Adjusting Surface Morphology and Electronic Structure of Moo42--Doped Ldhs to Enhance Areal Capacitance and Cyclic Stability

Abstract

The capacitance and cyclic stability of layered double hydroxides (LDHs) are severely limited by their inherent poor conductivity and serious agglomeration. In order to obtain higher energy density and better cyclic stability, MoO42--doped LDHs with varying element types and MoO42- concentrations were fabricated on phosphating nickel foam substrate (Ni12P5/NF). As a carrier with high conductivity and excellent electrochemical activity, Ni12P5 with rough surface can accelerate electron transfer and improve the contact area with LDHs. Moreover, the doped MoO42- adjusts the morphology and electronic structure of LDHs, significantly improving both in specific capacitance and cyclic stability. Benefiting from the synergistic effect of the trimetallic NiCoMo-LDH and the highly conductive Ni12P5 substrate, the performance of NiCoMo-LDH@Ni12P5 is much better than that of NiCo-LDH@Ni12P5, NiMo-LDH@Ni12P5 and CoMo-LDH@Ni12P5. The optimized NiCoMo-LDH@Ni12P5 exhibits an ultrahigh areal capacitance (11.73 F cm-2 at 2 mA cm-2) and superior capacity retention of 93.6% after 5000 cycles. The assembled asymmetric supercapacitor (NiCoMo-LDH@Ni12P5//AC) achieves a satisfactory energy density of 0.83 mWh cm-2 and demonstrates an excellent cyclic stability (capacity retention of 90.2% after 5000 cycles). Additionally, two ASC units simultaneously powered 10 LEDs for more than 2 minutes, indicating their excellent potential for energy storage applications.

Keywords: Layered double hydroxides, Surface morphology, Electronic structure, Areal capacitance, Cyclic stability, Supercapacitors