Ni(OH)₂ Nanoflakes Supported on 3D Ni₃Se₂ Nanowire Array as Highly Efficient Electrodes for Asymmetric Supercapacitor and Ni/MH Battery

Abstract

Porous Ni(OH)2 nanoflakes are directly grown on the surface of nickel foam supported Ni3Se2 nanowire arrays using an in situ growth procedure to form 3D Ni3Se2@Ni(OH)2 hybrid material. Owing to good conductivity of Ni3Se2, high specific capacitance of Ni(OH)2 and its unique architecture, the obtained Ni3Se2@Ni(OH)2 exhibits a high specific capacitance of 1689 µAh cm−2 (281.5 mAh g−1) at a discharge current of 3 mA cm−2 and a superior rate capability. Both the high energy density of 59.47 Wh kg−1 at a power density of 100.54 W kg−1 and remarkable cycling stability with only a 16.4% capacity loss after 10 000 cycles are demonstrated in an asymmetric supercapacitor cell comprising Ni3Se2@Ni(OH)2 as a positive electrode and activated carbon as a negative electrode. Furthermore, the cell achieved a high energy density of 50.9 Wh L−1 at a power density of 83.62 W L−1 in combination with an extraordinary coulombic efficiency of 97% and an energy efficiency of 88.36% at 5 mA cm−2 when activated carbon is replaced by metal hydride from a commercial NiMH battery. Excellent electrochemical performance indicates that Ni3Se2@Ni(OH)2 composite can become a promising electrode material for energy storage applications.

One‐dimensional and two‐dimensional synergized nanostructures for high‐performing energy storage and conversion

“…For electrocatalysis, the 1D morphology promotes the gas bubbles evolving and releasing from the catalyst surface, enhancing the electrolyte contact with the catalyst . Therefore, through a proper core/shell combination, synergistic properties are produced, leading to large and simultaneous enhancement of the overall performance …”

“…For example, several materials with 2D morphology of nanosheets/nanoflakes have been reported, including LDHs (NiFe‐LDH, Ni(OH) 2 , etc. ), oxides (NiCo 2 O 4 , MnO 2 , V 2 O 5 , Bi 2 O 3 , etc. ), TMDs (MoS 2 , ReS 2, etc.…”

“…Moreover, the Ni 3 Se 2 /Ni(OH) 2 nanocomposite composed of the Ni(OH) 2 nanoflakes hydrothermally formed on the surfaces of the Ni 3 Se 2 nanowires was demonstrated as well. The as‐obtained Ni 3 Se 2 /Ni(OH) 2 /activated carbon (AC) cell showed a high energy density of 59.47 W h kg −1 at the power density of 100.54 W kg −1 , together with considerable durability manifested by only 16.4% loss after 10 000 cycles . Taking another example here, 1D Mo 2 C NFs or TiN nanowires (TiN NWs) were prepared via a facile electrospinning and hydrothermal approach, respectively, which provided a “highway” to facilitate charge transport and ionic diffusion.…”

“…Among these energy technologies, LIBs, SIBs, LSBs, MABs, and SCs are energy storage systems; water splitting and CO 2 RR are representative energy conversion systems. As the performance of all these systems is intimately and largely dependent on the properties of their electrodes, it would be essential to develop highly efficient materials for them, at low cost for large‐scale applications …”

“…In particular, in the last decade, considerable efforts have been made to develop nanocomposites containing both 1D and 2D nanostructures, and the concept of 1D‐2D synergized nanostructure is proposed. By building up electrodes with such 1D‐2D synergized nanostructures, the structural features and electroactivities of each component can be manifested . More interestingly, the interface between the two segments can produce new attributes that are different from either of the single components …”