High-Capacity, High-Rate Bi–Sb Alloy Anodes for Lithium-Ion and Sodium-Ion Batteries

Homogeneous alloys consisting of Bi and Sb have been fabricated by a facile high-energy mechanical milling with carbon and evaluated as potential anode materials in both lithium-ion and sodium-ion batteries. Specifically, Bi0.57Sb0.43-C and Bi0.36Sb0.64-C have been made, and they exhibit electrochemical performances superior to those of their counterparts Bi-C and Sb-C. For example, the Bi0.57Sb0.43-C sample delivers an initial delithiation capacity of 410 mA h g–1 and cycles stably for 300 cycles with a capacity decay of 0.09% per cycle at a current density of 200 mA g–1. It also exhibits high rate capacities in lithium-ion cells: 355 mA h g–1 at 5C current and 326 mA h g–1 at 7.8C current. In the case of a sodium-ion cell, its initial desodiation capacity is 375 mA h g–1 with a capacity retention of 78% at the 50th cycle. At a high current rate of 2.6C (1000 mA h g–1), it still delivers a desodiation capacity of 326 mA h g–1.