Enhancement of Li+ transport through intermediate phase in high-content inorganic composite quasi-solid-state electrolytes

Quasi-solid-state electrolytes promise the safety of ceramics, the flexibility of polymers, and the conductivity of liquids—yet the “how” behind their superior ion transport has remained murky. Now, a joint team from Fudan University and the National Institute for Cryogenic & Isotopic Technologies (Romania), led by Professors Aishui Yu and Tao Huang, delivers a decisive answer in Nano-Micro Letters. Their review, “Enhancement of Li⁺ Transport Through Intermediate Phase in High-Content Inorganic Composite Electrolytes,” decodes the hidden chemistry that lets lithium sprint across solid/liquid boundaries.

The Secret Sauce: Acidic Interfaces

• Selective Anion Anchoring: Acidic LATP surfaces act as Lewis-acid traps for DFOB⁻ anions, loosening Li⁺ solvation cages and jacking the Li⁺ transference number from 0.31 → 0.53.
• Size Matters: Shrinking LATP particles to 200–300 nm boosts specific surface area and pushes ionic conductivity to 0.51 mS cm^-1 at room temperature.
• Dual-Phase Highways: An “intermediate phase” bridges ceramic and liquid domains, creating 3-D conduction networks that outpace single-phase polymers.

Performance that Speaks Louder than Theory

• 6000 h non-stop cycling in Li||Li symmetric cells at 0.1 mA cm^-2—no short-circuits.
• 80.5 % capacity retention after 200 cycles in a 5 V-class LNMO||Li full cell at 0.5 C.
• Pouch-cell demo drives LED arrays and mini-motors, proving scalability beyond coin cells.

Design Rules for Tomorrow’s Electrolytes

1. Surface Engineering > Bulk Chemistry: Acidic surface sites are the true catalysts; neutral or basic variants lag by 30 %.
2. Active Fillers Win: Ion-conductive LATP beats inert alumina, cutting activation energy and sustaining high-rate capability (155 mAh g^-1 at 0.1 C vs. 82 mAh g^-1).
3. SEI Self-Defense: LATP-induced decomposition forms a LiF-rich interphase that stops further Ti⁴⁺ reduction—self-limiting protection without extra coatings.

Future Outlook

• Nano-Architected Interfaces: Next-gen electrolytes will leverage tunable surface acidity and hierarchical porosity to push conductivities beyond 1 mS cm^-1.
• High-Loading Cathodes: 14 mg cm^-2 LNMO cathodes already retain 142 mAh g^-1—roadmap to >300 Wh kg^-1 pouch cells.
• Universal Design Toolkit: The acid-base descriptor framework can be ported to sulfides, chlorides, and beyond, fast-tracking the commercial leap from lab to EV.

Stay tuned as the Yu–Huang team turns interfacial chemistry into the next performance revolution for lithium-metal batteries.