such as silicene [9a] and ionic compounds [10a] were shown to speed up the Li 2 S lateral passivation rate, leading to lower capacities.Solvent has a strong impact on Li 2 S deposition. The kinetics and morphology of Li 2 S deposition in glyme-based polysulfide solutions was studied and a progressive nucleation and a 2D island growth model was proposed. [6a] In addition, the use of discharge mediator was reported to slow down the impingement of insulating Li 2 S islands on carbon and transform the 2D growth to a 3D growth. [11] This is in line with Cuisinier et al. [12] reporting a distinct Li 2 S deposition mechanism in electron pair donor electrolytes compared to glymes due to the partial solvation of Li 2 S and the additional chemical pathways provided by the increased stabilization of polysulfide radicals. Recently, Pan et al. [4] reported that solvents with medium donor number (DN) yield flower-like Li 2 S morphology, low-DN solvents make Li 2 S films, and high-DN solvents give rise small particles. These pioneering studies suggest that the solution mediation process plays a critical role in Li 2 S deposition and highlight the urgent need for developing quantitative and comprehensive correlation between solvent property and Li 2 S nucleation and growth.In this work, we establish structure-property relationship of solvent in controlling solid Li 2 S deposition and develop quantitative solvent-mediated Li 2 S growth models as guides to solvent selection. We investigate three solvent's properties and their roles on Li 2 S deposition: (1) the donicity which governs the stability of the polysulfide anions (i.e., the precursor of Li 2 S deposition) through (Li + ) sol -polysulfide interactions; [12,13] (2) the polarity (dielectric constant) which governs the solvation ability of the final product Li 2 S; [14] (3) the viscosity which strongly affects the diffusivity of polysulfide and dissolved Li 2 S. [15] We show that these solvent-controlled properties are essential factors pertaining to the sulfur utilization, electrode kinetics, and reversibility of electrochemical reduction of elemental sulfur. Finally, we demonstrate the effectiveness of the solvent selection criteria developed in this study in identifying new and more effective electrolytes for Li-S batteries. Results and DiscussionWe study Li 2 S deposition in electrolyte model systems of two major groups: (i) ether-based solvents: 1,2-dimethoxyethane (G1), diethylene glycol dimethyl ether (G2), triethylene glycol Controlling electrochemical deposition of lithium sulfide (Li 2 S) is a major challenge in lithium-sulfur batteries as premature Li 2 S passivation leads to low sulfur utilization and low rate capability. In this work, the solvent's roles in controlling solid Li 2 S deposition are revealed, and quantitative solventmediated Li 2 S growth models as guides to solvent selection are developed. It is shown that Li 2 S electrodeposition is controlled by electrode kinetics, Li 2 S solubility, and the diffusion of polysulfide/Li 2 S, which is dictated...
A new concept of exploiting bromide ions as a complexing agent to ‘free-up’ iodide ions for energy storage.
We report direct evidence of soluble LiO 2 generation upon Li 2 O 2 oxidation and reveal a strong solvent-controlled Li 2 O 2-oxidation reaction mechanism in Li-O 2 batteries. In high-donicity solvents, Li 2 O 2 oxidation follows a solution pathway by forming soluble LiO 2 intermediate. While in low-donicity solvent, Li 2 O 2 oxidation follows a solid-solution pathway by forming solid Li 2Àx O 2 intermediate. The preferential formation of soluble LiO 2 promotes the charging kinetics but leads to poor cycling stability. Our work shows that bypassing the generation of soluble LiO 2 will improve the stability of Li-O 2 batteries.
Reversible protonic ceramic electrochemical cells (R-PCECs) are a promising option for efficient and low-cost generation of electricity and hydrogen. Commercialization of R-PCECs, however, hinges on the development of highly active and robust air electrodes. Here, we report an air electrode consisting of PrBa 0.8 Ca 0.2 Co 2 O 5+δ and in situ exsolved BaCoO 3−δ nanoparticles (PBCC−BCO) that shows minimal polarization resistance (∼0.24 Ω cm 2 at 600 °C) and high stability when exposed to humidified air with 3−50% H 2 O. An R-PCEC utilizing PBCC-BCO demonstrates remarkable performances at 600 °C: achieving a peak power density of 1.06 W cm −2 in the fuel cell mode and a current density of 1.51 A cm −2 at 1.3 V in an electrolysis mode. More importantly, the R-PCECs demonstrate an exceptionally high durability over 1833 h of continuous operation in the electrolysis mode. This work offers an efficient approach to design of high-performance and durable electrodes for R-PCECs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.