Lithium intercalation and structural changes at the LiCoO2 surface under high voltage battery operation

• Published in: Journal of power sources Vol. 307; pp. 599 - 603
• Main Authors: Taminato, Sou, Hirayama, Masaaki, Suzuki, Kota, Tamura, Kazuhisa, Minato, Taketoshi, Arai, Hajime, Uchimoto, Yoshiharu, Ogumi, Zempachi, Kanno, Ryoji
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2016
• Subjects: Epitaxial film; Layered rock-salt structure; Lithium battery; Positive electrode; Surface coating; Lithium battery; Positive electrode; Epitaxial film; Surface coating; Layered rock-salt structure
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.12.133

An epitaxial-film model electrode of LiCoO2(104) was fabricated on SrRuO3(100)/Nb:SrTiO3(100) using pulsed laser deposition. The 50 nm thick LiCoO2(104) film exhibited lithium (de-)intercalation activity with a first discharge capacity of 119 mAh g−1 between 3.0 and 4.4 V, followed by a gradual capacity fading with subsequent charge-discharge cycles. In contrast, a 3.2 nm thick Li3PO4-coated film exhibited a higher intercalation capacity of 148 mAh g−1 with superior cycle retention than the uncoated film. In situ surface X-ray diffraction measurements revealed a small lattice change at the coated surface during the (de-)intercalation processes compared to the uncoated surface. The surface modification of LiCoO2 by the Li3PO4 coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage. •A model LiCoO2(104) electrode was fabricated by pulsed laser deposition.•Charge–discharge properties were investigated under high voltage battery operation.•The unmodified film exhibited limited intercalation capacity with poor stability.•Surface modification by Li3PO4 coating improved the capacity and cycle stability.•Crystal structure of the modified surface could be highly stable at high voltages.