A Flexible Electron-blocking Interfacial Shield for Dendrite-free Solid Lithium Metal Batteries

Solid-state batteries (SSBs) are considered to be the next-generation lithium-ion battery technology due to their enhanced energy density and safety. However, the high electronic conductivity of solid-state electrolytes (SSEs) leads to Li dendrite nucleation and proliferation. Uneven electric-field distribution resulting from poor interfacial contact can further promote dendritic deposition and lead to rapid short circuiting of SSBs. Herein, we propose a flexible electron-blocking interfacial shield (EBS) to protect garnet electrolytes from the electronic degradation. The EBS formed by an in-situ substitution reaction can not only increase lithiophilicity but also stabilize the Li volume change, maintaining the integrity of the interface during repeated cycling. Density functional theory calculations show a high electron-tunneling energy barrier from Li metal to the EBS, indicating an excellent capacity for electron-blocking. EBS protected cells exhibit an improved critical current density of 1.2 mA cm−2 and stable cycling for over 400 h at 1 mA cm−2 (1 mAh cm−2) at room temperature. These results demonstrate an effective strategy for the suppression of Li dendrites and present fresh insight into the rational design of the SSE and Li metal interface. The high electronic conductivity of solid-state electrolytes leads to Li dendrite growth, thus hindering the commercialization of solid-state batteries. Here, the authors propose a flexible electron-blocking interface to protect garnet electrolytes from the electronic degradation.