Sandwich-like Ni2P nanoarray/nitrogen-doped graphene nanoarchitecture as a high-performance anode for sodium and lithium ion batteries

Transition metal phosphides as battery electrode materials for energy storage have attracted tremendous attention owing to their high specific capacity and safety. However, challenges remain toward their ultimate applications in full potential, such as agglomeration of active materials during electrode fabrication and pulverization of electrode structure associated with volume changes during the long-term charge-discharge process. Here, for the first time, sandwich-like Ni2P nanoarray/nitrogen-doped graphene nanoarchitecture (Ni2P/NG/Ni2P) is designed as a novel battery anode for both sodium ion batteries (SIBs) and lithium ion batteries (LIBs). The as-prepared Ni2P/NG/Ni2P nanoarchitecture exhibits an excellent cycling stability with a high capacity retention of 188 mAh g−1 (57% of its initial capacity) at 0.5 A g−1 over 300 cycles as a SIB anode. Simultaneously, the synthesized nanoarchitecture delivers a capacity of 417 mA h g−1 at 0.3 A g−1 after 100 cycles when applied as anode for LIBs. The outstanding performance should be attributed to the highly conductive graphene intermediary that facilities the fast transport of electrons and the reinforced interaction between Ni2P and the nitrogen-doped graphene matrix that stabilizes the hybrid structure upon volume expansion during discharging. The excellent cycling stability, high capacity combined with the facile synthesis procedure position the sandwich-like Ni2P/NG/Ni2P nanoarchitecture a new kind of prospective anode material for SIBs and LIBs.