| Summary: | Due to the low capacity, low working potential, and lithium coating at fast charging rates of graphite material as an anode for Li-ion batteries (LIBs), it is necessary to develop novel anode materials for LIBs with higher capacity, excellent electrochemical stability, and good safety. Among different transition-metal oxides, AB<sub>2</sub>O<sub>4</sub> spinel oxides are promising anode materials for LIBs due to their high theoretical capacities, environmental friendliness, high abundance, and low cost. In this work, a novel, porous Zn<sub>0.5</sub>Mg<sub>0.5</sub>FeMnO<sub>4</sub> spinel oxide was successfully prepared via the sol–gel method and then studied as an anode material for Li-ion batteries (LIBs). Its crystal structure, morphology, and electrochemical properties were, respectively, analyzed through X-ray diffraction, high-resolution scanning electron microscopy, and cyclic voltammetry/galvanostatic discharge/charge measurements. From the X-ray diffraction, Zn<sub>0.5</sub>Mg<sub>0.5</sub>FeMnO<sub>4</sub> spinel oxide was found to crystallize in the cubic structure with <i>Fd</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover><mn>3</mn><mo>¯</mo></mover></mrow></semantics></math></inline-formula><i>m</i> symmetry. However, the Zn<sub>0.5</sub>Mg<sub>0.5</sub>FeMnO<sub>4</sub> spinel oxide exhibited a porous morphology formed by interconnected 3D nanoparticles. The porous Zn<sub>0.5</sub>Mg<sub>0.5</sub>FeMnO<sub>4</sub> anode showed good cycling stability in its capacity during the initial 40 cycles with a retention capacity of 484.1 mAh g<sup>−1</sup> after 40 cycles at a current density of 150 mA g<sup>−1</sup>, followed by a gradual decrease in the range of 40–80 cycles, which led to reaching a specific capacity close to 300.0 mAh g<sup>−1</sup> after 80 cycles. The electrochemical reactions of the lithiation/delithiation processes and the lithium-ion storage mechanism are discussed and extracted from the cyclic voltammetry curves.
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