A Ring-Shaped Lithium Metal Anode Enables High-Performance All-Solid-State Batteries Revealed by In Situ L-Band EPR Imaging

In traditional operations of all-solid-state lithium metal batteries (ASSLMBs), a small thin lithium metal circular disk is employed as a lithium metal anode (LMA). However, ASSLMBs with a circular-disk LMA often fail in <150 cycles with low capacity retention. In this work, we developed a new ring-shaped LMA to improve cyclability. Full cells consisting of a ring-shaped LMA, a LiCoO₂ cathode, and a Li₆PS₅Cl electrolyte maintain good capacity retention of 83.65% at 0.3C after 300 cycles. Moreover, in situ L-band electron paramagnetic resonance imaging (EPRI) showed that fewer Li dendrites are formed on a ring-shaped LMA. This work highlights the importance of the design of the shape of the LMA to mitigate the growth of lithium dendrites and shows that L-band EPRI is a useful technique for ASSLMBs.