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In the present work, we report synthesis of MgCo2O4 (MCO)/Li4Ti5O12 (LTO) composites for Li-ion battery anodes by a co-precipitation method. The objective of this work is to replace expensive Co with Mg and also to exploit advantages of both MCO and LTO. Three samples of MCO/LTO particles with different MCO proportion have various average particle sizes of 38.1, 56.9, and 58.5 nm, confirmed by scanning electron microscopy. Electrochemical studies show that a MCO/LTO anode offers a discharge capacity of ca. 300 mAh g−1, which is two times higher than that achieved by pristine LTO. The MCO/LTO anode also retains 75% of its initial capacity, even if the discharge rate is increased to 5 C. Cyclic stability test reveals that the composite anode still maintains nearly 85.5% of its initial capacity after 150 cycles. Electrochemical impedance spectroscopy indicates that the equivalent series resistance of MCO/LTO electrodes is significantly lower than that of LTO, i.e., from 35.5 to 9.9 Ω. The enhanced performance of the composite electrodes can be attributed to its improved conductivity as well as to the surface modification of LTO particles by MCO nanoparticle deposition which leads to increased number of active sites on the former. [ABSTRACT FROM AUTHOR]

Magnesium-ion batteries are fabricated with MgCo2O4/graphite composites as the cathode material. MgCo2O4 nanoparticles are prepared using a co-precipitation method. A three-dimensional mixing process is utilized to mechanically decorate MgCo2O4 nanoparticles on graphite particles. The MgCo2O4 spinel crystals of size ranging from 20 to 70 nm on micrometer-sized graphite chunks are analyzed by using X-ray diffraction and scanning electron microscopy. The electrochemical properties of the as-prepared composites are well characterized by cyclic voltammetry, charge and discharge cycling, and electrochemical impedance spectroscopy (EIS). Surprisingly, the MgCo2O4/graphite composite with a relatively low proportion of MgCo2O4, compared with the other as-prepared composites, achieves the highest specific capacity of 180 mAh g−1 at a C rate of 0.05 C. EIS results suggest that the electrical conductivity of the composite material is an increasing function of the graphite proportion. The superior performance of the MgCo2O4/graphite composite could be ascribed to the decoration of nanosized MgCo2O4 particles as well as to the increased conductivity provided by graphite. [ABSTRACT FROM AUTHOR]