Mechanically robust and electrochemically stable SiGe anode enabled by graphite coating and nitrogen-doped carbon nanotube scaffold

Here, a graphite-coated silicon‑germanium (SiGe) alloy anode supported by nitrogen-doped carbon nanotubes (C@SiGe@NCNT/CC) is developed for high-performance flexible lithium-ion batteries (FLIBs). The material is fabricated through a combined approach involving chemical vapor deposition and dual-mode direct current/radio frequency plasma-magnetron co-sputtering, using a flexible carbon cloth (CC) substrate to eliminate binders and current collectors. The three-dimensional NCNT/CC network enhances conductivity and mitigates volume stress during cycling. The SiGe alloy improves charge-transfer kinetics, while the graphite coating boosts structural stability. Electrochemical analysis demonstrates outstanding performance: the anode delivers an initial discharge capacity of 2877.6 mAh g⁻¹ at 0.2 A g⁻¹, maintaining 1127.6 mAh g⁻¹ with 88.1% retention after 200 cycles at 1 A g⁻¹. Under high-rate cycling (2 A g⁻¹ for 520 cycles), it sustains 751.1 mAh g⁻¹ (94.17% retention). Full cells with LiNi_0.8Co_0.1Mn_0.1O₂ or LiFePO₄ cathodes exhibit excellent cycling stability, retaining 80.6% capacity after 500 cycles at 2C. Pouch cell evaluations further confirm robust mechanical flexibility and electrochemical stability under deformation. These results highlight the synergistic benefits of the graphite-coated SiGe alloy and NCNT/CC framework, offering a promising approach for durable, high-capacity FLIBs. This work pioneers advanced anode architectures for next-generation energy storage.