Mesoporous Hierarchical Structure of Li4Ti5O12/Graphene with High Electrochemical Performance in Lithium-Ion Batteries

The combination of nanomaterials with complementary properties in a well-designed architecture is important to develop high-performance materials for applications in lithium-ion batteries. Herein, hierarchical mesoporous lithium titanate (LTO)/graphene hybrids were in situ synthesized using MAX compounds (such as Ti2AlC, Ti3SiC2) as raw materials via a hydrothermal route followed by heat treatment in Ar. The yielded primary 6-10 nm lithium titanate nanoparticles assembled into 50-200 nm secondary particles with a large number of mesopores, which were attached on the surface of carbon nanosheets with graphene-like structures. The unique hybrid architecture provided the product fast ion and electron transportation routes as well as stable crystalline structure. Thus, this hybrid electrode displayed high reversible capacity, good rate performance, and excellent cycling stability. A reversible capacity of 145 mA h g(-1) at 1 C was retained without any apparent capacity fading even after 600 charging-discharging cycles. In addition, more than 110 mA h g(-1) was achieved at an extraordinary high current rate of 50 C. Noting there are a large number of MAX phase compounds which have both Ti and C elements, this work suggests the design of different special architectures of in situ LTO/graphene or other alkali titanate/graphene hybrids using the layered MAX compounds as raw materials.