Metal organic framework-derived carbon nanosheets with fish-scale surface morphology as cathode materials for lithium–selenium batteries

Tailoring of carbon matrix with reasonable structures is considered to be an effective way to achieve excellent electrochemical performance of lithium−selenium batteries. For the first time, hierarchically porous carbon nanosheets with a fish-scale like surface morphology are prepared using self-assembled metal-organic frameworks (MOFs) as template and carbon source. The carbon nano-architecture has a large specific surface area and well-defined nanostructure. When evaluated as a cathode for lithium-selenium batteries, the carbon/selenium composite demonstrates high specific capacity and excellent cycling performance. At a current rate of 2 C, a discharge capacity of 311.8 mAh g⁻¹ is achieved after 200 cycles. Moreover, even at the current rate of 8 C, the charge-discharge efficiency is maintained at 99.9% after 1000 cycles. The enhanced electrochemical performance is closely related to their well-defined nanostructures, which not only provides stable electronic and ionic transfer channels, but also plays a key role as a strong absorbent to retain lithium polyselenides and accommodate volume variation during the charge–discharge process.