High performance sodium ion hybrid supercapacitors based on Na2Ti3O7 nanosheet arrays

Abstract

Sodium ion hybrid supercapacitors (SICs) have attracted considerable attentions as a result of the highly cost-effective advantages. However, the large radius of Na+ ions imparts the serious capacity fading and poor rate performance. In order to obtain the ideal SICs with appealing electrochemical performance, we utilized porous Na2Ti3O7 nanosheet arrays as anode and hierarchical carbon nanosheets on Al foils as cathode. The assembled SICs can afford a high energy density of 49.0 Wh kg−1 at the power density of 825 W kg−1 in the voltage window of 1.0–4.0 V. Even at the ultrahigh power density of 4000 W kg−1, the SICs still manifested an energy density of 35.6 Wh kg−1. Meanwhile, the SICs demonstrated superior electrochemical performance at a current density of 3.3 A g−1, with a capacity retention of 73.89% going through 2000 cycles. In this regard, it is considered that engineering array architecture is an efficient way for high performance SICs.