Pseudocapacitance-Enhanced Anode of CoP@C Particles Embedded in Graphene Aerogel toward Ultralong Cycling Stability Sodium-Ion Batteries

Developing an anode material with long-cycling stability and excellent rate performance is critical for enhancing the Na+ storage performance. Herein, an effective method is applied to prepare the carbon-coated CoP embedded into graphene aerogel (CoP@C/GA) as an anode material for sodium-ion batteries (SIBs). GA network with large specific surface area and cross-linked pores provides sites for loading CoP@C, which reduces the agglomeration of CoP@C and accelerates the electron and ion transfer kinetics. The CoP@C particles with abundant pores help to buffer the volume change of CoP during the Na+ insertion/extraction. Meanwhile, CoP crystal particles break down and become smaller during the long-cycling, resulting in an increase of contact area with the electrolyte. Therefore, the CoP@C/GA anode exhibits ultralong cycling stability (172.8 mAh g(-1) at 2000 mA g(-1) over 4000 cycles with capacity retention ratio of 115.2 %), and superior rate performance (gradually increasing from 50 mA g(-1) to 2000 mA g(-1) and returning to 50 mA g(-1), the capacity retention rate is 94.1 %). Furthermore, the storage mechanism of CoP@C/GA is mainly controlled by pseudocapacitive behavior, which leads to a rapid Na+ insertion/extraction and excellent rate performance. The prominent cycling stability of CoP@C/GA provides a bright prospect in SIB.