/porous carbon layer/embedding part/contains the lithium layer, wherein, the embedding part comprises the porous carbon layer that contains the lithium layer and is imbedded the porous carbon layer jointly by the embedding porous carbon layer.

Description

Lithium composite electrode and lithium ion battery

Technical Field

The utility model relates to an electrochemistry energy storage technical field, in particular to lithium negative pole for lithium ion battery.

Background

With the increasing demand of society for energy density of lithium ion batteries. First, a higher specific capacity anode material was used, and lithium metal was considered the most preferable anode material due to a capacity of 3860mAh/g and a low potential of-3.04V. Secondly, to reduce the mass of inactive materials, for example, to reduce the weight of the current collector, the thickness of the copper current collector is continuously reduced. Finally, the battery needs a certain rate performance, and the charge and discharge performance of the battery under the condition of high current density needs to be ensured by improving the contact between the negative active layer and the current collector.

The current copper foil current collector of the lithium ion battery reduces the thickness from 12 microns to 6 microns, and further adjusts the thickness down to 5 microns, reaches the limit of copper foil processing, and in order to realize interface adhesion and conductivity, the surface of the copper foil is coated with carbon.

In addition, a method for preparing a flexible electrode of a metallic lithium-framework material by hot-melt coating or vacuum deposition has been proposed. (CN201610252135.6), wherein metallic lithium is filled in the three-dimensional current collector mainly by hot melt coating or vacuum deposition. However, since metallic lithium is very reactive, hot-melt coating needs to be performed in high-purity argon gas, and the amount of metallic lithium filled and the thickness of the entire electrode cannot be effectively controlled. And by adopting the vacuum deposition method, because the current collector has a three-dimensional framework and a large specific surface area, long-time vacuum pumping is needed to achieve the required vacuum degree, the production efficiency is low, and in addition, metal lithium molecules are difficult to enter the internal pores and only deposit on the surface of the electrode.

Thus, the prior art has not been able to meet the requirements for metallic lithium negative electrodes for lithium batteries.

SUMMERY OF THE UTILITY MODEL

The utility model provides a special lithium electrode design will contain lithium layer lamination on two surfaces on porous carbon layer, make and contain lithium layer partial embedding porous carbon layer, like this, can be simple high-efficient, low-cost mode obtains the lithium negative pole that is applicable to lithium ion battery.

The utility model adopts the following technical scheme:

an aspect of the present invention provides a lithium composite electrode having a laminated composite structure including a lithium layer/insertion portion/porous carbon layer/insertion portion/lithium layer, wherein the insertion portion is composed of a lithium-containing layer inserted into the porous carbon layer and a porous carbon layer inserted into the lithium-containing layer.

According to one embodiment, the lithium-containing layer is embedded into the porous carbon layer to a degree of 10 to 50%.

According to one embodiment, the lithium-containing layer is a metallic lithium layer or a lithium alloy layer, and the lithium alloy may include lithium aluminum, lithium magnesium, lithium boron, lithium zinc, or lithium indium alloy.

According to one embodiment, the total thickness of the lithium composite electrode is in the range of 20-200 microns.

According to one embodiment, the porous carbon layer has a thickness in the range of 10-100 microns.

According to one embodiment, the porous carbon layer is woven from said carbon nanotubes or carbon fibres having a diameter of 3-15 nm and a length of 3-100 microns.

According to one embodiment, the porous carbon layer has a pore size of 50-2000 nm.

The above lithium composite electrode may be prepared according to the following method comprising: and sequentially or simultaneously compounding two lithium-containing layers on two surfaces of the porous carbon layer through pressure compounding, so that each lithium-containing layer after pressure compounding is partially embedded into the porous carbon layer. The pressure compounding may be performed in a roll-to-roll manner using a pressure roll. By changing the pressure and the roll gap clearance, partial embedding of the metallic lithium or lithium alloy into the porous carbon film is realized.

Another aspect of the present invention provides a lithium ion battery, which includes the above-mentioned lithium composite electrode as a negative electrode.

The utility model has at least one of the following advantages:

(1) the utility model overcomes metallic lithium tensile strength is low (tensile strength 11MPa), is less than the tensile strength of the anodal used mass flow body of present lithium ion battery far away, is unfavorable for the positive negative pole rolling's of the positive negative coiling in-process of battery problem. The utility model discloses a lithium/porous carbon film/lithium structure because the tensile strength of carbon film can reach more than 100MPa, and lithium or lithium alloy also partially imbed in the carbon film (utilize the porosity of porous carbon film) to greatly improved its tensile strength, conveniently carried out high-speed receipts and unreel.

(2) The metallic lithium or lithium alloy is embedded in the carbon film, has better contact, and the electron conductance of the carbon film is up to 10⁵And S/cm, a three-dimensional electronic path is formed, and the electrochemical performance under the condition of high current density is ensured. The problem that the conductivity of the electrode is reduced when an insulating material framework is adopted is solved.

