Presentation Information
[3P107]Nanometer-scale structural analysis of LiCoO2 cathodes coated by Zr oxides for high-capacity batteries
*Takafumi Kakeya1, Kohei Aso1, Hiroki Ito2, Sho Asano2, Yoshifumi Oshima1, Masaaki Hirayama2 (1. Japan Advanced Institute of Science and Technology, 2. Tokyo Institute of Technology)
Lithium cobalt oxides (LCO) are popular cathode materials for lithium-ion batteries. Operating below 4.2V maintains capacity over charge-discharge cycles. Although higher voltages can increase battery capacity, it leads to capacity fade due to irreversible structural changes in LCO. Coating cathodes with metal oxides can reduce capacity fade at high voltages. However, excessive coating may hinder Li (de)intercalation. To better understand the coating effect, this study used epitaxial growth to create a model battery with near-single crystalline LCO, coated with zirconium oxides. Two batteries were constructed: one with bare LCO and another with Zr oxide-coated LCO (LZO/LCO). After 25 charge-discharge cycles at 4.5V, the LZO/LCO maintained capacity while the bare LCO’s capacity decreased. STEM observations showed that bare LCO underwent irreversible structural changes to spinel-type Co3O4 at the surface, while LZO/LCO partially suppressed these changes under Zr oxides coating. The LZO-LCO interface may contain an interphase that realizes both ionic conductivity and protection for LCO.