Vanadium pentoxide interfacial layer enables high performance all-solid-state thin film batteries

• Published in: RSC advances 2024-05, Vol.14 (22), p.15261-15269
• Main Authors: Ma, Shiping, Wei, Kaiyuan, Zhao, Yu, Qiu, Jinxu, Xu, Rongrui, Li, Hongliang, Zhang, Hui, Cui, Yanhua
• Format: Article
• Language: English
• Subjects: Batteries; Cathodes; Cathodic polarization; Charge transfer; Chemistry; Cobalt oxides; Discharge; Electrode polarization; Electrolytes; Ion transport; Lithium compounds; Lithium ions; Magnetron sputtering; Solid state; Thin films; Vanadium pentoxide
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d4ra01849d

Lithium cobalt oxide (LiCoO 2 ) is considered as one of the promising building blocks that can be used to fabricate all-solid-state thin film batteries (TFBs) because of its easy accessibility, high working voltage, and high energy density. However, the slow interfacial dynamics between LiCoO 2 and LiPON in these TFBs results in undesirable side reactions and severe degradation of cycling and rate performance. Herein, amorphous vanadium pentoxide (V 2 O 5 ) film was employed as the interfacial layer of a cathode-electrolyte solid-solid interface to fabricate all-solid-state TFBs using a magnetron sputtering method. The V 2 O 5 thin film layer assisted in the construction of an ion transport network at the cathode/electrolyte interface, thus reducing the electrochemical redox polarization potential. The V 2 O 5 interfacial layer also effectively suppressed the side reactions between LiCoO 2 and LiPON. In addition, the interfacial resistance of TFBs was significantly decreased by optimizing the thickness of the interfacial modification layer. Compared to TFBs without the V 2 O 5 layer, TFBs based on LiCoO 2 /V 2 O 5 /LiPON/Li with a 5 nm thin V 2 O 5 interface modification layer exhibited a much smaller charge transfer impedance ( R ct ) value, significantly improved discharge specific capacity, and superior cycling and rate performance. The discharge capacity remained at 75.6% of its initial value after 1000 cycles at a current density of 100 μA cm −2 . This was mainly attributed to the enhanced lithium ion transport kinetics and the suppression of severe side reactions at the cathode-electrolyte interface in TFBs based on LiCoO 2 /V 2 O 5 /LiPON/Li with a 5 nm V 2 O 5 thin layer. The V 2 O 5 interfacial layer can effectively suppress side reaction between a LiCoO 2 cathode and LiPON electrolyte interface, which enables enhanced lithium ion transport kinetics and electrochemical performance in all-solid-state thin film batteries.