Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO<sub>4</sub>and LiMnPO<sub>4</sub>

Shi, Jianjian; Wang, Zhiguo; Fu, Yong Qing

doi:10.1088/0022-3727/49/50/505601

Cited by 15 publications

(14 citation statements)

References 57 publications

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“…As shown, the energy barriers between three minimum sites are 0.42 and 0.41 eV, respectively. The low-energy barrier of Li + diffusion from DFT is comparable to the reported values for LiMnPO 4 (0.60 eV), 49 Bi 2 M o O 6 (0.40 eV), 50 Bi 2 S 3 (0.57 eV), 51 and LiFe-PO 4 , 49 and it indicates a fast rate of Li + diffusion. To confirm the coupling between P doped CN and FeP, we calculate the charge difference of FeP on P doped CN, it is found that the coupling is very localized to the interface.…”

Section: Resultssupporting

confidence: 83%

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

et al. 2020

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Conversion-type transition-metal phosphide anode materials with high theoretical capacity usually suffer from low-rate capability and severe capacity decay, which are mainly caused by their inferior electronic conductivities and large volumetric variations together with the poor reversibility of discharge product (Li 3 P), impeding their practical applications. Herein, guided by density functional theory calculations, these obstacles are simultaneously mitigated by confining amorphous FeP nanoparticles into ultrathin 3D interconnected P-doped porous carbon nanosheets (denoted as FeP@CNs) via a facile approach, forming an intriguing 3D flake-CNs-like configuration. As an anode for lithium-ion batteries (LIBs), the resulting FeP@CNs electrode not only reaches a high reversible capacity (837 mA h g −1 after 300 cycles at 0.2 A g −1 ) and an exceptional rate capability (403 mA h g −1 at 16 A g −1 ) but also exhibits extraordinary durability (2500 cycles, 563 mA h g −1 at 4 A g −1 , 98% capacity retention). By combining DFT calculations, in situ transmission electron microscopy, and a suite of ex situ microscopic and spectroscopic techniques, we show that the superior performances of FeP@CNs anode originate from its prominent structural and compositional merits, which render fast electron/ion-transport kinetics and abundant active sites (amorphous FeP nanoparticles and structural defects in P-doped CNs) for charge storage, promote the reversibility of conversion reactions, and buffer the volume variations while preventing pulverization/aggregation of FeP during cycling, thus enabling a high rate and highly durable lithium storage. Furthermore, a full cell composed of the prelithiated FeP@CNs anode and commercial LiFePO 4 cathode exhibits impressive rate performance while maintaining superior cycling stability. This work fundamentally and experimentally presents a facile and effective structural engineering strategy for markedly improving the performance of conversion-type anodes for advanced LIBs.

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Section: Resultssupporting

confidence: 83%

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

et al. 2020

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“…From DFT calculations, the lowest energy barrier from the initial to the final state is 0.57 eV, whereas the energy barriers for the other two paths are 1.22 eV (Supplementary Figure S17), indicating that Li mainly diffuses through the channels along the b-axis or the (Bi 4 S 6 ) n moiety direction of the Bi 2 S 3 crystal. The low-energy barrier of Li diffusion from DFT is comparable to the reported values for LiMnPO 4 (0.60 eV), 42 bulk Bi 2 MoO 6 (∼0.40 eV), 43 and LiFePO 4 (0.48 eV), 42 and it is also consistent with the fast rate of initial Li intercalation. The high diffusivity can be related to the weak van der Waals (vdW) interactions between (Bi 4 S 6 ) n moieties in the Bi 2 S 3 crystal.…”

Section: T H I S C O N T E N T Isupporting

confidence: 86%

Mechanistic Origin of the High Performance of Yolk@Shell Bi₂S₃@N-Doped Carbon Nanowire Electrodes

et al. 2018

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High-performance lithium-ion batteries are commonly built with heterogeneous composite electrodes that combine multiple active components for serving various electrochemical and structural functions. Engineering these heterogeneous composite electrodes toward drastically improved battery performance is hinged on a fundamental understanding of the mechanisms of multiple active components and their synergy or trade-off effects. Herein, we report a rational design, fabrication, and understanding of yolk@shell Bi 2 S 3 @N-doped mesoporous carbon (C) composite anode, consisting of a Bi 2 S 3 nanowire (NW) core within a hollow space surrounded by a thin shell of N-doped mesoporous C. This composite anode exhibits desirable rate performance and long cycle stability (700 cycles, 501 mAhg −1 at 1.0 Ag −1 , 85% capacity retention). By in situ transmission electron microscopy (TEM), X-ray diffraction, and NMR experiments and computational modeling, we elucidate the dominant mechanisms of the phase transformation, structural evolution, and lithiation kinetics of the Bi 2 S 3 NWs anode. Our combined in situ TEM experiments and finite element simulations reveal that the hollow space between the Bi 2 S 3 NWs core and carbon shell can effectively accommodate the lithiation-induced expansion of Bi 2 S 3 NWs without cracking C shells. This work demonstrates an effective strategy of engineering the yolk@shell-architectured anodes and also sheds light onto harnessing the complex multistep reactions in metal sulfides to enable high-performance lithium-ion batteries.

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“…For Olivine LiFePO 4 , the Li + diffusion channel along the (010) direction is the most favorable. 92 From nudged elastic band (NEB) calculations, E diff is predicted to be 0.55 eV along the 010 direction, in good agreement with the previous reports of 0.6 eV using MD with GGA function 93 and 0.45 eV using DFT with LDA. The D Li also can be estimated by eq 3.…”

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confidence: 85%

First Atomic-Scale Insight into Degradation in Lithium Iron Phosphate Cathodes by Transmission Electron Microscopy

Jiang

et al. 2020

J. Phys. Chem. Lett.

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The capacity-voltage fade phenomenon in lithium iron phosphate (LiFePO4) lithium ion battery cathodes is not understood. We provide its first atomic-scale description, employing advanced transmission electron microscopy combined with electroanalysis and first-principles simulations. Cycling causes near-surface (∼30 nm) amorphization of the Olivine crystal structure, with isolated amorphous regions also being present deeper in the bulk crystal. Within this amorphous shell, some of the Fe2+ is transformed into Fe3+. Simulations predict that amorphization significantly impedes ion diffusion in LiFePO4 and even more severely in FePO4. The most significant barrier for ion transfer will be in the partially delithiated state due to the presence of FePO4, resulting in the inability to extract the remaining Li+ and the observed capacity fade. The pyrrole coating suppresses the dissolution of Fe and allows for extended retention of the Olivine structure. It also reduces the level of crossover of iron to the metal anode and stabilizes its solid electrolyte interphase, thus also contributing to the half-cell cycling stability.

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Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO₄and LiMnPO₄

Cited by 15 publications

References 57 publications

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

Mechanistic Origin of the High Performance of Yolk@Shell Bi₂S₃@N-Doped Carbon Nanowire Electrodes

First Atomic-Scale Insight into Degradation in Lithium Iron Phosphate Cathodes by Transmission Electron Microscopy

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Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO4and LiMnPO4

Cited by 15 publications

References 57 publications

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets

Mechanistic Origin of the High Performance of Yolk@Shell Bi2S3@N-Doped Carbon Nanowire Electrodes

First Atomic-Scale Insight into Degradation in Lithium Iron Phosphate Cathodes by Transmission Electron Microscopy

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Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO₄and LiMnPO₄

Mechanistic Origin of the High Performance of Yolk@Shell Bi₂S₃@N-Doped Carbon Nanowire Electrodes