Thio‐/LISICON and LGPS‐Type Solid Electrolytes for All‐Solid‐State Lithium‐Ion Batteries

Abstract

As an integral part of all‐solid‐state lithium (Li) batteries (ASSLBs), solid‐state electrolytes (SSEs) must meet requirements in high ionic conductivity, electrochemical/chemical stability toward the electrode. The ionic conductivity of the Li super ionic conductor (LISICON) is limited, and the thio‐LISICON is improved by replacing O2− in the LISICON with S2−. Currently, the ionic conductivity of Li10GeP2S12 (LGPS) has exceeded 10 mS cm−1, which meets the demands of commercial ASSLBs. However, poor stability of SSEs, baneful interfacial reactions, Li dendrite growth, and other factors have impeded the development of ASSLBs. Hence, this review first traces the development progress of thio‐/LISICON and LGPS‐type SSEs, analyzes the complicated ion transport mechanism, and summarizes the effective strategies for improving ionic conductivity. Moreover, exciting methods focusing on electrode interface engineering are outlined separately. As to SSE/anode interface, poor chemical or electrochemical compatibility, poor interfacial contact, and the mechanisms of dendrite formation are discussed. For the SSE/cathode interface, poor interfacial stability and non‐intimate solid–solid contact are daunting challenges. Then, effective methods to improve interface stability and electrochemical performance of ASSLBs with LGPS‐type SSEs are introduced. Finally, combined with the present chances and challenges, the possible future developing directions of LGPS‐based ASSLBs and the perspectives are proposed.

Review of the Developments and Difficulties in Inorganic Solid-State Electrolytes

“…Although oxide electrolytes do not have particularly high ionic conductivity, they have good mechanical properties and stability to the atmosphere and electrode. Sulfide electrolytes with S 2− replacing O 2− of oxides show higher ionic conductivities at room temperature; however, due to their chemical reactivity with moisture, they are less stable in the air [ 14 ]. This section discusses oxide electrolytes such as garnet-type, perovskite-type, and NASICON-type structures, sulfide electrolytes such as thio-LISICON systems, and their stability issues.…”

Recent Developments in the Field of Sulfide Ceramic Solid‐State Electrolytes

“…[9]. Li 7 PS 6 is a polymorph; being prepared by the common solid‐state synthesis (sintering of 80 mol% Li 2 S and 20 mol% of P 2 S 5 ), the cubic phase is stable at temperatures over 210 °C, and the orthorhombic phase is stable at temperatures below 210 °C [ 8 ] having σ RT of ≈8 × 10 −2 mS cm −1 . [ 50 ] The wet chemistry synthesis offers the way to prepare the room‐temperature stable modification of cubic Li 7 PS 6 with σ RT ≈ 0.11 mS cm −1 .…”

Charge–Discharge Properties of Sputtered Mg Anode in Flexible All-Solid-State Mg-Ion Batteries

“…Inorganic solid electrolytes (also known as ionic superconductors) exhibit high ionic conductivity at room temperature. Numerous studies have proposed the use of lithium oxides as solid electrolytes (e.g., perovskite, NASICON, LISICON, and LiPON systems), − which exhibit acceptable ionic conductivity and low activation energy at room temperature. However, the use of Li-based solid electrolytes is limited by the scarcity of Li mineral reserves.…”