Achieving Slope-Reigned Na-Ion Storage in Carbon Nanofibers by Constructing Defect-Rich Texture by a Cu-Activation Strategy

Hard carbons have showed promising application potential as anode materials for sodium ion batteries (SIBs), but adjusting the texture of hard carbons to manipulate their electrochemical behaviors remains a great challenge. In this work, a Cu-activation strategy is developed to control the defects of hard carbon nanofibers to achieve slope-reigned Na-ion storage behaviors. This method can effectively create defect-rich carbon texture, but not induce a soaring of surface area. With the addition of Cu-activator, carbon nanofibers with increasing defects are synthesized by electrospinning and subsequent annealing. When used as anode for SIBs, reversible capacity of carbon nanofibers is increased with the increasing of defects. Simultaneously, slope capacity gradually increases, while low voltage plateau capacity reduces. Especially, reversible capacity of Cu-activated nanofibers with more defects can be increased to 315 mA h g-1 with almost no plateau capacity compared with 203 mA h g-1 of inactivated nanofi...