Electrochemical performance of Cox/Li3Ti4Co1−xCrO12 as anode materials for lithium ion batteries

New anode materials (Cox/Li3Ti4Co1−xCrO12) had been successfully prepared via a high temperature solid-state method. Pure phase Co-Cr replaced solid solution (Li3Ti4CoCrO12) was obtained by calcinating the precursor under air atmosphere while the Co modified solid solutions (Cox/Li3Ti4Co1−xCrO12) were prepared under a reducing atmosphere. Various methods, such as XRD, SEM, EDX mapping, cyclic testing, EIS, CV, XPS and EPR were employed to characterize the powder samples and investigate their electrochemical behavior. SEM results showed spherical shape of the products with nano sized primary crystals. EDX mapping further confirmed the different existence of the Co element, uniform distribution of Co2+ ions within the spinel lattice and separated metallic Co on the particle surface. Cyclic tests revealed that the Co modified samples showed great promotion in their electrochemical performance. For the sample with x = 0.1, the best results with an initial capacity of 157.6 mA h/g and a capacity retention of 96.4% after 100 runs were observed. Such promotion can be explained by the improved electronic conductivity and enhanced Li+ diffusion coefficient confirmed by the EIS and CV simulation, which was caused by the oxygen vacancy produced during the calcination under the reducing atmosphere.