The Effect of Pressure on Cathode Performance in the Lithium Sulfur Battery

Abstract

This study was undertaken to understand the effect of applied pressure on the performance of the lithium sulfur cathode. Compressible carbon based cathodes and novel nickel based cathodes were fabricated. For each cathode, pore volume and void volume were quantified and void fraction was calculated, compression under 0 to 2MPa was measured, and lithium-sulfur cells were assembled and cycled at pressures between 0 and 1MPa. The cathodes studied had void fractions in the range of 0.45 to 0.90. Specific discharge capacities between 200 and 1100 mAh/g under 1MPa were observed in carbon-based cathodes. Nickel-based cathodes showed increased specific discharge capacity of up to 1300 mAh/g, with no degradation of performance under pressure. The high correlation of specific discharge capacity and void fraction, in conjunction with previous work, strongly suggest that the performance of lithium-sulfur cathodes is highly dependent on properties that influence ionic mass transport in the cathode.