Enhancement of Li+ Transport Through Intermediate Phase in High-Content Inorganic Composite Quasi-Solid-State Electrolytes

• A high-proportion inorganic composite quasi-solid-state electrolyte was fabricated via high-speed defoamed mixers and in situ polymerization, achieving enhanced ionic conductivity of 0.51 mS cm−1 at room temperature. • The intermediate phase, with anion-adsorbing affinity, facilitates partial dissociation of lithium-ion solvation structures, improving Li+ transport kinetics and transference numbers. • Exceptional interfacial stability is demonstrated by lithium-symmetric cells operating without short-circuiting for 6000 h at 0.1 mA cm−2. • The system maintains 80.5% capacity retention after 200 cycles at 0.5C in 5 V-class lithium metal full cells, highlighting its potential for high-voltage applications.