Multiscale designed niobium titanium oxide anode for fast charging lithium ion batteries

Fast charging of lithium ion batteries is essential for next-generation energy-storage systems. However, the poor ionic and electronic transport of anodes with its rather high mass loading limits the practical applications of this technology. Herein, a multiscale design from niobium titanium oxide anode material to electrode structure is proposed for fast charging lithium ion batteries with a practical level of areal capacity (3 mAh cm${}^{-2}$). At the atomic scale, the introduction of oxygen vacancy and surface carbon coating enables niobium titanium oxide (TiNb${}_2$O${}_{7-x}$@C) to possess excellent ionic and electronic conductivity. For the microscopic electrode structure, 1D TiNb${}_2$O${}_{7-x}$@C fibers are tightly assembled to form a high-speed transport network of ions and electrons throughout the electrode. As a result, the obtained TiNb${}_2$O${}_{7-x}$@C electrode shows excellent rate capability (1.83 mAh cm${}^{-2}$ at 1 C) and cycling stability under an areal capacity of 3 mAh cm${}^{-2}$ (2.35 mAh cm${}^{-2}$ after 100 cycles at 0.5 C) in half-cells. Significantly, a full-cell coupled with practical level mass loading of lithium cobalt oxide cathode is demonstrated to deliver 1.55 mAh cm${}^{-2}$ at 3 C for the first time. (© 2020 Wiley-VCH GmbH)