Investigation of Rechargeable Lithium-Sulfur Batteries By in-Situ Techniques

Abstract

Electrochemical reactionshigh theoretical capacity (1675 Ah kg sulfur -1 ) high energy density (2500 Wh kg -1 ) low cost and non-toxicity of sulfur high degradation due to loss of active material electrochemical processes and degradation mechanisms are still not well understood. Solid reactants Dissolved polysulfides intermediates Solid productDischarge Charge Lithium-sulfur battery Materials and methodsIn-situ XRD cell EIS End Voltages (V): 2.8/1.5 Discharge current: 300 A kg sulfur -1 Results Discharge ChargeVariation of the equivalent circuit elements during cycling determined by EIS analysis.• The highest electrolyte resistance, related to the highest concentration of polysulfides is detected at the end of the first discharge and charge plateau (43 % DOD and 56 % DOC).• The impedance contributions associated to the processes in the cell are strongly dependent on the depth of discharge and charge of the cell [2]. Swagelok-cellPotentiostatic: 5 mV amplitude Equidistant intervals of 50 mC Frequency range: 1 MHz to 60 mHz Discharge Charge • At discharge rate of 300 A kg -1 sulfur reduces consecutively during the first discharge to Li 2 S.• The formation of Li 2 S was observed for the first time at a depth of discharge of 60 % in the second discharge plateau at 1.8 V.• During the charge cycle, Li 2 S reacts entirely and sulfur recrystallizes with a different orientated structure and smaller particle size [1].The AFM results confirm the formation of an isolating layer in the cathode, which increases the surface resistance on the cathode, as observed through the analysis of the impedance at low frequencies (R 3 ).