Efficient preparation of uniform germanane nanosheets as anode with high-cycling stability in lithium-ion batteries

Two-dimensional germanane (2D GeH) is considered to be a potential anode material for lithium-ion batteries (LIBs) due to the unique structure and properties. In this study, an effective method for synthesizing GeH is proposed, involving the etching of ball-milled CaGe₂ with dilute hydrochloric acid at room temperature for a short duration. The resulting GeH nanosheets exhibit uniformity and high yield without the need for harsh reaction conditions or repeated ultrasound and centrifugation treatments. Comparative analysis reveals that GeH fabricated using this method exhibit superior cycling stability when employed as electrode in LIBs in comparison with reported techniques. Specifically, the as-prepared GeH anode can achieve a specific capacity of 1320 mAh/g after 400 cycles at 0.2C (1C = 1600 mAh/g) and 1020 mAh/g after 1000 cycles at 1C. Furthermore, GeH//LiFePO₄ full cell is assembled for evaluating its practical applications. The specific capacity remains stable, maintaining 108 mAh/g after 140 cycles at a current density of 1C (1C = 170 mAh/g). The results confirm that the nano refinement process presented in this study effectively simplifies the synthesis process and significantly enhances the anode stability of GeH materials in LIBs applications. Importantly, this work provides a promising and versatile approach for the mass production of 2D electrode materials with improved electrochemical performance.