Enhanced Electrochemical Stability and Extended Cycle Life in Sulfide‐Based All‐Solid‐State Batteries: The Role of Li10SnP2S12 Coating on Ni‐Rich NCM Cathode

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 11
• Main Authors: Park, Yongsun, Chang, Joon Ha, Oh, Gwangseok, Kim, A‐young, Chang, Hansen, Uenal, Mahir, Nam, Sangcheol, Kwon, Ohmin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 15-03-2024
• Subjects: all‐solid‐state batteries; Buffer layers; Cathodes; Commercialization; Core-shell structure; core‐shell structures; dry coating; Electrochemical analysis; Electrode materials; high capacity; Interface stability; LSnPS; Molten salt electrolytes; Solid electrolytes; Synthesis
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202305758

Recently, sulfide‐based all‐solid‐state batteries (ASSBs) have attracted great attention because of their excellent safety and high energy density. However, by‐products formed from side‐reactions between the oxide‐based cathodes and sulfide‐based solid electrolytes (SEs) increase the interfacial resistance and degrade the cell performance. Suppression of this interfacial resistance is thus critical. In this study, the extraordinarily high stability of the cathode/SE interface is discovered when a Li10SnP2S12 (LSnPS) is applied to a cathode buffer layer. The electrochemical properties of the cathode interface at high potential are improved by synthesizing a core–shell structure cathode using LSnPS. The synthesized LSnPS is uniformly coated on a Li2ZrO3‐coated LiNi0.8Co0.1Mn0.1O2 (LZO‐NCM) surface using the cost‐efficient mechano‐fusion method. The ASSB with LSnPS‐coated LZO‐NCM as the cathode and Li6PS5Cl (argyrodite, LPSCl) as the SE exhibited a capacity of 192 mAh g−1 and excellent cycle retention of ≈75% after 500 charge/discharge cycles. In addition, the degradation mechanism at the cathode/SE interface is investigated. The results indicated that LSnPS stabilizes the interface between NCM and argyrodite, thereby inhibiting the decomposition of the SE. This technology is expected to contribute to the commercialization of cathode materials for sulfide‐based ASSBs due to its enhanced cycle performance, low‐cost material application, and eco‐friendly process.
In this study, Li10SnP2S12 (LSnPS) material is discovered to apply as an interface stabilizer of interface between cathode and solid electrolyte (SE) due to high‐potential stability. Moreover, the mechano‐fusion method is used to fabricate the cathode material of LSnPS‐LiNi0.8Co0.1Mn0.1O2 (NCM) core‐shell structure. This approach significantly improves the initial capacity and cyclability, compared to conventional Li2ZrO3‐coated NCM.