High performance sodium ion hybrid supercapacitors based on Na2Ti3O7 nanosheet arrays

Highlights: • Porous Na₂Ti₃O₇ nanosheet arrays have been successfully prepared. • The SICs are based on the Na₂Ti₃O₇ nanosheet arrays and carbon nanosheets. • The SICs can afford an energy density of 49.0 Wh kg⁻¹. • The SICs demonstrated superior electrochemical stability through 2000 cycles. 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.