Insights into Changes in Voltage and Structure of Li<sub>2</sub>FeSiO<sub>4</sub> Polymorphs for Lithium-Ion Batteries

Eames, C.; Armstrong, A. Robert; Bruce, Peter G.; Islam, M. Saïful

doi:10.1021/cm300749w

Cited by 133 publications

(141 citation statements)

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“…36), were obtained between the first and second discharge cycles which would indicate that no major structural change occurred following the initial charge. Such changes are a dominant feature of Li2FeSiO4 electrodes, where stable cycling is only achieved after cation rearrangement to a stable phase and have been outlined in various reports [498,500]. XRD studies of cycled cells revealed that structural change occurred after the first charge cycle leading to the formation of a new, seemingly metastable phase.…”

Section: Transition Metal Silicates (Li2msio4)mentioning

confidence: 82%

“…Fe, Mn or Co have typically been utilised, with more attention recently devoted to Li2FeSiO4 structures, due in part to reasons of safety and cost. The structure of Li2FeSiO4 has been a focus of a number of recent studies owing to its rich display of polymorphism [494][495][496][497][498][499], where a number of different polymorphs, designated as βI, βII, γ0, γII and γs (see Fig. 35), have been identified and account for an experimental variation in the electrochemical performance of Li2FeSiO4 cathodes [498][499][500].…”

Section: Transition Metal Silicates (Li2msio4)mentioning

confidence: 99%

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Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

et al. 2013

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Access to the full text of the published version may require a subscription. Rights © Tsinghua University Press and Springer-Verlag Berlin ABSTRACTThe performance of the lithium-ion cell is heavily dependent on the ability of the host electrodes to accommodate and release Li + ions from the local structure. While the choice of electrode materials may define parameters such as cell potential and capacity, the process of intercalation may be physically limited by the rate of solid-state Li + diffusion. Increased diffusion rates in lithium-ion electrodes may be achieved through a reduction in the diffusion path, accomplished by a scaling of the respective electrode dimensions.In addition, some electrodes may undergo large volume changes associated with charging and discharging, the strain of which, may be better accommodated through nanostructuring. Failure of the host to accommodate such volume changes may lead to pulverisation of the local structure and a rapid loss of capacity. In this review article, we seek to highlight a number of significant gains in the development of nanostructured lithium-ion battery architectures (both anode and cathode), as drivers of potential next-generation electrochemical energy storage devices.

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Section: Transition Metal Silicates (Li2msio4)mentioning

confidence: 82%

Section: Transition Metal Silicates (Li2msio4)mentioning

confidence: 99%

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

et al. 2013

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“…Such DFT+U methods have been applied successfully to studies of other lithium battery materials. 52,59 3. DILUTE LI-ION AND NA-ION INTERCALATION:…”

Section: Methodsmentioning

confidence: 99%

Electrochemistry of Hollandite α-MnO₂: Li-Ion and Na-Ion Insertion and Li₂O Incorporation

2013

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MnO 2 is attracting considerable interest in the context of rechargeable batteries, supercapacitors, and Li−O 2 battery applications. This work investigates the electrochemical properties of hollandite α-MnO 2 using density functional theory with Hubbard U corrections (DFT+U). The favorable insertion sites for Li-ion and Na-ion insertion are determined, and we find good agreement with measured experimental voltages. By explicit calculation of the phonons we suggest multiple insertion sites are accessible in the dilute limit. Significant structural changes in α-(Li,Na) x MnO 2 during ion insertion are demonstrated by determining the low energy structures. The significant distortions to the unit cell and Mn coordination are likely to be active in causing the observed degradation of α-MnO 2 with cycling. The presence of Li 2 O in the structure reduces these distortions significantly and is the probable cause for the good experimental cycling stability of α-[0.143Li 2 O]-MnO 2 . However, the presence of Na 2 O is less effective in reducing the distortion of the Na-ion intercalated form. We also find a distinct change in the favored Li-ion insertion site, not identified in previous studies, for lithiation of α-Li x MnO 2 at x > 0.5. The migration barriers for both Li-ions and Na-ions increase from <0.3 eV in the dilute limit to >0.48 eV for α-(Li,Na) 0.75 MnO 2 . Finally, the electronic density of states in α-MnO 2 with the incorporation of Li 2 O has the character of a full metal, not a half metal as was suggested in previous work. This may be key to its good performance as a catalyst in Li−O 2 batteries.

