Electron density modulation of GaN nanowires by manganese incorporation for highly high-rate Lithium-ion storage

Abstract

Gallium nitride (GaN) has high theoretical capacity and low discharge platform. However, it still suffers from poor conductivity and unsatisfactory cycle performance in lithium-ion batteries (LIBs). In this work, the doped manganese (Mn) are realized in GaN nanowires through a simple and straight forward chemical vapor deposition (CVD) process. When the successful Mn doping was carefully examined in structural characterizations, it is discovered at the atomic level that the species of Mn dopants in GaN nanowires only exist in the feature of Mn+ rather than of metallic Mn, which can significantly promote the electrical conductivity and Li-ions transfer. The tested Mn doped GaN nanowire arrays electrode exhibit the capacity up to 780.3 mA h g−1 at 0.1 A g−1 after 100 cycles and 326.8 mA h g−1 at 5.0 A g−1 after 500 cycles, respectively. The tight and direct contact between Mn doped GaN nanowires and graphite layer provides ultrafast electronic transfer. Density functional theory (DFT) studies confirm that Mn covalent doping can generate the change of local atomic arrangement. Moreover, the electronic structure change significantly increase the electrical conductivity for the fast charge transfer efficiency. This covalent doping strategy for the electron densities regulation could boost the Li-ions storage performance for developing advanced electrode materials in energy storage and beyond.