Revisiting the Role of Polysulfides in Lithium–Sulfur Batteries

Li, Gaoran; Wang, Shun; Zhang, Yining; Li, Matthew; Chen, Zhongwei; Lü, Jun

doi:10.1002/adma.201705590

Cited by 511 publications

(400 citation statements)

References 173 publications

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“…The actual discharge products and energy conversion in each step are different between Li-S and Na-S, as shown in Figure 1B,C. [23][24][25] The Na + with a larger ionic radius than Li + can induce a more sluggish reaction. In comparison, although Na-S follows the similar conversion of solid→liquid→solid process, the lower-order intermediates (Na 2 S m , m ≤ 4) is formed at deep discharge (<1.65 V), which induces an increased resistance and prevents the further discharge process to fully release the theoretical capacity of sulfur electrode (1675 mAh g −1 ).…”

Section: Principles and Challenges Of Sulfur Cathodesmentioning

confidence: 99%

Rational Design of Binders for Stable Li‐S and Na‐S Batteries

Guo

Zheng

2019

Adv Funct Materials

133

111

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Binders play a critical role in stabilizing the sulfur cathode of Li-S and Na-S batteries. Over the past decade, the design of binder molecules has gone through tremendous evolution from primarily maintaining the structural integrity of the electrode against volume change to rationally immobilizing polysulfide intermediate and facilitating electron/ion transport in the charge and discharge process. This article reviews the development of binder for Li-S and Na-S batteries from the perspective of molecular design, and comprehensively discusses the correlation between the functions of the binder molecules and the cell performance. It also points out the future challenge and the potential solutions to address them. Figure 2. Timeline of the development of binders in terms of specific functions in Li-S and Na-S batteries. The binder in Li-S batteries has experienced a remarkable evolution in terms of functions, from fundamental structural and mechanical stabilizer (linear, hybrid, [30] dendrimer, [31] and crossedlinked binder [32,33] ) to versatile functions of polysulfide immobilization (polymer with functional groups [34][35][36] or cation groups [37] ) and facilitation of electron transport on the basis of conductive polymer. [38,39] It opens up the research of multifunctional binder. The analogous development route in the binder is found in Na-S batteries. [40,41] Reproduced with permission. [30]

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Section: Principles and Challenges Of Sulfur Cathodesmentioning

confidence: 99%

Rational Design of Binders for Stable Li‐S and Na‐S Batteries

Guo

Zheng

2019

Adv Funct Materials

133

111

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“…Li–S batteries have to overcome a pronounced initial energy barrier for the charge process due to limited conductive surface availability and low LiPS concentration that acts as a self‐mediator to promote Li 2 S 1/2 dissolution . Driven conversion from solid Li 2 S 1/2 to liquid LiPSs can also be boosted by Co‐N‐C electrocatalysts, evidenced by occurrence of current hump in the potentiostatic charge process at 2.30 V (Figure D).…”

Section: Introductionmentioning

confidence: 99%

Expediting redox kinetics of sulfur species by atomic‐scale electrocatalysts in lithium–sulfur batteries

Kong

Chang-xin

et al. 2019

InfoMat

282

170

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Lithium–sulfur (Li–S) batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications. Expediting redox kinetics of sulfur species is a decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution. Herein, we proposed a porphyrin‐derived atomic electrocatalyst to exert atomic‐efficient electrocatalytic effects on polysulfide intermediates. Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst. Benefiting from atomically dispersed “lithiophilic” and “sulfiphilic” sites on conductive substrates, the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity (cyclic decay rate of 0.10% in 300 cycles), excellent rate capability (1035 mAh g−1 at 2 C), and impressive areal capacity (10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2). The present work expands atomic electrocatalysts to the Li–S chemistry, deepens kinetic understanding of sulfur species evolution, and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.

