Controlling Li₂CuO₂ single phase transition to preserve cathode capacity and cyclability in Li-ion batteries

Li₂CuO₂ is synthesized via a solid-state reaction and its structure and microstructure is characterized using X-Ray Diffraction, Scanning Electron Microscopy and N₂ adsorption–desorption isotherms. The capacity of cathode material is evaluated at different preparation conditions to determine the factors affecting charge retention, cyclability, and assuring reproducibility during electrode fabrication. Progressing from previous reports, a maximum capacity retention of 140 mAh g^− 1 is attained in the potential window from 1.5 to 4.2 V (Li/Li⁰) during ten cycles at C/15. The low capacity retention at extended cycling has been associated to the participation of irreversible oxygen redox process evaluated by theoretical calculations and cyclic voltammetry. These processes are minimized when the cycling potential window is confined from 2.0 to 3.8 V (Li/Li⁰), thus, achieving a higher capacity retention up to 100 mAh g^− 1 during 60 cycles. Cycling at higher C/rates lowers the capacity down (60 mAh g^− 1 at C/5), but the maximum capacity is restored when returning to C/15. Thus, making Li₂CuO₂ an attractive material either as active compound or additive in cathodes for Li-ion batteries, as a result of its intrinsic properties such as environmental benign, abundance, cost and straightforward preparation process.