Constructing a Uniform and Stable Mixed Conductive Layer to Stabilize the Solid‐State Electrolyte/Li Interface by Cold Bonding at Mild Conditions

Abstract

Garnet‐type Li6.4La3Zr1.4Ta0.6O12 (LLZ) electrolyte is a promising candidate for high‐performance solid‐state batteries, while its applications are hindered by interfacial problems. Although the utilization of functional coatings and molten lithium (Li) effectively solves the LLZ interfacial compatibility problem with Li metal, it poses problems such as high cost, high danger, and structural damage. Herein, a mixed conductive layer (MCL) is introduced at the LLZ/Li interface (RT‐MCL) via an in situ cold bonding process at room temperature. Such a stable and compact RT‐MCL can effectively suppress side reactions and protect the crystal structure of LLZ, and it also inhibits growth of Li dendrites and promotes uniform Li deposition. The critical current density (CCD) of the Li symmetric cell composed of RT‐MCL‐LLZ is increased to 1.8 mA cm‐2 and provides stable cycling performance over 2000 h under 0.5 mA cm‐2. Additionally, this in situ cold bonding treatment can significantly reduce cost and eliminate potential safety issues caused by the high‐temperature processing of Li metal. This work highlights tremendous potential of this cold bonding technique in the reasonable design and optimization of the LLZ/Li interface.

Integration Plasma Strategy Controlled Interfacial Chemistry Regulation Enabling Planar Lithium Growth in Solid‐State Lithium Metal Batteries

“…[40] However, the high electronic conductivity of Ag-Li alloy also easily triggers the side reactions between the SSEs and Li metal, going against to the cycling stability of batteries. [26] IP-LAGP also delivers a decent rate performance in Li | NCM811 SSLMBs as shown in Figure 3f. When the current density increased from 0.05 to 1 C, the IP-LAGP still maintains a high discharge capacity of 133.1 mAh g −1 .…”

“…[6,[17][18][19][20][21][22][23][24] In addition to improving physical contact, a majority of metallic compounds induce complex chemical reactions with Li metal to regulate Li deposition. According to recent literature, [21,[25][26][27][28] metallic compounds (e.g., AgF, InN, and SnO 2 ) first undergo a conversion reaction to form metal atom and Li salt, and the typical equation can be summarized as:…”

“…[27,29] Despite the above-mentioned advantages, the proportion of formed M-Li alloy and Li salt in metallic compound-based interlayers are largely limiting by the intrinsic atomic ratio of M and E elements (AR E/M ) in raw materials (for example, the AR E/M is 1 in AgF or 2 in ZnF 2 ), according to the conversion reaction (Equation 1). When there is insufficient formation of Li salt, electrons can penetrate into SSE due to the high electronic conductivity of M-Li alloy, [26,30] but the superfluous Li salt is easy to decrease rate performance of batteries because the Li + diffusion rate on Li salt is far behind that of the Li-Li self-diffusion. [31,32] Another limitation is that M-Li alloy commonly suffers from significant volumetric expansion during alloying/dealloying processes, which leads to the morphological degradation of interlayers and further weakens their effects.…”

Advances in Inorganic Solid‐State Electrolyte/Li Interface

“…This work highlights the tremendous potential of this in-situ cold bonding technique in the reasonable design and optimization of the LLZO/Li interface. [36]…”

In Situ Conversion Reaction Triggered Alloy@Antiperovskite Hybrid Layers for Lithiophilic and Robust Lithium/Garnet Interfaces

“…[14,15] The following two key factors are widely acknowledged to induce the infiltration of Li dendrite across LLZO bulk. One is the crucial interfacial issues, [16,17] that is, the rigid LLZO makes poor contact with Li metal, forming generous micro gaps at Li/LLZO interfaces. Such unsatisfactory point contact induces an extended interfacial impedance and local electric field concentration, leading to the uneven Li deposition at interfaces and thus the preferential Li nucleation/growth at local regions.…”