Conclusion Anode foil for aluminum electrolytic capacitor was prepared by powder additive manufacturing technology. Based on the TG-DTG analysis, the sintering process was designed. Moreover, the effects of aluminum powder particle size and sintering temperature on electrical properties were investigated.
This closed-cell aluminum powder reduces the total surface area of the aluminum powder in the sintered foil, resulting in a decrease in specific capacitance. Furthermore, the formation of sintered necks between the aluminum powder in the sintered foil also contributes to the decrease in the surface area.
In contrast, an aluminum foil with a thickness of 120 μ m, produced using tunnel etching technology, has a lower expansion surface ratio of 65 or below. Therefore, the use of porous sintered foil significantly enhances the specific capacitance of the anode foil.
The performance of aluminum electrolytic capacitors largely depends on the specific surface area of the anode foil. A high specific surface area is commonly obtained by electrochemical etching, so that high-density etched tunnels (>10 7 /cm 2) are formed on aluminum foil [, , ].
Typically, the specific capacitance of the sintered foil increases with decreasing the size of the aluminum powder. In contrast, the specific capacitance of the sintered foils increases with an increase in the sphericity and volume fraction of the aluminum powder.
As the sintering temperature increased, the anode foil powder layer became denser, but the specific capacitance gradually decreased. However, low sintering temperature would cause the powder to peel off from the foil, which limited its application. The specific capacitance increased firstly and then decreased as the powder diameter rose.