At present, the electrolytes used for electrodepositing cobalt is chlorination system and sulfate system, while the electrolytes used for electrodepositing nickel is the sulfate system. The titanium anode suitable for chloride electrolytes is a chlorine evolution anode coated with precious metal oxides mainly containing ruthenium, while the titanium anode suitable for sulfate solutions is an oxygen evolution anode coated with precious metal oxides mainly containing iridium.
The application of iridium coated titanium anode in copper foil electrodeposition and post treatment in sulfuric acid system has a history of nearly 20 years, and the technology is quite mature. Although the one-time investment of titanium based coated anodes is large (about 1.5-2 times that of lead anodes), they have many unparalleled advantages compared to lead anodes, such as being recoated and having a lifespan 2-3 times that of lead anodes. After long-term use, the comprehensive cost will be significantly lower than that of lead anodes, while reducing environmental pollution. Replacing lead anode with titanium anode is a historical trend and an industrial upgrade.
Titanium anode has stable performance, corrosion resistance, and can be used for a long time. It has good electro catalytic activity in the process of anode to reduce the Overpotential and cell voltage of anode reaction.
Titanium anode: After surface treatment, titanium substrate is coated with Ru/Ir/Ta metals, and then sintered to form precious metal oxide solid melt. This oxide is anoxic, so electrons can be transported, conducted, and electrocatalysed for various electrochemical reactions.
Lead anode: PbO₂+2e+SO₄²-+4H+=PbSO₄+2H₂O Pb 2e+SO₄²-=PbSO₄
Total reaction: PbO₂+2 H₂SO₄+Pb=2 PbSO₄+2H₂O
Lead sulfate is slightly soluble in water, and the consumption of lead anode dissolution is small during electrodeposition. When Cl- is present in the solution, PbCl2 is easily soluble in water, which destroys the above reaction balance, leading to the rapid dissolution of lead. This reaction is often very fast, thus affecting the service life of lead anode.
The titanium anode provided by Baoji Changsheng Titanium company, is mainly used in the sulfate system for the nickel electrodeposition. The titanium anode suitable for chloride electrolytes is a chlorine evolution anode coated with precious metal oxides mainly containing ruthenium, while the titanium anode suitable for sulfate solutions is an oxygen evolution anode coated with precious metal oxides mainly containing iridium.
|Chlorination system||Cl - concentration: 60-150g/L|
|Solution temperature||50-70 ℃|
|Titanium coated ruthenium anode service life||>18 months|
|Sulfuric acid system||SO₄²- concentration<150g/L|
|Solution temperature||<60 ℃|
|Titanium coated iridium anode service life||> 36 months|