(3) In the preparation process, the utility model discloses only need through the pressure compound can, do not need hot melt or high vacuum, manufacturing cost is lower, efficiency is higher.

Drawings

Fig. 1 is a schematic structural diagram of a lithium composite electrode according to the present invention.

Fig. 2 is an SEM image of a side cross-section of a lithium composite electrode of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention. Furthermore, the technical features mentioned in the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Further, the following embodiments employ various product structure parameters, various reaction participants and process conditions, which are typical examples, but the present invention has been proved by a lot of experiments, and other different structure parameters, other types of reaction participants and other process conditions listed above are all applicable, and the claimed technical effects of the present invention can be achieved.

Fig. 1 is a schematic structural diagram of a lithium composite electrode according to the present invention. The lithium composite electrode has a laminated structure of a lithium-containing layer 1, a porous carbon layer 2 and a lithium-containing layer 1, and lithium-containing layers 1 on both sides are partially embedded in the porous carbon layer 2 to form an embedded part 3.

Fig. 2 is an SEM image of a side cross-section of a lithium composite electrode of the present invention, in which a portion where lithium is inserted into a porous carbon layer can be clearly seen.

In the lithium composite electrode, the lithium metal/lithium alloy on both sides is an active material of the electrode, and the lithium metal/lithium alloy and the porous carbon layer (carbon film) have closer contact due to the intercalation portion. Therefore, the carbon film can be used as a current collector, and simultaneously the tensile strength of the composite electrode is enhanced. The composite electrode can adopt high-purity metal lithium and can also adopt lithium alloy, such as lithium aluminum, lithium magnesium, lithium boron, lithium zinc and lithium indium. The carbon film is formed by interweaving carbon nano tubes or carbon fibers, has certain pores and has the capability of conducting electrons in three dimensions.

The composite electrode of the above laminated structure may be prepared by: sequentially putting the three layers of lithium-carbon film-lithium, and then performing pressure compounding by a rolling device. By adjusting the size of the roller gap and the roller pressure, composite electrodes with different thicknesses and the lithium intercalation degree in the carbon film can be realized.

Example 1

A carbon nanotube film (Suzhou Jiedi nanotechnology Co., Ltd.; pore size: 200nm) with a thickness of 10um and two lithium metal films with a thickness of 20um are adopted, a roller gap of a pressure roller is controlled to be 40um, the pressure is controlled to be 1MPa, the two lithium metal films are compounded on two surfaces of a porous carbon layer in a pressure mode, a lithium composite electrode with a thickness of 45um is obtained, and the tensile strength of lithium metal of the lithium composite electrode when tensile fracture occurs is 120 MPa.

Example 2

Similarly to example 1, the carbon nanotube film was replaced with a carbon fiber film (trade name: Beijing crystal Longte carbon technology Co., Ltd.; thickness: 40 μm; pore size: 50nm), and two lithium metal films having a thickness of 50 μm were combined. The roller gap of the pressure roller is controlled to be 85um, and the pressure is 1 MPa. The thickness of the obtained lithium composite electrode is 90um, and the tensile strength of the lithium metal when tensile fracture occurs is 2000 MPa.

Example 3

The lithium composite electrode in the embodiment 1 is adopted to carry out the winding process of the anode and the cathode of the battery, and the winding speed is 100 m/min. No stretching and breaking phenomena of the lithium negative electrode were observed. The positive electrode is made of nickel cobalt lithium manganate (Beijing Dangshi technology Co., Ltd.) to form a soft package battery with 20Ah, and the energy density of the soft package battery can reach 320 wh/kg. The 0.1C magnification was cycled 200 times without significant decay.

It should be understood that the above-described embodiments are merely exemplary of the present invention, and are not intended to limit the present invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A lithium composite electrode having a laminated composite structure of a lithium-containing layer/intercalation/porous carbon layer/intercalation/lithium-containing layer, wherein the intercalation is composed of both a lithium-containing layer intercalated in the porous carbon layer and an intercalated porous carbon layer.

2. The lithium composite electrode according to claim 1, wherein the lithium-containing layer is inserted into the porous carbon layer to an extent of 10 to 50% by thickness.

3. The lithium composite electrode of claim 1, wherein the lithium-containing layer is a metallic lithium layer or a lithium alloy layer.

4. The lithium composite electrode of claim 1, wherein the total thickness of the lithium composite electrode is in the range of 20-200 microns.

5. The lithium composite electrode according to claim 1, wherein the porous carbon layer has a thickness in the range of 10-100 microns.

6. The lithium composite electrode according to claim 1, wherein the porous carbon layer is woven from carbon nanotubes or carbon fibers having a diameter of 3-15 nanometers and a length of 3-100 microns.

7. The lithium composite electrode according to claim 1, wherein the porous carbon layer has a pore size of 50-2000 nm.

8. A lithium ion battery, characterized in that it comprises a lithium composite electrode according to any one of claims 1 to 7 as negative electrode.