Pseudocapacitance-Dominated MnNb2O6-C Nanofiber Anode for Li-Ion Batteries

Graphical MnNb 2 O 6 -C nanofibers (NFs) with MnNb 2 O 6 nanoparticles (~15 nm) confined in carbon NFs were prepared and evaluated as Li-ion battery anode. Microstructure reconstruction is verified in this kind of intercalation type anode material and that increases the pseudo-capacitance contributions, which is the main reason for the high-capacity achieved by the MnNb 2 O 6 -C NFs electrode. MnNb 2 O 6 anode has attracted much attention owing to its unique properties for holding Li ions. Unluckily, its application as a Li-ion battery anode is restricted by low capacity because of the inferior electronic conductivity and limited electron transfer. Previous studies suggest that structure and component optimization could improve its reversible capacity. This improvement is always companied by capacity increments, however, the reasons have rarely been identified. Herein, MnNb 2 O 6 -C nanofibers (NFs) with MnNb 2 O 6 nanoparticles (~15 nm) confined in carbon NFs, and the counterpart MnNb 2 O 6 NFs consisting of larger nanoparticles (40–100 nm) are prepared by electrospinning for clarifying this phenomenon. The electrochemical evaluations indicate that the capacity achieved by the MnNb 2 O 6 NF electrode presents an activation process and a degradation in subsequence. Meanwhile, the MnNb 2 O 6 -C NF electrode delivers high reversible capacity and ultra-stable cycling performance. Further analysis based on electrochemical behaviors and microstructure changes reveals that the partial structure rearrangement should be in charge of the capacity increment, mainly including pseudocapacitance increment. This work suggests that diminishing the dimensions of MnNb 2 O 6 nanoparticles and further confining them in a matrix could increase the pseudocapacitance-dominated capacity, providing a novel way to improve the reversible capacity of MnNb 2 O 6 and other intercalation reaction anodes.