Enhanced Lithium Ion Conductivity in Lithium Lanthanum Titanate Solid Electrolyte Nanowires Prepared By Electrospinning

Solid electrolytes have great potential to address the safety issues of Li-ion batteries, but better synthesis methods are still required for ceramics such as lithium lanthanum titanate (LLTO) since current techniques require high-temperature calcination for long times. Here we report a new approach that utilizes electrospinning to prepare phase-pure polycrystalline LLTO nanowires with well-crystallized tetragonal phase.

To synthesize LLTO nanowires, the electrospinning precursor was prepared by mixing a LLTO sol into a polymer solution [1]. In a typical electrospinning experiment, the voltage was set to 7 kV, the distance between the needle tip and the collector was kept at 10 cm, and the feed rate was 0.3 mL/h. The as-spun fibers were calcined at 1000 °C for 3 h to get the LLTO nanowires.

Pellets of electrospun LLTO and LLTO prepared with conventional sol-gel method [2] were made and sintered. Electrochemical impedance spectroscopy (EIS) was used for ionic conductivity measurement. Pellets prepared from the electrospun LLTO nanowires had higher density, less void space, and higher Li⁺ conductivity compared to those made from conventional sol-gel method. This work demonstrates the potential that electrospinning can provide towards improving the properties of sol-gel derived ceramics.

Acknowledgements

This work was supported by new faculty startup funds from the Fulton Schools of Engineering at ASU. We gratefully acknowledge the use of facilities within the LeRoy Center for Solid State Science and Goldwater Environmental Laboratory at ASU.

References

[1] T. Yang, Y. Li and C. K. Chan, Journal of Power Sources 287 (2015) 164-169.

[2] T. Wöhrle, P. Gómez-Romero, T. Fries, K. West, M.R. Palacín, N. Casañ-Pastor, Ionics 2 (1996) 442.