Enhanced Sodium Storageand Thermal Safety of NaNi_1/3Fe_1/3Mn_1/3O₂ Cathode viaIncorporation of TiN and WO₃

This study proposes an efficient, cost-effective, and industrially scalable electrode modulation strategy, which involves directly adding a small amount of high thermal and high conductance TiN and well interface compatible WO₃ to NaNi_1/3Fe_1/3Mn_1/3O₂ (NaNFMO-TW) cathode slurry, to effectively reduce electrode polarization and interface side reactions, reduce the Ohmic heat and polarization heat of the battery, and ultimately to significantly improve the sodium-ion storage and thermal safety performance of the battery. At room temperature (RT) and 1C rate, the modified NaNFMO-TW electrode exhibits a reversible capacity of ∼95 mAh g^–1 after 300 cycles, with a capacity retention rate of 82.6%, being higher than the 50.7% for NaNFMO. Furthermore, the assembled pouch battery with NaNFMO-TW retains 58.2% capacity after 300 cycles at RT&0.5C, being conspicuously superior to the 46.1% achieved by the NaNFMO||HC battery. In particular, adiabatic thermal tests and infrared thermal imaging tests reveal a marked improvement in the thermal safety of the modified battery, with a reduction in surface temperature of ∼1.3 and ∼2.2 °C during 3C charging and discharging, respectively. Moreover, the results confirmed the performance enhancement mechanism of NaNFMO by addition of TiN and WO₃. Such electrode modulation strategy provides a practical method for improving battery performance.