Ni-based electrodes on 3D substrates: Development and performance for asymmetric supercapacitors

Abstract

To produce high-performance supercapacitors, an easy hydrothermal method was utilized to fabricate the positive electrode employing transition metal nickel and carbonate, which exhibits good wettability and reacts well with aqueous electrolytes. In addition, electrodes without and with a 3D Ni foam substrate were compared, focusing on their surface area and electrochemical performance. The electrodes were fabricated using carbonate (CO32−) based compounds with high wettability. The Ni2(CO3)(OH)2 electrode without Ni foam substrates demonstrated higher electrochemical values at low current densities, while the Ni2(CO3)(OH)2 electrode with Ni foam substrates exhibited higher capacitance at increased current densities. As the current density increased from 3 A/g to 15 A/g, the capacitance of Ni2(CO3)(OH)2 without Ni foam and with Ni foam electrodes decreased by 58.1 % and 46.5 %, respectively. This indicates that higher electrochemical stability is possessed by electrodes directly deposited on Ni foam substrates. The significance of substrate selection for enhancing electrochemical performance is highlighted, with the Ni2(CO3)(OH)2 electrode deposited on Ni foam substrate showing a high capacitance of 101.5mAh/g at a current density of 3 A/g. Additionally, an asymmetric supercapacitor comprising Ni2(CO3)(OH)2 electrodes with Ni foam and graphene as positive and negative electrode, respectively, demonstrated a remarkable energy density of 22.1 W h kg−1 and power density of 673.1 W kg−1 at a current density of 2 A/g. Impressively, excellent cycling stability was exhibited by this asymmetric supercapacitor, with ∼83.4 % capacitance retention after 5000 cycles. © 2024 Elsevier B.V.