Amorphous Sb/C composite with isotropic expansion property as an ultra-stable and high-rate anode for lithium-ion batteries

Antimony (Sb) is an intriguing anode material for Li-ion batteries (LIBs) owing to its high theoretical capacity of 660 mAh·g⁻¹ and appropriate working potential of ~ 0.8 V (vs. Li⁺/Li). However, just like all alloying materials, the Sb anode suffers from huge volume expansion (230%) during repeated insertion/extraction of Li⁺ ions, resulting in structural deterioration and rapid capacity decay. In this work, a novel amorphous Sb/C composite with atomically dispersed Sb particles in carbon matrix is prepared via a straightforward high-energy ball milling approach. The intimate intermixing of amorphous Sb with C provides homogeneous element distribution and isotropic volume expansion during cycling, resulting in persistent structural stability. Meanwhile, the disordered structure of amorphous material shortens the diffusion distance of lithium ions/electrons, promoting fast reaction kinetics and rate capability. Benefiting from the aforementioned effects, the amorphous Sb/C exhibits a high reversible capacity of 537.4 mAh·g⁻¹ at 0.1 A·g⁻¹ and retains 201.0 mAh·g⁻¹ at an ultrahigh current rate of 10.0 A·g⁻¹. Even after 1500 deep cycles at 2.0 A·g⁻¹, the amorphous Sb/C electrode still maintains 86.3% of its initial capacity, which outperforms all existing Sb-based anodes reported so far. Post-mortem analysis further reveals a greatly reduced volume variation of merely 34.6% for the amorphous Sb/C electrode, much lower than that of 223.1% for crystalline Sb materials. This study presents a new approach to stabilizing Sb-based alloy anodes and contributes to the construction of high-performance amorphous anode materials for LIBs, enabling advanced energy storage.