Tuning Ion/Electron Conducting Properties at Electrified Interfaces for Practical All-Solid-State Li–Metal Batteries

Poly(ethylene oxide) (PEO) based solid-state electrolytes with good chemical stability against Li–metal, provide a promising solution for practical all solid-state Li–metal batteries (ASSLMBs). However, the risk of short circuit using thin PEO under semi-molten state and the oxidative decomposition of PEO by cathodes under high voltage hinder the practical application of PEO-based ASSLMBs. Here, it is found that by readjusting the Li⁺ and e^– conductivity at anode/cathode interface by introducing Nanodiamonds (NDs) into PEO electrolytes can greatly improve the electrochemical performance of PEO-based batteries. Under the mediation of high modulus and insulative NDs, the lifespan of Li symmetric cells can increase by 30 times at 0.8 mA cm^–2, and high-voltage Li/LiCoO₂ cells show excellent capacity retention under practical testing conditions (50 µm Li and 30 µm PEO electrolyte).