A self-healing layered GeP anode for high-performance Li-ion batteries enabled by low formation energy

Abstract

Ge is considered a promising anode candidate for Li-ion batteries (LIBs); however, its practical applicability is hindered by the relatively slow Li-ion diffusion owing to the stiffness of the diamond-like structure. Inspired by little difference in electronegativity between Ge and P, we have designed a novel layered GeP anode for LIBs, which can be readily synthesized using a mechano-chemical method and a subsequent low-temperature annealing. In particular, GeP demonstrates the best performances among all Ge-based anode materials studied, attributed to its fast Li-ion diffusion compared to Ge counterpart and a unique Li-storage mechanism that involves intercalation, conversion, and alloying, as confirmed by XRD, TEM, XPS, and Raman spectroscopy. Specially, the initial layered crystal structure of GeP can be reconstructed during charging due to its low formation energy, thus offering remarkable reversibility during cycling. Further, this study implies that the formation energy of crystal structures could be an important parameter for strategic design of large-capacity anode materials for LIBs.