Implications of 4 e<sup>–</sup> Oxygen Reduction via Iodide Redox Mediation in Li–O<sub>2</sub> Batteries

Burke, Colin M.; Black, Robert W.; Kochetkov, Ivan; Giordani, Vincent; Addison, Dan; Nazar, Linda F.; McCloskey, Bryan D.

doi:10.1021/acsenergylett.6b00328

Cited by 151 publications

(232 citation statements)

References 41 publications

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“…25 If this decomposition mechanism results in oxygen evolution, it would make a new reversible mechanism for the Li–O 2 battery, which is currently under debate as it has been proposed to be thermodynamically unfavorable 26 and it has been suggested that I – is oxidized rather than LiOH. 27 Burke et al 28 have recently reported that the LiOH crystallite was formed by a four-electron reduction process with the addition of LiI and H 2 O in the DME electrolyte upon discharge; however, the decomposition of the LiOH crystallite was primarily attributed to iodo–oxygen electrochemistry rather than reversible oxygen evolution.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction

Ganapathy

et al. 2017

Chem. Mater.

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The lithium air, or Li–O2, battery system is a promising electrochemical energy storage system because of its very high theoretical specific energy, as required by automotive applications. Fundamental research has resulted in much progress in mitigating detrimental (electro)chemical processes; however, the detailed structural evolution of the crystalline Li2O2 and LiOH discharge products, held at least partially responsible for the limited reversibility and poor rate performance, is hard to measure operando under realistic electrochemical conditions. This study uses Rietveld refinement of operando X-ray diffraction data during a complete discharge–charge cycle to reveal the detailed structural evolution of Li2O2 and LiOH crystallites in 1,2-dimethoxyethane (DME) and DME/LiI electrolytes, respectively. The anisotropic broadened reflections confirm and quantify the platelet crystallite shape of Li2O2 and LiOH and show how the average crystallite shape evolves during discharge and charge. Li2O2 is shown to form via a nucleation and growth mechanism, whereas the decomposition appears to start at the smallest Li2O2 crystallite sizes because of their larger exposed surface. In the presence of LiI, platelet LiOH crystallites are formed by a particle-by-particle nucleation and growth process, and at the end of discharge, H2O depletion is suggested to result in substoichiometric Li(OH)1–x, which appears to be preferentially decomposed during charging. Operando X-ray diffraction proves the cyclic formation and decomposition of the LiOH crystallites in the presence of LiI over multiple cycles, and the structural evolution provides key information for understanding and improving these highly relevant electrochemical systems.

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Section: Introductionmentioning

confidence: 99%

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction

Ganapathy

et al. 2017

Chem. Mater.

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“…For this purpose, some mediators such as LiI and LiBr have recently been applied to glymebased electrolytes to promote Li 2 O 2 oxidation at the air electrode. [13][14][15][16] Meanwhile, to suppress Li dendrite growth at the Li metal negative electrode (NE), a new inorganic Li salt, i.e., LiNO 3 , has been applied to glyme-based electrolytes to stabilize the surface by oxidation.…”

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confidence: 99%

Factors influencing fast ion transport in glyme-based electrolytes for rechargeable lithium–air batteries

et al. 2017

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To elucidate the determination factors affecting Li-ion transport in glyme-based electrolytes, six kinds of 1.0 M tetraglyme (G4) electrolytes were prepared containing a Li salt (LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , or LiN(SO 2 F) 2 ) or different concentrations (0.5, 2.0, or 2.7 M) of LiN(SO 2 CF 3 ) 2 . In addition to conventional bulk parameters such as ionic conductivity (s), viscosity (h), and density, self-diffusion coefficients of Li + , anions, and G4 were measured by pulsed-gradient spin-echo nuclear magnetic resonance method.Interaction energies (DE) were determined by density functional theory calculations based on the supermolecule method for Li + -anion (salt dissociation) and G4-Li + (Li + solvation) interactions. The DE values corresponded to ion diffusion radii formed by solvation and/or ion pairs. The order of dissociation energies DE was LiSO 3 CF 3 > LiN(SO 2 CF 3 ) 2 > LiN(SO 2 F) 2 , which agreed well with the dissociation degree of these salts in the electrolytes. From the obtained knowledge, we also demonstrated that increasing the mobility and number of carrier ions are effective ways to enhance s of glyme-based electrolytes by using 1,2-dimethoxyethane with lower h and similar dielectric constant to those of G4.

