Improvement of the Interface Contact between Solid Polymer Electrolytes and Electrodes via Ultrasonic-Press Fusion

All solid-state lithium batteries have high energy density, good safety, and broad prospects. However, the poor compatibility of the electrolyte/electrode interface limits its development. To improve the interface contact performance of batteries, this study proposes an ultrasonic-press fusion method. The electrolyte/electrode structure was pressed by an ultrasonic sonotrode, and fused tightly via thermal and mechanical effects produced by ultrasonic-press fusion. The results showed that the charge transfer impedance at the battery interface was reduced by 80.3% in AC impedance testing, and the battery interface impedance performance was significantly improved. By observing the surface and interface morphology of the electrolyte, it was found that ultrasonic-press fusion improved the electrolyte interface contact. The electrolyte melted and produced microscale rheological behavior under the action of ultrasonic-press fusion, ultimately filling the capillary structure of anode in the battery, improving contact performance of the interface. Furthermore, a molecular dynamics model of the interface was constructed to calculate the contact performance. It was found that ultrasonic-press fusion generates thermal and mechanical effects. The thermal effect facilitates the electrolyte melts, and the mechanical effect causes the melt to vibrate, which coordinate and act on the electrolyte and cause the electrolyte to solder to the anode.