Critical current density (CCD) is currently used to evaluate Li dendrite-suppression capability of solid-state electrolytes (SSEs). However, CCD values vary with engineering parameters, resulting in a large deviation of CCD values for the same SSE. Herein we evaluate lithium dendrite-suppression capability of SSEs using critical interphase overpotential (CIOP). The CIOP is the intrinsic property of the interphase, which depends on electronic/ionic conductivity, lithiophobicity and mechanical strength. When the applied interphase overpotential (AIOP) is larger than CIOP, Li will grow into interphase as dendrites. To reduce AIOP but increase CIOP, we design a mix-conductive Li₂NH-Mg interlayer between Li₆PS₅Cl SSE and Li-1.0 wt% La anode, which transfers into Li₆PS₅Cl/LiMgS_x/LiH-Li₃N/LiMgLa after Mg migration during annealing and activation cycles. The LiMgS_x interphase increases the CIOP from ~10 mV (for Li₆PS₅Cl) to ~220 mV. The Li plates on the LiMgLa surface, and reversible penetration into formed porous LiH-Li₃N reduces AIOP. The CIOP provides a design guideline for high-energy and room temperature all-solid-state lithium-metal batteries.

临界电流密度 (CCD) 目前用于评估固态电解质 (SSE) 的锂枝晶抑制能力。然而，CCD 值随工程参数的不同而不同，导致同一 SSE 的 CCD 值偏差较大。在此，我们使用临界相间过电位 (CIOP) 评估 SSE 的锂枝晶抑制能力。CIOP 是界面的固有特性，它取决于电子/离子电导率、疏锂性和机械强度。当施加的相间过电势（AIOP）大于CIOP时，Li将以枝晶形式生长到相间。为了降低 AIOP 但增加 CIOP，我们在 Li ₆ PS ₅之间设计了混合导电 Li _{2 NH-Mg 中间层}Cl SSE 和 Li-1.0 wt% La 阳极，在退火和活化循环期间 Mg 迁移后转移到 Li ₆ PS ₅ Cl/LiMgS _x /LiH-Li _{3 N/LiMgLa。}LiMgS _x界面将 CIOP 从 ~10 mV（对于 Li ₆ PS ₅ Cl）增加到~220 mV。LiMgLa 表面上的 Li 板以及可逆渗透到形成的多孔 LiH-Li ₃ N 中可降低 AIOP。CIOP 为高能和室温全固态锂金属电池提供了设计指南。