Preparation of carbon-coated Fe 2 O 3 @Ti 3 C 2 T x composites by mussel-like modifications as high-performance anodes for lithium-ion batteries.

Fe 2 O 3 with high theoretical capacity (1007 mA h g -1 ) and low cost is a potential anode material for lithium-ion batteries (LIBs), but its practical application is restricted by its low electrical conductivity and large volume changes during lithiation/delithiation. To solve these problems, Fe 2 O 3 @Ti 3 C 2 T x composites were synthesized by a mussel-like modification method, which relies on the self-polymerization of dopamine under mild conditions. During polymerization, the electronegative group (-OH) on dopamine can easily coordinate with Fe 3+ ions as well as form hydrogen bonds with the -OH terminal group on the surface of Ti 3 C 2 T x , which induces a uniform distribution of Fe 2 O 3 on the Ti 3 C 2 T x surface and mitigates self-accumulation of MXene nanosheets. In addition, the polydopamine-derived carbon layer protects Ti 3 C 2 T x from oxidation during the hydrothermal process, which can further improve the electrical conductivity of the composites and buffer the volume expansion and particle agglomeration of Fe 2 O 3 . As a result, Fe 2 O 3 @Ti 3 C 2 T x anodes exhibit ~100 % capacity retention with almost no capacity loss at 0.5 A g -1 after 250 cycles, and a stable capacity of 430 mA h g -1 at 2 A g -1 after 500 cycles. The unique structural design of this work provides new ideas for the development of MXene-based composites in energy storage applications.