Improvement of Hard Carbon Electrode Performance by Manipulating SEI Formation at High Charging Rates

Rangom, Yverick; Gaddam, Rohit Ranganathan; Duignan, Timothy T.; Xin, Zhao

doi:10.1021/acsami.9b07449

Cited by 48 publications

(39 citation statements)

References 60 publications

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“…Due to the formation of the SEI film, the half arc of the intermediate frequency region at 1.35 V becomes larger. The diameter of the semicircle decreases with the discharge process, indicating that the charge‐transfer resistance (Rct) gradually reduced, and the solid‐state diffusion of Li + in the active mAterials increased, which is consistent with the data in Table 1 [36] . In the EIS curves of TiCN‐5 mol anode (Figure 5f), the Z W (Warburg impedance)corresponds to the sloping line in the low frequency region, which is related to the Li + diffusion process.…”

Section: Resultssupporting

confidence: 87%

“…The diameter of the semicircle decreases with the discharge process, indicating that the charge-transfer resistance (Rct) gradually reduced, and the solid-state diffusion of Li + in the active mAterials increased, which is consistent with the data in Table 1. [36] In the EIS curves of TiCN-5 mol anode (Figure 5f), the Z W (Warburg impedance) corresponds to the sloping line in the low frequency region, which is related to the Li + diffusion process. The values of D Li + (diffusion coefficient of Li + ) can be calculated via the following equation [37]…”

Section: Resultsmentioning

confidence: 98%

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Tremella‐shaped TiCN Nanosheets as Anode mAterials of Lithium‐Ion Batteries

et al. 2020

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Transition metal carbides and nitrides have attracted more and more attention as excellent mAterials in the field of electrochemical energy storage. Here, we have taken a different approach to synthesize tremella-like unique titanium carbonitride (TiCN) nanosheets by hydrothermal method and high temperature solid phase sintering. Through microscopic characterization, the final products are gathered together in the form of nanosheets or ribbons like individual petals, which creates mAny ion transports channels and voids. In addition, two different products were prepared by changing the basic conditions of the precursor. After comparing the microstructures of the two groups of products and their precursors, TiCN-5 mol was mAinly studied. In terms of electrochemical performance, TiCN-5 mol nanosheets possess higher reversible specific capacity (476mAhg À 1 after 80 cycles) and excellent coulombic efficiency (98.5 % after 80 cycles) and superior rate performance up to 5000 mAg À 1 (100 % of its capacity at 100 mAg À 1 rate) compared to TiCN-10 mol. The enhanced electrochemical performance is primarily due to the high specific surface area and low ion diffusion barrier of the TiCN nanosheets, which provides high ion electrical conductivity and plays an important role in reducing large volume expansion during prolonged cycling.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 98%

Tremella‐shaped TiCN Nanosheets as Anode mAterials of Lithium‐Ion Batteries

et al. 2020

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“…Several prior investigations with anode materials (primarily graphite) have related formation current densities to the SEI composition and structure in particle-based electrodes. [29][30][31][32][33] These studies consistently show that denser SEI forms at low current density. However, the observations to date are somewhat scattered in that cells with formation cycles at lower current density do not necessarily show less capacity loss.…”

Section: Capacity Measurementsmentioning

confidence: 79%

Optimum Particle Size in Silicon Electrodes Dictated by Chemomechanical Deformation of the SEI

Jin

Guo

Xiao

et al. 2021

Adv Funct Materials

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Nanostructured alloy‐forming anode materials can resist fracture that is caused by extreme volume changes during cycling. However, the higher surface area per unit mass in nanomaterials increases exposure to the electrolyte reduction reactions that form a solid electrolyte interphase (SEI), which implies that capacity loss will increase as particle size decreases. This hypothesis is investigated with composite electrodes using different silicon nanoparticle sizes, and the expected particle size effect is not observed. Instead, there is an optimum particle size where capacity loss per volume is minimized. Finite element modeling demonstrates that the mechanical deformation of the SEI varies significantly with the silicon particle size. Smaller particles lead to the decrease of the tensile hoop strains in the outer portion of the SEI and simultaneously make the overall elastic strains in the inner portion more compressive. These results suggest that the SEI on smaller particles is more resistant to mechanical degradation, even though the higher specific surface areas increase initial SEI formation. The trade‐off between these effects leads to the observed optimum particle size.

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“…The irreversible reactions from NaPF 6 salt and carbonate solvents both occurred in the same narrow voltage range, which might generate loose and multi-components mixed SEI layer structures with poor protection effect for HC. [14,18] Therefore, the Na + -solvent-PF 6 − solvates in electrolytes could be used to engineer the structures and chemistry of SEI layer (will be further discussed later), furthermore, modify the performance of HC anodes for Na-ion batteries.…”

Section: Resultsmentioning

confidence: 99%

Engineering Solid Electrolyte Interface at Nano‐Scale for High‐Performance Hard Carbon in Sodium‐Ion Batteries

Cai

et al. 2021

Adv Funct Materials

145

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Engineering the structure and chemistry of solid electrolyte interface (SEI) on electrode materials is crucial for rechargeable batteries. Using hard carbon (HC) as a platform material, a correlation between Na + storage performance, and the properties of SEI is comprehensively explored. It is found that a "good" SEI layer on HC may not be directly associated with certain kinds of SEI components, such as NaF and Na 2 O. Whereas, arranging nano SEI components with refined structures constructs the foundation of "good" SEI that enables fast Na + storage and interface stability of HC in Na-ion batteries. A layer-by-layer SEI on HC with inorganic-rich inner layer and tolerant organic-rich outer flexible layer can facilitate excellent rate and cycling life. Besides, SEI layer as the gate for Na + from electrolyte to HC electrode can modulate interfacial crystallographic structures of HC with pillar-solvent that function as "pseudo-SEI" for fast and stable Na + storage in optimal 1 m NaPF 6 -TEGDME electrolytes. Such a layer-by-layer SEI combined with a "pseudo-SEI" layer for HC enables an outstanding rate of 192 mAh g −1 at 2 C and stable cycling over 1100 cycles at 0.5 C. This study provides valuable guidance to improve the electrochemical performance of electrode materials through regulation of SEI in optimal electrolytes.

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Improvement of Hard Carbon Electrode Performance by Manipulating SEI Formation at High Charging Rates

Cited by 48 publications

References 60 publications

Tremella‐shaped TiCN Nanosheets as Anode mAterials of Lithium‐Ion Batteries

Tremella‐shaped TiCN Nanosheets as Anode mAterials of Lithium‐Ion Batteries

Optimum Particle Size in Silicon Electrodes Dictated by Chemomechanical Deformation of the SEI

Engineering Solid Electrolyte Interface at Nano‐Scale for High‐Performance Hard Carbon in Sodium‐Ion Batteries

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