A Nonaqueous Na-Ion Hybrid Micro-Supercapacitor with Wide Potential Window and Ultrahigh Areal Energy Density

The increasing demand on smart miniaturized electronics has greatly boosted the development of high-performance micro-supercapacitors (MSCs). However, the unsatisfied electrochemical performance (e. g., narrow potential window, low areal energy density) impedes their wide applications. Here, we demonstrate a novel type of nonaqueous Na-ion hybrid MSC, using VS₂ nanosheets grown on electrochemically exfoliated graphene (VS₂@EG) as the negative electrode and activated carbon as the positive electrode in nonaqueous sodium-ion electrolyte. Such constructed nonaqueous Na-ion hybrid MSCs show a remarkable areal capacitance of 110.7 mF cm⁻² at 0.2 mA cm⁻² in a wide potential range of 0.01–3.5 V and an outstanding areal energy density of 188.3 μWh cm⁻². Besides, an impressive cycling stability up to 5000 cycles without noticeable decay is also achieved for the nonaqueous Na-ion hybrid MSCs. This new hybrid MSC holds great potential application in on-chip electronics.