High Ionic Conductiviy Composite Ceramic-Polymer Electrolyte

Solid-state electrolytes (SSE) such as the garnet LiLaZrO are of utmost interest. They offer high electrochemical stability and non-flammability. However, compared to liquid electrolytes, their ionic conductivity is low and their incorporation into battery fabrication is challenging. Integrating these ceramic materials into polymer matrixes to form composite electrolytes offers potential solutions to these problems. We have fabricated a cubic phase bismuth-doped LLZO ceramic (LLZBO) particles, and integrated them into poly (ethylene oxide) matrixes. The LLZBO average particle size was decreased by attrition milling to a range of 500 to 600 nm range. Several weight contents in the polymer were used to optimize the ionic conductivity. Size and the particle dispersion was characterized with SEM. An optimum weight content was found at 10%wt yielding an unprecedented high value of the ionic conductivity of 5.98x10^-3 S/ at 55C. Work by others in similar systems employing tetragonal phase LLZO in a PEO matrix yielded ionic conductivities of 4.42x10^-4 S/cm at the same temperature, but a weight content load in the polymer of at least 52.5% was needed. Experimental details of our composites will be presented and mechanisms will be described for the large ionic conductivities attained.