Preparation and Welded Properties of Nanotwinned Copper Foil for Battery

Conventionally, batteries such as zinc-ion batteries and lithium-ion batteries use coarse-grained Cu foil as the current collector; however, coarse-grained Cu with relatively low mechanical strength constitutes a significant limitation to battery performance. In addition, excessive charge–discharge cycling can lead to electrode active material, which markedly degrades battery performance and consequently restricts both safety and cycle life. In contrast, (111)-oriented nanotwinned Cu has attracted considerable attention owing to its superior mechanical and electrical properties. In this study, nanotwinned Cu foils with a high texture coefficient and uniform surface morphology were fabricated and utilized as cathode materials in zinc-ion battery, leading to an increase in cycle life from 74 cycles to over 200 cycles. Meanwhile, ultrasonic solid-state bonding is a widely adopted joining technique for battery current collectors. Accordingly, the mechanical properties of the nanotwinned Cu foils, as well as the microstructural evolution and mechanical behavior of ultrasonic solid-state bonded joints, were systematically characterized, thereby further enriching the theoretical basis for the design of highly reliable batteries. In summary, through the fabrication of nanotwinned Cu foils and comprehensive evaluation of their electrical and mechanical properties, together with battery performance and joint reliability, this study provides systematic theoretical and experimental support for the design and engineering application of high-performance battery with high reliability.