Phase Engineering in Cobalt Sulfide with Multiple Redox Modes for High‐Performance Lithium‐Ion Batteries

Abstract Transition metal sulfides with multivalent nature are regarded as promising anodes for lithium‐ion batteries owing to their high theoretical capacity. However, the structure‐activity relationship between atomic arrangement and lithium storage performance is pointedly ambiguous. Herein, we demonstrate a phase engineering strategy towards hollow nanostructured cobalt sulfides with different atomic arrangements for high‐performance anodes. By selectively controlling the synthesis of cobalt sulfides with two phases (i. e. hexagonal or cubic phase), we unravel that the arrangement of sulfur atoms endows cobalt sites with different electronic structures, resulting in an abnormal (de)lithiation reaction mechanism. Benefiting from the multiple redox transitions and the enhanced electronic conductivity, hexagonal cobalt sulfide achieves an outstanding rate performance (1203 mAh g⁻¹ at 0.1 A g⁻¹ and 190 mAh g⁻¹ at 10 A g⁻¹), and a high reversible capacity (800 mAh g⁻¹ after 200 cycles at 0.5 A g⁻¹). The mechanism studied here may provide insights into the design of other energy storage materials.