Effect and Research Progress on the Mechanism of Additives and Their Effects on Electrolytic Copper Foil - 5

Effect and Research Progress on the Mechanism of Additives and Their Effects on Electrolytic Copper Foil

1. Common Additives for Electrolytic Copper Foil

1.1 Sulfur-Containing Organic Compounds

1.1.1 Mechanism of Action of Sulfur-Containing Organic Compounds

1.2 Amine-Based Organic Compounds

1.2.1 Mechanism of Action of Amine-Based Organic Compounds

1.2.2 Influence of Amine-Based Organic Compounds on the Performance of Electrolytic Copper Foil

1.3 Ether Organic Compounds

1.3.1 Mechanism of Action of Ether Organic Compounds

1.3.2 Impact of Ether Organic Compounds on Additive Performance in Electrolytic Copper Foil

1.4 Chloride Ions

1.5 Rare Earth Elements

2. Interaction of organic additives

2.1 Interaction mechanism of organic additives

2.2 Synergistic Effects of Organic Additives

When the sulfur-containing organic compound and the amine organic compound act together, the electrolytic copper foil usually has better gloss, and the mechanical properties do not change much. When using sodium polydithiodipropane sulfonate (SPS) 2~10mg/L, N,N-dimethyl-dithiocarbonyl propane sulfonate (DPS) 2~10mg/L, isothioureapropanesulfonic acid Inner salt (UPS) 2~5mg/L these three kinds of sulfur-containing additives, combined with gelatin 2~10mg/L, etc., the copper foil prepared has good comprehensive performance, the gloss is greater than 80, the roughness of the rough surface is less than 1.5μm, and it can be used at room temperature. The tensile strength is higher than 400MPa, and the elongation is 3%~10%.

At present, the double-glossy copper foil used in lithium-ion batteries has certain requirements for gloss, so the research on the synergistic effect of additives rarely studies single additives, and most of them are direct comparisons or systems using three types of additives. For example, adding hydroxyethyl cellulose on the basis of the composite effect of collagen and SPS can improve the gloss and elongation of copper foil, but the tensile strength will decrease.

Summarize the additive formula corresponding to the electrolytic copper foil with good comprehensive performance such as patents and literature, usually contains at least one of the three types of additives, and the electrolyte system is relatively complex.

2.3 Modified Organic Additives

The nature of the interaction between organic additives and their influence on the properties of electrolytic copper foil is the effect of special functional groups. Therefore, in order to obtain more efficient additives, the usual way is to modify and modify some common organic additives with functional groups. The introduction of amine groups into sulfur-containing additives or polyether additives is a common modification method, and the obtained copper foil has good comprehensive properties. The introduction of amine groups on the sulfur-containing additives can give full play to the advantages of the joint action of the two and reduce the problems caused by the introduction of sulfur impurities by sulfur-containing organic compounds. For example, the use of thiourea and diethylenetriaminepentaacetic acid to prepare modified thiourea, It can effectively solve the problem of brittle copper foil caused by traditional thiourea additives, and at the same time make the grain structure fine and smooth and the surface density uniform. The introduction of amide groups into the polymer additives containing multiple ether bonds can introduce positively charged groups on the one hand, so that the modified additives can easily accept electrons and adsorb at the negative electrode of the cathode, and play the role of leveling and reducing internal resistance. Function; on the other hand, the performance of acid and alkali resistance, oxidation and reduction resistance of this kind of additives is optimized, and the scope of application is expanded. Copper foil with good tensile strength and elongation at break can be obtained when this modified additive is used in combination with other additives. For the modification of amine organic additives, there are mainly two ways: one is to introduce sulfur-containing groups (mainly -SH) on the amine molecule, so that it can play the role of two kinds of additives at the same time; the other is quaternary ammonium salt aryl modification. The most common amine organic compounds with sulfur-containing groups are sulfur-containing heterocyclic compounds, such as 2-mercaptopyridine (2-MP) whose sulfur-containing group is -SH. A comparative study of the effects of 2-MP and JGB on electrolytic copper revealed that 2-MP has a higher inhibitory effect and exhibits a stronger grain refinement effect than JGB. Since pyridine rings, pyrimidine rings and other structures can be adsorbed on the copper surface in parallel by electronic force, increasing the surface coverage and helping to inhibit copper deposition, and using 4,6-dimethyl-2-mercaptopyrimidine (DMP) with a similar structure 0~5mg/L, combined with 200mg/L PEG with a molecular weight of 8000, 1mg/L SPS and 30mg/L Cl-, a uniform, dense and smooth copper foil surface is obtained. When synthesizing diketopyrrolyl quaternary ammonium salt (DPP) derivatives with different aryl substituents, it will be found that the aryl modification can adjust the molecular orbital energy level and adsorption energy of DPP, and play an important role in regulating surface activity, interfacial adhesion and interaction with Aspects such as the interaction of the copper surface play an important role.

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