阅读说明：本技术 一种大功率锂-二氧化锰电池用正极极片及其制备方法 (Positive pole piece for high-power lithium-manganese dioxide battery and preparation method thereof ) 是由 王铭 高剑 谭铁宁 于 2020-07-09 设计创作，主要内容包括：本发明公开了一种大功率锂-二氧化锰电池用正极极片及其制备方法,该方法将作为活性物质的电解二氧化锰热处理后,与导电剂、粘结剂混合,进行研磨后加热烘干,再加入N-甲基吡咯烷酮搅拌混合成正极混合物；用涂布机将所述正极混合物均匀涂在集流体表面,烘干后用辊压机压至0.1～0.3mm,即成为大功率锂-二氧化锰电池用的正极极片。该方法工艺简单,通过控制电极厚度与孔隙率,可大幅度提升锂-二氧化锰电池的容量特性与大电流脉冲放电性能,满足高功率-二氧化锰电池的要求。(The invention discloses a positive pole piece for a high-power lithium-manganese dioxide battery and a preparation method thereof, the method comprises the steps of carrying out heat treatment on electrolytic manganese dioxide serving as an active substance, mixing the electrolytic manganese dioxide with a conductive agent and a binding agent, grinding, heating and drying, adding N-methyl pyrrolidone, stirring and mixing to obtain a positive pole mixture; and (3) uniformly coating the positive electrode mixture on the surface of the current collector by using a coating machine, drying, and pressing to 0.1-0.3 mm by using a roller press to obtain the positive electrode plate for the high-power lithium-manganese dioxide battery. The method has simple process, can greatly improve the capacity characteristic and the large-current pulse discharge performance of the lithium-manganese dioxide battery by controlling the thickness and the porosity of the electrode, and meets the requirement of the high-power manganese dioxide battery.)

1. A preparation method of a positive pole piece for a high-power lithium-manganese dioxide battery is characterized by comprising the following steps:

(1) mixing heat-treated electrolytic manganese dioxide powder serving as an active material with a conductive agent and a binder, and grinding to obtain a grinding mixture;

(2) drying the ground mixture to obtain a positive electrode mixture;

(3) adding N-methyl pyrrolidone serving as a solvent into the positive electrode mixture, fully mixing and stirring to prepare positive electrode slurry;

(4) uniformly coating the positive slurry on an aluminum foil serving as a current collector by using a coating machine, and drying in a vacuum drying oven;

(5) and (3) thinning the positive pole piece by using a roller press to obtain the positive pole piece for the high-power lithium-manganese dioxide battery.

2. The preparation method of the positive pole piece for the high-power lithium-manganese dioxide battery according to claim 1, wherein the active material is 80-96 wt%, the conductive agent is 2-10 wt%, the binder is 2-10 wt%, and the sum of the active material, the conductive agent and the binder is 100 wt%.

3. The preparation method of the positive pole piece for the high-power lithium-manganese dioxide battery as claimed in claim 1, wherein the conductive agent is one or more selected from carbon black, acetylene black, carbon nanotubes and graphene, and the binder is one or more selected from polyvinylidene fluoride, polyacrylate and polyacrylonitrile.

4. The method for preparing the positive pole piece of the high-power lithium-manganese dioxide battery according to claim 1, wherein the drying temperature of the grinding mixture in the step (2) is 50-90 ℃.

5. The preparation method of the positive pole piece for the high-power lithium-manganese dioxide battery according to claim 1, wherein the drying time of the ground mixture in the step (2) is 2-5 h.

6. The method for preparing the positive pole piece for the high-power lithium-manganese dioxide battery according to claim 1, wherein the solid content in the positive pole mixture obtained in the step (2) is 30-60%.

7. The preparation method of the positive pole piece for the high-power lithium-manganese dioxide battery according to claim 1, wherein the drying temperature in the step (4) is 110-160 ℃, and the drying time is 9-15 hours.

8. The preparation method of the positive pole piece for the high-power lithium-manganese dioxide battery according to claim 1, wherein the rolled thickness of the positive pole piece in the step (5) is 80-300 μm.

9. A positive pole piece for a high-power lithium-manganese dioxide battery is characterized by being prepared by the preparation method of any one of claims 1-8.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a positive pole piece for a high-power lithium-manganese dioxide battery and a preparation method thereof.

Background

A lithium-manganese dioxide battery belongs to a lithium primary battery and is prepared by taking metal lithium as a negative electrode, taking solid salt or salt dissolved in an organic solvent as an electrolyte and taking electrolytic manganese dioxide after heat treatment as a positive electrode. The device has wide application range and is mainly used for power supplies of electronic calculators, radios, flashlights, electric toys, watches, survival equipment, intelligent water meters, positioning emitters and instrument memory equipment.

With the gradual popularization of the internet of things technology, the battery requirements matched with the internet of things chip or terminal are increasing. Different from traditional electrical apparatus, the thing networking device is applied to response, wireless connection scene mostly, need support the signal at any time and in the equipment quick connection, requires the battery to have concurrently resistant storage and connect instantaneous heavy current pulse discharge ability, and at present, lithium primary battery will be the main power supply mode at thing networking chip and terminal.

