Nitrogen and phosphorous dual-doped graphene aerogel with rapid capacitive response for sodium-ion batteries

Abstract

Sodium-ion batteries are widely regarded as an alternative to lithium ion batteries, especially in large-scale energy storage applications. Developing a negative electrode material with high specific capacity and excellent cyclic stability is one of the most pressing problems for sodium-ion batteries. Herein, nitrogen and phosphorous dual-doped graphene aerogel (NPGA) is fabricated via a low temperature phosphidation of NH2-rich graphene aerogel precursor. Expanded interlayer spacing of 0.39 nm and high content of pyridinic-N are obtained in this architecture. These features lead to high sodium storage performance of NPGA, however, in a wide potential range. A large reversible capacity of 330 mAh g−1 at 50 mA g−1, and good rate capability of 218 mAh g−1 at 1 A g−1 and 189 mAh g−1 at 3 A g−1 can be achieved in the potential range from 0.005 to 3.0 V (vs. Na/Na+). Moreover, it delivers ultra-stable capacities of 195 mAh g−1 at 1 A g−1 after 1000 cycles and 132 mAh g−1 at 5 A g−1 after 2000 cycles. It should be underlined that in practice only half of this capacity values could be utilized in Na-ion accumulators, i.e., the capacity supplied from 0.005 to 1.5 V (vs. Na/Na+). The attractive electrochemical performance should be ascribed to the remarkable capacitive contribution. This strategy would be readily applied to construct high-performance carbonaceous anodes for sodium-ion batteries and/or electrochemical capacitors.