Synthesis of Co(CO3)0.5(OH)/Ni2(CO3)(OH)2 nanobelts and their application in flexible all-solid-state asymmetric supercapacitor

Design and synthesis of flexible electrode materials with high specific capacitance and rate capability is critical to supercapacitors. In this work, Co(CO3)0.5(OH)/Ni2(CO3)(OH)2 nanobelts with controllable size were successfully synthesized for the first time in the presence of appropriate amount ammonia. And we found that by adjusting the amount of ammonia, the size, morphology and phase composition proportion of Co(CO3)0.5(OH)/Ni2(CO3)(OH)2 could also be controlled. Impressively, benefiting from its special structure and large specific surface area (191.3 m2 g−1), the obtained nanobelts exhibited superior supercapacitor performance with the specific capacitance of 987 F g−1 at 1 A g−1 and 720 F g−1 at 30 A g−1, and an excellent rate performance. The all-solid-state asymmetric supercapacitor (ASC) assembled by using Co(CO3)0.5(OH)/Ni2(CO3)(OH)2 nanobelts as positive materials showed a high specific capacitance of 110.3 F g−1 at 1 A g−1 and 83.3% retention after 5000 cycles, which could provide an energy density of 22.7 Wh kg−1 at a power density of 24019 W kg−1, demonstrating a powerful energy storage capability at high power density for ASC. Moreover, the assembled ASC exhibited an outstanding flexibility, and its supercapacitor properties hardly changed after undergoing the different bending angles. In addition, the two ASCs in series could illuminate a yellow LED for 15 min. These results indicated that the Co(CO3)0.5(OH)/Ni2(CO3)(OH)2 nanobelts had great potential application prospects as a high power density all-solid-state flexible asymmetric supercapacitor electrode materials.