As global energy storage races toward higher safety, sustainability and energy density, traditional liquid electrolytes are hitting a “flammability-leakage” wall. Now, a team led by Prof. Guoxiu Wang (University of Technology Sydney) and Dr. Hao Tian has delivered a 66-page roadmap in Nano-Micro Letters that systematically reviews quasi-solid gel electrolytes (QSGEs) for Li/Na/K metal batteries. The work offers plug-and-play design rules that unite self-healing, flexible, biomimetic and biomass functions in one gel platform.

Why Quasi-Solid Gels Matter
• Safety First: QSGEs cut fire risk by locking solvents in a 3-D polymer net, passing nail-penetration and 150 °C thermal abuse tests without leakage.
• Dendrite Shield: In-situ formed Li–Al–O or Na–COO– layers homogenize ion flux, enabling > 3000 h Li stripping/plating at 0.5 mA cm^-2.
• Green Chemistry: Cellulose, chitosan and lignin replace petro-based monomers, giving 94 % biodegradability and 30 % cost reduction.

Innovative Design Toolbox
• Four Functional Families: (i) Self-healing (boronic-ester, disulfide, H-bond), (ii) Flexible (COF, PVDF-HFP, cellulose composite), (iii) Biomimetic (ant-nest SiO₂, leaf-like Al₂O₃, brain-like MOF-in-MOF), (iv) Biomass (bacterial cellulose-IL, lignocellulose, acetylated chitosan).
• Cross-linking Recipes: UV-triggered PEGDA-UPy delivers 1.0 × 10^-3 S cm^-1 at 25 °C; patterned electro-spinning raises toughness to 613 % elongation.
• Hybrid Ion Channels: Hollow UiO-66 with –COO– lined pores lifts Li⁺ transference number to 0.90 while blocking TFSI^-.

Applications & Benchmarks
• High-Voltage LMB: Li|QSGE|NCM811 pouch reaches 3.1 mAh cm^-2, 300 cycles at 1C with 80 % capacity and 99.7 % CE.
• Ultra-Long SMB: Na|TPDBD-CNa-QSSE|Na₃V₂(PO₄)₃ maintains 91 % after 1000 cycles at 60 mA g^-1.
• Extreme-Temp KIB: 48 M KAc gel operates from −20 °C (3.4 mS cm^-1) to 90 °C (23.5 mS cm^-1), delivering 250 mAh g^-1 at 0.5 A g^-1.

Challenges & Roadmap
Key gaps remain: (i) scaling roll-to-roll UV curing to ≤ 20 µm thickness, (ii) pushing ionic conductivity to ≥ 5 mS cm⁻¹ below −20 °C, (iii) closing the loop with fully recyclable QSGEs. Future work will integrate machine-learning-guided polymer discovery and in-line impedance monitoring for gigawatt-hour production.

This comprehensive review provides a one-stop blueprint for next-gen safe, sustainable and high-energy alkali-metal batteries. Stay tuned for more game-changing advances from Prof. Wang’s team at UTS!