Origin of High-Rate Performance of Sb₂Se₃/Sb Composite Anodes for Na-Ion Batteries

Improving the energy density of Na-ion batteries (NIBs) requires advances in anode materials. This study investigates Sb₂Se₃/Sb composite anodes, which offer better capacity and stability than the individual constituents. Operando X-ray diffraction (XRD) revealed that (de)-sodiation is driven by synergies between the operating mechanisms of Sb₂Se₃ and Sb, enabling a reversible capacity of 360 mAh g^-1 (at 1000 mA g^-1). This performance is also aided by amorphization of the sodiated phases, which promotes rapid Na-diffusion. The work emphasizes the need for continuous material and structural optimizations to fully harness their benefits for enabling efficient and fast-charging NIBs.