The electrochemical performance of electrodeposited nickel foam electrodes coated by nano-confined lithium borohydride-metal oxides composites

Abstract

In the present study, the electrochemical performance of the nickel (Ni)-foam electrodes (nano-confined-metal oxide composites: nc-SiO₂, nc-Al₂O₃, nc-MgO, nc-CaO) coated by electrodeposition via nano-confined lithium borohydride (nc-LiBH₄)-metal oxide (SiO₂, Al₂O₃, MgO, CaO) composites were investigated. Nano-confinement of LiBH₄ on metal-oxide structure approach was applied by a ball-milling process to prepare composites. The nc-metal oxide composites were electrodeposited on Ni foam using the chronoamperometry (CA) technique. The comparative study by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods at different scan rates and current densities were used for electrochemical characterization of nc-metal oxide composites towards neat LiBH₄ and metal oxide. Cross-sectional analyses of scanning electron microscope elucidated that nc-CaO composite uniformly blankets the inner and outer surfaces of foam. These composites showed superior stability and reduced porosity in their surface structures, predominantly characterized by granular morphology and weak interparticle bonding, in contrast to other composite materials. Among CV curves, nc-CaO electrodeposited Ni foam electrode displayed a reduction of charge storage and lower capacitance values due to reduced porosity of nc-CaO composite towards LiBH₄ advanced in nano-confinement approach. Comparing specific capacitance of the electrodes first increased up to around 130 F/g and then decreased when metal oxides were added, while Ni electrodes prepared without nc-metal oxide composites showed an inverse relation with increasing current. The highest capacitance retention still after 2000 cycles achieved 85% stability.