Electrochemical Properties of Composites Based on Lithium Titanate and Carbon Nanomaterials

Composites based on lithium titanate Li4Ti5O12 with different contents (5–10 wt %) of carbon nanotubes (nanoflakes), including heterosubstituted ones, have been obtained by mechanochemical activation in a planetary mill. With the introduction of a carbon nanomaterial, the electrical conductivity of the composites increases by several orders of magnitude, reaching 0.36 S/cm for a Li4Ti5O12 sample with 10 wt % carbon nanotubes doped with nitrogen. In addition, the obtained materials are characterized by higher values of reversible discharge capacity, including at high charge/discharge rates of the battery. The composite with heterosubstituted carbon nanotubes and Timcal carbon black demonstrates the highest values of electrochemical capacity equal to 154, 132, 115, and 97 mA h/g at a current density of 200, 800, 1600, and 3200 mA/g, respectively (similar values for the starting Li4Ti5O12 are 144, 107, 92, and 65 mA h/g). This effect is due not only to a decrease in the particle size of lithium titanate as a result of mechanical processing, but also to the formation of highly conductive contacts between the particles of the electrode material.