Interface bonding engineering for constructing a battery-type supercapacitor cathode with ultralong cycle life and high rate capability.

The low rate and poor cycle greatly limit the large-scale applications of supercapacitors electrodes in energy storage field. In this work, the SnS 2 /Ni 3 S 2 nanosheets arrays are bonded on N/S co-doped graphene nanotubes though N–Sn/Ni and S–Sn/Ni interface bonds employing a simple hydrothermal method to form a self-supported battery-type supercapacitors cathode. A series of characterization and DFT calculations indicate that the interface bonding not only automatically generates the internal electric field and allows more redox reactions to carry out easily, but also effectively reduces the OH− ions adsorption energy and maintains the integration of the electrode structure. This unique design greatly promotes the electronics/ions transfer and reaction kinetics of the cathode, and substantially enhances its rate capability and durability. Detailedly, a high specific capacity of 296.9 mAh g−1 at 2 A g−1 is obtained. More impressively, the cathode still holds 155.6 mAh g−1 when the current density is enlarged to 100 A g−1, as well as it can retain 84% initial capacity over 50,000 cycles. Besides, an assembled asymmetric supercapacitor utilizing the prepared N/S-GNTs@B–SnS 2 /Ni 3 S 2 nanosheets arrays cathode and activated carbon anode presents a large energy density of 51 W h kg−1 at 850 W kg−1 and outstanding cycling stability. This work provides an effective strategy for improving rate capability and cycle lifespan of battery-type supercapacitors electrodes, and pushes the metal compounds forward a significant step in the practical applications of energy storage devices. [ABSTRACT FROM AUTHOR]