Preparation Of Copper Cobaltite Electrode Materials For High-performance Supercapacitors

As an emerging energy storage device,supercapacitors have the far-ranging applications in flexible wearable electronics and hybrid electric vehicles based on the advantages of large power density,fast charge and discharge capability,long-term durable ability,safety and reliability.However,the unideal energy density makes the development of supercapacitors fall into a bottleneck period.Electrode material as the most significant and direct factor influencing the performance of supercapacitors,therefore,the development of high-performance electrode materials may be a feasible strategy to solve this problem.The CuCo₂O₄ electrode material has received extensive research interests due to its high theoretical specific capacity,environmental benign and low cost.This thesis aims to synthesize CuCo₂O₄ electrode materials with morphology control and excellent electrochemical properties.The main contents are described as follows:(1)Novel bundle-like CuCo₂O₄ microstructures were prepared via hydrothermal reactions at 120 ? for 15 h followed by the calcination process at 300 ? for 1 h.The BET tests showed that the bundle-like CuCo₂O₄ acquired a surface area of 114.36 m² g^-1 and an average pore diameter of 10.99 nm.The influence of hydrothermal temperature on the shape and size of the CuCo₂O₄ specimen was explored in details.The results of electrochemical measurements concluded that the bundle-like CuCo₂O₄ delivered a specific capacity of 303.22C g^-1 at 1 A g^-1 and the rate capability of 69.7%at 10 A g^-1,respectively,and the capacity was retained about 71.8%of the initial value over 5000 cycles at 5 A g^-1.A hybrid supercapacitor was constructed with AC as negative pole and bundle-like CuCo₂O₄ as positive pole.The device acquired a specific capacity of 152.25 C g^-1 under 1 A g^-1 and an energy density of39.95 W h kg^-1 under 944.63 W kg^-1.(2)The CuCo₂O₄ micro-rod precursor was firstly prepared by a simple solvothermal method in ethanol solvent,and then hollow CuCo₂O₄ microtubes were obtained after a calcination process at 350 ? for 2 h.The influence of reaction temperature on the morphology of CuCo₂O₄ products was further explored.The CuCo₂O₄ microtubes delivered a specific capacity of 393.66 C g^-1 at 1 A g^-1,and the capacity was preserved about 77.7%at 10A g^-1.The hybrid supercapacitor assembled with AC and CuCo₂O₄ microtubes achieved an energy density of 32.49 W h kg^-1 at 912.10 W kg^-1 and eminent cycling stability with 96.6%capacity preservation after 5000 cycles under 5 A g^-1.(3)The honeysuckle-like CuCo₂O₄/Cu O composite was hydrothermally synthesized at 120? for 6 h accompanied with an annealing conversion of the precursors at 450 ? for 1 h.At the same time,the influence of the amount of urea on the morphology and size of the samples was explored in details.The honeysuckle-like CuCo₂O₄/Cu O composite possessed a specific surface area of 36.09 m² g^-1,and it delivered a specific capacity of 350.69 C g^-1 at 1 A g^-1.After 5000 cycles at 5 A g^-1,the capacity of the composite was retained about 96.2%of its initial value.A hybrid supercapacitor constructed with AC and honeysuckle-like CuCo₂O₄/Cu O composite performed an energy density as high as 41.76 W h kg^-1 at 800.27 W kg^-1.