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

• Metal-free Na-ion battery is achieved; • The battery employs versatile chemical sodiated Sn-C alloying and NCAM cathode; • The Sn-C|NCAM full-cell reveals a maximum capacity of 120 mAh g cat –1 • The battery has energy and power densities of 300 Wh kg cat –1 and 650 W kg cat –1 • The battery is cycled at 200 mA g cat –1 with capacity of 85 mAh g cat –1 for 250 cycles. 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 Na x Sn-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 Na x Sn-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 Sn-C|NCAM cell reveals maximum capacity of 120 mAh g cat –1 , energy and power density respectively of 300 Wh kg cat –1 and 650 W kg cat –1 , and lifespan extended over 250 cycles.