A High‐Performance, Low‐Cost and Recyclable Solid Electrolyte for Practical All‐Solid‐State Lithium‐Based Batteries

ABSTRACT The commercialization of all‐solid‐state lithium metal batteries (ASSLMBs) is constrained by the absence of a suitable solid electrolyte (SE) that simultaneously offers high ionic conductivity, favorable processability, electrochemical stability with electrodes, and cost‐effectiveness. Herein, we report a novel polyoxometalate‐based SE, Li 4 SiW 12 O 40 (LSWO), featuring a Keggin‐type anion framework that constructs a three‐dimensionally interconnected lithium‐ion migration network, endowing it with a high room‐temperature ionic conductivity (6.19 × 10 −4 S cm −1 ). Additionally, the discrete Keggin‐type anion framework endows the material with excellent compressibility, achieving a relative density of 90.3% under 300 MPa. A robust gradient interfacial passivation layer can also be generated to stabilize the Li metal electrode, enabling the Li/LSWO/Li symmetric cell to achieve a critical current density of 4.2 mA cm −2 and sustain long‐term cycling for over 2400 h at 0.2 mA cm −2 . Notably, the ASSLMBs with Li/LSWO/LiNi 0.8 Mn 0.1 Co 0.1 O 2 configuration exhibit remarkable cycling stability, delivering capacity retentions of 93.3% after 140 cycles at 0.5 C in coin cells and 88.2% after 200 cycles at 0.5 C in pouch cells. Techno‐economic analysis reveals that LSWO exhibits significant cost‐effectiveness compared to representative SEs. The high‐performance and low‐cost LSWO SE presents a promising candidate to facilitate the commercialization of ASSLMBs.