▎ 摘　　要

Energy storage systems, including lithium-/sodium-ion batteries (LIBs/SIBs), are important for being able to use renewable energies efficiently. The anode material is a vital link in the great industrialization chain. Herein, a sandwich-like N-doped porous carbon/graphene (N-HCG) composite has been successfully achieved by using a facile and low-temperature liquid-phase method with melamine as the nitrogen source, followed by a carbonization process. The composite possesses a high specific surface area of 282.4 m(2)g(-1). As an anode in lithium-ion batteries, N-HCG delivers a capacity of 643 mAhg(-1) at 100 mAg(-1), and a high capacity of 406 mAhg(-1) is maintained even at 5 Ag-1 after 2700 cycles. For sodium-ion batteries, the obtained capacities of the N-HCG electrodes are 208 mAhg(-1) (100 mAg(-1) for 120 cycles) and 145 mAhg(-1) (1000 mAg(-1) for 700 cycles). The excellent electrochemical performance including the rate capability and lifespan of N-HCG can be attributed to the synergistic effects of the 2D sandwich-like nanosheets with pores and extrinsic nitrogen doping. Thus, the as-prepared N-HCG composite is a highly promising anode material for LIB/SIB applications.