Speaker
Description
To this date lithium dendrites remain one of the key challenges in solid-state Li-batteries (SSLB).1,2 The formation and growth of these dendrites cause an inevitable failure at charge rates far below the threshold set by industry (>3mA/cm2) and are believed to be driven by stress accumulation stemming from the deposited lithium itself. Upon reaching a critical pressure, the solid-state electrolyte (SSE) starts to crack, which propagates until the cell short-circuits.3 Herein, we propose that this fracturing is not of mechanical origin but can rather be related to an increased Li activity in the SSE near the protrusion, caused by the diffusion-controlled Li deposition. This destabilizes the local structure of the SSE and weakens it within a certain time frame. If current is applied for shorter durations than is required for the Li activity to reach critical values, as is with high frequency pulses, the structural destabilization of the SSE can be delayed, and higher critical current densities (CCD) can be reached. Applying 1 MHz current pulses, a sixfold increase of the CCD, compared to DC operation and a maximum value of around 6.3 mA/cm² was reached in this work. Since an adaption of the applied current waveform can be combined with other reported measures like interlayers, alloys or structured interfaces, the fast-charging goal set for electric vehicles, appears to become feasible.4,5,6 Hence, the application of pulsed currents represents a crucial step toward realization of SSLBs for electric vehicles and other emerging applications.