With electric vehicles and grid storage demanding ever‑safer and higher‑capacity batteries, the drawbacks of conventional lithium‑ion technology, especially the flammability of liquid electrolytes and the risk of lithium dendrites, are becoming critical. Solid‑state batteries, which replace liquid electrolytes with solid counterparts, offer a compelling solution. However, their core component, the solid-state electrolyte (SSE), still faces significant challenges in ionic conductivity, interfacial compatibility, and large-scale manufacturing.
A comprehensive review entitled “Strategies for Obtaining High-Performance Li-Ion Solid-State Electrolytes for Solid-State Batteries” recently published in the Journal of Electrochemistry (published on Sep. 22, 2025) outlines the progress and persisting hurdles of SSEs. The authors note that single‑component electrolytes, such as oxides, sulfides, and polymers, each face intrinsic trade‑offs. Oxide SSEs are chemically stable but form poor interfaces; sulfide SSEs show high conductivity but degrade in air; polymer SSEs are flexible yet suffer from low conductivity at room temperature.
To overcome these limitations, the authors highlight the promise of smartly designed multi‑phase systems that integrate the advantages of different components. The review gives particular emphasis to the emergence of soft solid‑state electrolytes (S³Es), which are built on two complementary strategies: (1) “Rigid‑Flexible Synergy” Composites: These materials combine flexible polymers, ionic liquids, or plastic crystals with rigid inorganic nanofillers (e.g., oxides). The flexible phase ensures close electrode contact, while the rigid component strengthens the electrolyte mechanically, suppresses lithium dendrite growth, and facilitates lithium‑ion transport. (2) “Li⁺‑Desolvation” Mechanism: This approach employs porous framework materials such as Metal‑Organic Frameworks (MOFs) or Covalent Organic Frameworks (COFs). Their nanoscale channels act as “molecular cages” that immobilize solvent molecules from the electrolyte, thereby regulating the lithium‑ion solvation structure. This mechanism can significantly widen the electrochemical stability window and enhance compatibility with lithium metal. S³Es thus offer a balanced portfolio: higher ionic conductivity, robust mechanical integrity, excellent interfacial adaptation, and better processability—key enablers for real‑world battery applications.
Despite the promise, challenges remain in achieving uniform component dispersion, stabilizing multi‑phase interfaces over long cycles, and scaling up production. Future advancement requires coordinated breakthroughs in material innovation, battery architecture design, manufacturing processes, and advanced characterization techniques. As research progresses, soft solid‑state electrolytes are poised to accelerate the transition of solid‑state batteries from lab to market, ultimately supporting the development of safer, higher‑energy‑density storage systems for transportation and renewable energy integration.
DOI: 10.61558/2993-074X.3585