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“…Motivated by renewed interest in β-MnO 2 , we performed an ab initio study of its intercalation behavior extending our recent computational work on lithium battery materials. 21,22 Of key interest is how mesoporous structuring enables intercalation into β-MnO 2 . Indeed, the rapidly growing interest in nanostructuring of many electrode materials 23,24 calls for investigation of the influence of surfaces and interfaces.…”

Section: ■ Introductionmentioning

confidence: 99%

Nanostructuring of β-MnO₂: The Important Role of Surface to Bulk Ion Migration

et al. 2013

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Manganese oxide materials are attracting considerable interest for clean energy storage applications such as rechargeable Li ion and Li−air batteries and electrochemical capacitors. The electrochemical behavior of nanostructured mesoporous β-MnO 2 is in sharp constrast to the bulk crystalline system, which can intercalate little or no lithium; this is not fully understood on the atomic scale. Here, the electrochemical properties of β-MnO 2 are investigated using density functional theory with Hubbard U corrections (DFT+U). We find good agreement between the measured experimental voltage, 3.0 V, and our calculated value of 3.2 V. We consider the pathways for lithium migration and find a small barrier of 0.17 eV for bulk β-MnO 2 , which is likely to contribute to its good performance as a lithium intercalation cathode in the mesoporous form. However, by explicit calculation of surface to bulk ion migration, we find a higher barrier of >0.6 eV for lithium insertion at the (101) surface that dominates the equilibrium morphology. This is likely to limit the practical use of bulk samples, and demonstrates the quantitative importance of surface to bulk ion migration in Li ion cathodes and supercapacitors. On the basis of the calculation of the electrostatic potential near the surface, we propose an efficient method to screen systems for the importance of surface migration effects. Such insight is valuable for the future optimization of manganese oxide nanomaterials for energy storage devices. KEYWORDS: lithium battery, surface, supercapacitor, DFT, cathode, manganese oxides ■ INTRODUCTIONEnergy storage for hybrid electric vehicles and renewable energy sources is a pressing technological challenge for which Li ion batteries and supercapacitors are key candidate systems. Due to rising future needs, there has been an intensive research effort to search for an alternative to the layered LiCoO 2 system conventionally used in rechargeable Li ion batteries. 1−4 Cobased materials pose problems due to high cost and environmental hazards upon disposal. Therefore, manganesebased oxides have been a promising class of materials for electrochemical energy storage. 5−10 β-MnO 2 has been extensively investigated as a cathode for rechargeable Li ion cells, but early work showed that bulk samples did not permit significant Li ion intercalation. 7,10,11 Initial work on β-MnO 2 supercapacitors 12 also indicated lower capacitance than for other polymorphs such as hollandite MnO 2 . Yet recent investigations have reinvigorated interest in the material. Mesoporous 10,13,14 and needle-like nanostructured 15,16 β-MnO 2 have been shown to allow good intercalation of Li ions. Both pore size and wall thickness of the mesoporous structures have been demonstrated to affect the rate capability. 9 The mesoporous β-MnO 2 cell has a capacity 10 of 284 mAh/g and good cycling stability. Recent studies of kinetics using ac impedance measurements 17 have demonstrated increased Li ion diffusion in nanosized materials. Additionally, β-MnO 2 has sho...

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Insights into Changes in Voltage and Structure of Li₂FeSiO₄ Polymorphs for Lithium-Ion Batteries

Cited by 133 publications

References 37 publications

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

Electrochemistry of Hollandite α-MnO₂: Li-Ion and Na-Ion Insertion and Li₂O Incorporation

Nanostructuring of β-MnO₂: The Important Role of Surface to Bulk Ion Migration

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Insights into Changes in Voltage and Structure of Li2FeSiO4 Polymorphs for Lithium-Ion Batteries

Cited by 133 publications

References 37 publications

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

Electrochemistry of Hollandite α-MnO2: Li-Ion and Na-Ion Insertion and Li2O Incorporation

Nanostructuring of β-MnO2: The Important Role of Surface to Bulk Ion Migration

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Insights into Changes in Voltage and Structure of Li₂FeSiO₄ Polymorphs for Lithium-Ion Batteries

Electrochemistry of Hollandite α-MnO₂: Li-Ion and Na-Ion Insertion and Li₂O Incorporation

Nanostructuring of β-MnO₂: The Important Role of Surface to Bulk Ion Migration