Unravelling the Chemistry and Microstructure Evolution of a Cathodic Interface in Sulfide-Based All-Solid-State Li-Ion Batteries

Abstract

All-solid-state lithium-ion batteries (SSLIBs) are promising candidates to meet the requirement of electric vehicles due to the intrinsic safety characteristics and high theoretical energy density. A stable cathodic interface is critical for maximizing the performance of SSLIBs. In this study, operando X-ray absorption near-edge spectroscopy (XANES) combined with transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) is employed to investigate the interfacial behavior between the Ni-rich layered cathodes and sulfide solid-state electrolyte. The study demonstrates a metastable intermediate state of sulfide electrolyte at high voltage and parasitic reactions with cathodes during the charge/discharge process, which leads to the surface structural reconstruction of Ni-rich cathodes. Constructing a uniform interlayer by atomic layer deposition (ALD) is also employed in this study to further investigate the cathodic interface stability. These results provide new insight into the cathodic interface reaction mechanism and highlight the importance of advanced operando characterizations for SSLIBs.

Interfacial Reactions in Inorganic All‐Solid‐State Lithium Batteries

“…The HAADF‐STEM with electron energy loss spectroscopy (EELS) (Figure 5e) was carried out to investigate the interface evolution between NMC811 and LGPS during the charge‐discharge process. Confirmed by the fast Fourier transformation (FFT), the atomic‐level structural TEM images present obvious differences in the lattice patterns between the LGPS and bulk region after cycling [106] . The lattice pattern at inner region is still the layered structure phase, but it can be indexed as the rock‐salt phase at interface.…”

“…e) Microstructure evolution of NMC811 cathodes after cycling in SSLIBs identified by STEM‐HAADF images and corresponding EELS spectra. Atomic‐level STEM‐HAADF image of a bare NMC811 cathode after cycling with corresponding FFT patterns and corresponding EELS spectra acquired from the regions [106] . Reproduced with permission from Ref.…”

“…Atomic-level STEM-HAADF image of a bare NMC811 cathode after cycling with corresponding FFT patterns and corresponding EELS spectra acquired from the regions. [106] Reproduced with permission from Ref. [106], copyright 2019, American Chemical Society.…”

“…[106] Reproduced with permission from Ref. [106], copyright 2019, American Chemical Society. f) Schematic illustrations of interface evolutions during the charge-discharge processes based on different vibration states of PÀ S bond in PS 4 3À at NCM/ Li 6 PS 5 Cl interface.…”

Advanced Characterization Techniques for Interface in All‐Solid‐State Batteries

“…The modified coin cell shown in Figure a was utilized for in situ XAS to investigate the influence of coating layer on LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NCM811) in NCM811/LGPS/Li ASSBs system. [ 130 ] The result of in situ XAS indicates that LiNbO 3 (LNO) coating layer isolates the cathode from solid‐state electrolyte, enhancing the stability of interface between NCM811 and LGPS, and hence improving the cycling process. Meanwhile, the local environment change tested by in situ XAS of Mn and Co from NCM811 is stable during the electrochemical process of ASSBs.…”