阅读说明：本技术 功率型锂亚硫酰氯电池正极制备方法 (Preparation method of positive electrode of power type lithium thionyl chloride battery ) 是由 孙英婴 徐杨明 吴际良 李文杰 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种功率型锂亚硫酰氯电池正极制备方法,其包括以下步骤：1)混料、2)上网、3)纤维化处理、4)纤维交错拉伸、5)裁切留白,其中,纤维交错拉伸步骤中使用一对表面有对称细小波浪纹的压块或压辊对正极镍拉网两面的不同方向及不同位置进行多次按压或辊压,使正极镍拉网填覆物料内部的粘接剂形成整体纤维链状网络粘连；然后再用光面压辊对正极镍拉网进行辊压整平。本发明无需二次粘贴,且能解决正极掉粉、脱落、翻边等问题,同时还提高了电池的容量及放电电压平台。(The invention discloses a preparation method of a positive electrode of a power type lithium thionyl chloride battery, which comprises the following steps: 1) mixing materials, 2) surfing the net, 3) performing fiberization treatment, 4) performing fiber staggered stretching, and 5) cutting and leaving white, wherein in the step of fiber staggered stretching, a pair of pressing blocks or pressing rollers with symmetrical fine wavy lines on the surfaces are used for pressing or rolling the two surfaces of the positive nickel netting for multiple times in different directions and different positions, so that the adhesive inside the positive nickel netting filling material forms an integral fiber chain network for adhesion; and then, rolling and leveling the positive nickel screen by using a smooth surface press roll. The invention does not need secondary adhesion, can solve the problems of anode powder falling, flanging and the like, and simultaneously improves the capacity and the discharge voltage platform of the battery.)

1. A preparation method of a power type lithium thionyl chloride battery positive electrode is characterized by comprising the following steps:

1) mixing material

Mixing acetylene black, absolute ethyl alcohol, pure water, a conductive agent and an adhesive according to a weight ratio to form a uniform semi-dry material;

putting the mixed semi-dry material into a drying box for drying;

2) internet access

Crushing the dried semi-dry material into fine granular materials with the grain diameter of 0.2 mm-1.2 mm;

uniformly filling fine particle materials on two surfaces of a nickel drawn net, and then compacting the filled fine particle materials by using a roller press to form a positive nickel drawn net;

3) fiberization treatment

Placing the positive electrode nickel net which is compacted by the filler into an oven for baking; then, putting the baked anode nickel screen into isopropanol or absolute ethyl alcohol for soaking;

4) fiber cross drawing

Pressing or rolling the two surfaces of the positive electrode nickel netting for multiple times in different directions and different positions by using a pair of pressing blocks or pressing rollers with symmetrical fine raised grains on the surfaces, so that the adhesive inside the positive electrode nickel netting filling material forms an integral fiber chain network for adhesion; then, rolling and leveling the positive nickel pull net by using a smooth surface press roller;

5) cutting and leaving white

And (3) putting the anode nickel screen subjected to the fiber staggered stretching treatment into a drying box for drying, cutting and scraping the materials to be welded to obtain the anode.

2. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1, characterized in that: in the step 1), the conductive agent is copper powder or nickel powder, and the adhesive is polytetrafluoroethylene emulsion or polyvinylidene fluoride emulsion.

3. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1 or 2, characterized in that: in the step 1), the weight ratio of acetylene black, absolute ethyl alcohol, pure water, a conductive agent and an adhesive is 1000: 100-250: 4000-6000: 60-90: 80-150 parts by weight.

4. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 3, characterized in that: in the step 1), the drying temperature is 50-75 ℃, and the drying time is 10-20 h.

5. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1, characterized in that: in the step 2), the dried semi-dry material is crushed into fine particles with the particle size of 0.2-1.2 mm by adopting a high-speed rotary blade type crushing machine.

6. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1 or 5, characterized in that: in the step 2), the density of the compacted fine particle material is as follows: 0.27g/cm³～0.32g/cm³。

7. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1, characterized in that: in the step 3), the baking temperature is 150-250 ℃, and the baking time is 20 min-2 h.

8. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1 or 7, characterized in that: in the step 3), the soaking time is 3-15 min.

9. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1, characterized in that: in the step 4), the height from the wave crest to the wave trough of the fine raised grain is 0.4 mm-1.2 mm, and the width of the single wave is as follows: 0.8 mm-3.0 mm; the pressing or rolling times of the pressing blocks or the pressing rollers with the fine raised grains are 2-8 times.

