In recent years, spinel-structured transition-metal oxide ZnMn₂O₄ has attracted attention as a low-cost anode material with high lithium-ion storage capacity. However, its practical application is limited by poor intrinsic electrical conductivity, sluggish reaction kinetics, and large volume changes during repeated lithiation and delithiation, leading to unstable cycling behavior. Although several strategies have been explored to improve cyclic stability, many reported systems still suffer from limited rate performance, multistep synthesis routes, and an incomplete understanding of nitrogen-doped graphene oxide (N-rGO)-induced interfacial effects. In this work, hybrid ZnMn₂O₄/N-rGO nanocomposites with controlled graphene oxide additions of 20 and 30 wt% were synthesized via a simple one-pot hydrothermal route, enabling intimate oxide–N-rGO interfacial contact. Structural, microscopic, and X-ray photoelectron spectroscopy analyses confirmed the formation of phase-pure tetragonal ZnMn₂O₄ nanoparticles uniformly distributed on the N-rGO framework. XPS revealed a redistribution of nitrogen bonding configurations at higher GO loading, with increased graphitic nitrogen contribution that may enhance electronic conductivity, while pyridinic and pyrrolic nitrogen species provide interfacial active sites. Brunauer-Emmett-Teller analysis showed that increasing GO content enhanced the specific surface area and pore volume while preserving mesoporous architecture. The ZnMn₂O₄/N-rGO nanocomposite containing 30 wt% graphene oxide (ZMO-30) delivered a reversible discharge capacity of 859.02 mAh g^-1 after 100 cycles at 100 mA g^-1 with superior rate performance and reduced charge-transfer resistance, demonstrating the beneficial role of oxide–N-rGO interfacial engineering in improving the kinetics and durability of ZnMn₂O₄ anodes.

The surging demand for high-energy density lithium-ion batteries (LIBs) necessitates the exploration of anode materials with higher storage capacity. Nickel‑cobalt (Ni-Co) based transition metal oxides (TMOs) are strong contenders due to their high theoretical capacity based on conversion reactions. The copper (Cu) doping strategy is adopted to improve the electrochemical performance through addressing the drawbacks of NiCo₂O_4, such as lower conductivity and volume expansion. In this work, Cu-doped NiCo₂O₄ nanomaterials are synthesized via a rapid, efficient, and scalable microwave-assisted synthesis route. When evaluated as an anode material for LIBs, the Cu-doped NiCo₂O₄ electrode delivers a high reversible specific capacity of 662 mAh g⁻¹ at a current density of 100 mAg⁻¹. The enhanced performance is attributed to the unique porous nanorod-like structure with a high surface area of 59.4 m²/g, which provides short lithium-ion diffusion pathways. Significantly, the copper acts as an inactive material that accommodates volume changes effectively during cycling when compared to pure NiCo₂O₄. Furthermore, the electrode exhibits an excellent rate capability and remarkable cycling stability. These findings indicate that copper doping is found to be an efficient approach for enhancing the cyclic performance of TMO-based anodes for next-generation LIBs.

In the search for effective high-tech materials for energy conversion and storage devices, spinel-structured nickel ferrite (NiFe₂O₄) has been identified as a promising anode material for lithium-ion batteries (LIBs). However, the influence of different morphologies and surface properties of NiFe₂O₄ nanoparticles on battery performance is hardly addressed. To understand the effect of different morphologies and surface properties on the lithium-ion storage performance, NiFe₂O₄ nanoparticles were synthesized through four different synthesis conditions: NFO-S, NFO-U, NFO-G, and NFO-C. The formation of polycrystalline inverse spinel NiFe₂O₄ was confirmed through XRD, FTIR, and Raman spectroscopy. The morphologies of the obtained samples were studied using FESEM, and it was found that the four different synthesis conditions employed here enabled us to obtain NiFe₂O₄ with four different morphologies. The surface chemistry, surface area and porosity of the NiFe₂O₄ samples were respectively characterized using XPS and BET. The electrochemical performance of the four NiFe₂O₄ samples as anode material was studied by fabricating lithium-ion half-cells. NiFe₂O₄ sample obtained from surfactant-free synthesis condition (NFO-S) displayed a high initial discharge and charge capacity of 2258 mAh/g and 1815 mAh/g, respectively at the current density of 100 mA/g. Even after 100 cycles, NFO-S showed a better discharge capacity of 116 mAh/g at the current density of 100 mA/g, compared to the other samples studied here. The observed higher capacity of the NFO-S sample is attributed to the higher surface area (40.8 m²/g) and pore volume (0.190 cm³/g). The NiFe₂O₄ sample prepared with cationic CTAB surfactant (NFO-C) showed better cyclic stability with a stable coulombic efficiency of 98.5% at the 100th cycle, mainly attributed to its nanocube morphology with lower surface area (16.1 m²/g) and pore volume (0.087 cm³/g).