<p>The series of the Fe_<i>x</i>Ti_2-2<i>x</i>Nb_10+<i>x</i>O₂₉ solid solutions (<i>x</i> = 0.0, 0.4, 0.5, 0.6, 1.0) with the monoclinic Wadsley-Roth crystallographic shear structure were prepared by the mechanochemically assisted solid-state synthesis and studied as anode materials for lithium-ion batteries. The phase purity of the synthesized samples was confirmed by X-ray powder diffraction and Mössbauer spectroscopy. The galvanostatic intermittent titration technique (GITT) results show that with an increase in the iron content in Fe_<i>x</i>Ti_2-2<i>x</i>Nb_10+<i>x</i>O₂₉, the Li⁺ diffusion coefficient, <i>D</i>_Li+, increases at the plateau region at 1.67&#xa0;V, whereas it decreases in the region at 1.5–1.2&#xa0;V. Fe_0.5TiNb_10.5O₂₉ represents a compromise between these two correlations; therefore, this sample has the highest average <i>D</i>_Li+ among the other Fe_<i>x</i>Ti_2-2<i>x</i>Nb_10+<i>x</i>O₂₉ samples. Therefore, the optimal composition, Fe_0.5TiNb_10.5O₂₉, exhibits the value of the specific charge capacity of 230 and 197 mAh g⁻¹ at the cycling rates of 10C and 20C, respectively, which is higher than those of Ti₂Nb₁₀O₂₉ (167 and 93 mAh g⁻¹) and FeNb₁₁O₂₉ (157 and 80 mAh g⁻¹).&#xa0;</p> Graphical abstract <p></p>