All-solid-state batteries are looked to for their high energy density and reduced capacity fade, and are a safer alternative to the conventional liquid electrolyte batteries currently being manufactured. However, few solid electrolytes are currently known. Amorphous lithium phosphorus oxynitride (LiPON) is a well-established solid electrolyte and is currently the only viable solid-state electrolyte for thin film batteries. LiPON is stable in contact with Li metal, but exhibits a relatively low ionic conductivity (10^-6 S/cm²) [1]. A variety of other solid electrolytes with higher ionic conductivities are currently being explored, such as lithium lanthanum titanate (LLTO), achieving high lattice ionic conductivity of >10^-3 S/cm² [2]. We aim to enable LLTO as an electrolyte for thin film batteries via pulsed laser deposition. Additionally, performance of all-solid-state batteries is largely influenced by interfacial impedance and phase evolution during charge and discharge. The thin film geometry provides an ideal platform for analyzing the various electrode/electrolyte interfaces. Using novel focused ion beam and dynamic in situ transmission electron microscopy techniques, we have fabricated electrochemically active nanobatteries and observed their cycling behavior in situ. These techniques have been demonstrated on the layered lithium cobalt oxide (LCO)/LiPON interface, elucidating the mechanism of interfacial impedance which was previously unknown via ex-situ cycling experiments [3].

[1] N.J. Dudney, “Solid-state thin film rechargeable batteries,” Materials Science and Engineering: B, 116 (2005) 245-249.

[2] O. Bohnke, “The fast lithium-ion conducting oxides Li_3xLa_{2/3 − x}TiO₃ from fundamentals to application,” Solid State Ionics, 179 (2008) 9-15.

[3] Z. Wang, D. Santhanagopalan, W. Zhang, F. Wang, H. Xin, K. He, J. Li, N. Dudney and Y.S. Meng, “In situ STEM/EELS Observation of Nanoscale Interfacial Phenomena in All-Solid-State Batteries,” Submitted.