Phase Conversion Accelerating “Zn‐Escape” Effect in ZnSe‐CFs Heterostructure for High Performance Sodium‐Ion Half/Full Batteries

Sodium‐ion batteries (SIBs) are considered as a promising large‐scale energy storage system owing to the abundant and low‐cost sodium resources. However, their practical application still needs to overcome some problems like slow redox kinetics and poor capacity retention rate. Here, a high‐performance ZnSe/carbon fibers (ZnSe‐CFs) anode is demonstrated with high electrons/Na+ transport efficiency for sodium‐ion half/full batteries by engineering ZnSe/C heterostructure. The electrochemical behavior of the ZnSe‐CFs heterostructure anode is deeply studied via in situ characterizations and theoretical calculations. Phase conversion is revealed to accelerate the “Zn‐escape” effect for the formation of robust solid electrolyte interphase (SEI). This leads to the ZnSe‐CFs delivering a superior rate performance of 206 mAh g−1 at 1500 mA g−1 for half battery and an initial discharge capacity of 197.4 mAh g−1 at a current density of 1 A g−1 for full battery. The work here heralds a promising strategy to synthesize advanced heterostructured anodes for SIBs, and provides the guidance for a better understanding of phase conversion anodes. A ZnSe/carbon fibers (ZnSe‐CFs) anode with high electrons/Na+ transport efficiency by engineering ZnSe/C heterostructure is designed for high performance sodium‐ion half/full batteries. Phase conversion is found to accelerate the “Zn‐escape” effect for the formation of robust solid electrolyte interphase, providing the guidance for a better understanding of phase conversion anodes for high‐performance sodium‐ion batteries.