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“…

The presence of electrocatalysis in lithium-sulfur batteries has been proposed but not yet sufficiently verified. [2] Thec apacity decay is tightly associated with the dissolution and diffusion of lithium polysulfide (LPS) intermediates in the electrolyte,w hich on the one hand facilitates the kinetics of electrochemical conversion [3] but on the other hand causes loss of active material and side reactions. As aresult, sulfur electrodes containing MoP nanoparticles show faster kinetics and more reversible conversion of sulfur species, leading to improvements in charging/discharging voltage profiles,c apacity,r ate performance,a nd cycling stability.

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mentioning

confidence: 99%

Electrocatalysis in Lithium Sulfur Batteries under Lean Electrolyte Conditions

et al. 2018

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The presence of electrocatalysis in lithium-sulfur batteries has been proposed but not yet sufficiently verified. In this study,m olybdenum phosphide (MoP) nanoparticles are shown to play ad efinitive electrocatalytic role for the sulfur cathode working under lean electrolyte conditions featuring alow electrolyte/active material ratio:the overpotentials for the charging and discharging reactions are greatly decreased. As aresult, sulfur electrodes containing MoP nanoparticles show faster kinetics and more reversible conversion of sulfur species, leading to improvements in charging/discharging voltage profiles,c apacity,r ate performance,a nd cycling stability. Taking advantage of the electrocatalytic properties of MoP, high-performance sulfur electrodes were successfully realized that are steadily cyclable at ah igh areal capacity of 5.0 mAh cm À2 with ac hallenging electrolyte/sulfur (E/S) ratio of 4 mL E mg À1 S .Lithium sulfur batteries (LSBs) have as uperior theoretical specific energy of 2600 Wh kg À1 ,b ut an unsatisfactory cycle life. [1] Thecathode material of LSBs,namely sulfur,islimited in cycling stability,d espite its high theoretical specific capacity of 1675 mAh g À1 . [2] Thec apacity decay is tightly associated with the dissolution and diffusion of lithium polysulfide (LPS) intermediates in the electrolyte,w hich on the one hand facilitates the kinetics of electrochemical conversion [3] but on the other hand causes loss of active material and side reactions. [4] Using polar material surfaces, for example,f unctionalized carbons, [5] metal oxides, [6] sulfides, [7] phosphides, [8] nitrides, [9] and metal-organic frameworks, [10] to confine LPS via chemical interactions has been found to be one of the most effective ways for improving the cycling stability of sulfur electrodes.B esides immobilizing LPS on the cathode,i ti sa lso crucial to ensure their rapid electrochemical conversion and thus capacity contribution. Fori nstance,w eh ave recently reported on molybdenum phosphide (MoP) nanoparticles serving an electrocatalystlike function for stabilizing the sulfur cathode. [8b] While the extension of cycle life was significant, electrocatalysis was only preliminarily implied by the larger cyclic voltammetry current on the MoP-modified electrode in aL PS electrolyte. Herein, we report anew observation of akey evidence for the electrocatalytic role played by MoP nanoparticles in LSBs:reduction of overpotential for the charging/discharging reactions of the sulfur cathode,w hich is only obvious under lean electrolyte conditions (that is,w ith al ow electrolyte/ active material ratio). Fora no rdinary sulfur electrode,t he average charging/discharging voltage hysteresis at ac urrent density of 0.8 mA cm À2 increases greatly to 0.43 Vw hen the electrolyte/sulfur (E/S; mL E mg À1 S )ratio is lowered to 6. With MoP nanoparticles incorporated in the electrode structure, the voltage hysteresis is reduced to 0.18 V. MoP effectively catalyzes the electrochemical conversion reactions of sulfur, which helps the...

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Revisiting the Role of Polysulfides in Lithium–Sulfur Batteries

Cited by 511 publications

References 173 publications

Rational Design of Binders for Stable Li‐S and Na‐S Batteries

Rational Design of Binders for Stable Li‐S and Na‐S Batteries

Expediting redox kinetics of sulfur species by atomic‐scale electrocatalysts in lithium–sulfur batteries

Electrocatalysis in Lithium Sulfur Batteries under Lean Electrolyte Conditions

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