Search

Nickel ferrite owns a lot of advantages as electrode materials for supercapacitor, such as high energy density and excellent theoretical capacity. Whereas, the electrochemical performances of NiFe 2 O 4 in terms of rate performance and cycle stability are not satisfactory due to the low conductivity. While carbon fiber is a kind of material with high conductivity. Hence, NiFe 2 O 4 @ slit modified hollow carbon fiber is obtained through the coaxial electrospinning method. The slits on hollow carbon fibers are beneficial to the contact of inner NiFe 2 O 4 nanoparticles with electrolyte. Results of electrochemical tests show that at a current density of 1 A/g, the specific capacitance of NiFe 2 O 4 @ slit modified hollow carbon fiber is calculated to be 225.4 F/g, higher than that of NiFe 2 O 4 nanoparticles of 134.8 F/g. Moreover, a better cycle and rate performances (100 % vs 80 %; 71.9 % vs 47.5 %) are achieved. This work displays that slit modified hollow carbon fiber can improve the electrochemical performance of NiFe 2 O 4 efficiently. [Display omitted] • Carbon fibers are introduced to enhance the rate and cycle performances of NiFe 2 O 4. • Slits are obtained utilizing Al 2 O 3 sacrificial hard templates. • Slits are beneficial to the contact of NiFe 2 O 4 and electrolyte. [ABSTRACT FROM AUTHOR]

In the recent years, MXenes (2D transition metal carbides, carbon nitrides and nitrides) and its precursor MAX phases have been widely investigated in electrochemical research. In this research, we successfully prepared a core-shell structured compound——Ti 3 C 2 @Ti 2 SnC/CNFs (MXene@TSC/C) as an anode material for lithium ion battery via electrospinning method. Results showed that this type of compound has a specific capacity of 288.9 mAh·g−1 at the current density of 0.4 A g−1 after 300 cycles, accompany with a retention rate of capacity of 105.4% in the rate performance test. These performances were benefit from the core-shell structured CNFs and Ti 3 C 2 MXenes. This work supported a novel way to improve the electrochemical property of MXene and MAX phases, which was expected to further explored. [ABSTRACT FROM AUTHOR]

A sol-gel method was employed for the synthesis of new High-entropy boride (HEB) powders, (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 , with nanoscale. The as-synthesized powders were obtained at a relatively low temperature of 1650 °C, and had small average particle size of 62.09 nm. X-ray diffraction confirmed that the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders were hexagonal single-phase without any oxide impurities. In particular, electrochemical performance of the (Hf 0.2 Nb 0.2 Cr 0.2 Ta 0.2 Mo 0.2)B 2 powders with multiphase and high-entropy single phase were investigated using a three-electrode system. The improved electrochemical performance of the HEB powders is realized, with 27% higher in specific capacitance compared to the powders with multiphase. The HEB powders electrode exhibits a high capacitance retention of 97.03% after 5000 cycles. [ABSTRACT FROM AUTHOR]

Transitional metal nitrides (TMNs) are regarded as comparatively promising electrode materials for supercapacitor due to the high electronic conductivity, good corrosion resistance and special electron structure. Herein, in this work a heterostructure Co 2 N-Ni 3 N nanosheets-nanowires arrays grown on Ni foam (NF) are designed and synthesized by a simple hydrothermal reaction and nitriding treatment. The prepared Co 2 N-Ni 3 N/NF nanoarrays has a high electrical conductivity, abundant surface active sites, charge transfer channels and the synergy effect between each component, which makes it exhibit outstanding electrochemical performance. Electrochemical test results revealed that the areal capacitance of Co 2 N-Ni 3 N/NF was 2.17 F cm−2 at 1 mA cm−2 using a three-electrode system in 1 M KOH. Meanwhile, when the current density increases to 20 mA cm−2, it can still retain 62.21% of the original capacitance, suggesting a good rate capability. In addition, in two-electrode test with Co 2 N-Ni 3 N/NF as the positive electrode and activated carbon as the negative electrode, a maximum energy density of 145.65 μWh cm−2 is shown when the power density is 0.75 mW cm−2. And it has 85.90% capacitance retention after 5000 cycles. [Display omitted] • Unique Co 2 N-Ni 3 N nanoarray heterostructure was successfully synthesized. • Co 2 N-Ni 3 N/NF achieves an areal capacitance 2.17 F cm-2 at current density of 1 mA cm-2. • The Co 2 N-Ni 3 N/NF // AC exhibits good electrochemical performance in two-electrode tests. [ABSTRACT FROM AUTHOR]