Investigation of the Self-Discharge Behavior of Lithium-Sulfur Batteries

Knap, Václav; Stroe, Daniel‐Ioan; Świerczyński, Maciej; Teodorescu, Remus; Schaltz, Erik

doi:10.1149/2.0641606jes

Cited by 88 publications

(104 citation statements)

References 12 publications

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“…This result is according to what was reported in Ref. 7 where the Li-S cell's self-discharge becomes more intense as SoC increases. The results also demonstrate that there is a breakpoint at a certain SoC value at which the effect of self-discharge becomes negligible and the trend continues after that.…”

Section: Li-s Cell Self-discharge Modellingsupporting

confidence: 92%

Self-Discharge Effects in Lithium-Sulfur Equivalent Circuit Networks for State Estimation

Yousif

Fotouhi

Auger

et al. 2017

J. Electrochem. Soc.

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This study considers application-oriented models of lithium-sulfur (Li-S) cells. Existing ECN models often neglect self-discharge, but this can be important in applications. After describing the context in which control-oriented models and estimators are based, the self-discharge phenomenon is investigated for a new 21 Ah Li-S cell. As a contribution of this study, an equivalent-circuit-network (ECN) model was extended to account for cells' self-discharge. Formal system identification techniques were used to parameterize a model from experimental data. The original model was then extended by adding terms to represent a self-discharge resistance. To obtain the self-discharge resistance, a particular new series of experiments were designed and performed on the Li-S cell at various temperature and initial state-of-charge (SoC) levels. The results demonstrate the dependency of self-discharge rate on the SoC and temperature. The self-discharge rate is much higher at high SoC levels and it increases as temperature decreases. Much of today's research into lithium-sulfur (Li-S) batteries concerns the development and understanding of materials, construction and the fundamental scientific understanding of cell behavior. Many will recognize the importance of this, but lithium-sulfur is beginning to reach maturity, and there is a need to develop the engineering science and techniques necessary for deployment in practical applications. In particular, there is a need to devise algorithms that can be used to estimate state-of-charge and state-of-health measures in operando. Electrochemistry is of course key here, but it is equally vital to draw from other disciplines: in particular, control theory has much to offer, particularly in respect of state estimation.When electrochemists create models, they usually do so 'as scientists': the aim of a scientific model is to enhance understanding. Of course, no model is perfect, and the pure scientist uses model imperfections to identify gaps in present knowledge and as the inspiration for further research. The aim is to improve understanding and get a 'better model'. However, at some point, cells may be put to practical use, and at this point, the application engineer will often have to make do with the best models available at that time, despite the model's imperfections.Control systems engineers are well accustomed to dealing with model errors and 'uncertainty': there are many excellent text books on control, and any of them will give a short overview of the key principles of control; Aström and Murray's work 1 is a good example. Typically, a dynamic system is modelled as a set of dynamic equations: x, u, w) [1]where u and y represent observed system input and outputs (voltages, currents and temperatures, for example), x comprehensively accounts for past history by representing the system's non-or partlymeasurable dynamic 'states' (perhaps including state of charge in a simple model, or concentrations of chemical species in a complex one), h(·) and f (·) are known functions describ...

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Section: Li-s Cell Self-discharge Modellingsupporting

confidence: 92%

Self-Discharge Effects in Lithium-Sulfur Equivalent Circuit Networks for State Estimation

Yousif

Fotouhi

Auger

et al. 2017

J. Electrochem. Soc.

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“…Thus, the Co-N x @NPC/G-PP separator has strong ability to suppress shuttle effect of polysulfides, which is further reflected by self-discharge behaviors. [43,46,47] As shown in Figure 4d, after these cells are kept at room temperature for 150 h, the stabilized voltage of Co-N x @NPC/G-PP cell is maintained at 2.36 V, which is higher than that of GO-PP (2.24 V) and PP (2.15 V). As a result, the Co-N x @NPC/G-PP cell exhibits low self-discharge effect, the capacity retention is 92.9% after rest for 200 h, which is higher than those in GO-PP (86.8%) and PP (78.6%) ( Figure S21, Supporting Information).…”

Section: Resultsmentioning

confidence: 92%

Separator Modified by Cobalt‐Embedded Carbon Nanosheets Enabling Chemisorption and Catalytic Effects of Polysulfides for High‐Energy‐Density Lithium‐Sulfur Batteries

