Prussian Blue Analogues "Dressed" in MXene Nanosheets Tightly for High Performance Lithium-Ion Batteries.

MXenes, have been considered as a new generation anode material in lithium-ion batteries for lower lithium-ion diffusion barriers and superior conductivity. Unfortunately, their structures are prone to aggregation and stacking, hindering further shuttle of lithium ions and electrons, resulting in lower discharge capacity. Therefore, the introduction of interlayer spacers for the preparation of MXene-based hybrids has attracted much attention. Introducing Prubssian blue analogues (PBAs) as a new interlayer spacer to combine with MXene nanosheets can not only preserve the high conductivity of MXene and inhibit the volume expansion and structural degradation of the PBA component, but also inherit the characteristics of large specific surface area and high porosity of PBAs. By intelligent regulating the size of MXene sheets, Co-PBA@MXene hybrids with common sandwich-like structures and superior core-shell-like structures have been successfully obtained. Furthermore, Co@M(x:y) hybrids are prepared by intelligently adjusting the shell thickness of MXene through intelligently controlling of the mass ratio between Co-PBA and MXene. Among them, the Co@M(5:2) anode exhibits an excellent capacity (603 mA h g at 0.2 A g after 100 cycles) and superior long-term cycling stability due to the protective and conductive properties provided by the MXene shell and multi-redox pairs and rich porosity from Co-PBA core.