Computational Study of the Mechanisms of Superoxide-Induced Decomposition of Organic Carbonate-Based Electrolytes

Bryantsev, Vyacheslav S.; Blanco, Mario

doi:10.1021/jz1016526

Cited by 186 publications

(200 citation statements)

References 36 publications

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“…For example, the carbonate based solvents, commonly used in Li-ion batteries, 13 were not appropriate for Li-O 2 batteries because of their susceptibility to nucleophilic attack by reduced O 2 − species. 10,[14][15][16][17] Li-O 2 batteries usually consist of a lithium foil anode, a lithium salt dissolved in an organic solvent as electrolyte and a porous carbonbased cathode. During the discharge metallic lithium anode releases lithium ions (Li + ) to the electrolyte, while electrons are transported to the cathode through an external circuit.…”

mentioning

confidence: 99%

Monitoring the Location of Cathode-Reactions in Li-O₂Batteries

Landa‐Medrano

Pinedo

Larramendi

et al. 2015

J. Electrochem. Soc.

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The performance of Li-O 2 batteries is typically evaluated by specific capacity and cyclability in order to facilitate quantitative comparison in literature. The accuracy of such comparison is limited, however, due to the wide range of factors which control the reported specific capacities. These comparisons are not always fair as some factors, which can highly influence the obtained specific capacities, are often neglected. A rigorous and systematic study has been conducted in order to identify the isolated effect of diverse parameters on the performance of these promising batteries. The analysis of cells with different carbon contents reveals that the discharge reactions do not necessarily take place throughout the electrode mass, but instead occur preferentially in closest proximity to the oxygen gas-electrolyte interface. The effective activity of the cathode material is therefore reduced as distance from this interface increases. This work demonstrates that the lack of standardized measurement protocols hinders the rapid development of this technology due to the difficulties inherent in the direct comparison of cells with wide-ranging measurement conditions. In addition, it has been demonstrated that both the employed carbon loading and current rate critically affect cycling lifetime. Lithium-oxygen (Li-O 2 ) rechargeable batteries with organic electrolytes have recently received extraordinary attention due to their potential to provide high gravimetric energies (∼3500 Wh/kg based on the cell reaction, 2Li + O 2 ↔ Li 2 O 2 ; 2.96 V vs Li/Li + ). 1 Consequently, these batteries are considered one of the most promising candidates for high energy storage devices such as electric vehicles (EVs) or hybrid electric vehicles (HEVs), which have become of special interest due to the fossil fuel depletion and the demand of a cheaper, nontoxic and environmentally friendly energetic model. This technology is still however in its early stages and some challenges need to be overcome in order to make them commercially available.2-12 Although existing lithium-ion technology was initially adopted in order to start investigating these relatively new batteries, numerous problems reveal that this is not always suitable. For example, the carbonate based solvents, commonly used in Li-ion batteries, 13 were not appropriate for Li-O 2 batteries because of their susceptibility to nucleophilic attack by reduced O 2 − species.10,14-17Li-O 2 batteries usually consist of a lithium foil anode, a lithium salt dissolved in an organic solvent as electrolyte and a porous carbonbased cathode. During the discharge metallic lithium anode releases lithium ions (Li + ) to the electrolyte, while electrons are transported to the cathode through an external circuit.Meanwhile, oxygen molecules are reduced (oxygen reduction reaction, (ORR)) at the cathode.18 The global reaction taking place in the battery is:Solubility and diffusion rate of oxygen in the electrolyte play key roles in determining battery performance. 21,22 Zhang et al. proposed a liqu...

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mentioning

confidence: 99%

Monitoring the Location of Cathode-Reactions in Li-O₂Batteries

Landa‐Medrano

Pinedo

Larramendi

et al. 2015

J. Electrochem. Soc.

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“…For both cases, the specific capacities are much smaller than those of nanostructured electrodes due to the reduction of surface area. Figure 6b shows the plateau discharge voltage as a function of nanostructure spacing of S = 4, 8,12,16,20,26,30, and 36 nm, where the discharge voltage monotonically increases from 2.636 V for S = 4 nm to 2.647 V for S = 36 nm. The results also show two different slopes for the plateau cell voltage versus nanostructure spacing curve.…”

Section: Resultsmentioning

confidence: 99%

“…However, the relatively new Li-air battery still underperforms in several key factors when compared to the more established Li-ion battery, such as low round trip efficiency (70% 9,12 vs. >95% 13 ), low drawing current density (0.1-1.0 mA cm −28,14 vs. 30 mA cm −214 ) and poor cycle life (∼100 15,16 vs. 5000 17 ). The source of these problems can be traced to a number of key issues, including the electric insulation of the reaction products, [18][19][20][21][22] parasitic irreversible side reactions, [23][24][25][26] electrolyte instability, 12,23,24 and electrode degradation. 12,27 These shortcomings must be overcome in order for the Li-air battery to become viable.…”

mentioning

confidence: 99%

Pore-Scale Transport Resolved Model Incorporating Cathode Microstructure and Peroxide Growth in Lithium-Air Batteries

