Grafting polymer from oxygen-vacancy-rich nanoparticles to enable protective layers for stable lithium metal anode

Fabricating an artificial solid electrolyte interface (SEI) is a promising approach to improve cycling stability of lithium metal batteries. In this work, a new category of artificial SEI based on oxygen vacancy-rich hybrid nanoparticles was prepared by covalently grafting polymers from yttria–stabilized zirconia (YSZ) nanoparticles via surface-initiated atom transfer radical polymerization (SI-ATRP). The hairy nanoparticles had high dispersibility in dimethylsulfoxide, and were solution casted into uniform thin films with high inorganic content, high ionic conductivity (>1 × 10−4 S/cm at r.t.), and good mechanical properties (Young's modulus 7.56 GPa). No dendrite formation was observed by in-situ optical microscopy on a lithium metal protected by such artificial SEI. Protected anodes were stably cycled at 3 mA/cm2 and 3 mA h/cm2 with low overpotentials (20 mV) for >2500 h. LiNi0.8Co0.15Al0.05O2 (NCA)|Li full cells with protected Li anode showed much higher specific discharge capacity at various rates and improved capacity retention compared to unprotected Li anode.