Most of conventional button-type lithium-manganese dioxide batteries adopt a sheet pressing method or a paste coating method to prepare a positive pole piece, the prepared positive pole piece is thick and about 2mm, and can meet the requirement of long-time minimum current discharge, but the battery voltage drop is increased when the battery discharges with large current due to the fact that the pole piece is too thick, the porosity is too low, the ohmic polarization is large, and the mass transfer characteristic of lithium ions is poor, so that the voltage output is influenced, and the battery cannot be applied to the scene of large-current pulse discharge.

Disclosure of Invention

One object of the present invention is: the positive pole piece for the lithium-manganese dioxide battery and the preparation method thereof are provided, can meet the requirement of large-current pulse discharge, and simultaneously improve the utilization rate of positive active substances and the capacity characteristic of the battery.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a positive pole piece for a lithium-manganese dioxide battery comprises the following steps:

(1) mixing heat-treated electrolytic manganese dioxide powder serving as an active material with a conductive agent and a binder, and grinding to obtain a grinding mixture;

(2) drying the ground mixture to obtain a positive electrode mixture;

(3) adding N-methyl pyrrolidone serving as a solvent into the positive electrode mixture, fully mixing and stirring to prepare positive electrode slurry;

(4) uniformly coating the positive slurry on an aluminum foil serving as a current collector by using a coating machine, and drying in a vacuum drying oven;

(5) and (3) thinning the positive pole piece by using a roller press to obtain the positive pole piece for the high-power lithium-manganese dioxide battery.

The preparation method is suitable for preparing the positive pole piece for the button and soft package lithium-manganese dioxide battery.

The further technical scheme is that the grinding mixture in the step (1) is mainly prepared from the following raw materials in percentage by mass:

manganese dioxide: 80 to 96 percent

Conductive agent: 2 to 10 percent

Adhesive: 2 to 10 percent

The sum of the mass percent of the raw materials is 100 percent

The further technical scheme is that the conductive agent is selected from any one or a combination of at least two of graphite, conductive carbon black, acetylene black, carbon nanotubes or graphene, and is further preferably a combination of graphite and conductive carbon black, wherein the mass ratio of the graphite to the conductive carbon black is 1: 1.

The further technical scheme is that the binder is selected from one or a combination of at least two of polyvinylidene fluoride, polyacrylate or polyacrylonitrile, and is further preferably polyvinylidene fluoride.

The further technical scheme is that the drying temperature in the step (2) is 50-90 ℃, such as 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ and the like, but not limited to the enumerated values, other unrecited values in the above numerical ranges are also used, and the further optimized temperature is 60-70 ℃.

The further technical scheme is that the drying time in the step (2) is 2-5 h, such as 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the enumerated values, and other unrecited values in the above numerical ranges are also used, and further preferably 2-3 h.

In a further technical solution, the solid content of the positive electrode slurry in the step (3) is 35% to 60%, such as 35%, 40%, 45%, 50%, 55%, 60%, etc., but the solid content is not limited to the recited values, and other unrecited values within the above numerical ranges are also used, and more preferably 45% to 50%.

The further technical scheme is that the drying temperature in the step (4) is 100-160 ℃, such as 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 160 ℃, but not limited to the recited values, and other unrecited values in the above numerical ranges are also used, and more preferably 110-130 ℃.

According to a further technical scheme, in the step (4), the drying time is 9-15 hours, such as 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours and the like, but the drying time is not limited to the enumerated values, other unrecited values in the above numerical ranges are also used, and the drying time is more preferably 10-12 hours.

Further, in the step (5), the rolling thickness is 80 to 300 μm, such as 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned value ranges are used in the same manner, and more preferably 180 to 220 μm.

The invention also provides the positive pole piece for the lithium-manganese dioxide battery, which is prepared by the preparation method.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method provided by the invention optimizes the mixing and homogenizing processes. In the prior art, the active substance is usually mixed with the conductive agent, and then the binder emulsion is added for homogenization. At higher solids content, the binder proportion in the binder emulsion is too high, resulting in a higher emulsion viscosity, difficulty in thorough mixing during homogenization, and possibly leading to coating failure of the slurry.

The method is optimized and improved aiming at the problems, the active substance, the conductive agent and the binder powder are fully mixed before homogenizing, the particle agglomeration phenomenon can be effectively reduced, the dry materials are fully mixed, the formation of a pole piece conductive network is promoted during homogenizing, and the adhesion of the pole piece is improved; meanwhile, the positive electrode mixture is dried, so that impurities such as water, polyvinyl alcohol and the like contained in the positive electrode active material electrolytic manganese dioxide can be effectively removed; in addition, according to the method, all dry materials are fully mixed, and then N-methyl pyrrolidone serving as a solvent or a dispersing agent is added, so that the solid content of the anode slurry is more controllable, the solid content can be increased, the fluidity of the slurry can be ensured, and a thicker pole piece can be prepared by adopting a coating method.

(2) According to the preparation method provided by the invention, the solid content and the thickness of the pole piece are controlled, so that the prepared pole piece has excellent high-current discharge performance while keeping high compaction density, and the compaction density can reach 2.7-2.8 g/cm³. The power supply device can be applied to power supply of chips or terminals of the Internet of things, and meets the requirement of pulse discharge.

(3) The preparation method provided by the invention has simple process, does not need to adjust the existing production process device, and is beneficial to industrial production.

Detailed Description

In order to better illustrate the present invention and to facilitate an understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

The following are typical but non-limiting examples of the invention: