EFFECT OF EXTERNAL MAGNETIC FIELD ON SODIUM-ION BATTERIES PERFORMANCE

Abstract

Sodium-based batteries present promising alternatives to lithium-ion systems in energy grid systems; however, issues like dendrite formation and limitations in charge transfer pose significant challenges to their overall performance. The effect of external magnetic field (MF) on sodium-based batteries is discussed in this work. The presence of MF while cycling sodium symmetrical cells showed an enhanced mass transfer due to the magnetohydrodynamic effect as shown by the decrease of polarisation and charge-transfer resistance. The optimal intensity of magnetic field strength was found to be 250 mT, meanwhile stronger and weaker magnetic fields resulted in slightly reduced performance. Sulphurised dehydrogenated polyacrylonitrile(SDPAN) was synthesised and tested as a cathode in sodium-sulphur battery. MF-exposed cells have had slightly higher capacities during galvanostatic cycling, typically around 100 mAh/g more than control samples, although both undergo capacity fading. Postmortem characterisation of the sulphur electrodes revealed considerable volume expansion and the formation of sharp spikes after cycling at high currents, likely attributed to polysulphides or side reaction-induced deposition. With MF, such formations are absent and the sulphur and nitrogen content on the electrode surface based on the elemental analysis from Energy-Dispersive X-ray Spectroscopy (EDS) was higher than in the control samples, indicating the preservation of the initial structures of SDPAN. Hard carbon anode was also tested in the presence of magnetic field, however no prominent changes in performance occurred.