Constructing Magnetic Ion Accelerator at Na2/3Ni1/3Mn2/3O2 Surface for Sodium Ion Batteries

Surface ion transportation and structural stability are generally the key factors determining the electrochemical performance of a specific electrode for secondary batteries. Therefore, building an effective and stable interface layer becomes the bottleneck for long-life and high-performance batteries. This study is the first to design and construct a magnetic Fe3O4 interfacial layer on the Na2/3Ni1/3Mn2/3O2 surface. Preliminary analysis and calculations indicated that the the Fe3O4 magnetic layer played a role as a surface ion accelerator, which effectively ameliorated the interfacial kinetic behavior through dispersing the aggregated ions at a tangential orientation under the Lorentz force. Electrochemical tests substantiated that the decorated cathode delivered a high capacity of 87 mA h g–1 and a capacity retention of 76% after 500 cycles under a rate of 5 C. This finding in the surface magnetic ion accelerator provides insight into efficient electrode design and applications of surface physical fields to enhance ion transportation and structural stability for advanced secondary batteries.