Two-dimensional layered nickel-based coordination polymer for supercapacitive performance

Abstract

Room temperature assisted nickel-coordination polymer (Ni-CP) is obtained by utilizing the slow diffusion method. The formation of Ni-CP has been confirmed using single-crystal X-ray diffraction (SC-XRD). Ni-CP established a 2D layer structure with average length to diameter (l/d) ratio of ∼4.19. The binder and additive-free Ni-CP exhibited outstanding pseudocapacitor behavior with a specific capacitance of 802 F g⁻¹ (64 mA h g⁻¹) at 3 A g⁻¹ by retaining ∼95% of the initial capacitance over 5000 cycles. For a comparative study, different electrolytic cations (Na⁺, K⁺, Li⁺) were employed to reveal the diffusion kinetics of Ni-CP. Furthermore, an asymmetric supercapacitor (ASC) device was assembled using Ni-CP as the positive and carbon black (CB) as the negative electrode, respectively. The as-fabricated ASC device displayed an energy density of 15 Wh kg⁻¹.