阅读说明：本技术 一种提高电解铜箔力学性能的方法及其所用的添加剂 (Method for improving mechanical property of electrolytic copper foil and additive used by method ) 是由 唐谊平 江晨浩 张建力 陈强 侯广亚 于 2021-06-08 设计创作，主要内容包括：本发明涉及一种提高电解铜箔力学性能的方法及其所用的添加剂,属于锂离子电池领域,为解决现有的电解铜箔存在力学性能较弱,其拉伸性能会随着其厚度减小而降低,并且针对性强化电解铜箔力学性能的工艺普遍存在成本高昂、工艺难度大等问题,本发明提供了一种提高电解铜箔力学性能的方法,在电解铜箔制备过程中,控制铜箔中晶粒晶体的晶面生长趋势,促进铜晶粒的(220)晶面生长,增大铜晶粒在(220)晶面上的织构系数,和/或增大铜沉积过程中的阴极极化、细化铜晶粒。本发明的方法能够有效降低成本、减小污染；改性处理方式简洁高效,无序额外的工序；能够诱导铜晶粒的生长取向,增强(220)晶面的取向；同时能够实现晶粒细化,强化铜箔的力学性能。(The invention relates to a method for improving the mechanical property of an electrolytic copper foil and an additive used by the method, belongs to the field of lithium ion batteries, and aims to solve the problems that the existing electrolytic copper foil is weaker in mechanical property, the tensile property of the existing electrolytic copper foil is reduced along with the reduction of the thickness of the existing electrolytic copper foil, the process aiming at the mechanical property of the existing electrolytic copper foil is high in cost, high in process difficulty and the like. The method can effectively reduce the cost and the pollution; the modification treatment mode is simple and efficient, and the additional process is disordered; the growth orientation of copper crystal grains can be induced, and the orientation of a (220) crystal face is enhanced; meanwhile, the grain refinement can be realized, and the mechanical property of the copper foil is enhanced.)

1. A method for improving the mechanical property of electrolytic copper foil is characterized by comprising the following steps:

in the preparation process of the electrolytic copper foil, the crystal face growth trend of crystal grain crystals in the copper foil is controlled, the (220) crystal face growth of the copper crystal grains is promoted, the texture coefficient of the copper crystal grains on the (220) crystal face is increased, and/or the cathode polarization and the refined copper crystal grains in the copper deposition process are increased.

2. The method for improving the mechanical properties of an electrodeposited copper foil according to claim 1,

the control of the crystal face growth trend of crystal grains in the copper foil is realized by adding an additive into an electrolyte used for electrolyzing the copper foil;

the additive contains ether bond and/or carbonyl and/or sulfonyl and/or amino and/or hydroxyl and/or sulfydryl;

the concentration of the additive is 0.005-0.015 mol/L.

3. An additive for use in the method of claim 2,

the additive contains ether bond, hydroxyl, sulfydryl, amino, carbonyl and/or sulfonyl.

4. An additive for use in the method of claim 2,

the additive is sodium polydithio-dipropyl sulfonate.

5. An additive for use in the method of claim 2,

the additive is polyethylene glycol.

6. An additive for use in the method of claim 2,

the additive is polyethyleneimine.

7. An additive for use in the method of claim 2,

the additive is carbonyl diphenylamine.

Technical Field

The invention belongs to the field of lithium ion batteries, and particularly relates to a method for improving the mechanical property of an electrolytic copper foil and an additive used by the method.

Background

The electrolytic copper foil is a metal foil, is an important raw material in the electronic and electrical industries, and is mainly used for manufacturing copper clad laminates, printed circuit boards, lithium batteries and the like. With the miniaturization of electronic devices, the continuous development of printed circuit surface mounting technology and the continuous increase of the requirements of multilayer printed circuit boards, the ultrathin high-performance electrolytic copper foil with few defects, fine grains, lower roughness, high strength, good ductility and wide application range is realized.

The quality of the electrolytic copper foil is mainly determined by the organization structure, the impurity content and the like of the electrolytic copper foil, and if the high-quality copper foil is obtained, the current density, the temperature of the electrolyte, the liquid inlet mode and the liquid inlet amount of an electrolytic bath, additives and the like must be strictly controlled. The additive is the most main control factor, and practice proves that adding a proper amount of additive is an effective measure for obtaining high-quality electrolytic copper foil with compact structure, smooth surface and low impurity content.

