Turning Spent Li‐ion Batteries into High‐Performance LICs via CuO‐NiO Hybrid Composite Nanostructures with rGO

ABSTRACT The rapid development of energy storage technologies has increased the demand for lithium‐based solutions due to their superior efficiency and scalability. Simultaneously, the growing global population and heavy reliance on electronic devices have resulted in substantial e‐waste generation. This study focuses on converting e‐waste, specifically spent battery components, into active materials for lithium‐ion capacitors (LICs). Through a straightforward wet‐chemical process, copper foil and graphite are recovered and converted into CuO‐NiO hybrid nanostructures and reduced graphene oxide (rGO), respectively. These materials are subsequently used as the negative and positive electrodes, respectively, in the LIC assembly. The fabricated half‐cell (Li/CuO‐NiO) demonstrated a reversible specific capacity of approximately 657 mAh g ⁻¹ . Prior to the LIC assembly with the rGO electrode, the hybrid nanostructures were pre‐lithiated (Cu ⁰ +Ni ⁰ +xLi ₂ O). The assembled rGOǁ(Cu ⁰ +Ni ⁰ +xLi ₂ O) LIC exhibited an energy density of 57.8 Wh kg ⁻¹ and a power density of 6.6 kW kg ⁻¹ , along with long cyclic stability. This approach emphasises the recycling of discarded battery components into functional active materials for LICs, presenting a sustainable pathway to convert e‐waste into high‐performance, value‐added products for next‐generation energy storage.