10. The method for preparing the positive electrode of the power type lithium thionyl chloride battery according to claim 1, characterized in that: in the step 5), the drying temperature is 60-150 ℃, and the drying time is 10-30 min.

Technical Field

The invention relates to the field of lithium battery manufacturing, in particular to a preparation method of a positive electrode of a power type lithium thionyl chloride battery.

Background

In the preparation of the anode of the existing power type lithium thionyl chloride battery, adhesives which are in an emulsion state and can be kept stable for a long time in a strong oxidizing environment are used as bonding materials, the principle of bonding the adhesives is very unique, the adhesives hardly have physical bonding property, the mixed anode materials are gradually fiberized and form a local grid structure after being baked at high temperature, and at the moment, the adhesives have some bonding characteristics from a macroscopic view, but the bonding effect is still very poor. Then the material baked at high temperature is soaked in isopropanol or absolute ethyl alcohol, the fiberized adhesive in the material can be fully unfolded, the soaked material is repeatedly extruded and extended, and the unfolded and continuously stretched adhesive fiber forms an integrally staggered fiber chain network structure in the material, so that a very good material adhesion effect is achieved.

For the preparation of the positive electrode of the power type lithium thionyl chloride battery, the most mature and widely applied film pressing and pasting process still comes from the 80 th century at present, and the basic flow is as follows: drying the mixed anode material in a semi-dry state in a high-temperature oven, fiberizing the adhesive, soaking the anode material in an organic solvent such as isopropanol or absolute ethyl alcohol, folding and rolling the anode material for multiple times by using a roller press to finally prepare an anode membrane, respectively sticking the anode membrane to two sides of a nickel mesh by using an adhesive such as prepared conductive paste, and cutting the anode by parts after the procedures of drying, carbonization and the like. The method has the greatest characteristic that the unique bonding principle of the adhesive is well utilized, the prepared anode membrane achieves a very good internal bonding effect by virtue of a fiber chain network formed by the adhesive, but has a plurality of outstanding problems at the same time: 1) the coating thickness and distribution state of adhesives such as conductive paste used for pasting the membrane onto the nickel mesh cannot be guaranteed to be uniform and consistent and are uncontrolled; 2) in the high-temperature carbonization process, adhesives such as conductive paste and the like cannot be fully and effectively carbonized, so that the internal resistance of the battery is increased, and the discharge performance of the battery is influenced; 3) adhesives such as conductive pastes that are not completely carbonized may undergo dehydration reactions in the battery, which exacerbates voltage hysteresis, resulting in degradation or even failure of the electrical performance of the battery.

A method for preparing a positive electrode through a dry powder web forming process is also gradually popularized and applied, and the preparation method comprises the following basic steps: 1) mixing materials, 2) crushing, 3) surfing the net, 4) high-temperature baking, 5) cutting and leaving white, although the integral forming of the anode material and the nickel netting is realized without secondary pasting of adhesives such as conductive paste, due to the lack of extrusion and extension operations on the materials, the bonding agent inside the pole piece cannot form integral fiber chain-shaped network adhesion, so that the bonding effect between the anode materials is poor, the problems of powder falling, flanging and the like are prominent, and the performance of the battery is seriously influenced. Therefore, a new method for preparing the positive electrode of the power type lithium thionyl chloride battery is urgently needed.

Disclosure of Invention

The invention aims to provide a preparation method of a positive electrode of a power type lithium thionyl chloride battery, which can enable an adhesive in a positive electrode material to form an integral fiber chain network for adhesion, does not need secondary adhesion, namely, the materials on two sides of a nickel pull net form an integral tightly adhered positive electrode through the nickel pull net, solves the problems of powder falling, flanging and the like of the positive electrode, and simultaneously improves the capacity and a discharge voltage platform of the battery.

The technical scheme adopted by the invention is as follows:

a preparation method of a power type lithium thionyl chloride battery positive electrode comprises the following steps:

1) mixing material

Mixing acetylene black, absolute ethyl alcohol, pure water, a conductive agent and an adhesive according to a weight ratio to form a uniform semi-dry material;

putting the mixed semi-dry material into a drying box for drying;

2) internet access

Crushing the dried semi-dry material into fine granular materials with the grain diameter of 0.2 mm-1.2 mm;

uniformly filling fine particles on two surfaces of a nickel screen through a filling tool or a continuous feeding forming machine, and compacting the filled fine particles by using a roller press to form a positive nickel screen;

3) fiberization treatment

Placing the positive electrode nickel net which is compacted by the filler into an oven for baking; then, putting the baked anode nickel screen into isopropanol or absolute ethyl alcohol for soaking;

4) fiber cross drawing

Pressing or rolling the two surfaces of the positive electrode nickel netting for multiple times in different directions and different positions by using a pair of pressing blocks or pressing rollers with symmetrical fine raised grains on the surfaces, so that the adhesive inside the positive electrode nickel netting filling material forms an integral fiber chain network for adhesion; then, rolling and leveling the positive nickel pull net by using a smooth surface press roller;

5) cutting and leaving white

And (3) putting the anode nickel screen subjected to the fiber staggered stretching treatment into a drying box for drying, cutting and scraping the materials to be welded to obtain the anode.

