The nanoscale effects on the morphology, microstructure and electrochemical performances of the cathodic deposited α-Ni(OH)2

In this study, α-Ni(OH)2 with controllable pristine crystal size is directly electrodeposited on a substrate of Ti wire mesh to fabricate the integrated electrode. The nanoscale effects on morphology, microstructure and electrochemical performance of the cathodic deposited α-Ni(OH)2 are studied. The results show that the morphology of α-Ni(OH)2 varies from irregular honeycomb-like nanopieces, ball-shaped particles to oval nanoplates as the cathodic deposition current density increases. The nanostructure diversity of the cathodic deposited α-Ni(OH)2 is due to the different nanosize which directly depends on the cathodic deposition current density. The electrochemical performances of the cathodic deposited α-Ni(OH)2 increase with the decrease of the pristine crystal size of α-Ni(OH)2. The oval α-Ni(OH)2 nanoplates consisting of nanosheets with a pristine crystal size of 3 ∼ 5 nm × 5 ∼ 7 nm show the ultrahigh specific capacities of ∼348 mAh g−1 and ∼312.5 mAh g−1 at charge/discharge current density of 5 A g−1 and 100 A g−1, respectively, and over 70% specific capacity still remains after 1000 cycles, while the irregular honeycomb-like α-Ni(OH)2 consisting of nanosheet with a pristine crystal size of 10 ∼ 15 nm × 15 ∼ 20 nm shows only ∼260 mAh g−1 specific capacity at 5 A g−1 and ∼150 mAh g−1 at 100 A g−1. The ultrahigh electrochemical performances are attributed to the nanoscale and the defective nanostructure of the cathodic deposited α-Ni(OH)2.