ZnO/MnO_xNanoflowers for High-Performance Supercapacitor Electrodes

Abstract

A crystalline ZnO/MnO x nanoflower (NF) nanocomposite was deposited on Ni nanocones via an economical synthesis method in which the ZnO NFs were first synthesized, and MnO x was then deposited on the ZnO petals to form a heterostructured composite. The effect of the MnO x coating on the performance of the nanocomposite was analyzed by comparing the performance of supercapacitors employing ZnO and the ZnO/ MnO x nanocomposites. The ZnO/MnO x nanocomposites exhibited excellent current rate capability and an excellent capacitance of 556 F•g −1 at a current density of 1 A•g −1 . The optimized ZnO/MnO x NF electrode presented a remarkable longterm cycling stability, with a capacitance retention of 96% after 10,000 cycles. In a coin cell assembly, at an operating voltage of 0.9 V, the energy density of the optimized supercapacitor cell was 16 Wh•kg, −1 at a power density of 225 W•kg −1 . Becasue of its excellent electrochemical performance, the optimized ZnO/MnO x NF composite electrode is promising for high-energy-density supercapacitor applications.

A Facile One‐Pot Hydrothermal Synthesis of Zn, Mn Co‐Doped NiCo2O4 as an Efficient Electrode for Supercapacitor Applications

“…Nyquist plot or complex impedance plot was drawn between imaginary part (Z”) and real part (Z’) as shown in Figure 9 and Supplementary information Figure S3.It is observed from the Nyquist plot that the semi‐circle in the high frequency region was almost negligible for both the working electrodes. It depicts that the lower internal resistance and high diffusion rate of the active materials [38–40] . In addition, the internal resistance of the co‐doped NiCo 2 O 4 is much lower when compared to the undoped nanoparticles.…”

“…It depicts that the lower internal resistance and high diffusion rate of the active materials. [38][39][40] In addition, the internal resistance of the co-doped NiCo 2 O 4 is much lower when compared to the undoped nanoparticles. Thus, the EIS result confirms that the effect of Zn, Mn co-doping improves the conductivity and diffusion rate kinetics on the NiCo 2 O 4 NPs than the individual doping.…”

Transition Metal Oxide Electrode Materials for Supercapacitors: A Review of Recent Developments

“…TMOs have gotten extensive attention because of their high redox activity, good theoretical capacitance, and low costs [ 130 ]. ZnO is a well-known active material that has the characteristics of environmental protection, natural abundance, and ideal capacitance [ 50 , 131 , 132 ]. Via the chemical coprecipitation method, Dhivya Angelin et al [ 133 ] modified the ZnO nanostructure with doping Zr.…”

“…However, its high price and toxicity to the environment seriously hinder its application in supercapacitors [ 47 , 48 , 49 ]. Co 3 O 4 , MnO 2 , and ZnO have the advantages of being natural abundant and high specific capacitance, which makes them substitutes for RuO 2 [ 50 , 51 ]. The disadvantage of poor electrical conductivity is exhibited by many metal oxide electrodes [ 52 ].…”

Facile Synthesis and Electrochemical Investigation of Undoped and Mn‐Doped ZnO Electrodes for the Energy Storage Application

“…[30] These redox peaks obtained from intercalation and deintercalation of K + from the electrolyte into ZnO shown in following reaction. [31] ZnO + K + + e − ↔ ZnO − K ( 2 ) The specific capacitance (SC) is calculated by following relation. [21] SC…”