Cu3Mo2O9 anodes for lithium-ion batteries with extended cyclability at high rates

Copper molybdate (Cu 3 Mo 2 O 9 ) has been synthesized through different routes, namely coprecipitation, the solvothermal method and solid-state methods using different kinds of ball-milled precursors. The effects of each synthesis route on the morphological, structural and compositional characteristics of the samples were assessed, as well as their influence on the electrochemical performance as anodes for lithium-ion batteries (LIBs). X-ray diffractometry and micro-Raman spectroscopy measurements confirmed the formation of single-phase, highly crystalline orthorhombic Cu 3 Mo 2 O 9 irrespective of the synthesis conditions, which in turn strongly influence particle size and shape, as revealed by scanning electron microscopy and transmission electron microscopy. Electrochemical tests, including cyclic voltammetry and galvanostatic charge-discharge measurements, demonstrated that Cu 3 Mo 2 O 9 -based anodes show a good specific capacity and excellent cycling stability. Notably, samples obtained by mechanical milling of Cu and Mo powders followed by oxygen annealing showed a capacity of 200 mA·h·g -1 for more than 2000 cycles at a high current density of 1 A·g -1 with coulombic efficiencies above 97%. Such an outstanding long-term cycling performance is attributed to the high structural stability and compositional homogeneity achieved at macroscopic and local scales through the mechanical milling process, making this material a promising candidate for long-life, high-rate LIB applications.