Carbon nanosheet with controlled porous and disorganized structures as high-rate anode for high-energy Na-ion hybrid capacitors

Abstract

Although sodium-ion capacitors (SICs) hold great application potential in the areas where energy and power output are both highly required, they still encounter the challenge to design suitable anode materials with quick dynamics to provide high power output. In present work, a ultra-thin porous carbon nanosheet (PCS) combing the structure advantages of soft carbon (ordered nature) and hard carbon (amorphous nature) was successfully designed, which facilitates the charge transport and Na+ migration and thus guarantees the high-rate capacity and long cycle life of PCS electrodes. When tested as anode for sodium-ion batteries (SIBs), the PCS can exhibit an impressive sodium storage performance, including an excellent specific capacity of 302 mAhg−1, a high-rate capacity and a superior cycling stability (85 % capacity retention after 500 cycles at 1C). Furthermore, SICs constructed by PCS can provide a maximum energy density of 158.2 Wh kg−1 and a maximum power density of 22.8 kW kg−1, together with superior cycle lifespan. The excellent electrochemical performance demonstrates that PCS is a prospective electrode material for sodium-ion storage.