Three-Tier Hierarchical Clusters of Carbon-Coated Li₄Ti₅O₁₂ Single Crystals as High-Power and High-Energy Anodes for Lithium-Ion Batteries

A novel three-tier hierarchical cluster lithium-ion battery (LIB) anode is reported here, consisting of 1)carbon-coated Li₄Ti₅O₁₂ crystals as the first nano-tier (ca. 10nm) for high-rate capability; 2)submicron spheres consisting of Li₄Ti₅O₁₂ crystals as the second submicron tier (100-300nm), facilitating electrolyte infiltration and Li⁺ diffusion; and 3)clusters comprising Li₄Ti₅O₁₂ spheres as the third micron-sized tier (1-2μm) to increase the packing density of active materials for high-power LIBs. The submicron tier acts as a transition zone between the nano-tier and micro-tier to further benefit Li⁺ diffusion, electrolyte infiltration, and electron transport. The carbon coating on Li₄Ti₅O₁₂ forms a uniform and continuous conductive network for fast electron transport and Li⁺ diffusion to address the low electronic conductivity obstacle of the Li₄Ti₅O₁₂ anode. The three-tier hierarchical clusters maximize the close contact between the electrolytes and the active materials for excellent electrochemical performance.