Engineering Ultra‐Stable Solid Electrolyte Interphase via Strong Crystal Face Coupling for High‐Rate Solid Lithium Batteries

ABSTRACT Enhancing the stability of the electrode/electrolyte interface is a critical challenge for achieving high‐performance lithium‐metal solid‐state batteries (LMSSBs). Constructing stable SEI is an effective strategy for interface improvement, however, utilizing side reactions for constructing the SEI generally leads to a great increase in interfacial impedance and capacity decay. Herein, this work reports the discovery that an ultra‐stable electrode/electrolyte interface is triggered by strong crystal face coupling between the (101) facet of MIL‐96 and TFSI − , while the (101) facet effectively suppresses decomposition reactions by modulating the molecular orbital energy levels of PEO/LiTFSI. Most impressively, the innate interface we constructed exhibited no interfacial side reactions, indicating a distinct difference from the traditional approach of forming an SEI interface through side reactions. Based on strong crystal face coupling, a CPE‐HBC solid‐state electrolyte with an ultra‐stable interface was obtained, extending the electrochemical window to 4.9 V. The Li|CPE‐HBC|Li achieved over 8000 h of stable cycling at 0.1 mA cm −2 , and the LiFePO 4 (LFP)|CPE‐HBC|Li retained 143.7 mAh g −1 after 300 cycles at 5 C. Furthermore, the assembled LFP|CPE‐HBC|Li pouch cells can stably power LEDs under various demanding conditions like blending and cutting, highlighting their potential for practical applications. The innate interface overcomes the limitations of conventional approaches that rely on interfacial side reactions to construct stable SEI layers, providing groundbreaking insights into the strategic design of high‐performance interphases in LMSSBs.