According to a fine-grain strengthening mechanism, the strength and toughness of the material can be improved after the internal crystal grains of the metal are refined, but the thickness of the copper foil only has a single-layer crystal grain, and the effect of improving the mechanical property of the copper foil is weakened by the fine-grain strengthening mechanism. And the use of proper additives induces the growth orientation of copper crystals, enhances the orientation of (220) crystal planes, can effectively enhance the mechanical properties of the copper foil, and is a difficult point of project research. And at present, no scheme for modifying the additive for the electrolytic copper foil exists.

Disclosure of Invention

The invention provides a method for improving the mechanical property of an electrolytic copper foil and provides a used additive, aiming at solving the problems that the existing electrolytic copper foil is weaker in mechanical property, the tensile property of the existing electrolytic copper foil is reduced along with the reduction of the thickness of the existing electrolytic copper foil, and the process with the strong mechanical property of the electrolytic copper foil generally has high cost, high process difficulty and the like.

The invention aims to:

firstly, the performance of the electrolytic copper foil can be enhanced in a simple, efficient and low-cost mode;

secondly, grain refinement of the copper foil can be realized;

thirdly, realizing the preferred orientation of copper crystal grains of the copper foil and improving the texture coefficient of the electrolytic copper foil in a specific direction;

fourthly, a large amount of dislocation and substructure are generated in the electrolytic copper foil in the electrolytic deposition process through the action of a proper additive, and the mechanical property of the electrolytic copper foil is improved.

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

A method for improving the mechanical property of electrolytic copper foil,

the method comprises the following steps:

in the preparation process of the electrolytic copper foil, the crystal face growth trend of crystal grain crystals in the copper foil is controlled, the (220) crystal face growth of the copper crystal grains is promoted, the texture coefficient of the copper crystal grains on the (220) crystal face is increased, and/or the cathode polarization and the refined copper crystal grains in the copper deposition process are increased.

According to the research of researchers of the invention, the texture coefficient of the electrolytic copper foil has great influence on the mechanical property of the electrolytic copper foil, so that the mechanical property of the electrolytic copper foil is improved in a mode of improving the texture coefficient of the electrolytic copper foil, the texture coefficient can directly influence the tensile strength and the ductility of the electrolytic copper foil, the cathode polarization in the deposition process is increased, the effect of refining crystal grains is further realized, and the refined crystal grains are known to be capable of comprehensively optimizing various mechanical properties of metal materials.

As a preference, the first and second liquid crystal compositions are,

the control of the crystal face growth trend of crystal grains in the copper foil is realized by adding an additive into an electrolyte used for electrolyzing the copper foil;

the additive contains ether bond and/or carbonyl and/or sulfonyl and/or amino and/or hydroxyl and/or sulfydryl;

the concentration of the additive is 0.005-0.015 mol/L.

Compared with other strengthening modes, the method disclosed by the invention has the characteristics of low cost, simplicity and high efficiency by adopting an additive mode to improve the mechanical property of the electrolytic copper foil, and researchers do not have relevant researches on improving the mechanical property of the electrolytic copper foil through the additive in the existing technical scheme.

In the research process, the research personnel of the invention find that the crystals of the copper crystals mainly grow epitaxially at the beginning of the electrodeposition of the electrolytic copper foil, namely the surface of the titanium roller has great influence on the nucleation and growth of the initial copper crystals; in the later growth period, the influence of the electrodeposition conditions on the copper crystallization is more and more obvious along with the increase of the thickness of the copper foil, namely, the state of each crystal face on the copper crystal has obvious influence on the subsequent deposition process. If proper additives are added in the electrolytic copper foil production process, preferential adsorption can be carried out on the specific crystal face of the crystal so as to inhibit texture generation. And at the beginning of deposition, metal atoms are adsorbed on the surface of the cathode. When present in the solution, the additive will significantly affect the deposition process of the metal ions, mainly the adsorption process of the metal. Many additives can be adsorbed on the surface of the cathode to form a compact adsorption layer, and the discharge process of metal ions or the surface diffusion of metal adsorption atoms is hindered, so that a coating with fine grains is obtained. The various effects of the additives on the coating are due to their diffusion depletion, adsorption polarization, and possible contamination of the coating with reduction products.

Therefore, the specific additive is selected, and the mechanical property of the electrolytic copper foil can be effectively optimized.

