Metastable Decomposition Realizing Dendrite-Free Solid-State Li Metal Batteries

A stable interface and preventing dendrite-growth are two crucial factors to realize long-life all-solid-state Li batteries (ASSLBs) using sulfide-based solid electrolytes (SEs) and Li metal anodes. But it remains a challenge to accomplish the two factors simultaneously. Here, an effective strategy is reported to realize this goal in Li-argyrodites via self-engineered metastable decomposition that is enabled by Si doping in Cl-rich argyrodites. It is shown that Cl atoms in the lattice become metastable and are highly reactive with Li atoms. The locally deposited/grown Li crystal nuclei are thus depleted by the metastable Cl during electrochemical cycling, in situ generating electrically insulated LiCl shells concentrated at the argyrodite grain boundaries. The shells in turn prevent the autochthonous Li redeposition and act as self-protective layers to restrain the continuous decomposition in the interior argyrodite, that is, self-assembly of reactive-cores-stable-shells to Li metal, thereby enabling an ultra-long life ASSLB using Li metal anodes at room temperature under relatively high current densities.

Automated summary

A stable interface and preventing dendrite-growth are crucial for the long-life of solid-state Li batteries using sulfide-based solid electrolytes (SEs) and Li metal anodes. This study reports a strategy using Si doping in Cl-rich argyrodites that enables self-engineered metastable decomposition, leading to the realization of these two factors simultaneously. The metastable Cl atoms react with Li atoms, depleting locally deposited/grown Li crystal nuclei and generating electrically insulated LiCl shells at the grain boundaries. These shells prevent Li redeposition and act as self-protective layers, enabling an ultra-long life ASSLB with Li metal anodes under high current densities at room temperature.