LAUSR

NiAl-LDH and CoAl-LDH as typical two-dimensional layered materials have been widely used as supercapacitor cathodes due to their special composition, morphology and rich electrochemically active centers. However, a clear strategy to enhance their electrochemical performances remains lacking. Here, with NixCo3-xAl1-LDHs (x = 1, 1.5 and 2, in short: NiCoAl-LDHs) as examples, a Co/Ni ion co-incorporation strategy was used to study the possible effects on their capacitive performance. Our work demonstrated that different cobalt contents in NiCoAl-LDHs show no obvious changes in their crystal structure, morphology, surface area, etc. However, incorporating more cobalt ions into NiCoAl-LDHs will generate more oxygen vacancies, causing more Ni3+ ions to appear on the surface, and higher concentrations of Ni3+ ions and more oxygen vacancies play active roles in enhancing the capacitive performances. The Ni1Co2Al1-LDH electrode with a Ni3+/Ni2+ ratio of 1.44 and an oxygen vacancy concentration of 54.83% delivers a high specific capacitance (728 C g-1 at 1 A g-1) and excellent capacitance retention (93.18% of initial capacitance at 30 A g-1 after 10 000 cycles).