Flexible Mn 3 O 4 /MXene Films with 2D-2D Architectures as Stable and Ultrafast Anodes for Li-Ion Batteries.

Mn 3 O 4 is regarded as a promising anode material for lithium-ion batteries (LIBs) based on its ultrahigh theoretical capacity (937 mAh g -1 ) and low cost but suffers from poor electronic conductivity and large volume variation during the lithiation/delithiation process, which result in dramatic capacity fading and inferior rate capability. Ti 3 C 2 T x MXene, a novel two-dimensional transition metal carbide with metallic conductivity, excellent mechanical properties, and hydrophilic surface, could be an ideal candidate to improve the lithium storage performance of Mn 3 O 4 . Here, a unique flexible, 2D-2D Mn 3 O 4 /MXene film is fabricated by assembling 2D Mn 3 O 4 with Ti 3 C 2 T x nanosheets through a simple vacuum filtration approach. In this unique 2D-2D nanostructure, MXene nanosheets buffer the volume change of Mn 3 O 4 during the charge/discharge process. Moreover, the introduction of MXene enables the fabricated 2D-2D nanostructure with excellent flexibility and can be directly used as an electrode for LIBs, which is beneficial for enhancing the energy density of the assembled batteries. As a result, the flexible film of Mn 3 O 4 -MXene-8-2 shows excellent lithium storage performances in terms of specific capacity (931 mAh g -1 at 0.05 A g -1 ), rate capability (624 mAh g -1 at 1 A g -1 ), and cycling stability, demonstrating its great potential for the application in LIBs.