Effective Shielding of Sodium Polysulfides Using Two-Dimensional Ceramic Based Polymer Membrane for Ambient Temperature Sodium Sulfur Battery

Abstract

The development of high energy density batteries is an essential requirement for the large-scale energy storage applications and the balance between cost as well as performance will drive a way to meet the energy needs. Focusing on low cost energy storage devices, sodium is widely available in the Earth’s crust (23600 ppm). The coupling of low cost sodium anode and sulfur cathode can lead to cost effective high energy density sodium sulfur battery. But the conventional sodium sulfur batteries are operated at a higher temperature of above 300 °C. Since the operating temperature far exceeds the melting points of sodium and sulfur, the problem of corrosion prevails and may bring safety issues. So, the operation of battery at room temperature will turn to improved safety and high energy density. Since solid electrolytes cannot conduct sodium ions at ambient condition, the ambient temperature sodium sulfur battery has to move towards the use of liquid electrolytes. But the dissolution of sodium polysulfides formed during the discharge process is highly soluble in liquid electrolytes and reduces the durability of the battery. Preventing the dissolution of sodium polysulfides by chemical binding towards the cathode is an effective strategy for obtaining the high energy density and durable sodium sulfur battery. This study employs a two-dimensional porous ceramic polymer membrane for suppressing the shuttling effect. The presence of boron and nitrogen in white graphite helps in chemical binding of higher order sodium polysulfides and helps to attain a reversible specific capacity of 1027 mAh g-1 at a current density of 50 mA g-1. The electrochemical impedance study validates the control of polysulfide shuttling using the porous ceramic membrane. This method provides a new technique of controlling the polysulfide shuttling and can lead to the development of room temperature sodium sulfur battery.