Cheng

Pan

Chen

et al. 2019

Advanced Energy Materials

174

109

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Lithium‐sulfur (Li‐S) batteries are considered to be one of the promising next‐generation energy storage systems. Considerable progress has been achieved in sulfur composite cathodes, but high cycling stability and discharging capacity at the expense of volumetric capacity have offset their advantages. Herein, a functional separator is presented by coating cobalt‐embedded nitrogen‐doped porous carbon nanosheets and graphene on one surface of a commercial polypropylene separator. The coating layer not only suppresses the polysulfide shuttle effect through chemical affinity, but also functions as an electrocatalyst to propel catalytic conversion of intercepted polysulfides. The slurry‐bladed carbon nanotubes/sulfur cathode with 90 wt% sulfur deliver high reversible capacity of 1103 mA h g−1 and volumetric capacity of 1062 mA h cm−3 at 0.2 C, and the freestanding carbon nanofibers/sulfur cathode provides a high discharging capacity of 1190 mA h g−1 and volumetric capacity of 1136 mA h cm−3 at high sulfur content of 78 wt% and sulfur loading of 10.5 mg cm−2. The electrochemical performance is comparable with or even superior to those in the state‐of‐the‐art carbon‐based sulfur cathodes. The separator reported in this work holds great promise for the development of high‐energy‐density Li‐S batteries.

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“…S1, † the dissolving free energies of PhS n Li (1 # n # 13) are almost above those of Li 2 S n (n ¼ 4, 6,8) which result in shuttle effect. Therefore, the solubilities of PhS n Li (1 # n # 13) are lower and the shuttle effect causes by PhS n Li is much weaker than that by Li 2 S n (n ¼ 4, 6,8). We take it that the excellent stability of longchain PhS n Li and the dissociation positions of S-S bonds jointly contribute to such a result.…”

Section: The Discharge Lithiation Process Of Phs N Ph Cathodesmentioning

confidence: 99%

“…The discharge order of PhS 10 Ph is shown in Table 2. In the rst step, PhS 10 Ph is reduced to PhS 2 Li and PhS 8 Li at 2.68 V. As the discharge depth increases, PhS 8 Li is reduced to PhS 6 Li, PhS 4 Li and PhS 2 Li in sequence with voltages of 2.52 V, 2.46 V In the whole discharge process, there is no Li 2 S 4 , Li 2 S 6 , Li 2 S 8 . To compare the dissolution of PhS n Li and Li 2 S n (n ¼ 4, 6,8) in the DOL/DME solvent, the dissolving free energies 37 of them with the solvent effect of DOL/DME (1 : 1, v/v) are calculated.…”

Section: The Discharge Lithiation Process Of Phs N Ph Cathodesmentioning

confidence: 99%

Diphenyl polysulfides: cathodes with excellent lithiation performance and high specific energy for LSBs

Wang

et al. 2019

RSC Adv.

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Reversible lithium-sulfur batteries (LSBs) are considered one of the most promising next-generation energy storage systems. However, the shuttling effect of lithium polysulfide significantly weakens the electrochemical properties and the cycle life, hindering its practical application. Organo-sulfides are unique materials with low cost, profuse content and high capacity. Here, via quantum chemical calculations, we introduce a class of diphenyl polysulfides, PhS n Ph (2 # n # 15), which are all structurally stable, confirmed by calculation of their Gibbs free energies. The theoretical specific energy of PhS 15 Ph is high, up to 2632 W h kg À1 , exceeding that of S 8 . By calculating the bond dissociation energy of S-S in PhS n Ph molecules, we analyze the breaking processes of the S-S bonds in each step of lithiation. The microscopic mechanism of the fast reaction kinetics of PhS n Ph cathodes is explored. It is phenyl that prevents the formation of soluble long-chain polysulfide molecules (Li 2 S 4 , Li 2 S 6 , Li 2 S 8 ) in the lithiation process, efficiently weakening the "shuttle effect".

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Investigation of the Self-Discharge Behavior of Lithium-Sulfur Batteries

Cited by 88 publications

References 12 publications

Self-Discharge Effects in Lithium-Sulfur Equivalent Circuit Networks for State Estimation

Self-Discharge Effects in Lithium-Sulfur Equivalent Circuit Networks for State Estimation

Separator Modified by Cobalt‐Embedded Carbon Nanosheets Enabling Chemisorption and Catalytic Effects of Polysulfides for High‐Energy‐Density Lithium‐Sulfur Batteries

Diphenyl polysulfides: cathodes with excellent lithiation performance and high specific energy for LSBs

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