Synthesis of amorphous hollow Ni(HCO3)2 nanostructures with excellent supercapacitor performance from nickel-containing electroplating sludge

The complex composition and recycling process of electroplating sludge are the two major obstacles restricting the recycling of metal resources. In this work, Ni(HCO 3 ) 2 hollow spheres with unique amorphous structure were prepared via a simple and controllable hydrothermal method using nickel-containing electroplating sludge as raw material and ascorbic acid (AA) as complexing agent . The introduction of AA not only changed the morphology of the sample, but also formed pure phase Ni(HCO 3 ) 2 . The controllable amorphous structure is beneficial to the diffusion of OH - in the electrolyte. More importantly, its disordered atomic arrangement and metastable structure provide a large number of active sites and ion transmission channels, which improve the specific capacity. Consequently, amorphous Ni(HCO 3 ) 2 delivers a large capacitance of 599.8 C g −1 at 1 A g −1 , besides large capacitance, it also exhibits large rate capability (61.02% at a current density of 10 A g −1 ) and cycle performance (capacitance retention 52.09% after 1000 cycles). Importantly, the recoveries of nickel, iron and aluminum are 95.57%, 99.92% and 92.30%, respectively, indicating that electroplating sludge has a good application prospect as electrode materials for supercapacitors .