Chemical approach to achieve sodiated alloying anode for direct application in Na-ion battery

Metal-free Na-ion battery with sodium-deficient cathodes such as layered oxides foresees a careful tuning of the sodium content at the negative side. We exploit a versatile chemical strategy to get sodiated versions of a tin-carbon (Sn-C) alloying electrode for application in full-cell. The process is performed by capillary contacting Sn-C and sodium metal to trigger the chemical alloying, which leads to the NaxSn-C electrode. The success of the reaction is monitored by X-ray diffraction (XRD) and Raman spectroscopy, while the morphological changes are exploited by scanning electron microscopy (SEM). The achieved NaxSn-C electrode is advantageously used as anode in combination with Al-doped, Na-defective layered oxide in a full-cell. The battery is cycled galvanostatically and fully investigated by electrochemical impedance spectroscopy (EIS). The optimized Sn-C|NCAM cell reveals maximum capacity of 120 mAh gcat–1, energy and power density respectively of 300 Wh kgcat–1 and 650 W kgcat–1, and lifespan extended over 250 cycles.