| Summary: | This work presents a contribution to the study of a new Ni-rich spinel cathode material, LiNiMnO<sub>4</sub>, for Li-ion batteries operating in the 5-V region. The LiNiMnO<sub>4</sub> compound was synthesized by a sol-gel method assisted by ethylene diamine tetra-acetic acid (EDTA) as a chelator. Structural analyses carried out by Rietveld refinements and Raman spectroscopy, selected area electron diffraction (SAED) and X-ray photoelectron (XPS) spectroscopy reveal that the product is a composite (LNM@NMO), including non-stoichiometric LiNiMnO<sub>4-δ</sub> spinel and a secondary Ni<sub>6</sub>MnO<sub>8</sub> cubic phase. Cyclic voltammetry and galvanostatic charge-discharge profiles show similar features to those of LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> bare. A comparison of the electrochemical performances of 4-V spinel LiMn<sub>2</sub>O<sub>4</sub> and 5-V spinel LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> with those of LNM@NMO composite demonstrates the long-term cycling stability of this new Ni-rich spinel cathode. Due to the presence of the secondary phase, the LNM@NMO electrode exhibits an initial specific capacity as low as 57 mAh g<sup>−1</sup> but shows an excellent electrochemical stability at 1C rate for 1000 cycles with a capacity decay of 2.7 × 10<sup>−3</sup> mAh g<sup>−1</sup> per cycle.
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