Zirconium doping facilitates a vertically aligned NiCoZr-layered hydroxide nanoneedle arrays electrode for hybrid supercapacitors exhibiting a 90,000 cycle durability

LDHs (Layered Double Hydroxides) are a kind of promising cathode material for high-performance hybrid supercapacitor . Nevertheless, it suffers quick capacitance decay after only thousands of cycles, which greatly prevents it from further application. In this contribution, zirconium (Zr) is introduced to the host layer of NiCo-LDH via a simple one-pot hydrothermal process. Owing to the strong bonding energy of Zr O (760 kJ mol −1 ) and special electronic structure (fully empty 4d orbits), the doped Zr could not only act as a structural stabilized element, but also change the mechanism of the energy storage process to alleviate the Jahn-Teller distortion of NiCo-LDH. Moreover, the introduction of Zr boosts an orderly growth of the LDHs, changing from disorder stack structure to vertically aligned nanoneedle arrays, which improve their structural stability. By controlling a varying level of Zr content, the electrode NiCoZr-LDH@CC with a Zr content ratio of 6.4 % delivers the best comprehensive electrochemical performance with a specific capacitance of 1758 F g −1 and good rate performance (73 % capacitance retention at 10 A g −1 ). The assembled asymmetric supercapacitor shows a highest energy density of 42.3 Wh kg −1 at 504 W kg −1 and an ultralong cycling lifespan beyond 90,000 cycles with a 97 % capacitance retention. The results exhibit the great potential of NiCoZr-LDH as a qualified candidate for high-performance hybrid supercapacitors.