Andersen

Qiu

et al. 2015

J. Electrochem. Soc.

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The electrode microstructure plays an integral role in the performance of the non-aqueous Li-air battery. Computational modeling has proven to be an indispensible tool in the analysis of battery systems, but previous macroscale, volume-averaged models that consider the porous electrode as a homogenous medium of uniform geometric properties are insufficient to probe the effect of precise electrode microstructures. Utilizing a pore-scale transport-resolved model of the Li-air battery, the complex electrode and Li 2 O 2 morphologies can be directly incorporated and their effects on the system-level performance can be evaluated. A thickness-dependent electrical conductivity of Li 2 O 2 is considered in the model based on inputs from the density functional theory. Model validation is presented along with a sensitivity study of the applied current density and the reaction rate coefficient. The effect of electrode geometry (e.g., nanostructure spacing and height) on cell performance, including its influence on pore blocking compared against electrical insulation, is investigated. Pore blocking is observed for cathodes with nanostructure spacing less than twice a critical insulating thickness of Li 2 O 2 , suggesting the loss of active surface area as the mechanism for decreased cell performance. While for cathodes with larger nanostructure spacing, the discharge capacity is dictated by the electrical insulation of Developing a battery with the energy density of fossil fuel has been an elusive goal that will likely usher in the widespread implementation of high-energy storage applications, such as electrified transportation 1 . Current Li-ion batteries (100 -480 Wh kg −1 practical 2-4 ) have only 5-28% of the specific energy of gasoline (1700 Wh kg −1 practical 5 ); in order to drive 300 miles, an electric car would need a 500 kg Liion battery.4 Alternatively, the non-aqueous Li-air (or more precisely Li-oxygen) batteries (1800 -2700 Wh kg −1 practical 6-10 ) have up to 5 times the energy density of Li-ion batteries, putting them well within the range of gasoline 1 . Several factors contribute to the high energy density of Li-air battery: (i) there is no heavy transition metal in the cell, 11 (ii) lithium is the lightest and most electronegative anode metal, and (iii) the gaseous reactant O 2 is not contained within the cell but instead can be drawn from the surroundings. However, the relatively new Li-air battery still underperforms in several key factors when compared to the more established Li-ion battery, such as low round trip efficiency (70% 9,12 vs. >95% 13 ), low drawing current density (0.1-1.0 mA cm −28,14 vs. 30 mA cm −214 ) and poor cycle life (∼100 15,16 vs. 5000 17 ). The source of these problems can be traced to a number of key issues, including the electric insulation of the reaction products, [18][19][20][21][22] parasitic irreversible side reactions, 23-26 electrolyte instability, 12,23,24 and electrode degradation. 12,27 These shortcomings must be overcome in order for the Li-air battery to become via...

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“…It was found that PC is susceptible to the attack of superoxide radical (O 2 − ) based on Density Functional theory (DFT) study and coupled-cluster calculations by Bryantsev and Blanco as shown in Fig. 10.3 [ 45 ]. Subsequent reactions lead to decomposition to form carbonate species as discharge products.…”

Section: Organic Carbonate Solvents: Lessons Learnedmentioning

confidence: 99%

Aprotic Electrolytes in Li–Air Batteries

Lau

Assary

Curtiss

2014

Modern Aspects of Electrochemistry

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Compared to Li-ion batteries, the Li-air battery is a relatively new concept and much of its problems remain to be solved. One of the key problems is the stability of the electrolytes, which is the subject of this chapter in which we review experimental and computational studies on this subject. The electrolyte stability is of concern during both charge and discharge at both the cathode and anode. In addition to electrochemical reactions, there can also be chemical reactions on the surfaces not directly involving electron transfer. Most experimental and computational studies so far have focused on the stability of solvents during charge and discharge at the cathode. Although there is strong evidence that the carbonates are decomposing at the cathode to form solid products such as Li 2 CO 3 , it is still not yet completely clear how the reduced O 2 species are directly related to the decomposition mechanism. Recent experimental and computational work has focused on the stability of etherbased electrolytes. Ether-based electrolytes have been found to have increased stability for oxygen reduction products during discharge as most studies do not see evidence for solid decomposition products. However, ethers still have stability issues arising from other decomposition mechanisms such as oxidation during charge and chemical decomposition on the lithium oxide surfaces. In addition, decomposition reactions may occur at the anode, involving an oxygen crossover effect. Meanwhile, independent of whether the solvent decomposition reaction proceeds via O 2 2− , LiO 2 , or another Li-air reactive species, it is now clear that a solvent that is resistant to attack by reduced O 2 species must be discovered in order to achieve a practical Li-air cell with a long cycle life. Besides the problems of solvent electrochemical stability, the electrochemical selectivity also has to be resolved.

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Computational Study of the Mechanisms of Superoxide-Induced Decomposition of Organic Carbonate-Based Electrolytes

Cited by 186 publications

References 36 publications

Monitoring the Location of Cathode-Reactions in Li-O₂Batteries

Monitoring the Location of Cathode-Reactions in Li-O₂Batteries

Pore-Scale Transport Resolved Model Incorporating Cathode Microstructure and Peroxide Growth in Lithium-Air Batteries

Aprotic Electrolytes in Li–Air Batteries

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Computational Study of the Mechanisms of Superoxide-Induced Decomposition of Organic Carbonate-Based Electrolytes

Cited by 186 publications

References 36 publications

Monitoring the Location of Cathode-Reactions in Li-O2Batteries

Monitoring the Location of Cathode-Reactions in Li-O2Batteries

Pore-Scale Transport Resolved Model Incorporating Cathode Microstructure and Peroxide Growth in Lithium-Air Batteries

Aprotic Electrolytes in Li–Air Batteries

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Product

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Monitoring the Location of Cathode-Reactions in Li-O₂Batteries

Monitoring the Location of Cathode-Reactions in Li-O₂Batteries