According to the scheme, in the step 1), the conductive agent is copper powder or nickel powder, and the adhesive is polytetrafluoroethylene emulsion or polyvinylidene fluoride emulsion.

According to the scheme, in the step 1), the weight ratio of acetylene black, absolute ethyl alcohol, pure water, a conductive agent and an adhesive is 1000: 100-250: 4000-6000: 60-90: 80-150 parts by weight.

According to the scheme, in the step 1), the drying temperature is 50-75 ℃, and the drying time is 10-20 h.

According to the scheme, in the step 2), the dried semi-dry material is crushed into fine particles with the particle size of 0.2-1.2 mm by adopting a high-speed rotary blade type crushing machine.

According to the scheme, in the step 2), the density of the compacted fine granules is as follows: 0.27g/cm³～0.32g/cm³。

According to the scheme, in the step 3), the baking temperature is 150-250 ℃, and the baking time is 20 min-2 h.

According to the scheme, in the step 3), the soaking time is 3-15 min.

According to the scheme, in the step 4), the height from the wave crest to the wave trough of the fine raised grain is 0.4-1.2 mm, and the width of the single wave is as follows: 0.8 mm-3.0 mm; the pressing or rolling times of the pressing blocks or the pressing rollers with the fine raised grains are 2-8 times.

According to the scheme, in the step 5), the drying temperature is 60-150 ℃, and the drying time is 10-30 min.

The invention has the beneficial effects that:

the positive nickel screen is pressed or rolled for many times in different directions and different positions on two surfaces of the positive nickel screen by adopting symmetrical fine wavy pressing blocks or pressing rollers, so that materials on two surfaces of the positive nickel screen can locally form vertical reciprocating movement in the vertical direction of the nickel screen, the staggered stretching of the adhesive fibers is locally realized, the multiple pressing or rolling is carried out in different directions and different positions, the staggered stretching of the adhesive fibers which are locally staggered can be further realized, the adhesive inside the positive nickel screen filling material forms an integral fiber chain network for adhesion, secondary adhesion is not needed, and the problems of powder falling, flanging and the like are effectively solved;

polytetrafluoroethylene or polyvinylidene fluoride is used as a bonding agent, and the two materials are proved to be stable for a long time in a strong oxidizing environment of thionyl chloride, so that technical risks caused by using other bonding agent materials are avoided;

adhesive such as conductive paste is not needed for secondary pasting, the content of effective materials in the positive electrode is relatively increased under the same size condition, and the capacity of the manufactured battery is improved;

materials on two sides of the positive electrode nickel screen penetrate through the nickel screen to form an integral tight adhesion structure, so that the contact resistance among the materials, the nickel screen and the materials can be reduced, and the discharge voltage platform of the manufactured battery is improved;

the semi-dry material is smashed into fine particle materials with the particle size of 0.2 mm-1.2 mm, so that the materials can be filled on two surfaces of a nickel hauling net more uniformly and effectively in the follow-up process, and enough size space is also ensured in the fine particle materials to form continuous adhesive fibers with a certain length, so that after the follow-up process of local fiber staggered stretching is completed, an integral fiber chain network can be further formed for adhesion;

the material dried by the high-speed rotating blade type crushing machine is crushed into fine particles because the dried material has the characteristic of softness, and the material is crushed by adopting the high-speed crushing mode of the rotating blade, so that the material can be prevented from being extruded, and the prepared fine particles can keep the physical characteristics of the material in the initial state.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic diagram of the operation of fiber cross-drawing, wherein a is a nickel wire, b is a material filled on the nickel wire, c is a fine corrugated pressing block, H is the height from the wave crest to the wave trough of the corrugations, and W is the width of a single wave;

fig. 2 is a comparison graph of typical discharge curves of 100mA discharge to 2.0V at normal temperature for a battery made of the positive electrode of the present invention and a battery made of the positive electrode prepared by a conventional lamination and lamination process.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

All the raw materials of the invention have no special requirement on the purity, and the purity can be obtained by adopting analytical purification or the conventional purity in the field of lithium batteries.