GaAl2P3: A new ternary cation-mixing aluminum-phosphorus compound toward superior Li-storage properties

Abstract

Aluminum (Al) is an ideal anode material due to its large theoretical Li-storage capacity of 993 mA h g−1 corresponded to the binary alloy of LiAl due to its light atomic weight, rich reserve, and mature industrial application. However, the large volume expansion and relatively sluggish Li-ion diffusion result in inferior performance, hindering its commercial application. Herein, through simple mechanochemical reactions, we prepare a new ternary compound of GaAl2P3, whose crystal structure is the cation-mixed cubic ZnS structure according to XRD refinement. Disordered lattice and all-lithium-reactive constituent elements enable the GaAl2P3 compound to store Li-ions in a fast and stable manner. GaAl2P3 compound offers a reversible capacity of 1,485 mA h g−1 with an initial Coulombic efficiency of 90 % based on a reversible Li-storage mechanism integrating an intercalation reaction and followed conversion reaction as confirmed by in-situ XRD and Raman characterization. Its carbon composite delivers 880 mA h g−1 capacity after 300 cycles at 1,000 mA g−1 and 575 mA h g−1 capacity at 10,000 mA g−1, surpassing most reported Al-based anodes studied before, holding the promise to be applied in real word. Broadly, this work will arouse immediate interest in energy storage of aluminum-based compounds.