Li/Na/K-ion reaction pathways in Ga and high-performance amorphous Ga composite anodes for Li-ion batteries

Abstract

To achieve high-performance Ga anodes for alkali-ion batteries, the electrochemical Li/Na/K-ion reaction pathways in Ga are thoroughly elucidated using ex situ analytical tools. Ga exhibits a high Li-ion storage reaction owing to the formation of Li2Ga (theoretical capacity: 769 mAh g−1). However, it exhibits poor Na- and K-ion storage reactions owing to the formation of NaGa4 (theoretical capacity: 96 mAh g−1) and K3Ga13 (theoretical capacity: 89 mAh g−1), respectively. The high Li-ion storage reaction in Ga demonstrates its potential as an anode for Li-ion batteries (LIBs). Therefore, we fabricate an amorphous Ga composite (Ga/C) comprising amorphous Ga homogeneously distributed in an amorphous carbon using a simple one-pot solid-state mechanical process. Ga/C exhibits high reversible capacity, long-term Li-ion storage stability, and high rate capability. In addition, three-step confinement of amorphous Ga in the composite during continuous cycling is demonstrated and suggested as an enhancement mechanism for high-performance Ga/C anodes for LIBs. The interesting Li-ion storage reaction in Ga and high-performance amorphous Ga composites are expected to be highly applicable to LIB anodes.