A Dynamically Stable Mixed Conducting Interphase for All‐Solid‐State Lithium Metal Batteries

Abstract

All‐solid‐state lithium (Li) metal batteries (ASSLMBs) employing sulfide solid electrolytes have attracted increasing attention owing to their superior safety and high energy density. However, the instability of sulfide electrolytes against Li metal generally induces the formation of two types of incompetent interphases, that is, solid‐state interphase (SEI) and mixed conducting interphase (MCI), which significantly blocks the rapid Li‐ion transport and induces uneven Li metal deposition and continuous interface degradation. In this contribution, a dynamically stable mixed conducting interphase (S‐MCI) is proposed by in‐situ stress self‐limiting reactions to achieve the compatibility of Li metal with composite sulfide electrolytes (Li6PS5Cl (LPSCl) and Li10GeP2S12 (LGPS)) and the suppression of Li dendrite penetration. The rational design of composite electrolyte utilizes the expansion stress after the decomposition of working electrolyte to in turn constrain the further continuous decomposition of LGPS. Consequently, the dense S‐MCI inherits the high dynamical stability of LPSCl‐derived SEI and lithiophilic affinity of Li‐Ge alloy in LGPS‐derived MCI. The Li||Li symmetric cells with the protection of S‐MCI can operate stably for 1500 h at 0.5 mA cm−2 and 0.5 mAh cm−2. The Li||NCM622 full cells present stable cycling for 100 cycles at 0.1 C with a high‐capacity retention of 93.7%. This work sheds fresh insight into constructing electrochemically stable interphase for high‐performance ASSLMBs.This article is protected by copyright. All rights reserved

Synergized Interface Engineering and Alloying Strategy for In Situ Construction of a Three-Dimensional Lithiophilic Carbon Skeleton: Motivating High-Performance Lithium Metal Batteries

“…Nyquist plots and equivalent circuit diagrams are shown in panels d and e of Figure 3 and Figure S4 of the Supporting Information, in which R s represents the electrolyte solution resistance, R SEI stands for the solid electrolyte interface resistance, and R ct is the charge transfer resistance. 40 The Li@CC electrode before cycling exhibits a significant interfacial resistance, and R SEI of the Li@CC symmetric cell decreases to 412, 286, 47.5, and 15.6 Ω after 1, 5, 10, and 50 cycles (Table S1 of the Supporting Information), respectively. The LiSn@CN@CC||LiSn@CN@CC cell exhibits a significantly smaller R SEI before cycling, suggesting that the Li− Sn alloy anode presents an impressive R SEI as well as superior charge carrier transport capability and stable interfacial properties compared to the pure lithium phase cathode.…”

“…EIS analysis of the Li@CC and LiSn@CN@CC electrodes was also performed. Nyquist plots and equivalent circuit diagrams are shown in panels d and e of Figure and Figure S4 of the Supporting Information, in which R s represents the electrolyte solution resistance, R SEI stands for the solid electrolyte interface resistance, and R ct is the charge transfer resistance . The Li@CC electrode before cycling exhibits a significant interfacial resistance, and R SEI of the Li@CC symmetric cell decreases to 412, 286, 47.5, and 15.6 Ω after 1, 5, 10, and 50 cycles (Table S1 of the Supporting Information), respectively.…”

Safer solid‐state lithium metal batteries: Mechanisms and strategies

“…37,38 Further, Cryo-TEM and time of flight secondary ion mass spectrometry (TOF-SIMS) can more professionally characterize the chemical reaction and evolution process of the metal Li-SSEs interface. [39][40][41] Therefore, the battery thermal failure mechanism can be deduced backwards from the material phase structure point of view, thus providing a clear understanding of the interface side reactions, especially for reactions associated with Li metal and cathode. 42,43 Moreover, the material perspective can also provide a guidance for the rational design of thermally stable battery materials in the future.…”

Operando Photoelectron Spectroscopy Analysis of Li6PS5Cl Electrochemical Decomposition Reactions in Solid-State Batteries

“…Unfortunately, most solid electrolytes (SEs) are not electrochemically stable at low potentials, e.g., at the operation potential of high-energy-density lithium metal and silicon anodes (i.e., negative electrodes) . Therefore, electrolyte reduction reactions occur at the anode|SE interface, forming either a solid electrolyte interphase (SEI) or a mixed conducting interphase (MCI) due to accumulation of decomposition products. − Electrolyte reduction reactions, and the succeeding interphase formation, will cause lithium inventory losses and impede the lithium transport kinetics at the anode|SE interface, , both leading to poor battery cycle life. Thus, it is crucial to determine the onset potential of different side reactions and reaction products not only through theoretical studies ,, but also through experiments since the actual chemical behavior may vary under practically relevant conditions.…”