Caterpillar structured Ni(OH)2@MnO2 core/shell nanocomposite arrays on nickel foam as high performance anode materials for lithium ion batteries

Abstract

Caterpillar structured Ni(OH)₂@MnO₂ core/shell nanocomposite arrays on nickel foams (CS Ni(OH)₂@MnO₂ NFs) are synthesized by a facile hydrothermal method. The nanocomposites consist of Ni(OH)₂ nanosheets which are coated by a series of ultrathin MnO₂ nanosheets as a secondary nanostructure. As an anode for lithium ion batteries (LIBs), the as-fabricated CS Ni(OH)₂@MnO₂ NFs show an improved electrochemical performance, which delivers a high specific capacity of 2223 mA h g⁻¹ in the initial discharge process and retains a reversible capacity of about 1210 mA h g⁻¹ after 80 cycles at 200 mA g⁻¹, corresponding to a capacity retention of 74.4% with comparison of the second cycle. CS Ni(OH)₂@MnO₂ NFs also show a remarkable rate capability of 650 mA h g⁻¹ after 100 cycles while cycling at 1000 mA g⁻¹. The improved electrochemical performance can be ascribed to a large surface area, more efficient electrolyte penetration, and multifunctionalities offered by the individual components of the caterpillar core/shell nanostructure. In addition, the self-supported nanocomposite arrays on NFs greatly simplify the fabrication processing of electrodes without applying a binder and conductive additive, which provide good electrical contact between the active materials and the substrate. Hence, CS Ni(OH)₂@MnO₂ NFs are promising anode candidates for lithium-ion batteries.