In this study, spent LiFePO₄ (LFP) cathode materials were recycled and transformed into amorphous FePO₄ (a-FePO₄) via a leaching–precipitation method for further use as a high-performance cathode material in lithium-ion batteries. To enhance its electrochemical performance, a-FePO4 was composited with graphene oxide (GO) and subsequently reduced at different temperatures (250–450 °C) under N₂ atmosphere to obtain a series of a-FePO₄/rGO composites. Among them, the a-FePO₄-rGO-1 (reduced at 250 °C) exhibited the most superior performance, delivering a specific high discharge capacity of 117 mAh·g⁻¹ after 100 cycles at 1 C and an excellent rate capability of 98 mAh·g⁻¹ even at 10 C. Electrochemical impedance spectroscopy revealed that this composite possessed the lowest charge transfer resistance and most efficient Li⁺ diffusion kinetics. This study demonstrates that moderate-temperature thermal reduction is a critical strategy for optimizing the conductive network of a-FePO₄-rGO composites, thereby significantly improving the electrochemical properties of recycled FePO₄-based cathode materials.

In this study, we successfully synthesized olivine-type FePO₄ via an in situ oxidation method and further developed two composite cathode materials (o-FePO₄-1/GR-1 and o-FePO₄-1/GR-2) by incorporating graphene. The composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS), revealing a three-dimensional porous layered structure with an enhanced surface area and strong interaction between FePO₄ nanoparticles and graphene layers. Electrochemical tests demonstrated that the composite electrodes exhibited significantly improved performance compared to pristine FePO₄, with discharge capacities of 147 mAh g⁻¹ at 1C and 163 mAh g⁻¹ at 0.1C for o-FePO₄-1/GR-2, approaching the level of LiFePO₄. The incorporation of graphene effectively enhanced the electrochemical reaction kinetics, highlighting the innovation of our method in developing high-performance cathode materials for lithium-ion batteries.