Effects of cathode electrolyte interfacial (CEI) layer on long term cycling of all-solid-state thin-film batteries

Abstract

All-solid-state lithium-ion batteries have the potential to not only push the current limits of energy density by utilizing Li metal, but also improve safety by avoiding flammable organic electrolyte. However, understanding the role of solid electrolyte-electrode interfaces will be critical to improve performance. In this study, we conducted long term cycling on commercially available lithium cobalt oxide (LCO)/lithium phosphorus oxynitride (LiPON)/lithium (Li) cells at elevated temperature to investigate the interfacial phenomena that lead to capacity decay. STEM-EELS analysis of samples revealed a previously unreported disordered layer between the LCO cathode and LiPON electrolyte. This electrochemically inactive layer grew in thickness leading to loss of capacity and increase of interfacial resistance when cycled at 80 ºC. The stabilization of this layer through interfacial engineering is crucial to improve the long term performance of thin-film batteries especially under thermal stress.

Self‐Standing 3D Cathodes for All‐Solid‐State Thin Film Lithium Batteries with Improved Interface Kinetics

“…All EIS spectra consist of two semicircles in high frequency region. The first small semicircle corresponds to the ionic conduction of Li + ions in LiPON, while the second large semicircle can be attributed to charge transfer process at the LMO/LiPON interface . The interfacial resistance of the Li/LiPON interface is negligible compared to the LMO/LiPON interface, so it is not included in the equivalent circuit for fitting .…”

“…The first small semicircle corresponds to the ionic conduction of Li + ions in LiPON, while the second large semicircle can be attributed to charge transfer process at the LMO/LiPON interface . The interfacial resistance of the Li/LiPON interface is negligible compared to the LMO/LiPON interface, so it is not included in the equivalent circuit for fitting . The first semicircle due to LiPON electrolyte is very small compared to the second one and the enlarged spectra for the first semicircle are shown in Figure h and Figure S10f in the Supporting Information for comparison.…”

Cryogenic Focused Ion Beam Characterization of Lithium Metal Anodes

“…After a catastrophic event such as crushing or rupture causing the battery to short, we observe significant porosity at the Li/electrolyte interface and growth of the disordered LCO layer, both indicative of increased interfacial resistance and poor cell performance (Figure 5c). 12,14 With the goal of enabling cryo-TEM analysis of Li metal anodes and Li/SSE interfaces, we demonstrate cryo-FIB TEM lift-outs of Li metal and Li metal solid-state batteries ( Figures S6 and 5d). Despite Li metal's sensitivity to local heating, control of beam conditions and sample temperature enables fabrication of TEM lamellae, which can then be thinned to electron transparency (<100 nm).…”

Ni–Al–Cr superalloy as high temperature cathode current collector for advanced thin film Li batteries

“…9 Even though the energy density of TF-SSBs is lower compared to the bulk case, they remain a promising energy storage technology for wearables, sensors, lab-on-chip, implantable and other smallsized portable devices, 10,11 and most suitable option for applications involving exible microdevices.…”