Design of composites based on lithium titanate and carbon nanomaterials for high-power lithium-ion batteries

Li₄Ti₅O₁₂ is considered as a promising anode material for lithium-ion batteries, primarily due to low degradation during cycling and high safety. However, its electronic and ionic conductivities are relatively low that limits its practical application. The design of composites with conductive materials, e.g., with carbon, is one of the approaches to improve the electrochemical properties of materials. In this work, the composite nanomaterials based on Li₄Ti₅O₁₂ and carbon nanotubes (CNTs) or carbon nanoflakes, including N-doped ones were prepared, in the aim to compare the effect of various carbon nanomaterials and synthesis method on the electrochemical performance of Li₄Ti₅O₁₂/C composites.

The composite nanomaterials based on hydrothermally or sol-gel synthesized Li₄Ti₅O₁₂ and CNTs or carbon nanoflakes, including N-doped ones were prepared and investigated by XRD, TEM, SEM, Raman spectroscopy, low-temperature nitrogen adsorption, dc-measurements, charge-discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. Carbon introduction provides the formation of a highly conductive 3D network resulting in increase in the electronic conductivity, lithium diffusion and thus improvement of high-rate performance.

At high charge/discharge rates, the discharge capacity of the prepared anodes significantly exceeds that of the pristine Li₄Ti₅O₁₂. At 37C rate, the reversible discharge capacities of lithium titanate, and its composites with CNTs and N-doped CNTs are of 60, 97, and 90 mAh/g, respectively. They exhibit a remarkable long-term cycling stability.