Experimental investigations of cyclic characteristics of binder-free nanostructured copper oxides as negative electrodes of lithium-ion batteries

Nanostructured copper oxides (CuO, Cu₂O) are regarded as promising anode materials for lithium-ion batteries (LIBs) due to owing high theoretical specific capacity and efficient conversion reaction mechanism with lithium under moderate conditions. On investigating the cyclic characteristics of binder-free CuO/Cu₂O anodes at 1C current rate, first charge and discharge capacities were observed to be 455.4 and 431.9 mAh/g, respectively, with a Coulombic efficiency of 94.8 %. However, a gradual mitigated capacity was evident as the discharge capacity was decreased to 352.2 mAh/g by the 20^th cycle, which can be attributed to solid electrolyte interphase (SEI) layer formation, electrode degradation, or loss of lithium. Beyond 20^th cycles, the battery exhibited a more stable cycling regime, with Coulombic efficiency stabilizing ranging around 82–85 %. By the 40th cycle, discharge capacity was further declined to 339 mAh/g, indicating the ongoing degradation mechanisms, however at a much lower rate, such as SEI layer thickening and electrode pulverization. However, despite the initial instability, the system demonstrated enhanced consistency in later cycles, emphasizing the potential of nanostructured copper oxides as efficient LIB anodes. Future efforts should focus on mitigating long-term capacity fading to enhance performance and cycle life.