Interface Degradation of LaCl<sub>3</sub>-Based Solid Electrolytes Coupled with Ultrahigh-Nickel Cathodes.

Wu, Ye-Chao; Li, Feng; Cheng, Xiaobin; Tan, Yihong; Huang, Xin; Luo, Jin-Da; Chen, Shu; Pan, Ruijun et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

Despite competitive compatibility with high-nickel cathodes, chloride solid electrolytes (SEs) still experience inevitable side reactions at the cathode/SE interface, causing capacity decay in all-solid-state lithium batteries (ASSLBs) during cycling. Herein, a three-electrode ASSLB testing device is developed to comprehensively reveal the interface failure mechanisms of the ultrahigh-nickel LiNi<sub>0.92</sub>Co<sub>0.05</sub>Mn<sub>0.03</sub>O<sub>2</sub> (NCM92) cathode paired with LaCl<sub>3</sub>-based chloride SE Li<sub>0.447</sub>La<sub>0.475</sub>Zr<sub>0.059</sub>Ta<sub>0.179</sub>Cl<sub>3</sub> (LLZTC). Distribution of relaxation time (DRT) analysis clearly shows the ASSLB degradation accompanied by a significant NCM92/LLZTC interface impedance increase, which becomes more pronounced at the higher cutoff charging voltage of 4.8 V <i>vs</i> Li<sup>+</sup>/Li. Furthermore, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and focused ion beam scanning electron microscopy (FIB-SEM) analysis also confirm the deterioration arising from active lattice oxygen and loss of physical contact at the NCM92/LLZTC interface. These findings reveal both electrochemical degradation and physical contact failure at the cathode/SE interface as key causes of the ASSLBs' capacity decay.