Partially Reducing Reaction Tailored Mesoporous 3D Carbon Coated NiCo-NiCoO2/Carbon Xerogel Hybrids as Anode Materials for Lithium Ion Battery with Enhanced Electrochemical Performance

Abstract

A facile sol–gel polymerization and impregnation route is developed to large-scale fabricate the novel mesoporous 3D interconnected NiCo-NiCoO2/carbon xerogel (CX) hybrids with a homogeneous carbon coating layer on the surface of NiCo and NiCoO2 nanoparticles, the metallic NiCo nanoparticles are introduced in the NiCo-NiCoO2/CX hybrids via a partially reducing chemical reaction at a high annealing temperature. The mesoporous 3D interconnected NiCo-NiCoO2/CX hybrids show significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as anode electrode materials for Lithium ion batteries (LIBs). After 100 cycles, the NiCo-NiCoO2/CX hybrids anode can still get a reversible capacity of 861mAhg−1 at current density of 100mAg−1, which is 2.8 and 1.9 times higher than that of the CX (305mAhg−1) and NiCoO2/CX hybrid (456mAhg−1), respectively. The greatly enhanced electrochemical lithium ion storage performance of the NiCo-NiCoO2/CX hybrids can be attributed to their unique microstructure characteristics. The elastic nature of CX matrices and carbon layer coating on the surfaces of NiCo and NiCoO2 nanoparticles, renders the NiCo-NiCoO2/CX hybrids very effective in accommodating the volume strain. The highly dispersed NiCo particles display catalytic effect, greatly improve the kinetics of charge-discharge process of the composite anode as the following reaction of NiCo+2Li2O↔NiO+CoO+4Li++4e−. The introduction of metallic NiCo can effectively facilitate the decomposition of Li2O and the SEI during the charge-discharge process, thus greatly enhance the electrochemical performance. Secondly, the presence of NiCo in the NiCo-NiCoO2/CX composite anode can greatly improve the electron conductivity, thus charge transfer kinetics of the composite anode for LIBs. EIS result can well confirm this result. While the homogeneous distribution of NiCoO2 with high theoretical capacity in the porous CX matrices, effectively reduces the active sites of the CX matrices, resulting in higher reversible capacity of the NiCo-NiCoO2/CX hybrids.