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“…In addition, sustainable charge redox mediators could accelerate the decomposition of insulating products by moving into the cathode electrode and facilitating the transport of electrons between the insulating products and the cathode electrode during charging. Many charge redox mediators have been reported, such as lithium iodide (LiI), [151,152] lithium bromide (LiBr), [148,153] tetrathiafulvalene (TTF), [82] tris [4-(diethylamino)phenyl]amine (TDPA), [154] 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), [155,156] phthalocyanine (FePc), [157] and heme molecules. [158] Taking the iodide (I -) ion as an example, it could be oxidized to I 3 − or I 2 on the surface of the electrode during charging and then react with Li 2 O 2 to form Li + and O 2 gas with the regeneration of I − ions.…”

Section: Charge Redox Mediatormentioning

confidence: 99%

Review of Electrolytes in Nonaqueous Lithium–Oxygen Batteries

Guo

Luo

Chen

et al. 2018

Advanced Sustainable Systems

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Based on an inexhaustible and ubiquitous source of oxygen, the lithium-oxygen batteries are currently the subject of much scientific investigation because of their potential for extremely high energy density. The electrocatalytic materials for them have been extensively researched during the past decade. Even though they are a key component in the lithium-oxygen batteries, however, the study of electrolytes is still in its primary stage. Electrolytes have an important influence on the electrochemical performance of lithium-oxygen batteries, especially on their cycling stability and rate capacity. Therefore, it is important to select an ideal electrolyte with excellent stability against attack by reaction intermediates, along with excellent oxygen solubility and diffusivity. In this review, the physicochemical and electrochemical properties of organic electrolytes for lithium-oxygen batteries are discussed and compared. Furthermore, possible research directions are proposed for the development of an ideal electrolyte for enhanced electrochemical performance. Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsGuo, H., Luo, W., Chen, J., Chou, S., Liu, H. & Wang, J. (2018 Figure 1. Unlike the intercalation mechanism of lithium-ion batteries or sodium-ion batteries, the Li-O 2 battery systems employ a dissolution/ deposition reaction with an air electrode that uses oxygen as the cathode electrode during the electrochemical processes. Research on the Li-O 2 battery is complicated by the need for exposure the air cathode to O 2 atmosphere.Many advances have been achieved, which include advances on cathode materials, electrolytes, anode materials, and redox mediators. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Several excellent reviews have been published to summarize recent developments and our current understanding of Li-O 2 batteries, especially with respect to the cathode electrocatalytic materials. [25][26][27][28][29][30][31][32][33][34][35] These reviews have comprehensively discussed the relationship between the structure of electrocatalytic materials and the electrochemical performance of Li-O 2 batteries. There are, however, few reviews focused on the effects of different electrolytes on the electrochemical performance of the Li-O 2 batteries. [36][37][38] For the aqueous Li-O 2 batteries, LiOH is generated or oxidized at the cathode during discharge and charge processes because H 2 O and O 2 are involved in the reactions. In the case of the nonaqueous Li-O 2 batteries, there are two essential processes that determine their electrochemical performance: the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). During the ORR process, the Li 2 O 2 is precipitated as the final discharge product on the air cathode, while during the OER process, Li 2 O 2 is then decomposed and the O 2 is regenerated. Therefore, there are huge differences between aqueous and nonaqueous Li-O 2 batteries. Since the nonaqueous Li-O 2 batteries have dominated ...

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Implications of 4 e^– Oxygen Reduction via Iodide Redox Mediation in Li–O₂ Batteries

Cited by 151 publications

References 41 publications

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction

Factors influencing fast ion transport in glyme-based electrolytes for rechargeable lithium–air batteries

Review of Electrolytes in Nonaqueous Lithium–Oxygen Batteries

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Implications of 4 e– Oxygen Reduction via Iodide Redox Mediation in Li–O2 Batteries

Cited by 151 publications

References 41 publications

Understanding the Electrochemical Formation and Decomposition of Li2O2 and LiOH with Operando X-ray Diffraction

Understanding the Electrochemical Formation and Decomposition of Li2O2 and LiOH with Operando X-ray Diffraction

Factors influencing fast ion transport in glyme-based electrolytes for rechargeable lithium–air batteries

Review of Electrolytes in Nonaqueous Lithium–Oxygen Batteries

Contact Info

Product

Resources

About

Implications of 4 e^– Oxygen Reduction via Iodide Redox Mediation in Li–O₂ Batteries

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction

Understanding the Electrochemical Formation and Decomposition of Li₂O₂ and LiOH with Operando X-ray Diffraction