Ultrasound overcomes dendrite puncture in Li metal batteries

Lithium (Li) metal is regarded as the most targeted anode material for rechargeable batteries. However, the emergence of a critical safety hazard arises from the short-circuit phenomenon caused by dendrites in Li metal batteries that puncture the separator. Herein, we propose employing external power ultrasound to induce cavitation effects in the electrolyte, which can effectively disrupt Li dendrites within the battery, thereby reducing dendrite height and preventing short-circuit phenomena. Upon executing the external power ultrasound after electrochemical cycling, it is observed that the average height of Li dendrites decreased by 68.19 %, and the surface roughness of the electrodes decreased by 75 % as compared to the cells without ultrasound. In addition, the damage effect of ultrasonic on Li dendrites is investigated in real time by in-situ optical microscopy. Ultimately, we integrated the capacity and Coulombic efficiency of the Cu||Li half-cell to demonstrate that ultrasound enhances the cellular structure while maintains capacity performance. We assembled the Li||LFP full cells and demonstrated that the full cells still have excellent cycling performance as well as long-term stability after ultrasound. Our finding offers a viable strategy to reduce the height of dendrites and decrease the chance of short-circuit and thus improve the safety performance of batteries.