Distinguishing the Effects of the Space-Charge Layer and Interfacial Side Reactions on Li10GeP2S12-Based All-Solid-State Batteries with Stoichiometric-Controlled LiCoO2

Guozhong Lu; Fushan Geng; Suyu Gu; Chao Li; Ming Shen; Bingwen Hu

doi:10.1021/acsami.2c05239

Distinguishing the Effects of the Space-Charge Layer and Interfacial Side Reactions on Li₁₀GeP₂S₁₂-Based All-Solid-State Batteries with Stoichiometric-Controlled LiCoO₂

ACS Appl Mater Interfaces. 2022 Jun 8;14(22):25556-25565. doi: 10.1021/acsami.2c05239. Epub 2022 May 26.

Authors

Guozhong Lu¹, Fushan Geng¹, Suyu Gu¹, Chao Li¹, Ming Shen¹, Bingwen Hu¹

Affiliation

¹ Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, P. R. China.

PMID: 35616325
DOI: 10.1021/acsami.2c05239

Abstract

All-solid-state lithium batteries (ASSLBs) with high volumetric energy density and enhanced safety are considered one of the most promising next-generation batteries. Elucidating the capacity-fading mechanism caused by the space-charge layer (SCL) and the interfacial side reaction (ISR) is crucial for the future development of high-energy-density ASSLBs with a longer cycle life. Here, a systematic study to probe the electrochemical performance of Li₁₀GeP₂S₁₂-based ASSLBs with stoichiometric-controlled Li_xCoO₂ was performed with the aid of density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS), focused ion beam-field emission scanning electron microscopy (FIB-SEM), and solid-state nuclear magnetic resonance (NMR) spectroscopy. We discovered that the overstoichiometric Li_1.042CoO₂ shows a high capacity at first cycle with the smallest overpotential, but the capacity gradually decreases, which is ascribed to the weak SCL effect and strong interfacial side reactions. On the contrary, the lithium-deficient Li_0.945CoO₂ achieves the best cycling stability with a very low capacity associated with the strongest SCL effect and weak interfacial side reactions. The SCL effect is indeed coupled with ISR, which eventually leads to capacity fading in long-term operation. We believe that the new insights gained from this work will accelerate the future development of LiCoO₂/LGPS-based ASSLBs with both a mitigated SCL effect and a longer cycle life.

Keywords: XPS; interfacial side reactions; oxide cathodes; solid-state NMR; space-charge layer; sulfide electrolyte.