The tube transducer as a novel source for power ultrasound: A case study in delamination of graphite coating from lithium-ion battery anode

Abstract: Developing high throughput applications of sonochemistry and sonoprocessing is an outstanding ultrasonic engineering challenge that continues to limit widespread industrial adoption. Conventional mass-produced Langevin-based technologies, such as the sonotrode or cleaning bath transducers, are not particularly well suited to treating large liquid volumes or flow-based systems, with a compromise between cavitation intensity and distribution through liquid bulk typically required. We report on the development of a tube transducer from a single element radially poled tubular piezoceramic, excited to generate an axially focused field. High-speed imaging and sonochemiluminescence are used to characterise the cavitation generated, which is also compared to the well-known activity at the tip of a sonotrode. Tube transducer and sonotrode sonications are then assessed for the material recycling application of graphite coating delamination from lithium-ion battery anode, both for intact and flaked anode sheets. The findings show that the tube transducer generates cavitation at sonotrode-like intensities or higher but distributed throughout the bore of the tube, with peak activity at the central axis. Prospects for developing tube transducer technology for high throughput flow-based applications are discussed.