Further, the following four categories are classified according to the effects produced:

additives of type I: the crystal contains ether bond and/or hydroxyl, which can be selectively adsorbed on a certain crystal face to realize the effect of inhibiting the growth of a certain orientation texture;

class II additives: the crystal contains carbonyl and/or sulfonyl, which can be selectively adsorbed on certain crystal faces, and the effect of promoting the growth of certain orientation texture is realized through the difference of adsorption energy;

group III additives: the copper-based composite material contains sulfydryl, can be uniformly adsorbed on each copper crystal face, can weaken the growth orientation of crystal grains and assist in enhancing the grain refining effect;

additives of group IV: contains sulfonyl and/or amino and/or hydroxyl groups, and has stronger adsorbability to the titanium crystal face than the copper crystal face, enabling effective grain refinement to be actively achieved.

An additive used in a method for improving the mechanical property of an electrolytic copper foil,

the additive contains ether bond, hydroxyl, sulfydryl, amino, carbonyl and/or sulfonyl.

The various groups can cooperate to produce a very excellent mechanical property improvement effect. For example, ether bonds have very obvious selectivity on three crystal planes of copper crystal grains, and the adsorption energy on the (111) plane of the copper crystal grains is much larger than that on the other two crystal planes, which shows that the ether bonds can well hinder the growth of the (111) crystal plane and play a role in inhibiting the (111) crystal plane texture. And for another example, carbonyl and sulfonyl have obvious adsorbability on three crystal faces of copper crystal grains, carbonyl has weak adsorbability on the three crystal faces, sulfonyl has strong adsorbability on the three crystal faces, and sulfonyl has relatively strong adsorbability on the Cu (111) crystal face, so that the copper foil has certain capability of realizing oriented growth of the copper foil and changing the texture of the copper foil. The hydroxyl has obvious selectivity on three crystal faces of the copper crystal grains, the adsorptivity on the three crystal faces is similar, but the adsorptivity on the (220) crystal face is slightly stronger than that on the other two crystal faces, the texture coefficient of the copper foil (220) crystal face can be reduced theoretically, and the effect of crystal grain refinement can be realized actually.

The sulfydryl has almost the same adsorbability on the (111) crystal face, the (200) crystal face and the (220) crystal face of the copper crystal grain, can be adsorbed on the surface of each crystal face of the copper foil, increases the cathode polarization on the premise of keeping the texture coefficient, realizes a good crystal grain refining effect, and further realizes the effect of strengthening the mechanical property of the copper foil.

The amino and hydroxyl have relatively similar effects, but in fact sulfonyl, amino and hydroxyl also have extremely strong adsorbability on a titanium roller matrix, and the adsorbability on a Ti (101) crystal face is far greater than that on a copper crystal face, so that when the three are used, the three are preferentially adsorbed on the surface of the titanium roller actually, the growth of copper crystal grains is hindered in the transverse direction, the growth direction of the (220) crystal face texture perpendicular to the copper foil is changed, the internal stress of the copper foil is improved, and the effect of optimizing the mechanical property of the copper foil is realized.

An additive used in the method is sodium polydithio dipropyl sulfonate.

An additive for use in the above method, said additive being polyethylene glycol.

An additive for use in the above process, said additive being a polyethyleneimine.

An additive used in the method is carbonyl diphenylamine.

The four additives are all additives with better practical effect after being optimized, the optimal concentration is basically 0.01-0.015 mol/L, and good modification effect can be realized by adopting extremely low concentration.

The invention has the beneficial effects that:

1) the method provides a distinctive copper foil mechanical property optimization mode, and can effectively reduce cost and pollution;

2) the modification treatment mode is simple and efficient, and the additional process is disordered;

3) the growth orientation of copper crystal grains can be induced, and the orientation of a (220) crystal face is enhanced;

4) meanwhile, the grain refinement can be realized, and the mechanical property of the copper foil is enhanced.

Drawings

FIG. 1 is a graph showing the results of measurement of texture coefficients of the electrolytic copper foil obtained in example 1.

FIG. 2 is a graph showing the results of measurement of texture coefficients of the electrolytic copper foil prepared in comparative example 1.

FIG. 3 is an SEM representation of the matte side of the electrolytic copper foil obtained in example 1.

FIG. 4 is an SEM representation of the matte side of the electrolytic copper foil obtained in comparative example 1.

FIG. 5 is an SEM representation of the matte side of the electrolytic copper foil obtained in example 2.

FIG. 6 is an SEM representation of the matte side of the electrolytic copper foil obtained in example 3.

FIG. 7 is a graph showing the results of measurement of texture coefficients of the electrolytic copper foil obtained in example 4.

FIG. 8 is an SEM representation of the matte side of the electrolytic copper foil obtained in example 4.

Detailed Description

The invention is described in further detail below with reference to specific embodiments and the attached drawing figures. Those skilled in the art will be able to implement the invention based on these teachings. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.

Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all those known to those skilled in the art.

Unless otherwise specified, the basic formula adopted in the embodiment of the invention is copper sulfate/sulfuric acid aqueous solution, and the specific concentrations are as follows: 0.5 mol/L of copper sulfate and 1.0 mol/L of sulfuric acid.

Example 1

The additives selected in this example were: sodium polydithio-dipropyl sulfonate, and the addition amount of the additive is as follows: 0.01 mol/L.

The copper foil is prepared by the process of preparing the industrial conventional copper foil. The specific process comprises the following steps: controlling the current density to be 5A/m²。

The prepared electrolytic copper foil is detected according to the national standard GB/T-5230, and the detection shows that the tensile strength of the prepared electrolytic copper foil is 476.6 MPa. Further, the measurement results of the texture coefficients of the Cu (111), Cu (200) and Cu (220) crystal planes were obtained as shown in FIG. 1. In the figure: a is a smooth surface (right pillar) of the electrolytic copper foil, and b is a matte surface (left pillar) of the electrolytic copper foil.

Comparative example 1

The procedure is as in example 1, except that: no additives were added.

The prepared electrolytic copper foil is detected according to the national standard GB/T-5230, and the detection shows that the tensile strength of the prepared electrolytic copper foil is 325.24 MPa. Further, the measurement results of the texture coefficients of the Cu (111), Cu (200) and Cu (220) crystal planes were obtained, and are shown in FIG. 2. In the figure: a is a smooth surface (right pillar) of the electrolytic copper foil, and b is a matte surface (left pillar) of the electrolytic copper foil.

As is apparent from comparison between FIG. 1 and FIG. 2, the use of the additive can significantly improve the mechanical properties of the electrodeposited copper foil. And SEM characterization is performed on example 1 and comparative example 1, wherein an SEM characterization graph of the rough surface of the electrolytic copper foil prepared in example 1 is shown in FIG. 3, and an SEM characterization graph of the rough surface of the electrolytic copper foil prepared in comparative example 1 is shown in FIG. 4. As can be seen from the figure, the surface structure of the electrolytic copper foil is obviously changed after the additive is used, an obvious grain refinement effect is formed, an irregular convex structure is reduced, and the texture orientation of the copper foil is improved.

Example 2

The procedure is as in example 1, except that the additive is polyethylene glycol.

The prepared electrolytic copper foil is detected according to the national standard GB/T-5230, and the detection shows that the tensile strength of the prepared electrolytic copper foil is 451.45 MPa. The SEM representation of the matte surface of the obtained electrolytic copper foil is shown in FIG. 5.

As is apparent from fig. 5, the surface of the electrodeposited copper foil is very clearly grain-refined after the addition of the alcohol additive, and disordered protrusions are significantly reduced as in fig. 4.

Example 3

The procedure is as in example 1, except that the additives are 0.05 mol/L diethyl ether and 0.05 mol/L polyethyleneimine.

The prepared electrolytic copper foil is detected according to the national standard GB/T-5230, and the detection shows that the tensile strength of the prepared electrolytic copper foil is 511.61 MPa. The SEM representation of the matte surface of the obtained electrolytic copper foil is shown in FIG. 6.

As is apparent from fig. 6, after the ether and amine additives are added, the growth direction of the copper foil crystal grains is obviously changed, and the copper foil crystal grains are obviously refined, so that the texture characteristics of the copper foil are changed, and the mechanical properties of the copper foil are obviously improved.

Example 4

The procedure is as in example 1, except that the additives are 0.005 mol/L sodium polydithio-dipropyl sulfonate, 0.005 mol/L polyethylene glycol and 0.005 mol/L polyethyleneimine.

The prepared electrolytic copper foil is detected according to the national standard GB/T-5230, and the detection shows that the tensile strength of the prepared electrolytic copper foil is 534.8 MPa. Further, the measurement results of the texture coefficients of the Cu (111), Cu (200) and Cu (220) crystal planes were obtained, and are shown in FIG. 7. In the figure: a is a smooth surface (right pillar) of the electrolytic copper foil, and b is a matte surface (left pillar) of the electrolytic copper foil.

As is apparent from FIG. 7, the additive significantly improves the texture coefficient of the Cu (220) crystal plane of the rough surface of the electrolytic copper foil, so that the electrolytic copper foil produces a significant strengthening effect. Specifically, an SEM characteristic image of the electrodeposited copper foil produced in this example is shown in fig. 8. Under the coordination of various additives, the copper foil crystal grains are obviously refined, and the orientation growth trend is more obvious.