Potential-Driven Selective Na Metal Deposition-Enabled Interphase with High Lithium Dendrite Suppression Capability

Voids formation during Li stripping and Li dendrite growth during Li plating are critical challenges that restrict the practical application of all-solid-state Li-metal batteries (ASSLBs). Extensive research efforts typically address these issues in isolation, thereby limiting the ability of ASSLBs to achieve a stable cyclic performance under low stack pressure. Herein, we address these two challenges simultaneously by using hard carbon-Sn (HC-Sn) as an interlayer and LiNa as an anode. After Li plating/stripping cycles, the Li6PS5Cl/HC-Sn/LiNa in situ transfers to the Li6PS5Cl/HC-LixSnNa/Na/LiNa structure, where HC-LixSnNa represents HC-LixSn embedded within the sodium metal. The fast Li+ diffusivity of HC-LixSn promotes uniform Li deposition at the HC-LixSnNa/Na interface, while the soft Na in the HC-LixSn layer and at the HC-LixSnNa/LiNa interface suppresses void formation during Li stripping, thus, high lithium dendrite suppression capability is achieved in Li6PS5Cl/HC-Sn/LiNa. As a result, the LiNa/HC-Sn/Li6PS5Cl/HC-Sn/LiNa symmetric cell shows stable Li plating/stripping cycles of 1184 h at 1.0 mA cm-2/4.0 mAh cm-2 under a low stack pressure of 2.0 MPa. The Co0.1Fe0.9S2/Li6PS5Cl/HC-Sn/LiNa cell shows high cycling stability with a capacity retention of 90.0% after 1000 cycles at an areal capacity of ∼1.5 mAh cm-2 and a high reversible capacity of 3.14 mAh cm-2 after 300 cycles at an areal capacity of ∼4.0 mAh cm-2 under the same low stack pressure of 2.0 MPa. This work provides a strategy to design ASSLSBs with a long cycle life at low stack pressure for practical application.