Continuous Shuttle Current Measurement Method for Lithium Sulfur Cells

Abstract

Lithium Sulfur (Li-S) batteries are a promising energy storage technology with very high theoretical limits in terms of specific capacity and specific energy. However, these batteries suffer from high self-discharge rates, associated with a low coulombic efficiency due to the polysulfide shuttle mechanism. A better understanding of the self-discharge characteristics and suppression of the self-discharge is of great interest for most applications. Hence, a continuous self-discharge current measurement method is applied to evaluate the self-discharge behavior of a Li-S battery, based on a corrected reference open-circuit voltage. The result is a continuous self-discharge current measurement method, that investigates the self-discharge in the upper plateau of a Li-S battery at 10 °C and 25 °C. This self-discharge current displays a plateau and extended balancing times directly before this plateau and is validated by a discrete self-discharge current measurement method at 10 °C and 25 °C. Furthermore, the activation energy is continuously calculated for the upper plateau and compared to a discrete reference measurement.

Investigation on Cycling and Calendar Aging Processes of 3.4 Ah Lithium-Sulfur Pouch Cells

“…These results are in agreement with Refs. [44,47]. Chien and et al [48] have justified these observations, reporting that the crystalline sulfur species formation and disappearance were correlated directly with the internal resistance trend and diffusion resistance coefficient.…”

“…However, in the case of the 10% SOC, the curves are slightly different and do not overlap. On this subject, it was previously proven that in SOC levels above 75%, the elemental sulfur is reduced to polysulfides and forms the long-chain polysulfides (Li 2 S x , 4 ≤ x ≤ 8), which are soluble in the organic electrolyte) [44][45][46]. However, for SOCs less than 75%, the long-chain polysulfides undergo further reductions into short-chain polysulfide form (Li 2 S and Li 2 S 2 , which are insoluble in the organic electrolyte).…”

Recent Progress and Emerging Application Areas for Lithium–Sulfur Battery Technology

“…A continuous shuttle current measurement method for lithium–sulfur cells was developed by TU Munich in collaboration with Daimler AG in 2020. [ 107 ] A simple analytical model of capacity fading for lithium–sulfur cells was published by Brno University of Technology in collaboration with OXIS Energy. [ 108 ] A 3D image‐based modeling of transport parameters in lithium–sulfur batteries was conducted by UCL.…”

A review on theoretical models for lithium–sulfur battery cathodes

“…[19][20][21][22] However, there remain several drawbacks for Li-S batteries especially for the cathode, which severely hinders their practical applications. 23,24 Specifically, the low electrical conductivity of sulfur (10 À7 to 10 À30 S cm À1 at room temperature) and the insulating nature of sulfur as well as its discharge products (Li 2 S or Li 2 S 2 ) render it deficient to be directly applied as the cathode. 25 Volume expansion of the electrode ($80%) is also an imperative issue originating from the different volumetric densities of S 8 and Li 2 S. 17 More seriously, the notorious "polysulfide shuttle effect" not only induces a self-discharge but also corrodes lithium metal anodes and consequently causes rapid capacity degradation.…”

“…More importantly, the cathode materials, elemental sulfur, afford profitable features like natural abundance, environmental friendliness, and low cost 19–22 . However, there remain several drawbacks for Li–S batteries especially for the cathode, which severely hinders their practical applications 23,24 . Specifically, the low electrical conductivity of sulfur (10 −7 to 10 −30 S cm −1 at room temperature) and the insulating nature of sulfur as well as its discharge products (Li 2 S or Li 2 S 2 ) render it deficient to be directly applied as the cathode 25 .…”