Reasonable Designing of Free-standing MnO2/Graphene Composite Membrane for Lithium-ion Storage

Free-standing membranes show extraordinary promise in energy storage applications, however are usually limited by low capacity and poor rate capabilities. Herein, we assembled a series of free-standing MnO2/GO composite membranes with ZIF67 particles embedded between two-dimensional (2D) layers. The particle size of ZIF67 can be adjusted to achieve tunable interlayer spacing. The lithium storage performance of the as-obtained membranes with different interlayer spaces was systematically studied. The MnO2/GO composite membrane embedded with ZIF67 particles with an average diameter of 30 nm (denoted as MnO2/nZIF67/GO) delivers a good long cycling performance, and it retains a capacity of 340.7 mA·h·g−1 after 400 cycles at 0.05 A/g. The MnO2/GO composite membrane embedded with ZIF67 particles with an average diameter of 500 nm (denoted as MnO2/mZIF67/GO) exhibits good rate performance. Regardless of the size of the ZIF67 particles, the performance of the membrane containing ZIF67 is significantly better than that of the membrane without ZIF67, indicating that the ZIF67 particles can enhance the lithium storage performance of the assembled membranes. This work provides a method to fabricate a free-standing membrane for lithium storage with tunable electrochemical performance.