Controllable architecture of the NiCoZnS@NiCoFe layered double hydroxide coral-like structure for high-performance supercapacitors

Abstract

The rational design of the morphological structure of electrode materials is considered as an important strategy to obtain high-performance supercapacitors. So, NiCoZnS materials with different Ni/Co/Zn molar ratios on Ni foam (NF) were synthesized, in which the Ni/Co/Zn molar ratio plays a key role in the morphological structure and electrochemical performances. Furthermore, the pre-prepared NiCoZnS materials act as substrates to guide the self-assembling of NiCoFe layered double hydroxide (LDH) nanosheets on the substrate surface to form core–shell electrode materials (NiCoZnS@NiCoFe-LDH) with a 3D mesoporous hierarchical network structure for further improving electrochemical performances. The unique interconnected coral-like NiCoZnS₁@NiCoFe-LDH with a large specific surface area (93.1 m² g⁻¹) and high specific capacitance is achieved at the Ni/Co/Zn molar ratio of 1 : 1 : 1. Benefiting from the unique structural feature and respective merits of the NiCoZnS and NiCoFe-LDH, the NiCoZnS₁@NiCoFe-LDH demonstrates an ultrahigh specific capacitance of 1524.0 C g⁻¹ (3386.7 F g⁻¹) at 1.0 A g⁻¹ and excellent 95.0% capacitance retention at 10 A g⁻¹ after 5000 cycles. As for practical application, the assembled NiCoZnS₁@NiCoFe-LDH//AC delivers a favorable energy density of 66.25 W h kg⁻¹ at 1500 W kg⁻¹ and a long-term cycling lifetime (86.04% retention at 5.0 A g⁻¹ after 10 000 cycles), which suggests promising potential in energy storage and conversion.